[linux.git] / fs / fat / fatent.c

/*
 * Copyright (C) 2004, OGAWA Hirofumi
 * Released under GPL v2.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>

struct fatent_operations {
	void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
	void (*ent_set_ptr)(struct fat_entry *, int);
	int (*ent_bread)(struct super_block *, struct fat_entry *,
			 int, sector_t);
	int (*ent_get)(struct fat_entry *);
	void (*ent_put)(struct fat_entry *, int);
	int (*ent_next)(struct fat_entry *);
};

static void fat12_ent_blocknr(struct super_block *sb, int entry,
			      int *offset, sector_t *blocknr)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	int bytes = entry + (entry >> 1);
	WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
	*offset = bytes & (sb->s_blocksize - 1);
	*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
}

static void fat_ent_blocknr(struct super_block *sb, int entry,
			    int *offset, sector_t *blocknr)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	int bytes = (entry << sbi->fatent_shift);
	WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
	*offset = bytes & (sb->s_blocksize - 1);
	*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
}

static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
{
	struct buffer_head **bhs = fatent->bhs;
	if (fatent->nr_bhs == 1) {
		WARN_ON(offset >= (bhs[0]->b_size - 1));
		fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
		fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
	} else {
		WARN_ON(offset != (bhs[0]->b_size - 1));
		fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
		fatent->u.ent12_p[1] = bhs[1]->b_data;
	}
}

static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
{
	WARN_ON(offset & (2 - 1));
	fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
}

static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
{
	WARN_ON(offset & (4 - 1));
	fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
}

static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
			   int offset, sector_t blocknr)
{
	struct buffer_head **bhs = fatent->bhs;

	WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
	bhs[0] = sb_bread(sb, blocknr);
	if (!bhs[0])
		goto err;

	if ((offset + 1) < sb->s_blocksize)
		fatent->nr_bhs = 1;
	else {
		/* This entry is block boundary, it needs the next block */
		blocknr++;
		bhs[1] = sb_bread(sb, blocknr);
		if (!bhs[1])
			goto err_brelse;
		fatent->nr_bhs = 2;
	}
	fat12_ent_set_ptr(fatent, offset);
	return 0;

err_brelse:
	brelse(bhs[0]);
err:
	printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
	       (unsigned long long)blocknr);
	return -EIO;
}

static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
			 int offset, sector_t blocknr)
{
	struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;

	WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
	fatent->bhs[0] = sb_bread(sb, blocknr);
	if (!fatent->bhs[0]) {
		printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
		       (unsigned long long)blocknr);
		return -EIO;
	}
	fatent->nr_bhs = 1;
	ops->ent_set_ptr(fatent, offset);
	return 0;
}

static int fat12_ent_get(struct fat_entry *fatent)
{
	u8 **ent12_p = fatent->u.ent12_p;
	int next;

	if (fatent->entry & 1)
		next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
	else
		next = (*ent12_p[1] << 8) | *ent12_p[0];
	next &= 0x0fff;
	if (next >= BAD_FAT12)
		next = FAT_ENT_EOF;
	return next;
}

static int fat16_ent_get(struct fat_entry *fatent)
{
	int next = le16_to_cpu(*fatent->u.ent16_p);
	WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
	if (next >= BAD_FAT16)
		next = FAT_ENT_EOF;
	return next;
}

static int fat32_ent_get(struct fat_entry *fatent)
{
	int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
	WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
	if (next >= BAD_FAT32)
		next = FAT_ENT_EOF;
	return next;
}

static void fat12_ent_put(struct fat_entry *fatent, int new)
{
	u8 **ent12_p = fatent->u.ent12_p;

	if (new == FAT_ENT_EOF)
		new = EOF_FAT12;

	if (fatent->entry & 1) {
		*ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
		*ent12_p[1] = new >> 4;
	} else {
		*ent12_p[0] = new & 0xff;
		*ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
	}

	mark_buffer_dirty(fatent->bhs[0]);
	if (fatent->nr_bhs == 2)
		mark_buffer_dirty(fatent->bhs[1]);
}

static void fat16_ent_put(struct fat_entry *fatent, int new)
{
	if (new == FAT_ENT_EOF)
		new = EOF_FAT16;

	*fatent->u.ent16_p = cpu_to_le16(new);
	mark_buffer_dirty(fatent->bhs[0]);
}

static void fat32_ent_put(struct fat_entry *fatent, int new)
{
	if (new == FAT_ENT_EOF)
		new = EOF_FAT32;

	WARN_ON(new & 0xf0000000);
	new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
	*fatent->u.ent32_p = cpu_to_le32(new);
	mark_buffer_dirty(fatent->bhs[0]);
}

static int fat12_ent_next(struct fat_entry *fatent)
{
	u8 **ent12_p = fatent->u.ent12_p;
	struct buffer_head **bhs = fatent->bhs;
	u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);

	fatent->entry++;
	if (fatent->nr_bhs == 1) {
		WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
		WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
		if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
			ent12_p[0] = nextp - 1;
			ent12_p[1] = nextp;
			return 1;
		}
	} else {
		WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
		WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
		ent12_p[0] = nextp - 1;
		ent12_p[1] = nextp;
		brelse(bhs[0]);
		bhs[0] = bhs[1];
		fatent->nr_bhs = 1;
		return 1;
	}
	ent12_p[0] = NULL;
	ent12_p[1] = NULL;
	return 0;
}

static int fat16_ent_next(struct fat_entry *fatent)
{
	const struct buffer_head *bh = fatent->bhs[0];
	fatent->entry++;
	if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
		fatent->u.ent16_p++;
		return 1;
	}
	fatent->u.ent16_p = NULL;
	return 0;
}

static int fat32_ent_next(struct fat_entry *fatent)
{
	const struct buffer_head *bh = fatent->bhs[0];
	fatent->entry++;
	if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
		fatent->u.ent32_p++;
		return 1;
	}
	fatent->u.ent32_p = NULL;
	return 0;
}

static struct fatent_operations fat12_ops = {
	.ent_blocknr	= fat12_ent_blocknr,
	.ent_set_ptr	= fat12_ent_set_ptr,
	.ent_bread	= fat12_ent_bread,
	.ent_get	= fat12_ent_get,
	.ent_put	= fat12_ent_put,
	.ent_next	= fat12_ent_next,
};

static struct fatent_operations fat16_ops = {
	.ent_blocknr	= fat_ent_blocknr,
	.ent_set_ptr	= fat16_ent_set_ptr,
	.ent_bread	= fat_ent_bread,
	.ent_get	= fat16_ent_get,
	.ent_put	= fat16_ent_put,
	.ent_next	= fat16_ent_next,
};

static struct fatent_operations fat32_ops = {
	.ent_blocknr	= fat_ent_blocknr,
	.ent_set_ptr	= fat32_ent_set_ptr,
	.ent_bread	= fat_ent_bread,
	.ent_get	= fat32_ent_get,
	.ent_put	= fat32_ent_put,
	.ent_next	= fat32_ent_next,
};

static inline void lock_fat(struct msdos_sb_info *sbi)
{
	mutex_lock(&sbi->fat_lock);
}

static inline void unlock_fat(struct msdos_sb_info *sbi)
{
	mutex_unlock(&sbi->fat_lock);
}

void fat_ent_access_init(struct super_block *sb)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);

	mutex_init(&sbi->fat_lock);

	switch (sbi->fat_bits) {
	case 32:
		sbi->fatent_shift = 2;
		sbi->fatent_ops = &fat32_ops;
		break;
	case 16:
		sbi->fatent_shift = 1;
		sbi->fatent_ops = &fat16_ops;
		break;
	case 12:
		sbi->fatent_shift = -1;
		sbi->fatent_ops = &fat12_ops;
		break;
	}
}

static inline int fat_ent_update_ptr(struct super_block *sb,
				     struct fat_entry *fatent,
				     int offset, sector_t blocknr)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct fatent_operations *ops = sbi->fatent_ops;
	struct buffer_head **bhs = fatent->bhs;

	/* Is this fatent's blocks including this entry? */
	if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
		return 0;
	/* Does this entry need the next block? */
	if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
		if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1))
			return 0;
	}
	ops->ent_set_ptr(fatent, offset);
	return 1;
}

int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
	struct fatent_operations *ops = sbi->fatent_ops;
	int err, offset;
	sector_t blocknr;

	if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
		fatent_brelse(fatent);
		fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
		return -EIO;
	}

	fatent_set_entry(fatent, entry);
	ops->ent_blocknr(sb, entry, &offset, &blocknr);

	if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
		fatent_brelse(fatent);
		err = ops->ent_bread(sb, fatent, offset, blocknr);
		if (err)
			return err;
	}
	return ops->ent_get(fatent);
}

/* FIXME: We can write the blocks as more big chunk. */
static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
			  int nr_bhs)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct buffer_head *c_bh;
	int err, n, copy;

	err = 0;
	for (copy = 1; copy < sbi->fats; copy++) {
		sector_t backup_fat = sbi->fat_length * copy;

		for (n = 0; n < nr_bhs; n++) {
			c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
			if (!c_bh) {
				err = -ENOMEM;
				goto error;
			}
			memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
			set_buffer_uptodate(c_bh);
			mark_buffer_dirty(c_bh);
			if (sb->s_flags & MS_SYNCHRONOUS)
				err = sync_dirty_buffer(c_bh);
			brelse(c_bh);
			if (err)
				goto error;
		}
	}
error:
	return err;
}

int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
		  int new, int wait)
{
	struct super_block *sb = inode->i_sb;
	struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
	int err;

	ops->ent_put(fatent, new);
	if (wait) {
		err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
		if (err)
			return err;
	}
	return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
}

static inline int fat_ent_next(struct msdos_sb_info *sbi,
			       struct fat_entry *fatent)
{
	if (sbi->fatent_ops->ent_next(fatent)) {
		if (fatent->entry < sbi->max_cluster)
			return 1;
	}
	return 0;
}

static inline int fat_ent_read_block(struct super_block *sb,
				     struct fat_entry *fatent)
{
	struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
	sector_t blocknr;
	int offset;

	fatent_brelse(fatent);
	ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
	return ops->ent_bread(sb, fatent, offset, blocknr);
}

static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
			    struct fat_entry *fatent)
{
	int n, i;

	for (n = 0; n < fatent->nr_bhs; n++) {
		for (i = 0; i < *nr_bhs; i++) {
			if (fatent->bhs[n] == bhs[i])
				break;
		}
		if (i == *nr_bhs) {
			get_bh(fatent->bhs[n]);
			bhs[i] = fatent->bhs[n];
			(*nr_bhs)++;
		}
	}
}

int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct fatent_operations *ops = sbi->fatent_ops;
	struct fat_entry fatent, prev_ent;
	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
	int i, count, err, nr_bhs, idx_clus;

	BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2));	/* fixed limit */

	lock_fat(sbi);
	if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) {
		unlock_fat(sbi);
		return -ENOSPC;
	}

	err = nr_bhs = idx_clus = 0;
	count = FAT_START_ENT;
	fatent_init(&prev_ent);
	fatent_init(&fatent);
	fatent_set_entry(&fatent, sbi->prev_free + 1);
	while (count < sbi->max_cluster) {
		if (fatent.entry >= sbi->max_cluster)
			fatent.entry = FAT_START_ENT;
		fatent_set_entry(&fatent, fatent.entry);
		err = fat_ent_read_block(sb, &fatent);
		if (err)
			goto out;

		/* Find the free entries in a block */
		do {
			if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
				int entry = fatent.entry;

				/* make the cluster chain */
				ops->ent_put(&fatent, FAT_ENT_EOF);
				if (prev_ent.nr_bhs)
					ops->ent_put(&prev_ent, entry);

				fat_collect_bhs(bhs, &nr_bhs, &fatent);

				sbi->prev_free = entry;
				if (sbi->free_clusters != -1)
					sbi->free_clusters--;
				sb->s_dirt = 1;

				cluster[idx_clus] = entry;
				idx_clus++;
				if (idx_clus == nr_cluster)
					goto out;

				/*
				 * fat_collect_bhs() gets ref-count of bhs,
				 * so we can still use the prev_ent.
				 */
				prev_ent = fatent;
			}
			count++;
			if (count == sbi->max_cluster)
				break;
		} while (fat_ent_next(sbi, &fatent));
	}

	/* Couldn't allocate the free entries */
	sbi->free_clusters = 0;
	sb->s_dirt = 1;
	err = -ENOSPC;

out:
	unlock_fat(sbi);
	fatent_brelse(&fatent);
	if (!err) {
		if (inode_needs_sync(inode))
			err = fat_sync_bhs(bhs, nr_bhs);
		if (!err)
			err = fat_mirror_bhs(sb, bhs, nr_bhs);
	}
	for (i = 0; i < nr_bhs; i++)
		brelse(bhs[i]);

	if (err && idx_clus)
		fat_free_clusters(inode, cluster[0]);

	return err;
}

int fat_free_clusters(struct inode *inode, int cluster)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct fatent_operations *ops = sbi->fatent_ops;
	struct fat_entry fatent;
	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
	int i, err, nr_bhs;

	nr_bhs = 0;
	fatent_init(&fatent);
	lock_fat(sbi);
	do {
		cluster = fat_ent_read(inode, &fatent, cluster);
		if (cluster < 0) {
			err = cluster;
			goto error;
		} else if (cluster == FAT_ENT_FREE) {
			fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
				     __FUNCTION__);
			err = -EIO;
			goto error;
		}

