[PATCH v3] writeback: Fix inode->i_io_list not be protected by inode->i_lock error

[Jchao Sun <sunjunchao2870@xxxxxxxxx>]

Commit b35250c0816c ("writeback: Protect inode->i_io_list with
inode->i_lock") made inode->i_io_list not only protected by
wb->list_lock but also inode->i_lock, but inode_io_list_move_locked()
was missed. Add lock there and also update comment describing things
protected by inode->i_lock.

Fixes: b35250c0816c ("writeback: Protect inode->i_io_list with inode->i_lock")
Signed-off-by: Jchao Sun <sunjunchao2870@xxxxxxxxx>
---
Thank you very much for your patient and detailed explanation.

 fs/fs-writeback.c | 17 +++++++++++------
 fs/inode.c        |  2 +-
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 591fe9cf1659..c879bcc41d28 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -120,6 +120,7 @@ static bool inode_io_list_move_locked(struct inode *inode,
 				      struct list_head *head)
 {
 	assert_spin_locked(&wb->list_lock);
+	assert_spin_locked(&inode->i_lock);
 
 	list_move(&inode->i_io_list, head);
 
@@ -2351,6 +2352,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 {
 	struct super_block *sb = inode->i_sb;
 	int dirtytime = 0;
+	struct bdi_writeback *wb;
 
 	trace_writeback_mark_inode_dirty(inode, flags);
 
@@ -2402,6 +2404,9 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 			inode->i_state &= ~I_DIRTY_TIME;
 		inode->i_state |= flags;
 
+		wb = locked_inode_to_wb_and_lock_list(inode);
+		spin_lock(&inode->i_lock);
+
 		/*
 		 * If the inode is queued for writeback by flush worker, just
 		 * update its dirty state. Once the flush worker is done with
@@ -2409,7 +2414,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 		 * list, based upon its state.
 		 */
 		if (inode->i_state & I_SYNC_QUEUED)
-			goto out_unlock_inode;
+			goto out_unlock;
 
 		/*
 		 * Only add valid (hashed) inodes to the superblock's
@@ -2417,22 +2422,19 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 		 */
 		if (!S_ISBLK(inode->i_mode)) {
 			if (inode_unhashed(inode))
-				goto out_unlock_inode;
+				goto out_unlock;
 		}
 		if (inode->i_state & I_FREEING)
-			goto out_unlock_inode;
+			goto out_unlock;
 
 		/*
 		 * If the inode was already on b_dirty/b_io/b_more_io, don't
 		 * reposition it (that would break b_dirty time-ordering).
 		 */
 		if (!was_dirty) {
-			struct bdi_writeback *wb;
 			struct list_head *dirty_list;
 			bool wakeup_bdi = false;
 
-			wb = locked_inode_to_wb_and_lock_list(inode);
-
 			inode->dirtied_when = jiffies;
 			if (dirtytime)
 				inode->dirtied_time_when = jiffies;
@@ -2446,6 +2448,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 							       dirty_list);
 
 			spin_unlock(&wb->list_lock);
+			spin_unlock(&inode->i_lock);
 			trace_writeback_dirty_inode_enqueue(inode);
 
 			/*
@@ -2460,6 +2463,8 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 			return;
 		}
 	}
+out_unlock:
+	spin_unlock(&wb->list_lock);
 out_unlock_inode:
 	spin_unlock(&inode->i_lock);
 }
diff --git a/fs/inode.c b/fs/inode.c
index 9d9b422504d1..bd4da9c5207e 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -27,7 +27,7 @@
  * Inode locking rules:
  *
  * inode->i_lock protects:
- *   inode->i_state, inode->i_hash, __iget()
+ *   inode->i_state, inode->i_hash, __iget(), inode->i_io_list
  * Inode LRU list locks protect:
  *   inode->i_sb->s_inode_lru, inode->i_lru
  * inode->i_sb->s_inode_list_lock protects:
--
2.17.1