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authorLong Li <leo.lilong@huawei.com>2022-11-18 00:02:56 +0300
committerDarrick J. Wong <djwong@kernel.org>2022-11-21 21:00:01 +0300
commit28b4b0596343d19d140da059eee0e5c2b5328731 (patch)
treec33a8c9c5251fede2e7cafd56205187f909083d3 /fs/xfs
parent64c80dfd04d1dd2ecf550542c8f3f41b54b20207 (diff)
downloadlinux-28b4b0596343d19d140da059eee0e5c2b5328731.tar.xz
xfs: fix incorrect i_nlink caused by inode racing
The following error occurred during the fsstress test: XFS: Assertion failed: VFS_I(ip)->i_nlink >= 2, file: fs/xfs/xfs_inode.c, line: 2452 The problem was that inode race condition causes incorrect i_nlink to be written to disk, and then it is read into memory. Consider the following call graph, inodes that are marked as both XFS_IFLUSHING and XFS_IRECLAIMABLE, i_nlink will be reset to 1 and then restored to original value in xfs_reinit_inode(). Therefore, the i_nlink of directory on disk may be set to 1. xfsaild xfs_inode_item_push xfs_iflush_cluster xfs_iflush xfs_inode_to_disk xfs_iget xfs_iget_cache_hit xfs_iget_recycle xfs_reinit_inode inode_init_always xfs_reinit_inode() needs to hold the ILOCK_EXCL as it is changing internal inode state and can race with other RCU protected inode lookups. On the read side, xfs_iflush_cluster() grabs the ILOCK_SHARED while under rcu + ip->i_flags_lock, and so xfs_iflush/xfs_inode_to_disk() are protected from racing inode updates (during transactions) by that lock. Fixes: ff7bebeb91f8 ("xfs: refactor the inode recycling code") # goes further back than this Signed-off-by: Long Li <leo.lilong@huawei.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_icache.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index eae7427062cf..f35e2cee5265 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -342,6 +342,9 @@ xfs_iget_recycle(
trace_xfs_iget_recycle(ip);
+ if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
+ return -EAGAIN;
+
/*
* We need to make it look like the inode is being reclaimed to prevent
* the actual reclaim workers from stomping over us while we recycle
@@ -355,6 +358,7 @@ xfs_iget_recycle(
ASSERT(!rwsem_is_locked(&inode->i_rwsem));
error = xfs_reinit_inode(mp, inode);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
if (error) {
/*
* Re-initializing the inode failed, and we are in deep
@@ -518,6 +522,8 @@ xfs_iget_cache_hit(
if (ip->i_flags & XFS_IRECLAIMABLE) {
/* Drops i_flags_lock and RCU read lock. */
error = xfs_iget_recycle(pag, ip);
+ if (error == -EAGAIN)
+ goto out_skip;
if (error)
return error;
} else {