		ops->ent_put(&fatent, FAT_ENT_FREE);
		if (sbi->free_clusters != -1) {
			sbi->free_clusters++;
			sb->s_dirt = 1;
		}

		if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
			if (sb->s_flags & MS_SYNCHRONOUS) {
				err = fat_sync_bhs(bhs, nr_bhs);
				if (err)
					goto error;
			}
			err = fat_mirror_bhs(sb, bhs, nr_bhs);
			if (err)
				goto error;
			for (i = 0; i < nr_bhs; i++)
				brelse(bhs[i]);
			nr_bhs = 0;
		}
		fat_collect_bhs(bhs, &nr_bhs, &fatent);
	} while (cluster != FAT_ENT_EOF);

	if (sb->s_flags & MS_SYNCHRONOUS) {
		err = fat_sync_bhs(bhs, nr_bhs);
		if (err)
			goto error;
	}
	err = fat_mirror_bhs(sb, bhs, nr_bhs);
error:
	fatent_brelse(&fatent);
	for (i = 0; i < nr_bhs; i++)
		brelse(bhs[i]);
	unlock_fat(sbi);

	fat_clusters_flush(sb);

	return err;
}

EXPORT_SYMBOL_GPL(fat_free_clusters);

int fat_count_free_clusters(struct super_block *sb)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct fatent_operations *ops = sbi->fatent_ops;
	struct fat_entry fatent;
	int err = 0, free;

	lock_fat(sbi);
	if (sbi->free_clusters != -1)
		goto out;

	free = 0;
	fatent_init(&fatent);
	fatent_set_entry(&fatent, FAT_START_ENT);
	while (fatent.entry < sbi->max_cluster) {
		err = fat_ent_read_block(sb, &fatent);
		if (err)
			goto out;

