mm,memory_hotplug: allocate memmap from the added memory range

[linux.git] / fs / ext4 / xattr.c

// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/ext4/xattr.c
 *
 * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
 *
 * Fix by Harrison Xing <[email protected]>.
 * Ext4 code with a lot of help from Eric Jarman <[email protected]>.
 * Extended attributes for symlinks and special files added per
 *  suggestion of Luka Renko <[email protected]>.
 * xattr consolidation Copyright (c) 2004 James Morris <[email protected]>,
 *  Red Hat Inc.
 * ea-in-inode support by Alex Tomas <[email protected]> aka bzzz
 *  and Andreas Gruenbacher <[email protected]>.
 */

/*
 * Extended attributes are stored directly in inodes (on file systems with
 * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
 * field contains the block number if an inode uses an additional block. All
 * attributes must fit in the inode and one additional block. Blocks that
 * contain the identical set of attributes may be shared among several inodes.
 * Identical blocks are detected by keeping a cache of blocks that have
 * recently been accessed.
 *
 * The attributes in inodes and on blocks have a different header; the entries
 * are stored in the same format:
 *
 *   +------------------+
 *   | header           |
 *   | entry 1          | |
 *   | entry 2          | | growing downwards
 *   | entry 3          | v
 *   | four null bytes  |
 *   | . . .            |
 *   | value 1          | ^
 *   | value 3          | | growing upwards
 *   | value 2          | |
 *   +------------------+
 *
 * The header is followed by multiple entry descriptors. In disk blocks, the
 * entry descriptors are kept sorted. In inodes, they are unsorted. The
 * attribute values are aligned to the end of the block in no specific order.
 *
 * Locking strategy
 * ----------------
 * EXT4_I(inode)->i_file_acl is protected by EXT4_I(inode)->xattr_sem.
 * EA blocks are only changed if they are exclusive to an inode, so
 * holding xattr_sem also means that nothing but the EA block's reference
 * count can change. Multiple writers to the same block are synchronized
 * by the buffer lock.
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/mbcache.h>
#include <linux/quotaops.h>
#include <linux/iversion.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"
#include "acl.h"

#ifdef EXT4_XATTR_DEBUG
# define ea_idebug(inode, fmt, ...)                                     \
        printk(KERN_DEBUG "inode %s:%lu: " fmt "\n",                    \
               inode->i_sb->s_id, inode->i_ino, ##__VA_ARGS__)
# define ea_bdebug(bh, fmt, ...)                                        \
        printk(KERN_DEBUG "block %pg:%lu: " fmt "\n",                   \
               bh->b_bdev, (unsigned long)bh->b_blocknr, ##__VA_ARGS__)
#else
# define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
# define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
#endif

static void ext4_xattr_block_cache_insert(struct mb_cache *,
                                          struct buffer_head *);
static struct buffer_head *
ext4_xattr_block_cache_find(struct inode *, struct ext4_xattr_header *,
                            struct mb_cache_entry **);
static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
                                    size_t value_count);
static void ext4_xattr_rehash(struct ext4_xattr_header *);

static const struct xattr_handler * const ext4_xattr_handler_map[] = {
        [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
#ifdef CONFIG_EXT4_FS_POSIX_ACL
        [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
        [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
#endif
        [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
#ifdef CONFIG_EXT4_FS_SECURITY
        [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
#endif
        [EXT4_XATTR_INDEX_HURD]              = &ext4_xattr_hurd_handler,
};

const struct xattr_handler *ext4_xattr_handlers[] = {
        &ext4_xattr_user_handler,
        &ext4_xattr_trusted_handler,
#ifdef CONFIG_EXT4_FS_POSIX_ACL
        &posix_acl_access_xattr_handler,
        &posix_acl_default_xattr_handler,
#endif
#ifdef CONFIG_EXT4_FS_SECURITY
        &ext4_xattr_security_handler,
#endif
        &ext4_xattr_hurd_handler,
        NULL
};

#define EA_BLOCK_CACHE(inode)   (((struct ext4_sb_info *) \
                                inode->i_sb->s_fs_info)->s_ea_block_cache)

#define EA_INODE_CACHE(inode)   (((struct ext4_sb_info *) \
                                inode->i_sb->s_fs_info)->s_ea_inode_cache)

static int
ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
                        struct inode *inode);

#ifdef CONFIG_LOCKDEP
void ext4_xattr_inode_set_class(struct inode *ea_inode)
{
        lockdep_set_subclass(&ea_inode->i_rwsem, 1);
}
#endif

static __le32 ext4_xattr_block_csum(struct inode *inode,
                                    sector_t block_nr,
                                    struct ext4_xattr_header *hdr)
{
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        __u32 csum;
        __le64 dsk_block_nr = cpu_to_le64(block_nr);
        __u32 dummy_csum = 0;
        int offset = offsetof(struct ext4_xattr_header, h_checksum);

        csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
                           sizeof(dsk_block_nr));
        csum = ext4_chksum(sbi, csum, (__u8 *)hdr, offset);
        csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
        offset += sizeof(dummy_csum);
        csum = ext4_chksum(sbi, csum, (__u8 *)hdr + offset,
                           EXT4_BLOCK_SIZE(inode->i_sb) - offset);

        return cpu_to_le32(csum);
}

static int ext4_xattr_block_csum_verify(struct inode *inode,
                                        struct buffer_head *bh)
{
        struct ext4_xattr_header *hdr = BHDR(bh);
        int ret = 1;

        if (ext4_has_metadata_csum(inode->i_sb)) {
                lock_buffer(bh);
                ret = (hdr->h_checksum == ext4_xattr_block_csum(inode,
                                                        bh->b_blocknr, hdr));
                unlock_buffer(bh);
        }
        return ret;
}

static void ext4_xattr_block_csum_set(struct inode *inode,
                                      struct buffer_head *bh)
{
        if (ext4_has_metadata_csum(inode->i_sb))
                BHDR(bh)->h_checksum = ext4_xattr_block_csum(inode,
                                                bh->b_blocknr, BHDR(bh));
}

static inline const struct xattr_handler *
ext4_xattr_handler(int name_index)
{
        const struct xattr_handler *handler = NULL;

        if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
                handler = ext4_xattr_handler_map[name_index];
        return handler;
}

static int
ext4_xattr_check_entries(struct ext4_xattr_entry *entry, void *end,
                         void *value_start)
{
        struct ext4_xattr_entry *e = entry;

        /* Find the end of the names list */
        while (!IS_LAST_ENTRY(e)) {
                struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
                if ((void *)next >= end)
                        return -EFSCORRUPTED;
                if (strnlen(e->e_name, e->e_name_len) != e->e_name_len)
                        return -EFSCORRUPTED;
                e = next;
        }

        /* Check the values */
        while (!IS_LAST_ENTRY(entry)) {
                u32 size = le32_to_cpu(entry->e_value_size);

                if (size > EXT4_XATTR_SIZE_MAX)
                        return -EFSCORRUPTED;

                if (size != 0 && entry->e_value_inum == 0) {
                        u16 offs = le16_to_cpu(entry->e_value_offs);
                        void *value;

                        /*
                         * The value cannot overlap the names, and the value
                         * with padding cannot extend beyond 'end'.  Check both
                         * the padded and unpadded sizes, since the size may
                         * overflow to 0 when adding padding.
                         */
                        if (offs > end - value_start)
                                return -EFSCORRUPTED;
                        value = value_start + offs;
                        if (value < (void *)e + sizeof(u32) ||
                            size > end - value ||
                            EXT4_XATTR_SIZE(size) > end - value)
                                return -EFSCORRUPTED;
                }
                entry = EXT4_XATTR_NEXT(entry);
        }

        return 0;
}

static inline int
__ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
                         const char *function, unsigned int line)
{
        int error = -EFSCORRUPTED;

        if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
            BHDR(bh)->h_blocks != cpu_to_le32(1))
                goto errout;
        if (buffer_verified(bh))
                return 0;

        error = -EFSBADCRC;
        if (!ext4_xattr_block_csum_verify(inode, bh))
                goto errout;
        error = ext4_xattr_check_entries(BFIRST(bh), bh->b_data + bh->b_size,
                                         bh->b_data);
errout:
        if (error)
                __ext4_error_inode(inode, function, line, 0, -error,
                                   "corrupted xattr block %llu",
                                   (unsigned long long) bh->b_blocknr);
        else
                set_buffer_verified(bh);
        return error;
}

#define ext4_xattr_check_block(inode, bh) \
        __ext4_xattr_check_block((inode), (bh),  __func__, __LINE__)


static int
__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
                         void *end, const char *function, unsigned int line)
{
        int error = -EFSCORRUPTED;

        if (end - (void *)header < sizeof(*header) + sizeof(u32) ||
            (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)))
                goto errout;
        error = ext4_xattr_check_entries(IFIRST(header), end, IFIRST(header));
errout:
        if (error)
                __ext4_error_inode(inode, function, line, 0, -error,
                                   "corrupted in-inode xattr");
        return error;
}

#define xattr_check_inode(inode, header, end) \
        __xattr_check_inode((inode), (header), (end), __func__, __LINE__)

static int
xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry,
                 void *end, int name_index, const char *name, int sorted)
{
        struct ext4_xattr_entry *entry, *next;
        size_t name_len;
        int cmp = 1;

        if (name == NULL)
                return -EINVAL;
        name_len = strlen(name);
        for (entry = *pentry; !IS_LAST_ENTRY(entry); entry = next) {
                next = EXT4_XATTR_NEXT(entry);
                if ((void *) next >= end) {
                        EXT4_ERROR_INODE(inode, "corrupted xattr entries");
                        return -EFSCORRUPTED;
                }
                cmp = name_index - entry->e_name_index;
                if (!cmp)
                        cmp = name_len - entry->e_name_len;
                if (!cmp)
                        cmp = memcmp(name, entry->e_name, name_len);
                if (cmp <= 0 && (sorted || cmp == 0))
                        break;
        }
        *pentry = entry;
        return cmp ? -ENODATA : 0;
}

static u32
ext4_xattr_inode_hash(struct ext4_sb_info *sbi, const void *buffer, size_t size)
{
        return ext4_chksum(sbi, sbi->s_csum_seed, buffer, size);
}

static u64 ext4_xattr_inode_get_ref(struct inode *ea_inode)
{
        return ((u64)ea_inode->i_ctime.tv_sec << 32) |
                (u32) inode_peek_iversion_raw(ea_inode);
}

static void ext4_xattr_inode_set_ref(struct inode *ea_inode, u64 ref_count)
{
        ea_inode->i_ctime.tv_sec = (u32)(ref_count >> 32);
        inode_set_iversion_raw(ea_inode, ref_count & 0xffffffff);
}

static u32 ext4_xattr_inode_get_hash(struct inode *ea_inode)
{
        return (u32)ea_inode->i_atime.tv_sec;
}

static void ext4_xattr_inode_set_hash(struct inode *ea_inode, u32 hash)
{
        ea_inode->i_atime.tv_sec = hash;
}

/*
 * Read the EA value from an inode.
 */
static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
{
        int blocksize = 1 << ea_inode->i_blkbits;
        int bh_count = (size + blocksize - 1) >> ea_inode->i_blkbits;
        int tail_size = (size % blocksize) ?: blocksize;
        struct buffer_head *bhs_inline[8];
        struct buffer_head **bhs = bhs_inline;
        int i, ret;

        if (bh_count > ARRAY_SIZE(bhs_inline)) {
                bhs = kmalloc_array(bh_count, sizeof(*bhs), GFP_NOFS);
                if (!bhs)
                        return -ENOMEM;
        }

        ret = ext4_bread_batch(ea_inode, 0 /* block */, bh_count,
                               true /* wait */, bhs);
        if (ret)
                goto free_bhs;

        for (i = 0; i < bh_count; i++) {
                /* There shouldn't be any holes in ea_inode. */
                if (!bhs[i]) {
                        ret = -EFSCORRUPTED;
                        goto put_bhs;
                }
                memcpy((char *)buf + blocksize * i, bhs[i]->b_data,
                       i < bh_count - 1 ? blocksize : tail_size);
        }
        ret = 0;
put_bhs:
        for (i = 0; i < bh_count; i++)
                brelse(bhs[i]);
free_bhs:
        if (bhs != bhs_inline)
                kfree(bhs);
        return ret;
}

