This is a note to let you know that I've just added the patch titled f2fs: fix to set/clear I_LINKABLE under i_lock to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: f2fs-fix-to-set-clear-i_linkable-under-i_lock.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 2aa50353291cd0570e5ce7d492e17251718ea79e Author: Chao Yu <yuchao0@xxxxxxxxxx> Date: Tue Jan 12 09:55:09 2021 +0800 f2fs: fix to set/clear I_LINKABLE under i_lock [ Upstream commit 46085f37fc9e12d5c3539fb768b5ad7951e72acf ] fsstress + fault injection test case reports a warning message as below: WARNING: CPU: 13 PID: 6226 at fs/inode.c:361 inc_nlink+0x32/0x40 Call Trace: f2fs_init_inode_metadata+0x25c/0x4a0 [f2fs] f2fs_add_inline_entry+0x153/0x3b0 [f2fs] f2fs_add_dentry+0x75/0x80 [f2fs] f2fs_do_add_link+0x108/0x160 [f2fs] f2fs_rename2+0x6ab/0x14f0 [f2fs] vfs_rename+0x70c/0x940 do_renameat2+0x4d8/0x4f0 __x64_sys_renameat2+0x4b/0x60 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Following race case can cause this: Thread A Kworker - f2fs_rename - f2fs_create_whiteout - __f2fs_tmpfile - f2fs_i_links_write - f2fs_mark_inode_dirty_sync - mark_inode_dirty_sync - writeback_single_inode - __writeback_single_inode - spin_lock(&inode->i_lock) - inode->i_state |= I_LINKABLE - inode->i_state &= ~dirty - spin_unlock(&inode->i_lock) - f2fs_add_link - f2fs_do_add_link - f2fs_add_dentry - f2fs_add_inline_entry - f2fs_init_inode_metadata - f2fs_i_links_write - inc_nlink - WARN_ON(!(inode->i_state & I_LINKABLE)) Fix to add i_lock to avoid i_state update race condition. Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c index 5d9584281935..3a97ac56821b 100644 --- a/fs/f2fs/namei.c +++ b/fs/f2fs/namei.c @@ -797,7 +797,11 @@ static int __f2fs_tmpfile(struct inode *dir, struct dentry *dentry, if (whiteout) { f2fs_i_links_write(inode, false); + + spin_lock(&inode->i_lock); inode->i_state |= I_LINKABLE; + spin_unlock(&inode->i_lock); + *whiteout = inode; } else { d_tmpfile(dentry, inode); @@ -996,7 +1000,11 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry, err = f2fs_add_link(old_dentry, whiteout); if (err) goto put_out_dir; + + spin_lock(&whiteout->i_lock); whiteout->i_state &= ~I_LINKABLE; + spin_unlock(&whiteout->i_lock); + iput(whiteout); }