		do {
			if (ops->ent_get(&fatent) == FAT_ENT_FREE)
				free++;
		} while (fat_ent_next(sbi, &fatent));
	}
	sbi->free_clusters = free;
	sb->s_dirt = 1;
	fatent_brelse(&fatent);
out:
	unlock_fat(sbi);
	return err;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2004, OGAWA Hirofumi
	3	* Released under GPL v2.
	4	*/
	5
	6	#include <linux/module.h>
	7	#include <linux/fs.h>
	8	#include <linux/msdos_fs.h>
	9
	10	struct fatent_operations {
	11	void (ent_blocknr)(struct super_block , int, int , sector_t );
	12	void (ent_set_ptr)(struct fat_entry , int);
	13	int (ent_bread)(struct super_block , struct fat_entry *,
	14	int, sector_t);
	15	int (ent_get)(struct fat_entry );
	16	void (ent_put)(struct fat_entry , int);
	17	int (ent_next)(struct fat_entry );
	18	};
	19
	20	static void fat12_ent_blocknr(struct super_block *sb, int entry,
	21	int offset, sector_t blocknr)
	22	{
	23	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	24	int bytes = entry + (entry >> 1);
	25	WARN_ON(entry < FAT_START_ENT \|\| sbi->max_cluster <= entry);
	26	*offset = bytes & (sb->s_blocksize - 1);
	27	*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
	28	}
	29
	30	static void fat_ent_blocknr(struct super_block *sb, int entry,
	31	int offset, sector_t blocknr)
	32	{
	33	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	34	int bytes = (entry << sbi->fatent_shift);
	35	WARN_ON(entry < FAT_START_ENT \|\| sbi->max_cluster <= entry);
	36	*offset = bytes & (sb->s_blocksize - 1);
	37	*blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
	38	}
	39
	40	static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
	41	{
	42	struct buffer_head **bhs = fatent->bhs;
	43	if (fatent->nr_bhs == 1) {
	44	WARN_ON(offset >= (bhs[0]->b_size - 1));
	45	fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
	46	fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
	47	} else {
	48	WARN_ON(offset != (bhs[0]->b_size - 1));
	49	fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
	50	fatent->u.ent12_p[1] = bhs[1]->b_data;
	51	}
	52	}
	53
	54	static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
	55	{
	56	WARN_ON(offset & (2 - 1));
	57	fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
	58	}
	59
	60	static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
	61	{
	62	WARN_ON(offset & (4 - 1));
	63	fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
	64	}
65
66	static int fat12_ent_bread(struct super_block sb, struct fat_entry fatent,
67	int offset, sector_t blocknr)
68	{
69	struct buffer_head **bhs = fatent->bhs;
70
71	WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
72	bhs[0] = sb_bread(sb, blocknr);
73	if (!bhs[0])
74	goto err;
75
76	if ((offset + 1) < sb->s_blocksize)
77	fatent->nr_bhs = 1;
78	else {
79	/* This entry is block boundary, it needs the next block */
80	blocknr++;
81	bhs[1] = sb_bread(sb, blocknr);
82	if (!bhs[1])
83	goto err_brelse;
84	fatent->nr_bhs = 2;
85	}
86	fat12_ent_set_ptr(fatent, offset);
87	return 0;
88
89	err_brelse:
90	brelse(bhs[0]);
91	err:
92	printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
93	(unsigned long long)blocknr);
94	return -EIO;
95	}
96
97	static int fat_ent_bread(struct super_block sb, struct fat_entry fatent,
98	int offset, sector_t blocknr)
99	{
100	struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
101
102	WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
103	fatent->bhs[0] = sb_bread(sb, blocknr);
104	if (!fatent->bhs[0]) {
105	printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
106	(unsigned long long)blocknr);
107	return -EIO;
108	}
109	fatent->nr_bhs = 1;
110	ops->ent_set_ptr(fatent, offset);
111	return 0;
112	}
113
114	static int fat12_ent_get(struct fat_entry *fatent)
115	{
116	u8 **ent12_p = fatent->u.ent12_p;
117	int next;
118
119	if (fatent->entry & 1)
120	next = (ent12_p[0] >> 4) \| (ent12_p[1] << 4);
121	else
122	next = (ent12_p[1] << 8) \| ent12_p[0];
123	next &= 0x0fff;
124	if (next >= BAD_FAT12)
125	next = FAT_ENT_EOF;
126	return next;
127	}
128
129	static int fat16_ent_get(struct fat_entry *fatent)
130	{
131	int next = le16_to_cpu(*fatent->u.ent16_p);
132	WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
133	if (next >= BAD_FAT16)
134	next = FAT_ENT_EOF;
135	return next;
136	}
137
138	static int fat32_ent_get(struct fat_entry *fatent)