#define EXT4_XATTR_INODE_GET_PARENT(inode) ((__u32)(inode)->i_mtime.tv_sec)

static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
                                 u32 ea_inode_hash, struct inode **ea_inode)
{
        struct inode *inode;
        int err;

        inode = ext4_iget(parent->i_sb, ea_ino, EXT4_IGET_NORMAL);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                ext4_error(parent->i_sb,
                           "error while reading EA inode %lu err=%d", ea_ino,
                           err);
                return err;
        }

        if (is_bad_inode(inode)) {
                ext4_error(parent->i_sb,
                           "error while reading EA inode %lu is_bad_inode",
                           ea_ino);
                err = -EIO;
                goto error;
        }

        if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
                ext4_error(parent->i_sb,
                           "EA inode %lu does not have EXT4_EA_INODE_FL flag",
                            ea_ino);
                err = -EINVAL;
                goto error;
        }

        ext4_xattr_inode_set_class(inode);

        /*
         * Check whether this is an old Lustre-style xattr inode. Lustre
         * implementation does not have hash validation, rather it has a
         * backpointer from ea_inode to the parent inode.
         */
        if (ea_inode_hash != ext4_xattr_inode_get_hash(inode) &&
            EXT4_XATTR_INODE_GET_PARENT(inode) == parent->i_ino &&
            inode->i_generation == parent->i_generation) {
                ext4_set_inode_state(inode, EXT4_STATE_LUSTRE_EA_INODE);
                ext4_xattr_inode_set_ref(inode, 1);
        } else {
                inode_lock(inode);
                inode->i_flags |= S_NOQUOTA;
                inode_unlock(inode);
        }

        *ea_inode = inode;
        return 0;
error:
        iput(inode);
        return err;
}

static int
ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
                               struct ext4_xattr_entry *entry, void *buffer,
                               size_t size)
{
        u32 hash;

        /* Verify stored hash matches calculated hash. */
        hash = ext4_xattr_inode_hash(EXT4_SB(ea_inode->i_sb), buffer, size);
        if (hash != ext4_xattr_inode_get_hash(ea_inode))
                return -EFSCORRUPTED;

        if (entry) {
                __le32 e_hash, tmp_data;

                /* Verify entry hash. */
                tmp_data = cpu_to_le32(hash);
                e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len,
                                               &tmp_data, 1);
                if (e_hash != entry->e_hash)
                        return -EFSCORRUPTED;
        }
        return 0;
}

/*
 * Read xattr value from the EA inode.
 */
static int
ext4_xattr_inode_get(struct inode *inode, struct ext4_xattr_entry *entry,
                     void *buffer, size_t size)
{
        struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
        struct inode *ea_inode;
        int err;

        err = ext4_xattr_inode_iget(inode, le32_to_cpu(entry->e_value_inum),
                                    le32_to_cpu(entry->e_hash), &ea_inode);
        if (err) {
                ea_inode = NULL;
                goto out;
        }

        if (i_size_read(ea_inode) != size) {
                ext4_warning_inode(ea_inode,
                                   "ea_inode file size=%llu entry size=%zu",
                                   i_size_read(ea_inode), size);
                err = -EFSCORRUPTED;
                goto out;
        }

        err = ext4_xattr_inode_read(ea_inode, buffer, size);
        if (err)
                goto out;

        if (!ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE)) {
                err = ext4_xattr_inode_verify_hashes(ea_inode, entry, buffer,
                                                     size);
                if (err) {
                        ext4_warning_inode(ea_inode,
                                           "EA inode hash validation failed");
                        goto out;
                }

                if (ea_inode_cache)
                        mb_cache_entry_create(ea_inode_cache, GFP_NOFS,
                                        ext4_xattr_inode_get_hash(ea_inode),
                                        ea_inode->i_ino, true /* reusable */);
        }
out:
        iput(ea_inode);
        return err;
}

static int
ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
                     void *buffer, size_t buffer_size)
{
        struct buffer_head *bh = NULL;
        struct ext4_xattr_entry *entry;
        size_t size;
        void *end;
        int error;
        struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);

        ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
                  name_index, name, buffer, (long)buffer_size);

        if (!EXT4_I(inode)->i_file_acl)
                return -ENODATA;
        ea_idebug(inode, "reading block %llu",
                  (unsigned long long)EXT4_I(inode)->i_file_acl);
        bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
        if (IS_ERR(bh))
                return PTR_ERR(bh);
        ea_bdebug(bh, "b_count=%d, refcount=%d",
                atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
        error = ext4_xattr_check_block(inode, bh);
        if (error)
                goto cleanup;
        ext4_xattr_block_cache_insert(ea_block_cache, bh);
        entry = BFIRST(bh);
        end = bh->b_data + bh->b_size;
        error = xattr_find_entry(inode, &entry, end, name_index, name, 1);
        if (error)
                goto cleanup;
        size = le32_to_cpu(entry->e_value_size);
        error = -ERANGE;
        if (unlikely(size > EXT4_XATTR_SIZE_MAX))
                goto cleanup;
        if (buffer) {
                if (size > buffer_size)
                        goto cleanup;
                if (entry->e_value_inum) {
                        error = ext4_xattr_inode_get(inode, entry, buffer,
                                                     size);
                        if (error)
                                goto cleanup;
                } else {
                        u16 offset = le16_to_cpu(entry->e_value_offs);
                        void *p = bh->b_data + offset;

                        if (unlikely(p + size > end))
                                goto cleanup;
                        memcpy(buffer, p, size);
                }
        }
        error = size;

cleanup:
        brelse(bh);
        return error;
}

int
ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
                     void *buffer, size_t buffer_size)
{
        struct ext4_xattr_ibody_header *header;
        struct ext4_xattr_entry *entry;
        struct ext4_inode *raw_inode;
        struct ext4_iloc iloc;
        size_t size;
        void *end;
        int error;

        if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
                return -ENODATA;
        error = ext4_get_inode_loc(inode, &iloc);
        if (error)
                return error;
        raw_inode = ext4_raw_inode(&iloc);
        header = IHDR(inode, raw_inode);
        end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
        error = xattr_check_inode(inode, header, end);
        if (error)
                goto cleanup;
        entry = IFIRST(header);
        error = xattr_find_entry(inode, &entry, end, name_index, name, 0);
        if (error)
                goto cleanup;
        size = le32_to_cpu(entry->e_value_size);
        error = -ERANGE;
        if (unlikely(size > EXT4_XATTR_SIZE_MAX))
                goto cleanup;
        if (buffer) {
                if (size > buffer_size)
                        goto cleanup;
                if (entry->e_value_inum) {
                        error = ext4_xattr_inode_get(inode, entry, buffer,
                                                     size);
                        if (error)
                                goto cleanup;
                } else {
                        u16 offset = le16_to_cpu(entry->e_value_offs);
                        void *p = (void *)IFIRST(header) + offset;

                        if (unlikely(p + size > end))
                                goto cleanup;
                        memcpy(buffer, p, size);
                }
        }
        error = size;

cleanup:
        brelse(iloc.bh);
        return error;
}

/*
 * ext4_xattr_get()
 *
 * Copy an extended attribute into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
int
ext4_xattr_get(struct inode *inode, int name_index, const char *name,
               void *buffer, size_t buffer_size)
{
        int error;

        if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
                return -EIO;

        if (strlen(name) > 255)
                return -ERANGE;

        down_read(&EXT4_I(inode)->xattr_sem);
        error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
                                     buffer_size);
        if (error == -ENODATA)
                error = ext4_xattr_block_get(inode, name_index, name, buffer,
                                             buffer_size);
        up_read(&EXT4_I(inode)->xattr_sem);
        return error;
}

static int
ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
                        char *buffer, size_t buffer_size)
{
        size_t rest = buffer_size;

        for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
                const struct xattr_handler *handler =
                        ext4_xattr_handler(entry->e_name_index);

                if (handler && (!handler->list || handler->list(dentry))) {
                        const char *prefix = handler->prefix ?: handler->name;
                        size_t prefix_len = strlen(prefix);
                        size_t size = prefix_len + entry->e_name_len + 1;

                        if (buffer) {
                                if (size > rest)
                                        return -ERANGE;
                                memcpy(buffer, prefix, prefix_len);
                                buffer += prefix_len;
                                memcpy(buffer, entry->e_name, entry->e_name_len);
                                buffer += entry->e_name_len;
                                *buffer++ = 0;
                        }
                        rest -= size;
                }
        }
        return buffer_size - rest;  /* total size */
}

static int
ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
{
        struct inode *inode = d_inode(dentry);
        struct buffer_head *bh = NULL;
        int error;

        ea_idebug(inode, "buffer=%p, buffer_size=%ld",
                  buffer, (long)buffer_size);

        if (!EXT4_I(inode)->i_file_acl)
                return 0;
        ea_idebug(inode, "reading block %llu",
                  (unsigned long long)EXT4_I(inode)->i_file_acl);
        bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
        if (IS_ERR(bh))
                return PTR_ERR(bh);
        ea_bdebug(bh, "b_count=%d, refcount=%d",
                atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
        error = ext4_xattr_check_block(inode, bh);
        if (error)
                goto cleanup;
        ext4_xattr_block_cache_insert(EA_BLOCK_CACHE(inode), bh);
        error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer,
                                        buffer_size);
cleanup:
        brelse(bh);
        return error;
}

static int
ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
{
        struct inode *inode = d_inode(dentry);
        struct ext4_xattr_ibody_header *header;
        struct ext4_inode *raw_inode;
        struct ext4_iloc iloc;
        void *end;
        int error;

        if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
                return 0;
        error = ext4_get_inode_loc(inode, &iloc);
        if (error)
                return error;
        raw_inode = ext4_raw_inode(&iloc);
        header = IHDR(inode, raw_inode);
        end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
        error = xattr_check_inode(inode, header, end);
        if (error)
                goto cleanup;
        error = ext4_xattr_list_entries(dentry, IFIRST(header),
                                        buffer, buffer_size);

cleanup:
        brelse(iloc.bh);
        return error;
}

/*
 * Inode operation listxattr()
 *
 * d_inode(dentry)->i_rwsem: don't care
 *
 * Copy a list of attribute names into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
ssize_t
ext4_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
{
        int ret, ret2;

        down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
        ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
        if (ret < 0)
                goto errout;
        if (buffer) {
                buffer += ret;
                buffer_size -= ret;
        }
        ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
        if (ret < 0)
                goto errout;
        ret += ret2;
errout:
        up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
        return ret;
}

/*
 * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 * not set, set it.
 */
static void ext4_xattr_update_super_block(handle_t *handle,
                                          struct super_block *sb)
{
        if (ext4_has_feature_xattr(sb))
                return;

        BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
        if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
                lock_buffer(EXT4_SB(sb)->s_sbh);
                ext4_set_feature_xattr(sb);
                ext4_superblock_csum_set(sb);
                unlock_buffer(EXT4_SB(sb)->s_sbh);
                ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
        }
}

int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
{
        struct ext4_iloc iloc = { .bh = NULL };
        struct buffer_head *bh = NULL;
        struct ext4_inode *raw_inode;
        struct ext4_xattr_ibody_header *header;
        struct ext4_xattr_entry *entry;
        qsize_t ea_inode_refs = 0;
        void *end;
        int ret;

        lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem);

        if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
                ret = ext4_get_inode_loc(inode, &iloc);
                if (ret)
                        goto out;
                raw_inode = ext4_raw_inode(&iloc);
                header = IHDR(inode, raw_inode);
                end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
                ret = xattr_check_inode(inode, header, end);
                if (ret)
                        goto out;

                for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
                     entry = EXT4_XATTR_NEXT(entry))
                        if (entry->e_value_inum)
                                ea_inode_refs++;
        }

        if (EXT4_I(inode)->i_file_acl) {
                bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
                if (IS_ERR(bh)) {
                        ret = PTR_ERR(bh);
                        bh = NULL;
                        goto out;
                }

                ret = ext4_xattr_check_block(inode, bh);
                if (ret)
                        goto out;

                for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
                     entry = EXT4_XATTR_NEXT(entry))
                        if (entry->e_value_inum)
                                ea_inode_refs++;
        }
        *usage = ea_inode_refs + 1;
        ret = 0;
out:
        brelse(iloc.bh);
        brelse(bh);
        return ret;
}

static inline size_t round_up_cluster(struct inode *inode, size_t length)
{
        struct super_block *sb = inode->i_sb;
        size_t cluster_size = 1 << (EXT4_SB(sb)->s_cluster_bits +
                                    inode->i_blkbits);
        size_t mask = ~(cluster_size - 1);

        return (length + cluster_size - 1) & mask;
}

static int ext4_xattr_inode_alloc_quota(struct inode *inode, size_t len)
{
        int err;

        err = dquot_alloc_inode(inode);
        if (err)
                return err;
        err = dquot_alloc_space_nodirty(inode, round_up_cluster(inode, len));
        if (err)
                dquot_free_inode(inode);
        return err;
}

static void ext4_xattr_inode_free_quota(struct inode *parent,
                                        struct inode *ea_inode,
                                        size_t len)
{
        if (ea_inode &&
            ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE))
                return;
        dquot_free_space_nodirty(parent, round_up_cluster(parent, len));
        dquot_free_inode(parent);
}

int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
                             struct buffer_head *block_bh, size_t value_len,
                             bool is_create)
{
        int credits;
        int blocks;

        /*
         * 1) Owner inode update
         * 2) Ref count update on old xattr block
         * 3) new xattr block
         * 4) block bitmap update for new xattr block
         * 5) group descriptor for new xattr block
         * 6) block bitmap update for old xattr block
         * 7) group descriptor for old block
         *
         * 6 & 7 can happen if we have two racing threads T_a and T_b
         * which are each trying to set an xattr on inodes I_a and I_b
         * which were both initially sharing an xattr block.
         */
        credits = 7;

        /* Quota updates. */
        credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(sb);

        /*
         * In case of inline data, we may push out the data to a block,
         * so we need to reserve credits for this eventuality
         */
        if (inode && ext4_has_inline_data(inode))
                credits += ext4_writepage_trans_blocks(inode) + 1;

        /* We are done if ea_inode feature is not enabled. */
        if (!ext4_has_feature_ea_inode(sb))
                return credits;

        /* New ea_inode, inode map, block bitmap, group descriptor. */
        credits += 4;

        /* Data blocks. */
        blocks = (value_len + sb->s_blocksize - 1) >> sb->s_blocksize_bits;

        /* Indirection block or one level of extent tree. */
        blocks += 1;

        /* Block bitmap and group descriptor updates for each block. */
        credits += blocks * 2;

        /* Blocks themselves. */
        credits += blocks;

        if (!is_create) {
                /* Dereference ea_inode holding old xattr value.
                 * Old ea_inode, inode map, block bitmap, group descriptor.
                 */
                credits += 4;

                /* Data blocks for old ea_inode. */
                blocks = XATTR_SIZE_MAX >> sb->s_blocksize_bits;

                /* Indirection block or one level of extent tree for old
                 * ea_inode.
                 */
                blocks += 1;

                /* Block bitmap and group descriptor updates for each block. */
                credits += blocks * 2;
        }

        /* We may need to clone the existing xattr block in which case we need
         * to increment ref counts for existing ea_inodes referenced by it.
         */
        if (block_bh) {
                struct ext4_xattr_entry *entry = BFIRST(block_bh);

                for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry))
                        if (entry->e_value_inum)
                                /* Ref count update on ea_inode. */
                                credits += 1;
        }
        return credits;
}

static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
                                       int ref_change)
{
        struct mb_cache *ea_inode_cache = EA_INODE_CACHE(ea_inode);
        struct ext4_iloc iloc;
        s64 ref_count;
        u32 hash;
        int ret;

        inode_lock(ea_inode);

        ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
        if (ret)
                goto out;

        ref_count = ext4_xattr_inode_get_ref(ea_inode);
        ref_count += ref_change;
        ext4_xattr_inode_set_ref(ea_inode, ref_count);

        if (ref_change > 0) {
                WARN_ONCE(ref_count <= 0, "EA inode %lu ref_count=%lld",
                          ea_inode->i_ino, ref_count);

                if (ref_count == 1) {
                        WARN_ONCE(ea_inode->i_nlink, "EA inode %lu i_nlink=%u",
                                  ea_inode->i_ino, ea_inode->i_nlink);

                        set_nlink(ea_inode, 1);
                        ext4_orphan_del(handle, ea_inode);

                        if (ea_inode_cache) {
                                hash = ext4_xattr_inode_get_hash(ea_inode);
                                mb_cache_entry_create(ea_inode_cache,
                                                      GFP_NOFS, hash,
                                                      ea_inode->i_ino,
                                                      true /* reusable */);
                        }
                }
        } else {
                WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld",
                          ea_inode->i_ino, ref_count);

                if (ref_count == 0) {
                        WARN_ONCE(ea_inode->i_nlink != 1,
                                  "EA inode %lu i_nlink=%u",
                                  ea_inode->i_ino, ea_inode->i_nlink);

                        clear_nlink(ea_inode);
                        ext4_orphan_add(handle, ea_inode);

                        if (ea_inode_cache) {
                                hash = ext4_xattr_inode_get_hash(ea_inode);
                                mb_cache_entry_delete(ea_inode_cache, hash,
                                                      ea_inode->i_ino);
                        }
                }
        }

        ret = ext4_mark_iloc_dirty(handle, ea_inode, &iloc);
        if (ret)
                ext4_warning_inode(ea_inode,
                                   "ext4_mark_iloc_dirty() failed ret=%d", ret);
out:
        inode_unlock(ea_inode);
        return ret;
}

static int ext4_xattr_inode_inc_ref(handle_t *handle, struct inode *ea_inode)
{
        return ext4_xattr_inode_update_ref(handle, ea_inode, 1);
}

static int ext4_xattr_inode_dec_ref(handle_t *handle, struct inode *ea_inode)
{
        return ext4_xattr_inode_update_ref(handle, ea_inode, -1);
}

static int ext4_xattr_inode_inc_ref_all(handle_t *handle, struct inode *parent,
                                        struct ext4_xattr_entry *first)
{
        struct inode *ea_inode;
        struct ext4_xattr_entry *entry;
        struct ext4_xattr_entry *failed_entry;
        unsigned int ea_ino;
        int err, saved_err;

        for (entry = first; !IS_LAST_ENTRY(entry);
             entry = EXT4_XATTR_NEXT(entry)) {
                if (!entry->e_value_inum)
                        continue;
                ea_ino = le32_to_cpu(entry->e_value_inum);
                err = ext4_xattr_inode_iget(parent, ea_ino,
                                            le32_to_cpu(entry->e_hash),
                                            &ea_inode);
                if (err)
                        goto cleanup;
                err = ext4_xattr_inode_inc_ref(handle, ea_inode);
                if (err) {
                        ext4_warning_inode(ea_inode, "inc ref error %d", err);
                        iput(ea_inode);
                        goto cleanup;
                }
                iput(ea_inode);
        }
        return 0;

cleanup:
        saved_err = err;
        failed_entry = entry;

        for (entry = first; entry != failed_entry;
             entry = EXT4_XATTR_NEXT(entry)) {
                if (!entry->e_value_inum)
                        continue;
                ea_ino = le32_to_cpu(entry->e_value_inum);
                err = ext4_xattr_inode_iget(parent, ea_ino,
                                            le32_to_cpu(entry->e_hash),
                                            &ea_inode);
                if (err) {
                        ext4_warning(parent->i_sb,
                                     "cleanup ea_ino %u iget error %d", ea_ino,
                                     err);
                        continue;
                }
                err = ext4_xattr_inode_dec_ref(handle, ea_inode);
                if (err)
                        ext4_warning_inode(ea_inode, "cleanup dec ref error %d",
                                           err);
                iput(ea_inode);
        }
        return saved_err;
}

static int ext4_xattr_restart_fn(handle_t *handle, struct inode *inode,
                        struct buffer_head *bh, bool block_csum, bool dirty)
{
        int error;

        if (bh && dirty) {
                if (block_csum)
                        ext4_xattr_block_csum_set(inode, bh);
                error = ext4_handle_dirty_metadata(handle, NULL, bh);
                if (error) {
                        ext4_warning(inode->i_sb, "Handle metadata (error %d)",
                                     error);
                        return error;
                }
        }
        return 0;
}

static void
ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
                             struct buffer_head *bh,
                             struct ext4_xattr_entry *first, bool block_csum,
                             struct ext4_xattr_inode_array **ea_inode_array,
                             int extra_credits, bool skip_quota)
{
        struct inode *ea_inode;
        struct ext4_xattr_entry *entry;
        bool dirty = false;
        unsigned int ea_ino;
        int err;
        int credits;

        /* One credit for dec ref on ea_inode, one for orphan list addition, */
        credits = 2 + extra_credits;

        for (entry = first; !IS_LAST_ENTRY(entry);
             entry = EXT4_XATTR_NEXT(entry)) {
                if (!entry->e_value_inum)
                        continue;
                ea_ino = le32_to_cpu(entry->e_value_inum);
                err = ext4_xattr_inode_iget(parent, ea_ino,
                                            le32_to_cpu(entry->e_hash),
                                            &ea_inode);
                if (err)
                        continue;

                err = ext4_expand_inode_array(ea_inode_array, ea_inode);
                if (err) {
                        ext4_warning_inode(ea_inode,
                                           "Expand inode array err=%d", err);
                        iput(ea_inode);
                        continue;
                }

                err = ext4_journal_ensure_credits_fn(handle, credits, credits,
                        ext4_free_metadata_revoke_credits(parent->i_sb, 1),
                        ext4_xattr_restart_fn(handle, parent, bh, block_csum,
                                              dirty));
                if (err < 0) {
                        ext4_warning_inode(ea_inode, "Ensure credits err=%d",
                                           err);
                        continue;
                }
                if (err > 0) {
                        err = ext4_journal_get_write_access(handle, bh);
                        if (err) {
                                ext4_warning_inode(ea_inode,
                                                "Re-get write access err=%d",
                                                err);
                                continue;
                        }
                }

                err = ext4_xattr_inode_dec_ref(handle, ea_inode);
                if (err) {
                        ext4_warning_inode(ea_inode, "ea_inode dec ref err=%d",
                                           err);
                        continue;
                }

                if (!skip_quota)
                        ext4_xattr_inode_free_quota(parent, ea_inode,
                                              le32_to_cpu(entry->e_value_size));

                /*
                 * Forget about ea_inode within the same transaction that
                 * decrements the ref count. This avoids duplicate decrements in
                 * case the rest of the work spills over to subsequent
                 * transactions.
                 */
                entry->e_value_inum = 0;
                entry->e_value_size = 0;

                dirty = true;
        }

        if (dirty) {
                /*
                 * Note that we are deliberately skipping csum calculation for
                 * the final update because we do not expect any journal
                 * restarts until xattr block is freed.
                 */

                err = ext4_handle_dirty_metadata(handle, NULL, bh);
                if (err)
                        ext4_warning_inode(parent,
                                           "handle dirty metadata err=%d", err);
        }
}

/*
 * Release the xattr block BH: If the reference count is > 1, decrement it;
 * otherwise free the block.
 */
static void
ext4_xattr_release_block(handle_t *handle, struct inode *inode,
                         struct buffer_head *bh,
                         struct ext4_xattr_inode_array **ea_inode_array,
                         int extra_credits)
{
        struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
        u32 hash, ref;
        int error = 0;

        BUFFER_TRACE(bh, "get_write_access");
        error = ext4_journal_get_write_access(handle, bh);
        if (error)
                goto out;

        lock_buffer(bh);
        hash = le32_to_cpu(BHDR(bh)->h_hash);
        ref = le32_to_cpu(BHDR(bh)->h_refcount);
        if (ref == 1) {
                ea_bdebug(bh, "refcount now=0; freeing");
                /*
                 * This must happen under buffer lock for
                 * ext4_xattr_block_set() to reliably detect freed block
                 */
                if (ea_block_cache)
                        mb_cache_entry_delete(ea_block_cache, hash,
                                              bh->b_blocknr);
                get_bh(bh);
                unlock_buffer(bh);

                if (ext4_has_feature_ea_inode(inode->i_sb))
                        ext4_xattr_inode_dec_ref_all(handle, inode, bh,
                                                     BFIRST(bh),
                                                     true /* block_csum */,
                                                     ea_inode_array,
                                                     extra_credits,
                                                     true /* skip_quota */);
                ext4_free_blocks(handle, inode, bh, 0, 1,
                                 EXT4_FREE_BLOCKS_METADATA |
                                 EXT4_FREE_BLOCKS_FORGET);
        } else {
                ref--;
                BHDR(bh)->h_refcount = cpu_to_le32(ref);
                if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
                        struct mb_cache_entry *ce;

                        if (ea_block_cache) {
                                ce = mb_cache_entry_get(ea_block_cache, hash,
                                                        bh->b_blocknr);
                                if (ce) {
                                        ce->e_reusable = 1;
                                        mb_cache_entry_put(ea_block_cache, ce);
                                }
                        }
                }

                ext4_xattr_block_csum_set(inode, bh);
                /*
                 * Beware of this ugliness: Releasing of xattr block references
                 * from different inodes can race and so we have to protect
                 * from a race where someone else frees the block (and releases
                 * its journal_head) before we are done dirtying the buffer. In
                 * nojournal mode this race is harmless and we actually cannot
                 * call ext4_handle_dirty_metadata() with locked buffer as
                 * that function can call sync_dirty_buffer() so for that case
                 * we handle the dirtying after unlocking the buffer.
                 */
                if (ext4_handle_valid(handle))
                        error = ext4_handle_dirty_metadata(handle, inode, bh);
                unlock_buffer(bh);
                if (!ext4_handle_valid(handle))
                        error = ext4_handle_dirty_metadata(handle, inode, bh);
                if (IS_SYNC(inode))
                        ext4_handle_sync(handle);
                dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
                ea_bdebug(bh, "refcount now=%d; releasing",
                          le32_to_cpu(BHDR(bh)->h_refcount));
        }
out:
        ext4_std_error(inode->i_sb, error);
        return;
}

/*
 * Find the available free space for EAs. This also returns the total number of
 * bytes used by EA entries.
 */
static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
                                    size_t *min_offs, void *base, int *total)
{
        for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
                if (!last->e_value_inum && last->e_value_size) {
                        size_t offs = le16_to_cpu(last->e_value_offs);
                        if (offs < *min_offs)
                                *min_offs = offs;
                }
                if (total)
                        *total += EXT4_XATTR_LEN(last->e_name_len);
        }
        return (*min_offs - ((void *)last - base) - sizeof(__u32));
}

/*
 * Write the value of the EA in an inode.
 */
static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
                                  const void *buf, int bufsize)
{
        struct buffer_head *bh = NULL;
        unsigned long block = 0;
        int blocksize = ea_inode->i_sb->s_blocksize;
        int max_blocks = (bufsize + blocksize - 1) >> ea_inode->i_blkbits;
        int csize, wsize = 0;
        int ret = 0, ret2 = 0;
        int retries = 0;

retry:
        while (ret >= 0 && ret < max_blocks) {
                struct ext4_map_blocks map;
                map.m_lblk = block += ret;
                map.m_len = max_blocks -= ret;

                ret = ext4_map_blocks(handle, ea_inode, &map,
                                      EXT4_GET_BLOCKS_CREATE);
                if (ret <= 0) {
                        ext4_mark_inode_dirty(handle, ea_inode);
                        if (ret == -ENOSPC &&
                            ext4_should_retry_alloc(ea_inode->i_sb, &retries)) {
                                ret = 0;
                                goto retry;
                        }
                        break;
                }
        }

        if (ret < 0)
                return ret;

        block = 0;
        while (wsize < bufsize) {
                brelse(bh);
                csize = (bufsize - wsize) > blocksize ? blocksize :
                                                                bufsize - wsize;
                bh = ext4_getblk(handle, ea_inode, block, 0);
                if (IS_ERR(bh))
                        return PTR_ERR(bh);
                if (!bh) {
                        WARN_ON_ONCE(1);
                        EXT4_ERROR_INODE(ea_inode,
                                         "ext4_getblk() return bh = NULL");
                        return -EFSCORRUPTED;
                }
                ret = ext4_journal_get_write_access(handle, bh);
                if (ret)
                        goto out;

                memcpy(bh->b_data, buf, csize);
                set_buffer_uptodate(bh);
                ext4_handle_dirty_metadata(handle, ea_inode, bh);

                buf += csize;
                wsize += csize;
                block += 1;
        }

        inode_lock(ea_inode);
        i_size_write(ea_inode, wsize);
        ext4_update_i_disksize(ea_inode, wsize);
        inode_unlock(ea_inode);

        ret2 = ext4_mark_inode_dirty(handle, ea_inode);
        if (unlikely(ret2 && !ret))
                ret = ret2;

out:
        brelse(bh);

        return ret;
}

/*
 * Create an inode to store the value of a large EA.
 */
static struct inode *ext4_xattr_inode_create(handle_t *handle,
                                             struct inode *inode, u32 hash)
{
        struct inode *ea_inode = NULL;
        uid_t owner[2] = { i_uid_read(inode), i_gid_read(inode) };
        int err;

        /*
         * Let the next inode be the goal, so we try and allocate the EA inode
         * in the same group, or nearby one.
         */
        ea_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
                                  S_IFREG | 0600, NULL, inode->i_ino + 1, owner,
                                  EXT4_EA_INODE_FL);
        if (!IS_ERR(ea_inode)) {
                ea_inode->i_op = &ext4_file_inode_operations;
                ea_inode->i_fop = &ext4_file_operations;
                ext4_set_aops(ea_inode);
                ext4_xattr_inode_set_class(ea_inode);
                unlock_new_inode(ea_inode);
                ext4_xattr_inode_set_ref(ea_inode, 1);
                ext4_xattr_inode_set_hash(ea_inode, hash);
                err = ext4_mark_inode_dirty(handle, ea_inode);
                if (!err)
                        err = ext4_inode_attach_jinode(ea_inode);
                if (err) {
                        iput(ea_inode);
                        return ERR_PTR(err);
                }

                /*
                 * Xattr inodes are shared therefore quota charging is performed
                 * at a higher level.
                 */
                dquot_free_inode(ea_inode);
                dquot_drop(ea_inode);
                inode_lock(ea_inode);
                ea_inode->i_flags |= S_NOQUOTA;
                inode_unlock(ea_inode);
        }

        return ea_inode;
}

static struct inode *
ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
                            size_t value_len, u32 hash)
{
        struct inode *ea_inode;
        struct mb_cache_entry *ce;
        struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
        void *ea_data;

        if (!ea_inode_cache)
                return NULL;

        ce = mb_cache_entry_find_first(ea_inode_cache, hash);
        if (!ce)
                return NULL;

        WARN_ON_ONCE(ext4_handle_valid(journal_current_handle()) &&
                     !(current->flags & PF_MEMALLOC_NOFS));

        ea_data = kvmalloc(value_len, GFP_KERNEL);
        if (!ea_data) {
                mb_cache_entry_put(ea_inode_cache, ce);
                return NULL;
        }

        while (ce) {
                ea_inode = ext4_iget(inode->i_sb, ce->e_value,
                                     EXT4_IGET_NORMAL);
                if (!IS_ERR(ea_inode) &&
                    !is_bad_inode(ea_inode) &&
                    (EXT4_I(ea_inode)->i_flags & EXT4_EA_INODE_FL) &&
                    i_size_read(ea_inode) == value_len &&
                    !ext4_xattr_inode_read(ea_inode, ea_data, value_len) &&
                    !ext4_xattr_inode_verify_hashes(ea_inode, NULL, ea_data,
                                                    value_len) &&
                    !memcmp(value, ea_data, value_len)) {
                        mb_cache_entry_touch(ea_inode_cache, ce);
                        mb_cache_entry_put(ea_inode_cache, ce);
                        kvfree(ea_data);
                        return ea_inode;
                }

                if (!IS_ERR(ea_inode))
                        iput(ea_inode);
                ce = mb_cache_entry_find_next(ea_inode_cache, ce);
        }
        kvfree(ea_data);
        return NULL;
}

/*
 * Add value of the EA in an inode.
 */
static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
                                          const void *value, size_t value_len,
                                          struct inode **ret_inode)
{
        struct inode *ea_inode;
        u32 hash;
        int err;

        hash = ext4_xattr_inode_hash(EXT4_SB(inode->i_sb), value, value_len);
        ea_inode = ext4_xattr_inode_cache_find(inode, value, value_len, hash);
        if (ea_inode) {
                err = ext4_xattr_inode_inc_ref(handle, ea_inode);
                if (err) {
                        iput(ea_inode);
                        return err;
                }

                *ret_inode = ea_inode;
                return 0;
        }

        /* Create an inode for the EA value */
        ea_inode = ext4_xattr_inode_create(handle, inode, hash);
        if (IS_ERR(ea_inode))
                return PTR_ERR(ea_inode);

        err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
        if (err) {
                ext4_xattr_inode_dec_ref(handle, ea_inode);
                iput(ea_inode);
                return err;
        }

        if (EA_INODE_CACHE(inode))
                mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
                                      ea_inode->i_ino, true /* reusable */);

        *ret_inode = ea_inode;
        return 0;
}

/*
 * Reserve min(block_size/8, 1024) bytes for xattr entries/names if ea_inode
 * feature is enabled.
 */
#define EXT4_XATTR_BLOCK_RESERVE(inode) min(i_blocksize(inode)/8, 1024U)

static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
                                struct ext4_xattr_search *s,
                                handle_t *handle, struct inode *inode,
                                bool is_block)
{
        struct ext4_xattr_entry *last, *next;
        struct ext4_xattr_entry *here = s->here;
        size_t min_offs = s->end - s->base, name_len = strlen(i->name);
        int in_inode = i->in_inode;
        struct inode *old_ea_inode = NULL;
        struct inode *new_ea_inode = NULL;
        size_t old_size, new_size;
        int ret;

        /* Space used by old and new values. */
        old_size = (!s->not_found && !here->e_value_inum) ?
                        EXT4_XATTR_SIZE(le32_to_cpu(here->e_value_size)) : 0;
        new_size = (i->value && !in_inode) ? EXT4_XATTR_SIZE(i->value_len) : 0;

        /*
         * Optimization for the simple case when old and new values have the
         * same padded sizes. Not applicable if external inodes are involved.
         */
        if (new_size && new_size == old_size) {
                size_t offs = le16_to_cpu(here->e_value_offs);
                void *val = s->base + offs;

                here->e_value_size = cpu_to_le32(i->value_len);
                if (i->value == EXT4_ZERO_XATTR_VALUE) {
                        memset(val, 0, new_size);
                } else {
                        memcpy(val, i->value, i->value_len);
                        /* Clear padding bytes. */
                        memset(val + i->value_len, 0, new_size - i->value_len);
                }
                goto update_hash;
        }

