[PATCH v1 3/3] btrfs: replace kmalloc() and memcpy() with kmemdup()

[Mirsad Todorovac]

The static analyser tool gave the following advice:

./fs/btrfs/ioctl.c:4987:9-16: WARNING opportunity for kmemdup

   4986                 if (!iov) {
 → 4987                         iov = kmalloc(sizeof(struct iovec) * args.iovcnt, GFP_NOFS);
   4988                         if (!iov) {
   4989                                 unlock_extent(io_tree, start, lockend, &cached_state);
   4990                                 btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
   4991                                 ret = -ENOMEM;
   4992                                 goto out_acct;
   4993                         }
   4994
 → 4995                         memcpy(iov, iovstack, sizeof(struct iovec) * args.iovcnt);
   4996                 }

Replacing kmalloc() + memcpy() with kmemdump() doesn't change semantics.
Original code works without fault, so this is not a bug fix but proposed improvement.

Link: https://lwn.net/Articles/198928/
Fixes: 34310c442e175 ("btrfs: add io_uring command for encoded reads (ENCODED_READ ioctl)")
Cc: Chris Mason <clm@xxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: linux-btrfs@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Mirsad Todorovac <mtodorovac69@xxxxxxxxx>
---
 v1:
	initial version.

 fs/btrfs/ioctl.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3af8bb0c8d75..c2f769334d3c 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4984,15 +4984,13 @@ static int btrfs_uring_encoded_read(struct io_uring_cmd *cmd, unsigned int issue
 		 * undo this.
 		 */
 		if (!iov) {
-			iov = kmalloc(sizeof(struct iovec) * args.iovcnt, GFP_NOFS);
+			iov = kmemdup(iovstack, sizeof(struct iovec) * args.iovcnt, GFP_NOFS);
 			if (!iov) {
 				unlock_extent(io_tree, start, lockend, &cached_state);
 				btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
 				ret = -ENOMEM;
 				goto out_acct;
 			}
-
-			memcpy(iov, iovstack, sizeof(struct iovec) * args.iovcnt);
 		}
 
 		count = min_t(u64, iov_iter_count(&iter), disk_io_size);
-- 
2.43.0