139	{
140	int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
141	WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
142	if (next >= BAD_FAT32)
143	next = FAT_ENT_EOF;
144	return next;
145	}
146
147	static void fat12_ent_put(struct fat_entry *fatent, int new)
148	{
149	u8 **ent12_p = fatent->u.ent12_p;
150
151	if (new == FAT_ENT_EOF)
152	new = EOF_FAT12;
153
154	if (fatent->entry & 1) {
155	ent12_p[0] = (new << 4) \| (ent12_p[0] & 0x0f);
156	*ent12_p[1] = new >> 4;
157	} else {
158	*ent12_p[0] = new & 0xff;
159	ent12_p[1] = (ent12_p[1] & 0xf0) \| (new >> 8);
160	}
161
162	mark_buffer_dirty(fatent->bhs[0]);
163	if (fatent->nr_bhs == 2)
164	mark_buffer_dirty(fatent->bhs[1]);
165	}
166
167	static void fat16_ent_put(struct fat_entry *fatent, int new)
168	{
169	if (new == FAT_ENT_EOF)
170	new = EOF_FAT16;
171
172	*fatent->u.ent16_p = cpu_to_le16(new);
173	mark_buffer_dirty(fatent->bhs[0]);
174	}
175
176	static void fat32_ent_put(struct fat_entry *fatent, int new)
177	{
178	if (new == FAT_ENT_EOF)
179	new = EOF_FAT32;
180
181	WARN_ON(new & 0xf0000000);
182	new \|= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
183	*fatent->u.ent32_p = cpu_to_le32(new);
184	mark_buffer_dirty(fatent->bhs[0]);
185	}
186
187	static int fat12_ent_next(struct fat_entry *fatent)
188	{
189	u8 **ent12_p = fatent->u.ent12_p;
190	struct buffer_head **bhs = fatent->bhs;
191	u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
192
193	fatent->entry++;
194	if (fatent->nr_bhs == 1) {
195	WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
196	WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
197	if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
198	ent12_p[0] = nextp - 1;
199	ent12_p[1] = nextp;
200	return 1;
201	}
202	} else {
203	WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
204	WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
205	ent12_p[0] = nextp - 1;
206	ent12_p[1] = nextp;
207	brelse(bhs[0]);
208	bhs[0] = bhs[1];
209	fatent->nr_bhs = 1;
210	return 1;
211	}
212	ent12_p[0] = NULL;
213	ent12_p[1] = NULL;
214	return 0;
215	}
216
217	static int fat16_ent_next(struct fat_entry *fatent)
218	{
219	const struct buffer_head *bh = fatent->bhs[0];
220	fatent->entry++;
221	if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
222	fatent->u.ent16_p++;
223	return 1;
224	}
225	fatent->u.ent16_p = NULL;
226	return 0;
227	}
228
229	static int fat32_ent_next(struct fat_entry *fatent)
230	{
231	const struct buffer_head *bh = fatent->bhs[0];
232	fatent->entry++;
233	if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
234	fatent->u.ent32_p++;
235	return 1;
236	}
237	fatent->u.ent32_p = NULL;
238	return 0;
239	}
240
241	static struct fatent_operations fat12_ops = {
242	.ent_blocknr = fat12_ent_blocknr,
243	.ent_set_ptr = fat12_ent_set_ptr,
244	.ent_bread = fat12_ent_bread,
245	.ent_get = fat12_ent_get,
246	.ent_put = fat12_ent_put,
247	.ent_next = fat12_ent_next,
248	};
249
250	static struct fatent_operations fat16_ops = {
251	.ent_blocknr = fat_ent_blocknr,
252	.ent_set_ptr = fat16_ent_set_ptr,
253	.ent_bread = fat_ent_bread,
254	.ent_get = fat16_ent_get,
255	.ent_put = fat16_ent_put,
256	.ent_next = fat16_ent_next,
257	};
258
259	static struct fatent_operations fat32_ops = {
260	.ent_blocknr = fat_ent_blocknr,
261	.ent_set_ptr = fat32_ent_set_ptr,
262	.ent_bread = fat_ent_bread,
263	.ent_get = fat32_ent_get,
264	.ent_put = fat32_ent_put,
265	.ent_next = fat32_ent_next,
266	};
267
268	static inline void lock_fat(struct msdos_sb_info *sbi)
269	{
6b9438e1	270	mutex_lock(&sbi->fat_lock);
1da177e4 LT	271	}
	272
	273	static inline void unlock_fat(struct msdos_sb_info *sbi)
	274	{
6b9438e1	275	mutex_unlock(&sbi->fat_lock);
1da177e4 LT	276	}
	277
	278	void fat_ent_access_init(struct super_block *sb)
	279	{
	280	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	281
6b9438e1	282	mutex_init(&sbi->fat_lock);
1da177e4 LT	283
	284	switch (sbi->fat_bits) {
	285	case 32:
	286	sbi->fatent_shift = 2;
	287	sbi->fatent_ops = &fat32_ops;
	288	break;
	289	case 16:
	290	sbi->fatent_shift = 1;
	291	sbi->fatent_ops = &fat16_ops;
	292	break;
	293	case 12:
	294	sbi->fatent_shift = -1;
	295	sbi->fatent_ops = &fat12_ops;
	296	break;
	297	}
	298	}
	299