        /* Compute min_offs and last. */
        last = s->first;
        for (; !IS_LAST_ENTRY(last); last = next) {
                next = EXT4_XATTR_NEXT(last);
                if ((void *)next >= s->end) {
                        EXT4_ERROR_INODE(inode, "corrupted xattr entries");
                        ret = -EFSCORRUPTED;
                        goto out;
                }
                if (!last->e_value_inum && last->e_value_size) {
                        size_t offs = le16_to_cpu(last->e_value_offs);
                        if (offs < min_offs)
                                min_offs = offs;
                }
        }

        /* Check whether we have enough space. */
        if (i->value) {
                size_t free;

                free = min_offs - ((void *)last - s->base) - sizeof(__u32);
                if (!s->not_found)
                        free += EXT4_XATTR_LEN(name_len) + old_size;

                if (free < EXT4_XATTR_LEN(name_len) + new_size) {
                        ret = -ENOSPC;
                        goto out;
                }

                /*
                 * If storing the value in an external inode is an option,
                 * reserve space for xattr entries/names in the external
                 * attribute block so that a long value does not occupy the
                 * whole space and prevent futher entries being added.
                 */
                if (ext4_has_feature_ea_inode(inode->i_sb) &&
                    new_size && is_block &&
                    (min_offs + old_size - new_size) <
                                        EXT4_XATTR_BLOCK_RESERVE(inode)) {
                        ret = -ENOSPC;
                        goto out;
                }
        }

        /*
         * Getting access to old and new ea inodes is subject to failures.
         * Finish that work before doing any modifications to the xattr data.
         */
        if (!s->not_found && here->e_value_inum) {
                ret = ext4_xattr_inode_iget(inode,
                                            le32_to_cpu(here->e_value_inum),
                                            le32_to_cpu(here->e_hash),
                                            &old_ea_inode);
                if (ret) {
                        old_ea_inode = NULL;
                        goto out;
                }
        }
        if (i->value && in_inode) {
                WARN_ON_ONCE(!i->value_len);

                ret = ext4_xattr_inode_alloc_quota(inode, i->value_len);
                if (ret)
                        goto out;

                ret = ext4_xattr_inode_lookup_create(handle, inode, i->value,
                                                     i->value_len,
                                                     &new_ea_inode);
                if (ret) {
                        new_ea_inode = NULL;
                        ext4_xattr_inode_free_quota(inode, NULL, i->value_len);
                        goto out;
                }
        }

        if (old_ea_inode) {
                /* We are ready to release ref count on the old_ea_inode. */
                ret = ext4_xattr_inode_dec_ref(handle, old_ea_inode);
                if (ret) {
                        /* Release newly required ref count on new_ea_inode. */
                        if (new_ea_inode) {
                                int err;

                                err = ext4_xattr_inode_dec_ref(handle,
                                                               new_ea_inode);
                                if (err)
                                        ext4_warning_inode(new_ea_inode,
                                                  "dec ref new_ea_inode err=%d",
                                                  err);
                                ext4_xattr_inode_free_quota(inode, new_ea_inode,
                                                            i->value_len);
                        }
                        goto out;
                }

                ext4_xattr_inode_free_quota(inode, old_ea_inode,
                                            le32_to_cpu(here->e_value_size));
        }

        /* No failures allowed past this point. */

        if (!s->not_found && here->e_value_size && !here->e_value_inum) {
                /* Remove the old value. */
                void *first_val = s->base + min_offs;
                size_t offs = le16_to_cpu(here->e_value_offs);
                void *val = s->base + offs;

                memmove(first_val + old_size, first_val, val - first_val);
                memset(first_val, 0, old_size);
                min_offs += old_size;

                /* Adjust all value offsets. */
                last = s->first;
                while (!IS_LAST_ENTRY(last)) {
                        size_t o = le16_to_cpu(last->e_value_offs);

                        if (!last->e_value_inum &&
                            last->e_value_size && o < offs)
                                last->e_value_offs = cpu_to_le16(o + old_size);
                        last = EXT4_XATTR_NEXT(last);
                }
        }

        if (!i->value) {
                /* Remove old name. */
                size_t size = EXT4_XATTR_LEN(name_len);

                last = ENTRY((void *)last - size);
                memmove(here, (void *)here + size,
                        (void *)last - (void *)here + sizeof(__u32));
                memset(last, 0, size);
        } else if (s->not_found) {
                /* Insert new name. */
                size_t size = EXT4_XATTR_LEN(name_len);
                size_t rest = (void *)last - (void *)here + sizeof(__u32);

                memmove((void *)here + size, here, rest);
                memset(here, 0, size);
                here->e_name_index = i->name_index;
                here->e_name_len = name_len;
                memcpy(here->e_name, i->name, name_len);
        } else {
                /* This is an update, reset value info. */
                here->e_value_inum = 0;
                here->e_value_offs = 0;
                here->e_value_size = 0;
        }

        if (i->value) {
                /* Insert new value. */
                if (in_inode) {
                        here->e_value_inum = cpu_to_le32(new_ea_inode->i_ino);
                } else if (i->value_len) {
                        void *val = s->base + min_offs - new_size;

                        here->e_value_offs = cpu_to_le16(min_offs - new_size);
                        if (i->value == EXT4_ZERO_XATTR_VALUE) {
                                memset(val, 0, new_size);
                        } else {
                                memcpy(val, i->value, i->value_len);
                                /* Clear padding bytes. */
                                memset(val + i->value_len, 0,
                                       new_size - i->value_len);
                        }
                }
                here->e_value_size = cpu_to_le32(i->value_len);
        }

update_hash:
        if (i->value) {
                __le32 hash = 0;

                /* Entry hash calculation. */
                if (in_inode) {
                        __le32 crc32c_hash;

                        /*
                         * Feed crc32c hash instead of the raw value for entry
                         * hash calculation. This is to avoid walking
                         * potentially long value buffer again.
                         */
                        crc32c_hash = cpu_to_le32(
                                       ext4_xattr_inode_get_hash(new_ea_inode));
                        hash = ext4_xattr_hash_entry(here->e_name,
                                                     here->e_name_len,
                                                     &crc32c_hash, 1);
                } else if (is_block) {
                        __le32 *value = s->base + le16_to_cpu(
                                                        here->e_value_offs);

                        hash = ext4_xattr_hash_entry(here->e_name,
                                                     here->e_name_len, value,
                                                     new_size >> 2);
                }
                here->e_hash = hash;
        }

        if (is_block)
                ext4_xattr_rehash((struct ext4_xattr_header *)s->base);

        ret = 0;
out:
        iput(old_ea_inode);
        iput(new_ea_inode);
        return ret;
}

struct ext4_xattr_block_find {
        struct ext4_xattr_search s;
        struct buffer_head *bh;
};

static int
ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
                      struct ext4_xattr_block_find *bs)
{
        struct super_block *sb = inode->i_sb;
        int error;

        ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
                  i->name_index, i->name, i->value, (long)i->value_len);

        if (EXT4_I(inode)->i_file_acl) {
                /* The inode already has an extended attribute block. */
                bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
                if (IS_ERR(bs->bh)) {
                        error = PTR_ERR(bs->bh);
                        bs->bh = NULL;
                        return error;
                }
                ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
                        atomic_read(&(bs->bh->b_count)),
                        le32_to_cpu(BHDR(bs->bh)->h_refcount));
                error = ext4_xattr_check_block(inode, bs->bh);
                if (error)
                        return error;
                /* Find the named attribute. */
                bs->s.base = BHDR(bs->bh);
                bs->s.first = BFIRST(bs->bh);
                bs->s.end = bs->bh->b_data + bs->bh->b_size;
                bs->s.here = bs->s.first;
                error = xattr_find_entry(inode, &bs->s.here, bs->s.end,
                                         i->name_index, i->name, 1);
                if (error && error != -ENODATA)
                        return error;
                bs->s.not_found = error;
        }
        return 0;
}

static int
ext4_xattr_block_set(handle_t *handle, struct inode *inode,
                     struct ext4_xattr_info *i,
                     struct ext4_xattr_block_find *bs)
{
        struct super_block *sb = inode->i_sb;
        struct buffer_head *new_bh = NULL;
        struct ext4_xattr_search s_copy = bs->s;
        struct ext4_xattr_search *s = &s_copy;
        struct mb_cache_entry *ce = NULL;
        int error = 0;
        struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
        struct inode *ea_inode = NULL, *tmp_inode;
        size_t old_ea_inode_quota = 0;
        unsigned int ea_ino;


#define header(x) ((struct ext4_xattr_header *)(x))

        if (s->base) {
                BUFFER_TRACE(bs->bh, "get_write_access");
                error = ext4_journal_get_write_access(handle, bs->bh);
                if (error)
                        goto cleanup;
                lock_buffer(bs->bh);

                if (header(s->base)->h_refcount == cpu_to_le32(1)) {
                        __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);

                        /*
                         * This must happen under buffer lock for
                         * ext4_xattr_block_set() to reliably detect modified
                         * block
                         */
                        if (ea_block_cache)
                                mb_cache_entry_delete(ea_block_cache, hash,
                                                      bs->bh->b_blocknr);
                        ea_bdebug(bs->bh, "modifying in-place");
                        error = ext4_xattr_set_entry(i, s, handle, inode,
                                                     true /* is_block */);
                        ext4_xattr_block_csum_set(inode, bs->bh);
                        unlock_buffer(bs->bh);
                        if (error == -EFSCORRUPTED)
                                goto bad_block;
                        if (!error)
                                error = ext4_handle_dirty_metadata(handle,
                                                                   inode,
                                                                   bs->bh);
                        if (error)
                                goto cleanup;
                        goto inserted;
                } else {
                        int offset = (char *)s->here - bs->bh->b_data;

                        unlock_buffer(bs->bh);
                        ea_bdebug(bs->bh, "cloning");
                        s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
                        error = -ENOMEM;
                        if (s->base == NULL)
                                goto cleanup;
                        memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
                        s->first = ENTRY(header(s->base)+1);
                        header(s->base)->h_refcount = cpu_to_le32(1);
                        s->here = ENTRY(s->base + offset);
                        s->end = s->base + bs->bh->b_size;

                        /*
                         * If existing entry points to an xattr inode, we need
                         * to prevent ext4_xattr_set_entry() from decrementing
                         * ref count on it because the reference belongs to the
                         * original block. In this case, make the entry look
                         * like it has an empty value.
                         */
                        if (!s->not_found && s->here->e_value_inum) {
                                ea_ino = le32_to_cpu(s->here->e_value_inum);
                                error = ext4_xattr_inode_iget(inode, ea_ino,
                                              le32_to_cpu(s->here->e_hash),
                                              &tmp_inode);
                                if (error)
                                        goto cleanup;

                                if (!ext4_test_inode_state(tmp_inode,
                                                EXT4_STATE_LUSTRE_EA_INODE)) {
                                        /*
                                         * Defer quota free call for previous
                                         * inode until success is guaranteed.
                                         */
                                        old_ea_inode_quota = le32_to_cpu(
                                                        s->here->e_value_size);
                                }
                                iput(tmp_inode);

