From: Jchao Sun sunjunchao2870@gmail.com

mainline inclusion from mainline-v5.19-rc2 commit 10e14073107dd0b6d97d9516a02845a8e501c2c9 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAZJPL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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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. This also fixes a race where __mark_inode_dirty() could move inode under flush worker's hands and thus sync(2) could miss writing some inodes.

Fixes: b35250c0816c ("writeback: Protect inode->i_io_list with inode->i_lock") Link: https://lore.kernel.org/r/20220524150540.12552-1-sunjunchao2870@gmail.com CC: stable@vger.kernel.org Signed-off-by: Jchao Sun sunjunchao2870@gmail.com Signed-off-by: Jan Kara jack@suse.cz

Conflicts: fs/fs-writeback.c [Context conflict caused by commit 35d14f278e53 ("fs: clean up __mark_inode_dirty() a bit") not being backported.] Signed-off-by: Baokun Li libaokun1@huawei.com --- fs/fs-writeback.c | 37 ++++++++++++++++++++++++++++--------- fs/inode.c | 2 +- 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 0549aba84eca..f9371d249e51 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);

@@ -1260,9 +1261,9 @@ static int move_expired_inodes(struct list_head *delaying_queue, inode = wb_inode(delaying_queue->prev); if (inode_dirtied_after(inode, dirtied_before)) break; + spin_lock(&inode->i_lock); list_move(&inode->i_io_list, &tmp); moved++; - spin_lock(&inode->i_lock); inode->i_state |= I_SYNC_QUEUED; spin_unlock(&inode->i_lock); if (sb_is_blkdev_sb(inode->i_sb)) @@ -1278,7 +1279,12 @@ static int move_expired_inodes(struct list_head *delaying_queue, goto out; }

- /* Move inodes from one superblock together */ + /* + * Although inode's i_io_list is moved from 'tmp' to 'dispatch_queue', + * we don't take inode->i_lock here because it is just a pointless overhead. + * Inode is already marked as I_SYNC_QUEUED so writeback list handling is + * fully under our control. + */ while (!list_empty(&tmp)) { sb = wb_inode(tmp.prev)->i_sb; list_for_each_prev_safe(pos, node, &tmp) { @@ -1700,8 +1706,8 @@ static long writeback_sb_inodes(struct super_block *sb, * We'll have another go at writing back this inode * when we completed a full scan of b_io. */ - spin_unlock(&inode->i_lock); requeue_io(inode, wb); + spin_unlock(&inode->i_lock); trace_writeback_sb_inodes_requeue(inode); continue; } @@ -2238,6 +2244,7 @@ void __mark_inode_dirty(struct inode *inode, int flags) { struct super_block *sb = inode->i_sb; int dirtytime; + struct bdi_writeback *wb = NULL;

trace_writeback_mark_inode_dirty(inode, flags);

@@ -2279,6 +2286,17 @@ void __mark_inode_dirty(struct inode *inode, int flags) inode->i_state &= ~I_DIRTY_TIME; inode->i_state |= flags;

+ /* + * Grab inode's wb early because it requires dropping i_lock and we + * need to make sure following checks happen atomically with dirty + * list handling so that we don't move inodes under flush worker's + * hands. + */ + if (!was_dirty) { + 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 @@ -2286,7 +2304,7 @@ 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 @@ -2294,22 +2312,19 @@ 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; @@ -2323,6 +2338,7 @@ 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);

/* @@ -2337,6 +2353,9 @@ void __mark_inode_dirty(struct inode *inode, int flags) return; } } +out_unlock: + if (wb) + spin_unlock(&wb->list_lock); out_unlock_inode: spin_unlock(&inode->i_lock); } diff --git a/fs/inode.c b/fs/inode.c index c4eaa1db9d1a..6fa868738f94 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -28,7 +28,7 @@ * 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: