ksmbd: avoid restoring only in-memory EOF after allocation change

When SetAllocation requests a size below the allocated block count but
above EOF, ksmbd truncates the file to that size and restores only the
in-memory i_size. The larger EOF remains on disk and reappears after a
reboot. A 3-byte file preallocated to 64 KiB can acquire a 4 KiB EOF
after reducing its allocation to 4 KiB. Extending EOF this way is not
a reliable way to reclaim the preallocation beyond the old EOF either.

Only use this truncate path when the requested allocation is at or below
the observed EOF. A truncate to the existing EOF still lets filesystems
release preallocated blocks beyond EOF. Remove the in-memory-only i_size
restoration. The size check still precedes vfs_truncate() taking the
inode lock, so a concurrent shrink can make the truncate extend EOF;
that race also existed in the original path.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

0 files changed, 0 insertions, 0 deletions