                                s->here->e_value_inum = 0;
                                s->here->e_value_size = 0;
                        }
                }
        } else {
                /* Allocate a buffer where we construct the new block. */
                s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
                error = -ENOMEM;
                if (s->base == NULL)
                        goto cleanup;
                header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
                header(s->base)->h_blocks = cpu_to_le32(1);
                header(s->base)->h_refcount = cpu_to_le32(1);
                s->first = ENTRY(header(s->base)+1);
                s->here = ENTRY(header(s->base)+1);
                s->end = s->base + sb->s_blocksize;
        }

        error = ext4_xattr_set_entry(i, s, handle, inode, true /* is_block */);
        if (error == -EFSCORRUPTED)
                goto bad_block;
        if (error)
                goto cleanup;

        if (i->value && s->here->e_value_inum) {
                /*
                 * A ref count on ea_inode has been taken as part of the call to
                 * ext4_xattr_set_entry() above. We would like to drop this
                 * extra ref but we have to wait until the xattr block is
                 * initialized and has its own ref count on the ea_inode.
                 */
                ea_ino = le32_to_cpu(s->here->e_value_inum);
                error = ext4_xattr_inode_iget(inode, ea_ino,
                                              le32_to_cpu(s->here->e_hash),
                                              &ea_inode);
                if (error) {
                        ea_inode = NULL;
                        goto cleanup;
                }
        }

inserted:
        if (!IS_LAST_ENTRY(s->first)) {
                new_bh = ext4_xattr_block_cache_find(inode, header(s->base),
                                                     &ce);
                if (new_bh) {
                        /* We found an identical block in the cache. */
                        if (new_bh == bs->bh)
                                ea_bdebug(new_bh, "keeping");
                        else {
                                u32 ref;

                                WARN_ON_ONCE(dquot_initialize_needed(inode));

                                /* The old block is released after updating
                                   the inode. */
                                error = dquot_alloc_block(inode,
                                                EXT4_C2B(EXT4_SB(sb), 1));
                                if (error)
                                        goto cleanup;
                                BUFFER_TRACE(new_bh, "get_write_access");
                                error = ext4_journal_get_write_access(handle,
                                                                      new_bh);
                                if (error)
                                        goto cleanup_dquot;
                                lock_buffer(new_bh);
                                /*
                                 * We have to be careful about races with
                                 * freeing, rehashing or adding references to
                                 * xattr block. Once we hold buffer lock xattr
                                 * block's state is stable so we can check
                                 * whether the block got freed / rehashed or
                                 * not.  Since we unhash mbcache entry under
                                 * buffer lock when freeing / rehashing xattr
                                 * block, checking whether entry is still
                                 * hashed is reliable. Same rules hold for
                                 * e_reusable handling.
                                 */
                                if (hlist_bl_unhashed(&ce->e_hash_list) ||
                                    !ce->e_reusable) {
                                        /*
                                         * Undo everything and check mbcache
                                         * again.
                                         */
                                        unlock_buffer(new_bh);
                                        dquot_free_block(inode,
                                                         EXT4_C2B(EXT4_SB(sb),
                                                                  1));
                                        brelse(new_bh);
                                        mb_cache_entry_put(ea_block_cache, ce);
                                        ce = NULL;
                                        new_bh = NULL;
                                        goto inserted;
                                }
                                ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
                                BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
                                if (ref >= EXT4_XATTR_REFCOUNT_MAX)
                                        ce->e_reusable = 0;
                                ea_bdebug(new_bh, "reusing; refcount now=%d",
                                          ref);
                                ext4_xattr_block_csum_set(inode, new_bh);
                                unlock_buffer(new_bh);
                                error = ext4_handle_dirty_metadata(handle,
                                                                   inode,
                                                                   new_bh);
                                if (error)
                                        goto cleanup_dquot;
                        }
                        mb_cache_entry_touch(ea_block_cache, ce);
                        mb_cache_entry_put(ea_block_cache, ce);
                        ce = NULL;
                } else if (bs->bh && s->base == bs->bh->b_data) {
                        /* We were modifying this block in-place. */
                        ea_bdebug(bs->bh, "keeping this block");
                        ext4_xattr_block_cache_insert(ea_block_cache, bs->bh);
                        new_bh = bs->bh;
                        get_bh(new_bh);
                } else {
                        /* We need to allocate a new block */
                        ext4_fsblk_t goal, block;

                        WARN_ON_ONCE(dquot_initialize_needed(inode));

                        goal = ext4_group_first_block_no(sb,
                                                EXT4_I(inode)->i_block_group);

                        /* non-extent files can't have physical blocks past 2^32 */
                        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
                                goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;

                        block = ext4_new_meta_blocks(handle, inode, goal, 0,
                                                     NULL, &error);
                        if (error)
                                goto cleanup;

                        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
                                BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);

                        ea_idebug(inode, "creating block %llu",
                                  (unsigned long long)block);

                        new_bh = sb_getblk(sb, block);
                        if (unlikely(!new_bh)) {
                                error = -ENOMEM;
getblk_failed:
                                ext4_free_blocks(handle, inode, NULL, block, 1,
                                                 EXT4_FREE_BLOCKS_METADATA);
                                goto cleanup;
                        }
                        error = ext4_xattr_inode_inc_ref_all(handle, inode,
                                                      ENTRY(header(s->base)+1));
                        if (error)
                                goto getblk_failed;
                        if (ea_inode) {
                                /* Drop the extra ref on ea_inode. */
                                error = ext4_xattr_inode_dec_ref(handle,
                                                                 ea_inode);
                                if (error)
                                        ext4_warning_inode(ea_inode,
                                                           "dec ref error=%d",
                                                           error);
                                iput(ea_inode);
                                ea_inode = NULL;
                        }

                        lock_buffer(new_bh);
                        error = ext4_journal_get_create_access(handle, new_bh);
                        if (error) {
                                unlock_buffer(new_bh);
                                error = -EIO;
                                goto getblk_failed;
                        }
                        memcpy(new_bh->b_data, s->base, new_bh->b_size);
                        ext4_xattr_block_csum_set(inode, new_bh);
                        set_buffer_uptodate(new_bh);
                        unlock_buffer(new_bh);
                        ext4_xattr_block_cache_insert(ea_block_cache, new_bh);
                        error = ext4_handle_dirty_metadata(handle, inode,
                                                           new_bh);
                        if (error)
                                goto cleanup;
                }
        }

        if (old_ea_inode_quota)
                ext4_xattr_inode_free_quota(inode, NULL, old_ea_inode_quota);

        /* Update the inode. */
        EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;

        /* Drop the previous xattr block. */
        if (bs->bh && bs->bh != new_bh) {
                struct ext4_xattr_inode_array *ea_inode_array = NULL;

                ext4_xattr_release_block(handle, inode, bs->bh,
                                         &ea_inode_array,
                                         0 /* extra_credits */);
                ext4_xattr_inode_array_free(ea_inode_array);
        }
        error = 0;

cleanup:
        if (ea_inode) {
                int error2;

                error2 = ext4_xattr_inode_dec_ref(handle, ea_inode);
                if (error2)
                        ext4_warning_inode(ea_inode, "dec ref error=%d",
                                           error2);

                /* If there was an error, revert the quota charge. */
                if (error)
                        ext4_xattr_inode_free_quota(inode, ea_inode,
                                                    i_size_read(ea_inode));
                iput(ea_inode);
        }
        if (ce)
                mb_cache_entry_put(ea_block_cache, ce);
        brelse(new_bh);
        if (!(bs->bh && s->base == bs->bh->b_data))
                kfree(s->base);

        return error;

cleanup_dquot:
        dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
        goto cleanup;

bad_block:
        EXT4_ERROR_INODE(inode, "bad block %llu",
                         EXT4_I(inode)->i_file_acl);
        goto cleanup;

#undef header
}

int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
                          struct ext4_xattr_ibody_find *is)
{
        struct ext4_xattr_ibody_header *header;
        struct ext4_inode *raw_inode;
        int error;

        if (EXT4_I(inode)->i_extra_isize == 0)
                return 0;
        raw_inode = ext4_raw_inode(&is->iloc);
        header = IHDR(inode, raw_inode);
        is->s.base = is->s.first = IFIRST(header);
        is->s.here = is->s.first;
        is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
        if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
                error = xattr_check_inode(inode, header, is->s.end);
                if (error)
                        return error;
                /* Find the named attribute. */
                error = xattr_find_entry(inode, &is->s.here, is->s.end,
                                         i->name_index, i->name, 0);
                if (error && error != -ENODATA)
                        return error;
                is->s.not_found = error;
        }
        return 0;
}

int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
                                struct ext4_xattr_info *i,
                                struct ext4_xattr_ibody_find *is)
{
        struct ext4_xattr_ibody_header *header;
        struct ext4_xattr_search *s = &is->s;
        int error;

        if (EXT4_I(inode)->i_extra_isize == 0)
                return -ENOSPC;
        error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
        if (error)
                return error;
        header = IHDR(inode, ext4_raw_inode(&is->iloc));
        if (!IS_LAST_ENTRY(s->first)) {
                header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
                ext4_set_inode_state(inode, EXT4_STATE_XATTR);
        } else {
                header->h_magic = cpu_to_le32(0);
                ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
        }
        return 0;
}

static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
                                struct ext4_xattr_info *i,
                                struct ext4_xattr_ibody_find *is)
{
        struct ext4_xattr_ibody_header *header;
        struct ext4_xattr_search *s = &is->s;
        int error;

        if (EXT4_I(inode)->i_extra_isize == 0)
                return -ENOSPC;
        error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
        if (error)
                return error;
        header = IHDR(inode, ext4_raw_inode(&is->iloc));
        if (!IS_LAST_ENTRY(s->first)) {
                header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
                ext4_set_inode_state(inode, EXT4_STATE_XATTR);
        } else {
                header->h_magic = cpu_to_le32(0);
                ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
        }
        return 0;
}

static int ext4_xattr_value_same(struct ext4_xattr_search *s,
                                 struct ext4_xattr_info *i)
{
        void *value;

        /* When e_value_inum is set the value is stored externally. */
        if (s->here->e_value_inum)
                return 0;
        if (le32_to_cpu(s->here->e_value_size) != i->value_len)
                return 0;
        value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
        return !memcmp(value, i->value, i->value_len);
}

static struct buffer_head *ext4_xattr_get_block(struct inode *inode)
{
        struct buffer_head *bh;
        int error;

        if (!EXT4_I(inode)->i_file_acl)
                return NULL;
        bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
        if (IS_ERR(bh))
                return bh;
        error = ext4_xattr_check_block(inode, bh);
        if (error) {
                brelse(bh);
                return ERR_PTR(error);
        }
        return bh;
}

/*
 * ext4_xattr_set_handle()
 *
 * Create, replace or remove an extended attribute for this inode.  Value
 * is NULL to remove an existing extended attribute, and non-NULL to
 * either replace an existing extended attribute, or create a new extended
 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 * specify that an extended attribute must exist and must not exist
 * previous to the call, respectively.
 *
 * Returns 0, or a negative error number on failure.
 */
int
ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
                      const char *name, const void *value, size_t value_len,
                      int flags)
{
        struct ext4_xattr_info i = {
                .name_index = name_index,
                .name = name,
                .value = value,
                .value_len = value_len,
                .in_inode = 0,
        };
        struct ext4_xattr_ibody_find is = {
                .s = { .not_found = -ENODATA, },
        };
        struct ext4_xattr_block_find bs = {
                .s = { .not_found = -ENODATA, },
        };
        int no_expand;
        int error;

        if (!name)
                return -EINVAL;
        if (strlen(name) > 255)
                return -ERANGE;

        ext4_write_lock_xattr(inode, &no_expand);

        /* Check journal credits under write lock. */
        if (ext4_handle_valid(handle)) {
                struct buffer_head *bh;
                int credits;

                bh = ext4_xattr_get_block(inode);
                if (IS_ERR(bh)) {
                        error = PTR_ERR(bh);
                        goto cleanup;
                }

                credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
                                                   value_len,
                                                   flags & XATTR_CREATE);
                brelse(bh);

                if (jbd2_handle_buffer_credits(handle) < credits) {
                        error = -ENOSPC;
                        goto cleanup;
                }
                WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS));
        }

        error = ext4_reserve_inode_write(handle, inode, &is.iloc);
        if (error)
                goto cleanup;

        if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
                struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
                memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
                ext4_clear_inode_state(inode, EXT4_STATE_NEW);
        }

        error = ext4_xattr_ibody_find(inode, &i, &is);
        if (error)
                goto cleanup;
        if (is.s.not_found)
                error = ext4_xattr_block_find(inode, &i, &bs);
        if (error)
                goto cleanup;
        if (is.s.not_found && bs.s.not_found) {
                error = -ENODATA;
                if (flags & XATTR_REPLACE)
                        goto cleanup;
                error = 0;
                if (!value)
                        goto cleanup;
        } else {
                error = -EEXIST;
                if (flags & XATTR_CREATE)
                        goto cleanup;
        }

        if (!value) {
                if (!is.s.not_found)
                        error = ext4_xattr_ibody_set(handle, inode, &i, &is);
                else if (!bs.s.not_found)
                        error = ext4_xattr_block_set(handle, inode, &i, &bs);
        } else {
                error = 0;
                /* Xattr value did not change? Save us some work and bail out */
                if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
                        goto cleanup;
                if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
                        goto cleanup;

                if (ext4_has_feature_ea_inode(inode->i_sb) &&
                    (EXT4_XATTR_SIZE(i.value_len) >
                        EXT4_XATTR_MIN_LARGE_EA_SIZE(inode->i_sb->s_blocksize)))
                        i.in_inode = 1;
retry_inode:
                error = ext4_xattr_ibody_set(handle, inode, &i, &is);
                if (!error && !bs.s.not_found) {
                        i.value = NULL;
                        error = ext4_xattr_block_set(handle, inode, &i, &bs);
                } else if (error == -ENOSPC) {
                        if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
                                brelse(bs.bh);
                                bs.bh = NULL;
                                error = ext4_xattr_block_find(inode, &i, &bs);
                                if (error)
                                        goto cleanup;
                        }
                        error = ext4_xattr_block_set(handle, inode, &i, &bs);
                        if (!error && !is.s.not_found) {
                                i.value = NULL;
                                error = ext4_xattr_ibody_set(handle, inode, &i,
                                                             &is);
                        } else if (error == -ENOSPC) {
                                /*
                                 * Xattr does not fit in the block, store at
                                 * external inode if possible.
                                 */
                                if (ext4_has_feature_ea_inode(inode->i_sb) &&
                                    i.value_len && !i.in_inode) {
                                        i.in_inode = 1;
                                        goto retry_inode;
                                }
                        }
                }
        }
        if (!error) {
                ext4_xattr_update_super_block(handle, inode->i_sb);
                inode->i_ctime = current_time(inode);
                if (!value)
                        no_expand = 0;
                error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
                /*
                 * The bh is consumed by ext4_mark_iloc_dirty, even with
                 * error != 0.
                 */
                is.iloc.bh = NULL;
                if (IS_SYNC(inode))
                        ext4_handle_sync(handle);
        }
        ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR);

cleanup:
        brelse(is.iloc.bh);
        brelse(bs.bh);
        ext4_write_unlock_xattr(inode, &no_expand);
        return error;
}

int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
                           bool is_create, int *credits)
{
        struct buffer_head *bh;
        int err;

        *credits = 0;

        if (!EXT4_SB(inode->i_sb)->s_journal)
                return 0;

        down_read(&EXT4_I(inode)->xattr_sem);

        bh = ext4_xattr_get_block(inode);
        if (IS_ERR(bh)) {
                err = PTR_ERR(bh);
        } else {
                *credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
                                                    value_len, is_create);
                brelse(bh);
                err = 0;
        }

        up_read(&EXT4_I(inode)->xattr_sem);
        return err;
}

/*
 * ext4_xattr_set()
 *
 * Like ext4_xattr_set_handle, but start from an inode. This extended
 * attribute modification is a filesystem transaction by itself.
 *
 * Returns 0, or a negative error number on failure.
 */
int
ext4_xattr_set(struct inode *inode, int name_index, const char *name,
               const void *value, size_t value_len, int flags)
{
        handle_t *handle;
        struct super_block *sb = inode->i_sb;
        int error, retries = 0;
        int credits;

        error = dquot_initialize(inode);
        if (error)
                return error;

retry:
        error = ext4_xattr_set_credits(inode, value_len, flags & XATTR_CREATE,
                                       &credits);
        if (error)
                return error;

        handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
        if (IS_ERR(handle)) {
                error = PTR_ERR(handle);
        } else {
                int error2;

                error = ext4_xattr_set_handle(handle, inode, name_index, name,
                                              value, value_len, flags);
                error2 = ext4_journal_stop(handle);
                if (error == -ENOSPC &&
                    ext4_should_retry_alloc(sb, &retries))
                        goto retry;
                if (error == 0)
                        error = error2;
        }
        ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR);

        return error;
}

/*
 * Shift the EA entries in the inode to create space for the increased
 * i_extra_isize.
 */
static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
                                     int value_offs_shift, void *to,
                                     void *from, size_t n)
{
        struct ext4_xattr_entry *last = entry;
        int new_offs;

        /* We always shift xattr headers further thus offsets get lower */
        BUG_ON(value_offs_shift > 0);

        /* Adjust the value offsets of the entries */
        for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
                if (!last->e_value_inum && last->e_value_size) {
                        new_offs = le16_to_cpu(last->e_value_offs) +
                                                        value_offs_shift;
                        last->e_value_offs = cpu_to_le16(new_offs);
                }
        }
        /* Shift the entries by n bytes */
        memmove(to, from, n);
}

/*
 * Move xattr pointed to by 'entry' from inode into external xattr block
 */
static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
                                    struct ext4_inode *raw_inode,
                                    struct ext4_xattr_entry *entry)
{
        struct ext4_xattr_ibody_find *is = NULL;
        struct ext4_xattr_block_find *bs = NULL;
        char *buffer = NULL, *b_entry_name = NULL;
        size_t value_size = le32_to_cpu(entry->e_value_size);
        struct ext4_xattr_info i = {
                .value = NULL,
                .value_len = 0,
                .name_index = entry->e_name_index,
                .in_inode = !!entry->e_value_inum,
        };
        struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
        int error;

        is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
        bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
        buffer = kmalloc(value_size, GFP_NOFS);
        b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
        if (!is || !bs || !buffer || !b_entry_name) {
                error = -ENOMEM;
                goto out;
        }

        is->s.not_found = -ENODATA;
        bs->s.not_found = -ENODATA;
        is->iloc.bh = NULL;
        bs->bh = NULL;

        /* Save the entry name and the entry value */
        if (entry->e_value_inum) {
                error = ext4_xattr_inode_get(inode, entry, buffer, value_size);
                if (error)
                        goto out;
        } else {
                size_t value_offs = le16_to_cpu(entry->e_value_offs);
                memcpy(buffer, (void *)IFIRST(header) + value_offs, value_size);
        }

        memcpy(b_entry_name, entry->e_name, entry->e_name_len);
        b_entry_name[entry->e_name_len] = '\0';
        i.name = b_entry_name;

        error = ext4_get_inode_loc(inode, &is->iloc);
        if (error)
                goto out;

        error = ext4_xattr_ibody_find(inode, &i, is);
        if (error)
                goto out;

        /* Remove the chosen entry from the inode */
        error = ext4_xattr_ibody_set(handle, inode, &i, is);
        if (error)
                goto out;

        i.value = buffer;
        i.value_len = value_size;
        error = ext4_xattr_block_find(inode, &i, bs);
        if (error)
                goto out;

        /* Add entry which was removed from the inode into the block */
        error = ext4_xattr_block_set(handle, inode, &i, bs);
        if (error)
                goto out;
        error = 0;
out:
        kfree(b_entry_name);
        kfree(buffer);
        if (is)
                brelse(is->iloc.bh);
        if (bs)
                brelse(bs->bh);
        kfree(is);
        kfree(bs);

        return error;
}

static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
                                       struct ext4_inode *raw_inode,
                                       int isize_diff, size_t ifree,
                                       size_t bfree, int *total_ino)
{
        struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
        struct ext4_xattr_entry *small_entry;
        struct ext4_xattr_entry *entry;
        struct ext4_xattr_entry *last;
        unsigned int entry_size;        /* EA entry size */
        unsigned int total_size;        /* EA entry size + value size */
        unsigned int min_total_size;
        int error;

        while (isize_diff > ifree) {
                entry = NULL;
                small_entry = NULL;
                min_total_size = ~0U;
                last = IFIRST(header);
                /* Find the entry best suited to be pushed into EA block */
                for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
                        /* never move system.data out of the inode */
                        if ((last->e_name_len == 4) &&
                            (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) &&
                            !memcmp(last->e_name, "data", 4))
                                continue;
                        total_size = EXT4_XATTR_LEN(last->e_name_len);
                        if (!last->e_value_inum)
                                total_size += EXT4_XATTR_SIZE(
                                               le32_to_cpu(last->e_value_size));
                        if (total_size <= bfree &&
                            total_size < min_total_size) {
                                if (total_size + ifree < isize_diff) {
                                        small_entry = last;
                                } else {
                                        entry = last;
                                        min_total_size = total_size;
                                }
                        }
                }

                if (entry == NULL) {
                        if (small_entry == NULL)
                                return -ENOSPC;
                        entry = small_entry;
                }

                entry_size = EXT4_XATTR_LEN(entry->e_name_len);
                total_size = entry_size;
                if (!entry->e_value_inum)
                        total_size += EXT4_XATTR_SIZE(
                                              le32_to_cpu(entry->e_value_size));
                error = ext4_xattr_move_to_block(handle, inode, raw_inode,
                                                 entry);
                if (error)
                        return error;

                *total_ino -= entry_size;
                ifree += total_size;
                bfree -= total_size;
        }

        return 0;
}

/*
 * Expand an inode by new_extra_isize bytes when EAs are present.
 * Returns 0 on success or negative error number on failure.
 */
int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
                               struct ext4_inode *raw_inode, handle_t *handle)
{
        struct ext4_xattr_ibody_header *header;
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        static unsigned int mnt_count;
        size_t min_offs;
        size_t ifree, bfree;
        int total_ino;
        void *base, *end;
        int error = 0, tried_min_extra_isize = 0;
        int s_min_extra_isize = le16_to_cpu(sbi->s_es->s_min_extra_isize);
        int isize_diff; /* How much do we need to grow i_extra_isize */

retry:
        isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
        if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
                return 0;

        header = IHDR(inode, raw_inode);

        /*
         * Check if enough free space is available in the inode to shift the
         * entries ahead by new_extra_isize.
         */

        base = IFIRST(header);
        end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
        min_offs = end - base;
        total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);

        error = xattr_check_inode(inode, header, end);
        if (error)
                goto cleanup;

        ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino);
        if (ifree >= isize_diff)
                goto shift;

