From: Christoph Hellwig <hch@lst.de>
Date: Wed, 30 Apr 2025 21:26:50 +0000 (-0700)
Subject: xfs: remove a racy if_bytes check in xfs_reflink_end_cow_extent
X-Git-Tag: v6.1.138~72
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2edfd2c87c56a231f1c617703511c47065a3f39b;p=thirdparty%2Fkernel%2Fstable.git

xfs: remove a racy if_bytes check in xfs_reflink_end_cow_extent

[ Upstream commit 86de848403abda05bf9c16dcdb6bef65a8d88c41 ]

Accessing if_bytes without the ilock is racy.  Remove the initial
if_bytes == 0 check in xfs_reflink_end_cow_extent and let
ext_iext_lookup_extent fail for this case after we've taken the ilock.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Acked-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 0405226fb74c8..d539487eaf1a7 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -718,12 +718,6 @@ xfs_reflink_end_cow_extent(
 	int			nmaps;
 	int			error;
 
-	/* No COW extents?  That's easy! */
-	if (ifp->if_bytes == 0) {
-		*offset_fsb = end_fsb;
-		return 0;
-	}
-
 	resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
 			XFS_TRANS_RESERVE, &tp);