[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 <c...@fb.com>
Cc: Josef Bacik <jo...@toxicpanda.com>
Cc: David Sterba <dste...@suse.com>
Cc: linux-bt...@vger.kernel.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Mirsad Todorovac <mtodorova...@gmail.com>
---
 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