        /*
         * Enough free space isn't available in the inode, check if
         * EA block can hold new_extra_isize bytes.
         */
        if (EXT4_I(inode)->i_file_acl) {
                struct buffer_head *bh;

                bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
                if (IS_ERR(bh)) {
                        error = PTR_ERR(bh);
                        goto cleanup;
                }
                error = ext4_xattr_check_block(inode, bh);
                if (error) {
                        brelse(bh);
                        goto cleanup;
                }
                base = BHDR(bh);
                end = bh->b_data + bh->b_size;
                min_offs = end - base;
                bfree = ext4_xattr_free_space(BFIRST(bh), &min_offs, base,
                                              NULL);
                brelse(bh);
                if (bfree + ifree < isize_diff) {
                        if (!tried_min_extra_isize && s_min_extra_isize) {
                                tried_min_extra_isize++;
                                new_extra_isize = s_min_extra_isize;
                                goto retry;
                        }
                        error = -ENOSPC;
                        goto cleanup;
                }
        } else {
                bfree = inode->i_sb->s_blocksize;
        }

        error = ext4_xattr_make_inode_space(handle, inode, raw_inode,
                                            isize_diff, ifree, bfree,
                                            &total_ino);
        if (error) {
                if (error == -ENOSPC && !tried_min_extra_isize &&
                    s_min_extra_isize) {
                        tried_min_extra_isize++;
                        new_extra_isize = s_min_extra_isize;
                        goto retry;
                }
                goto cleanup;
        }
shift:
        /* Adjust the offsets and shift the remaining entries ahead */
        ext4_xattr_shift_entries(IFIRST(header), EXT4_I(inode)->i_extra_isize
                        - new_extra_isize, (void *)raw_inode +
                        EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
                        (void *)header, total_ino);
        EXT4_I(inode)->i_extra_isize = new_extra_isize;

cleanup:
        if (error && (mnt_count != le16_to_cpu(sbi->s_es->s_mnt_count))) {
                ext4_warning(inode->i_sb, "Unable to expand inode %lu. Delete some EAs or run e2fsck.",
                             inode->i_ino);
                mnt_count = le16_to_cpu(sbi->s_es->s_mnt_count);
        }
        return error;
}

#define EIA_INCR 16 /* must be 2^n */
#define EIA_MASK (EIA_INCR - 1)

/* Add the large xattr @inode into @ea_inode_array for deferred iput().
 * If @ea_inode_array is new or full it will be grown and the old
 * contents copied over.
 */
static int
ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
                        struct inode *inode)
{
        if (*ea_inode_array == NULL) {
                /*
                 * Start with 15 inodes, so it fits into a power-of-two size.
                 * If *ea_inode_array is NULL, this is essentially offsetof()
                 */
                (*ea_inode_array) =
                        kmalloc(offsetof(struct ext4_xattr_inode_array,
                                         inodes[EIA_MASK]),
                                GFP_NOFS);
                if (*ea_inode_array == NULL)
                        return -ENOMEM;
                (*ea_inode_array)->count = 0;
        } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) {
                /* expand the array once all 15 + n * 16 slots are full */
                struct ext4_xattr_inode_array *new_array = NULL;
                int count = (*ea_inode_array)->count;

                /* if new_array is NULL, this is essentially offsetof() */
                new_array = kmalloc(
                                offsetof(struct ext4_xattr_inode_array,
                                         inodes[count + EIA_INCR]),
                                GFP_NOFS);
                if (new_array == NULL)
                        return -ENOMEM;
                memcpy(new_array, *ea_inode_array,
                       offsetof(struct ext4_xattr_inode_array, inodes[count]));
                kfree(*ea_inode_array);
                *ea_inode_array = new_array;
        }
        (*ea_inode_array)->inodes[(*ea_inode_array)->count++] = inode;
        return 0;
}

/*
 * ext4_xattr_delete_inode()
 *
 * Free extended attribute resources associated with this inode. Traverse
 * all entries and decrement reference on any xattr inodes associated with this
 * inode. This is called immediately before an inode is freed. We have exclusive
 * access to the inode. If an orphan inode is deleted it will also release its
 * references on xattr block and xattr inodes.
 */
int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
                            struct ext4_xattr_inode_array **ea_inode_array,
                            int extra_credits)
{
        struct buffer_head *bh = NULL;
        struct ext4_xattr_ibody_header *header;
        struct ext4_iloc iloc = { .bh = NULL };
        struct ext4_xattr_entry *entry;
        struct inode *ea_inode;
        int error;

        error = ext4_journal_ensure_credits(handle, extra_credits,
                        ext4_free_metadata_revoke_credits(inode->i_sb, 1));
        if (error < 0) {
                EXT4_ERROR_INODE(inode, "ensure credits (error %d)", error);
                goto cleanup;
        }

        if (ext4_has_feature_ea_inode(inode->i_sb) &&
            ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {

                error = ext4_get_inode_loc(inode, &iloc);
                if (error) {
                        EXT4_ERROR_INODE(inode, "inode loc (error %d)", error);
                        goto cleanup;
                }

                error = ext4_journal_get_write_access(handle, iloc.bh);
                if (error) {
                        EXT4_ERROR_INODE(inode, "write access (error %d)",
                                         error);
                        goto cleanup;
                }

                header = IHDR(inode, ext4_raw_inode(&iloc));
                if (header->h_magic == cpu_to_le32(EXT4_XATTR_MAGIC))
                        ext4_xattr_inode_dec_ref_all(handle, inode, iloc.bh,
                                                     IFIRST(header),
                                                     false /* block_csum */,
                                                     ea_inode_array,
                                                     extra_credits,
                                                     false /* skip_quota */);
        }

        if (EXT4_I(inode)->i_file_acl) {
                bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
                if (IS_ERR(bh)) {
                        error = PTR_ERR(bh);
                        if (error == -EIO) {
                                EXT4_ERROR_INODE_ERR(inode, EIO,
                                                     "block %llu read error",
                                                     EXT4_I(inode)->i_file_acl);
                        }
                        bh = NULL;
                        goto cleanup;
                }
                error = ext4_xattr_check_block(inode, bh);
                if (error)
                        goto cleanup;

                if (ext4_has_feature_ea_inode(inode->i_sb)) {
                        for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
                             entry = EXT4_XATTR_NEXT(entry)) {
                                if (!entry->e_value_inum)
                                        continue;
                                error = ext4_xattr_inode_iget(inode,
                                              le32_to_cpu(entry->e_value_inum),
                                              le32_to_cpu(entry->e_hash),
                                              &ea_inode);
                                if (error)
                                        continue;
                                ext4_xattr_inode_free_quota(inode, ea_inode,
                                              le32_to_cpu(entry->e_value_size));
                                iput(ea_inode);
                        }

                }

                ext4_xattr_release_block(handle, inode, bh, ea_inode_array,
                                         extra_credits);
                /*
                 * Update i_file_acl value in the same transaction that releases
                 * block.
                 */
                EXT4_I(inode)->i_file_acl = 0;
                error = ext4_mark_inode_dirty(handle, inode);
                if (error) {
                        EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
                                         error);
                        goto cleanup;
                }
                ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR);
        }
        error = 0;
cleanup:
        brelse(iloc.bh);
        brelse(bh);
        return error;
}

void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *ea_inode_array)
{
        int idx;

        if (ea_inode_array == NULL)
                return;

        for (idx = 0; idx < ea_inode_array->count; ++idx)
                iput(ea_inode_array->inodes[idx]);
        kfree(ea_inode_array);
}

/*
 * ext4_xattr_block_cache_insert()
 *
 * Create a new entry in the extended attribute block cache, and insert
 * it unless such an entry is already in the cache.
 *
 * Returns 0, or a negative error number on failure.
 */
static void
ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
                              struct buffer_head *bh)
{
        struct ext4_xattr_header *header = BHDR(bh);
        __u32 hash = le32_to_cpu(header->h_hash);
        int reusable = le32_to_cpu(header->h_refcount) <
                       EXT4_XATTR_REFCOUNT_MAX;
        int error;

        if (!ea_block_cache)
                return;
        error = mb_cache_entry_create(ea_block_cache, GFP_NOFS, hash,
                                      bh->b_blocknr, reusable);
        if (error) {
                if (error == -EBUSY)
                        ea_bdebug(bh, "already in cache");
        } else
                ea_bdebug(bh, "inserting [%x]", (int)hash);
}

/*
 * ext4_xattr_cmp()
 *
 * Compare two extended attribute blocks for equality.
 *
 * Returns 0 if the blocks are equal, 1 if they differ, and
 * a negative error number on errors.
 */
static int
ext4_xattr_cmp(struct ext4_xattr_header *header1,
               struct ext4_xattr_header *header2)
{
        struct ext4_xattr_entry *entry1, *entry2;

        entry1 = ENTRY(header1+1);
        entry2 = ENTRY(header2+1);
        while (!IS_LAST_ENTRY(entry1)) {
                if (IS_LAST_ENTRY(entry2))
                        return 1;
                if (entry1->e_hash != entry2->e_hash ||
                    entry1->e_name_index != entry2->e_name_index ||
                    entry1->e_name_len != entry2->e_name_len ||
                    entry1->e_value_size != entry2->e_value_size ||
                    entry1->e_value_inum != entry2->e_value_inum ||
                    memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
                        return 1;
                if (!entry1->e_value_inum &&
                    memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
                           (char *)header2 + le16_to_cpu(entry2->e_value_offs),
                           le32_to_cpu(entry1->e_value_size)))
                        return 1;

                entry1 = EXT4_XATTR_NEXT(entry1);
                entry2 = EXT4_XATTR_NEXT(entry2);
        }
        if (!IS_LAST_ENTRY(entry2))
                return 1;
        return 0;
}

/*
 * ext4_xattr_block_cache_find()
 *
 * Find an identical extended attribute block.
 *
 * Returns a pointer to the block found, or NULL if such a block was
 * not found or an error occurred.
 */
static struct buffer_head *
ext4_xattr_block_cache_find(struct inode *inode,
                            struct ext4_xattr_header *header,
                            struct mb_cache_entry **pce)
{
        __u32 hash = le32_to_cpu(header->h_hash);
        struct mb_cache_entry *ce;
        struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);

        if (!ea_block_cache)
                return NULL;
        if (!header->h_hash)
                return NULL;  /* never share */
        ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
        ce = mb_cache_entry_find_first(ea_block_cache, hash);
        while (ce) {
                struct buffer_head *bh;

                bh = ext4_sb_bread(inode->i_sb, ce->e_value, REQ_PRIO);
                if (IS_ERR(bh)) {
                        if (PTR_ERR(bh) == -ENOMEM)
                                return NULL;
                        bh = NULL;
                        EXT4_ERROR_INODE(inode, "block %lu read error",
                                         (unsigned long)ce->e_value);
                } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
                        *pce = ce;
                        return bh;
                }
                brelse(bh);
                ce = mb_cache_entry_find_next(ea_block_cache, ce);
        }
        return NULL;
}

#define NAME_HASH_SHIFT 5
#define VALUE_HASH_SHIFT 16

/*
 * ext4_xattr_hash_entry()
 *
 * Compute the hash of an extended attribute.
 */
static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
                                    size_t value_count)
{
        __u32 hash = 0;

        while (name_len--) {
                hash = (hash << NAME_HASH_SHIFT) ^
                       (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
                       *name++;
        }
        while (value_count--) {
                hash = (hash << VALUE_HASH_SHIFT) ^
                       (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
                       le32_to_cpu(*value++);
        }
        return cpu_to_le32(hash);
}

#undef NAME_HASH_SHIFT
#undef VALUE_HASH_SHIFT

#define BLOCK_HASH_SHIFT 16

/*
 * ext4_xattr_rehash()
 *
 * Re-compute the extended attribute hash value after an entry has changed.
 */
static void ext4_xattr_rehash(struct ext4_xattr_header *header)
{
        struct ext4_xattr_entry *here;
        __u32 hash = 0;

        here = ENTRY(header+1);
        while (!IS_LAST_ENTRY(here)) {
                if (!here->e_hash) {
                        /* Block is not shared if an entry's hash value == 0 */
                        hash = 0;
                        break;
                }
                hash = (hash << BLOCK_HASH_SHIFT) ^
                       (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
                       le32_to_cpu(here->e_hash);
                here = EXT4_XATTR_NEXT(here);
        }
        header->h_hash = cpu_to_le32(hash);
}

#undef BLOCK_HASH_SHIFT

#define HASH_BUCKET_BITS        10

struct mb_cache *
ext4_xattr_create_cache(void)
{
        return mb_cache_create(HASH_BUCKET_BITS);
}

void ext4_xattr_destroy_cache(struct mb_cache *cache)
{
        if (cache)
                mb_cache_destroy(cache);
}