[PATCH] ksmbd: Do not skip lock checks for single-byte ranges

[Guangshuo Li]

check_lock_range() uses inclusive ranges. Its callers pass the end
offset as start + length - 1, so start == end represents a valid
single-byte range rather than an empty range.

The start == end shortcut therefore skips mandatory byte-range lock
checks for one-byte reads, writes, copychunk operations and one-byte
truncate ranges. A conflicting lock covering that byte is not checked
and the operation is allowed to proceed.

Remove the shortcut. The truncate size == inode->i_size case is already
handled by only calling check_lock_range() when the new size differs
from the current file size.

Fixes: 5d510ac31626 ("ksmbd: skip lock-range check on equal size to avoid size==0 underflow")
Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
---
 fs/smb/server/vfs.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index f5fa22d87603..9605a25c93b1 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -297,9 +297,6 @@ static int check_lock_range(struct file *filp, loff_t start, loff_t end,
 	struct file_lock_context *ctx = locks_inode_context(file_inode(filp));
 	int error = 0;
 
-	if (start == end)
-		return 0;
-
 	if (!ctx || list_empty_careful(&ctx->flc_posix))
 		return 0;
 
-- 
2.43.0