From: Long Li <leo.lilong@huawei.com> hulk inclusion category: bugfix bugzilla: 187286, https://gitee.com/openeuler/kernel/issues/I4KIAO CVE: NA -------------------------------- 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. Signed-off-by: Long Li <leo.lilong@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- 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 986d087df226..93e24f85eb8d 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -361,6 +361,9 @@ 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 @@ -374,6 +377,7 @@ xfs_iget_recycle( ASSERT(!rwsem_is_locked(&inode->i_rwsem)); error = xfs_reinit_inode(mp, inode); + xfs_iunlock(ip, XFS_ILOCK_EXCL); if (error) { bool wake; @@ -542,6 +546,8 @@ 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 { -- 2.20.1