	300	static inline int fat_ent_update_ptr(struct super_block *sb,
	301	struct fat_entry *fatent,
	302	int offset, sector_t blocknr)
	303	{
	304	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	305	struct fatent_operations *ops = sbi->fatent_ops;
	306	struct buffer_head **bhs = fatent->bhs;
	307
	308	/* Is this fatent's blocks including this entry? */
	309	if (!fatent->nr_bhs \|\| bhs[0]->b_blocknr != blocknr)
	310	return 0;
	311	/* Does this entry need the next block? */
	312	if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
	313	if (fatent->nr_bhs != 2 \|\| bhs[1]->b_blocknr != (blocknr + 1))
	314	return 0;
	315	}
	316	ops->ent_set_ptr(fatent, offset);
	317	return 1;
	318	}
	319
	320	int fat_ent_read(struct inode inode, struct fat_entry fatent, int entry)
	321	{
	322	struct super_block *sb = inode->i_sb;
	323	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
	324	struct fatent_operations *ops = sbi->fatent_ops;
	325	int err, offset;
	326	sector_t blocknr;
	327
	328	if (entry < FAT_START_ENT \|\| sbi->max_cluster <= entry) {
	329	fatent_brelse(fatent);
	330	fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
	331	return -EIO;
	332	}
	333
	334	fatent_set_entry(fatent, entry);
	335	ops->ent_blocknr(sb, entry, &offset, &blocknr);
	336
	337	if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
	338	fatent_brelse(fatent);
	339	err = ops->ent_bread(sb, fatent, offset, blocknr);
	340	if (err)
	341	return err;
	342	}
	343	return ops->ent_get(fatent);
	344	}
	345
	346	/* FIXME: We can write the blocks as more big chunk. */
347	static int fat_mirror_bhs(struct super_block sb, struct buffer_head *bhs,
348	int nr_bhs)
349	{
350	struct msdos_sb_info *sbi = MSDOS_SB(sb);
351	struct buffer_head *c_bh;
352	int err, n, copy;
353
354	err = 0;
355	for (copy = 1; copy < sbi->fats; copy++) {
356	sector_t backup_fat = sbi->fat_length * copy;
357
358	for (n = 0; n < nr_bhs; n++) {
359	c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
360	if (!c_bh) {
361	err = -ENOMEM;
362	goto error;
363	}
364	memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
365	set_buffer_uptodate(c_bh);
366	mark_buffer_dirty(c_bh);
367	if (sb->s_flags & MS_SYNCHRONOUS)
368	err = sync_dirty_buffer(c_bh);
369	brelse(c_bh);
370	if (err)
371	goto error;
372	}
373	}
374	error:
375	return err;
376	}
377
378	int fat_ent_write(struct inode inode, struct fat_entry fatent,
379	int new, int wait)
380	{
381	struct super_block *sb = inode->i_sb;
382	struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
383	int err;
384
385	ops->ent_put(fatent, new);
386	if (wait) {
387	err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
388	if (err)
389	return err;
390	}
391	return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
392	}
393
394	static inline int fat_ent_next(struct msdos_sb_info *sbi,
395	struct fat_entry *fatent)
396	{
397	if (sbi->fatent_ops->ent_next(fatent)) {
398	if (fatent->entry < sbi->max_cluster)
399	return 1;
400	}
401	return 0;
402	}
403
404	static inline int fat_ent_read_block(struct super_block *sb,
405	struct fat_entry *fatent)
406	{
407	struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
408	sector_t blocknr;
409	int offset;
410
411	fatent_brelse(fatent);
412	ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
413	return ops->ent_bread(sb, fatent, offset, blocknr);
414	}
415
416	static void fat_collect_bhs(struct buffer_head *bhs, int nr_bhs,
417	struct fat_entry *fatent)
418	{
419	int n, i;
420
421	for (n = 0; n < fatent->nr_bhs; n++) {
422	for (i = 0; i < *nr_bhs; i++) {
423	if (fatent->bhs[n] == bhs[i])
424	break;
425	}
426	if (i == *nr_bhs) {
427	get_bh(fatent->bhs[n]);
428	bhs[i] = fatent->bhs[n];
429	(*nr_bhs)++;
430	}
431	}
432	}
433
434	int fat_alloc_clusters(struct inode inode, int cluster, int nr_cluster)
435	{
436	struct super_block *sb = inode->i_sb;
437	struct msdos_sb_info *sbi = MSDOS_SB(sb);
438	struct fatent_operations *ops = sbi->fatent_ops;
439	struct fat_entry fatent, prev_ent;
440	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
441	int i, count, err, nr_bhs, idx_clus;
442
443	BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2)); /* fixed limit */
444
445	lock_fat(sbi);
446	if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) {
447	unlock_fat(sbi);
448	return -ENOSPC;
449	}
450
