smb3: update allocation size more accurately on write completion

Changes to allocation size are approximated for extending writes of cached
files until the server returns the actual value (on SMB3 close or query info
for example), but it was setting the estimated value for number of blocks
to larger than the file size even if the file is likely sparse which
breaks various xfstests (e.g. generic/129, 130, 221, 228).

When i_size and i_blocks are updated in write completion do not increase
allocation size more than what was written (rounded up to 512 bytes).

Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 9cff5f7dc062ee671d514c499c5ddf8193dc2e6a..24534b7e3aca84bfd93bd718b4523607fbb6b3bb 100644 (file)
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -3094,8 +3094,15 @@ static int cifs_write_end(struct file *file, struct address_space *mapping,
        if (rc > 0) {
                spin_lock(&inode->i_lock);
                if (pos > inode->i_size) {
+                       loff_t additional_blocks = (512 - 1 + copied) >> 9;
+
                        i_size_write(inode, pos);
-                       inode->i_blocks = (512 - 1 + pos) >> 9;
+                       /*
+                        * Estimate new allocation size based on the amount written.
+                        * This will be updated from server on close (and on queryinfo)
+                        */
+                       inode->i_blocks = min_t(blkcnt_t, (512 - 1 + pos) >> 9,
+                                               inode->i_blocks + additional_blocks);
                }
                spin_unlock(&inode->i_lock);
        }