From: Long Li leo.lilong@huawei.com
[ Upstream commit 28b4b0596343d19d140da059eee0e5c2b5328731 ]
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 Signed-off-by: Leah Rumancik leah.rumancik@gmail.com Acked-by: Darrick J. Wong djwong@kernel.org --- fs/xfs/xfs_icache.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index d884cba1d707..dd5a664c294f 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 @@ -523,6 +527,8 @@ 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 {