451	err = nr_bhs = idx_clus = 0;
452	count = FAT_START_ENT;
453	fatent_init(&prev_ent);
454	fatent_init(&fatent);
455	fatent_set_entry(&fatent, sbi->prev_free + 1);
456	while (count < sbi->max_cluster) {
457	if (fatent.entry >= sbi->max_cluster)
458	fatent.entry = FAT_START_ENT;
459	fatent_set_entry(&fatent, fatent.entry);
460	err = fat_ent_read_block(sb, &fatent);
461	if (err)
462	goto out;
463
464	/* Find the free entries in a block */
465	do {
466	if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
467	int entry = fatent.entry;
468
469	/* make the cluster chain */
470	ops->ent_put(&fatent, FAT_ENT_EOF);
471	if (prev_ent.nr_bhs)
472	ops->ent_put(&prev_ent, entry);
473
474	fat_collect_bhs(bhs, &nr_bhs, &fatent);
475
476	sbi->prev_free = entry;
477	if (sbi->free_clusters != -1)
478	sbi->free_clusters--;
a6bf6b21	479	sb->s_dirt = 1;
1da177e4 LT	480
	481	cluster[idx_clus] = entry;
	482	idx_clus++;
	483	if (idx_clus == nr_cluster)
	484	goto out;
	485
	486	/*
	487	* fat_collect_bhs() gets ref-count of bhs,
	488	* so we can still use the prev_ent.
	489	*/
	490	prev_ent = fatent;
	491	}
	492	count++;
	493	if (count == sbi->max_cluster)
	494	break;
	495	} while (fat_ent_next(sbi, &fatent));
	496	}
	497
	498	/* Couldn't allocate the free entries */
	499	sbi->free_clusters = 0;
a6bf6b21	500	sb->s_dirt = 1;
1da177e4 LT	501	err = -ENOSPC;
	502
	503	out:
	504	unlock_fat(sbi);
	505	fatent_brelse(&fatent);
	506	if (!err) {
	507	if (inode_needs_sync(inode))
	508	err = fat_sync_bhs(bhs, nr_bhs);
	509	if (!err)
	510	err = fat_mirror_bhs(sb, bhs, nr_bhs);
	511	}
	512	for (i = 0; i < nr_bhs; i++)
	513	brelse(bhs[i]);
1da177e4 LT	514
	515	if (err && idx_clus)
	516	fat_free_clusters(inode, cluster[0]);
	517
	518	return err;
	519	}
	520
	521	int fat_free_clusters(struct inode *inode, int cluster)
	522	{
	523	struct super_block *sb = inode->i_sb;
	524	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	525	struct fatent_operations *ops = sbi->fatent_ops;
	526	struct fat_entry fatent;
	527	struct buffer_head *bhs[MAX_BUF_PER_PAGE];
	528	int i, err, nr_bhs;
	529
	530	nr_bhs = 0;
	531	fatent_init(&fatent);
	532	lock_fat(sbi);
	533	do {
	534	cluster = fat_ent_read(inode, &fatent, cluster);
	535	if (cluster < 0) {
	536	err = cluster;
	537	goto error;
	538	} else if (cluster == FAT_ENT_FREE) {
	539	fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
	540	__FUNCTION__);
	541	err = -EIO;
	542	goto error;
	543	}
	544
	545	ops->ent_put(&fatent, FAT_ENT_FREE);
a6bf6b21	546	if (sbi->free_clusters != -1) {
1da177e4	547	sbi->free_clusters++;
a6bf6b21 OH	548	sb->s_dirt = 1;
a6bf6b21 OH	549	}
1da177e4 LT	550
	551	if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
	552	if (sb->s_flags & MS_SYNCHRONOUS) {
	553	err = fat_sync_bhs(bhs, nr_bhs);
	554	if (err)
	555	goto error;
	556	}
	557	err = fat_mirror_bhs(sb, bhs, nr_bhs);
	558	if (err)
	559	goto error;
	560	for (i = 0; i < nr_bhs; i++)
	561	brelse(bhs[i]);
	562	nr_bhs = 0;
	563	}
	564	fat_collect_bhs(bhs, &nr_bhs, &fatent);
	565	} while (cluster != FAT_ENT_EOF);
	566
	567	if (sb->s_flags & MS_SYNCHRONOUS) {
	568	err = fat_sync_bhs(bhs, nr_bhs);
	569	if (err)
	570	goto error;
	571	}
	572	err = fat_mirror_bhs(sb, bhs, nr_bhs);
	573	error:
	574	fatent_brelse(&fatent);
	575	for (i = 0; i < nr_bhs; i++)
	576	brelse(bhs[i]);
	577	unlock_fat(sbi);
	578
	579	fat_clusters_flush(sb);
	580
	581	return err;
	582	}
	583
7c709d00	584	EXPORT_SYMBOL_GPL(fat_free_clusters);
1da177e4 LT	585
	586	int fat_count_free_clusters(struct super_block *sb)
	587	{
	588	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	589	struct fatent_operations *ops = sbi->fatent_ops;
	590	struct fat_entry fatent;
	591	int err = 0, free;
	592
	593	lock_fat(sbi);
	594	if (sbi->free_clusters != -1)
	595	goto out;
	596
	597	free = 0;
	598	fatent_init(&fatent);
	599	fatent_set_entry(&fatent, FAT_START_ENT);
	600	while (fatent.entry < sbi->max_cluster) {
	601	err = fat_ent_read_block(sb, &fatent);
	602	if (err)
	603	goto out;
	604
	605	do {
	606	if (ops->ent_get(&fatent) == FAT_ENT_FREE)
	607	free++;
	608	} while (fat_ent_next(sbi, &fatent));
	609	}
	610	sbi->free_clusters = free;
a6bf6b21	611	sb->s_dirt = 1;
1da177e4 LT	612	fatent_brelse(&fatent);
	613	out:
	614	unlock_fat(sbi);
	615	return err;
	616	}