fs/9p/vfs_addr.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * This file contians vfs address (mmap) ops for 9P2000.
   4  *
   5  *  Copyright (C) 2005 by Eric Van Hensbergen <[email protected]>
   6  *  Copyright (C) 2002 by Ron Minnich <[email protected]>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/errno.h>
  11 #include <linux/fs.h>
  12 #include <linux/file.h>
  13 #include <linux/stat.h>
  14 #include <linux/string.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/sched.h>
  17 #include <linux/swap.h>
  18 #include <linux/uio.h>
  19 #include <linux/netfs.h>
  20 #include <net/9p/9p.h>
  21 #include <net/9p/client.h>
  22 #include <trace/events/netfs.h>
  23
  24 #include "v9fs.h"
  25 #include "v9fs_vfs.h"
  26 #include "cache.h"
  27 #include "fid.h"
  28
  29 /*
  30  * Writeback calls this when it finds a folio that needs uploading.  This isn't
  31  * called if writeback only has copy-to-cache to deal with.
  32  */
  33 static void v9fs_begin_writeback(struct netfs_io_request *wreq)
  34 {
  35         struct p9_fid *fid;
  36
  37         fid = v9fs_fid_find_inode(wreq->inode, true, INVALID_UID, true);
  38         if (!fid) {
  39                 WARN_ONCE(1, "folio expected an open fid inode->i_ino=%lx\n",
  40                           wreq->inode->i_ino);
  41                 return;
  42         }
  43
  44         wreq->wsize = fid->clnt->msize - P9_IOHDRSZ;
  45         if (fid->iounit)
  46                 wreq->wsize = min(wreq->wsize, fid->iounit);
  47         wreq->netfs_priv = fid;
  48         wreq->io_streams[0].avail = true;
  49 }
  50
  51 /*
  52  * Issue a subrequest to write to the server.
  53  */
  54 static void v9fs_issue_write(struct netfs_io_subrequest *subreq)
  55 {
  56         struct p9_fid *fid = subreq->rreq->netfs_priv;
  57         int err, len;
  58
  59         len = p9_client_write(fid, subreq->start, &subreq->io_iter, &err);
  60         netfs_write_subrequest_terminated(subreq, len ?: err, false);
  61 }
  62
  63 /**
  64  * v9fs_issue_read - Issue a read from 9P
  65  * @subreq: The read to make
  66  */
  67 static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
  68 {
  69         struct netfs_io_request *rreq = subreq->rreq;
  70         struct p9_fid *fid = rreq->netfs_priv;
  71         int total, err;
  72
  73         total = p9_client_read(fid, subreq->start + subreq->transferred,
  74                                &subreq->io_iter, &err);
  75
  76         /* if we just extended the file size, any portion not in
  77          * cache won't be on server and is zeroes */
  78         __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
  79
  80         netfs_subreq_terminated(subreq, err ?: total, false);
  81 }
  82
  83 /**
  84  * v9fs_init_request - Initialise a request
  85  * @rreq: The read request
  86  * @file: The file being read from
  87  */
  88 static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
  89 {
  90         struct p9_fid *fid;
  91         bool writing = (rreq->origin == NETFS_READ_FOR_WRITE ||
  92                         rreq->origin == NETFS_WRITETHROUGH ||
  93                         rreq->origin == NETFS_UNBUFFERED_WRITE ||
  94                         rreq->origin == NETFS_DIO_WRITE);
  95
  96         if (rreq->origin == NETFS_WRITEBACK)
  97                 return 0; /* We don't get the write handle until we find we
  98                            * have actually dirty data and not just
  99                            * copy-to-cache data.
 100                            */
 101
 102         if (file) {
 103                 fid = file->private_data;
 104                 if (!fid)
 105                         goto no_fid;
 106                 p9_fid_get(fid);
 107         } else {
 108                 fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true);
 109                 if (!fid)
 110                         goto no_fid;
 111         }
 112
 113         rreq->wsize = fid->clnt->msize - P9_IOHDRSZ;
 114         if (fid->iounit)
 115                 rreq->wsize = min(rreq->wsize, fid->iounit);
 116
 117         /* we might need to read from a fid that was opened write-only
 118          * for read-modify-write of page cache, use the writeback fid
 119          * for that */
 120         WARN_ON(rreq->origin == NETFS_READ_FOR_WRITE && !(fid->mode & P9_ORDWR));
 121         rreq->netfs_priv = fid;
 122         return 0;
 123
 124 no_fid:
 125         WARN_ONCE(1, "folio expected an open fid inode->i_ino=%lx\n",
 126                   rreq->inode->i_ino);
 127         return -EINVAL;
 128 }
 129
 130 /**
 131  * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq
 132  * @rreq: The I/O request to clean up
 133  */
 134 static void v9fs_free_request(struct netfs_io_request *rreq)
 135 {
 136         struct p9_fid *fid = rreq->netfs_priv;
 137
 138         p9_fid_put(fid);
 139 }
 140
 141 const struct netfs_request_ops v9fs_req_ops = {
 142         .init_request           = v9fs_init_request,
 143         .free_request           = v9fs_free_request,
 144         .issue_read             = v9fs_issue_read,
 145         .begin_writeback        = v9fs_begin_writeback,
 146         .issue_write            = v9fs_issue_write,
 147 };
 148
 149 const struct address_space_operations v9fs_addr_operations = {
 150         .read_folio             = netfs_read_folio,
 151         .readahead              = netfs_readahead,
 152         .dirty_folio            = netfs_dirty_folio,
 153         .release_folio          = netfs_release_folio,
 154         .invalidate_folio       = netfs_invalidate_folio,
 155         .direct_IO              = noop_direct_IO,
 156         .writepages             = netfs_writepages,
 157 };