linux-kernel - [PATCH] xfs: removed useless condition in function xfs_attr_node

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Message-Id: <20220706133627.11198-1-strochuk@ispras.ru>
Date:   Wed,  6 Jul 2022 16:36:27 +0300
From:   Andrey Strachuk <strochuk@...ras.ru>
To:     "Darrick J. Wong" <djwong@...nel.org>
Cc:     Andrey Strachuk <strochuk@...ras.ru>,
        Dave Chinner <dchinner@...hat.com>,
        Allison Henderson <allison.henderson@...cle.com>,
        Chandan Babu R <chandan.babu@...cle.com>,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org
Subject: [PATCH] xfs: removed useless condition in function xfs_attr_node_get

At line 1561, variable "state" is being compared
with NULL every loop iteration.

-------------------------------------------------------------------
1561	for (i = 0; state != NULL && i < state->path.active; i++) {
1562		xfs_trans_brelse(args->trans, state->path.blk[i].bp);
1563		state->path.blk[i].bp = NULL;
1564	}
-------------------------------------------------------------------

However, it cannot be NULL.

----------------------------------------
1546	state = xfs_da_state_alloc(args);
----------------------------------------

xfs_da_state_alloc calls kmem_cache_zalloc. kmem_cache_zalloc is
called with __GFP_NOFAIL flag and, therefore, it cannot return NULL.

--------------------------------------------------------------------------
	struct xfs_da_state *
	xfs_da_state_alloc(
	struct xfs_da_args	*args)
	{
		struct xfs_da_state	*state;

		state = kmem_cache_zalloc(xfs_da_state_cache, GFP_NOFS | __GFP_NOFAIL);
		state->args = args;
		state->mp = args->dp->i_mount;
		return state;
	}
--------------------------------------------------------------------------

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Andrey Strachuk <strochuk@...ras.ru>

Fixes: 4d0cdd2bb8f0 ("xfs: clean up xfs_attr_node_hasname")
---
 fs/xfs/libxfs/xfs_attr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 224649a76cbb..6b8857e53add 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -1558,7 +1558,7 @@ xfs_attr_node_get(
 	 * If not in a transaction, we have to release all the buffers.
 	 */
 out_release:
-	for (i = 0; state != NULL && i < state->path.active; i++) {
+	for (i = 0; i < state->path.active; i++) {
 		xfs_trans_brelse(args->trans, state->path.blk[i].bp);
 		state->path.blk[i].bp = NULL;
 	}
-- 
2.25.1