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| author | Huiwen He <hehuiwen@kylinos.cn> | 2026-06-24 10:15:46 +0800 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2026-06-24 16:48:56 -0500 |
| commit | 99cd0a6eeb6c20fc6b914e7ce192c6b08e1ef906 (patch) | |
| tree | b117e50e617b7f445ea32a9a64583e262706e788 /fs | |
| parent | 2a4b3d2db5c6fcdba889baf7b2ae5661b0beac89 (diff) | |
| download | ath-99cd0a6eeb6c20fc6b914e7ce192c6b08e1ef906.tar.gz | |
smb/client: do not account EOF extension as allocation
cifs_setsize() updates the local inode size after SetEOF succeeds. It also
used the new EOF as a local i_blocks estimate, but extending EOF does not
prove that the intervening range was allocated.
For example, after writing 1 MiB and then extending EOF to 10 MiB, the
client can report the file as fully allocated even though the server still
reports a much smaller AllocationSize:
$ dd if=/dev/zero of=test bs=1M count=1
$ truncate -s 10M test && stat -c 'size=%s blocks=%b' test
$ stat --cached=never -c 'size=%s blocks=%b' test
client stat: size=10485760 blocks=20480
server stat: size=10485760 blocks=2056
client stat after revalidation: size=10485760 blocks=2056
A later attribute revalidation may correct i_blocks, but callers such as
xfstests generic/495 invoke swapon immediately after truncate. The swapfile
hole check can therefore observe the inflated local i_blocks value and
accept a sparse file.
Do not grow i_blocks from cifs_setsize() on EOF extension. Only clamp it
on shrink; allocation growth must come from write completion or from
server-reported AllocationSize.
With this change, EOF extension no longer makes a sparse file appear
fully allocated before the next attribute revalidation, and xfstests
generic/495 no longer accepts it through the inflated local i_blocks value.
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/smb/client/inode.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c index 56b0f109e41b4..1dbcfd163ff06 100644 --- a/fs/smb/client/inode.c +++ b/fs/smb/client/inode.c @@ -3038,13 +3038,20 @@ int cifs_fiemap(struct inode *inode, struct fiemap_extent_info *fei, u64 start, void cifs_setsize(struct inode *inode, loff_t offset) { + loff_t old_size; + u64 blocks = CIFS_INO_BLOCKS(offset); + spin_lock(&inode->i_lock); + old_size = i_size_read(inode); i_size_write(inode, offset); + /* - * Until we can query the server for actual allocation size, - * this is best estimate we have for blocks allocated for a file. + * Extending EOF does not allocate the intervening range. Only clamp + * i_blocks on shrink; allocation growth comes from writes or from the + * server-reported AllocationSize. */ - inode->i_blocks = CIFS_INO_BLOCKS(offset); + if (offset < old_size && (u64)inode->i_blocks > blocks) + inode->i_blocks = blocks; spin_unlock(&inode->i_lock); inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); truncate_pagecache(inode, offset); |