[PATCH 4.19 094/125] writeback: Protect inode->i_io_list with inode->i_lock

Greg Kroah-Hartman
2020-09-01T15:30:14Z

From: Jan Kara <jack@suse.cz>

commit b35250c0816c7cf7d0a8de92f5fafb6a7508a708 upstream.

Currently, operations on inode->i_io_list are protected by
wb->list_lock. In the following patches we'll need to maintain
consistency between inode->i_state and inode->i_io_list so change the
code so that inode->i_lock protects also all inode's i_io_list handling.

Reviewed-by: Martijn Coenen <maco@android.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
CC: stable@vger.kernel.org # Prerequisite for "writeback: Avoid skipping inode writeback"
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/fs-writeback.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)

--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -160,6 +160,7 @@ static void inode_io_list_del_locked(str
struct bdi_writeback *wb)
{
assert_spin_locked(&wb->list_lock);
+ assert_spin_locked(&inode->i_lock);

list_del_init(&inode->i_io_list);
wb_io_lists_depopulated(wb);
@@ -1042,7 +1043,9 @@ void inode_io_list_del(struct inode *ino
struct bdi_writeback *wb;

wb = inode_to_wb_and_lock_list(inode);
+ spin_lock(&inode->i_lock);
inode_io_list_del_locked(inode, wb);
+ spin_unlock(&inode->i_lock);
spin_unlock(&wb->list_lock);
}

@@ -1091,8 +1094,10 @@ void sb_clear_inode_writeback(struct ino
* the case then the inode must have been redirtied while it was being written
* out and we don't reset its dirtied_when.
*/
-static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
+static void redirty_tail_locked(struct inode *inode, struct bdi_writeback *wb)
{
+ assert_spin_locked(&inode->i_lock);
+
if (!list_empty(&wb->b_dirty)) {
struct inode *tail;

@@ -1103,6 +1108,13 @@ static void redirty_tail(struct inode *i
inode_io_list_move_locked(inode, wb, &wb->b_dirty);
}

+static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
+{
+ spin_lock(&inode->i_lock);
+ redirty_tail_locked(inode, wb);
+ spin_unlock(&inode->i_lock);
+}
+
/*
* requeue inode for re-scanning after bdi->b_io list is exhausted.
*/
@@ -1313,7 +1325,7 @@ static void requeue_inode(struct inode *
* writeback is not making progress due to locked
* buffers. Skip this inode for now.
*/
- redirty_tail(inode, wb);
+ redirty_tail_locked(inode, wb);
return;
}

@@ -1333,7 +1345,7 @@ static void requeue_inode(struct inode *
* retrying writeback of the dirty page/inode
* that cannot be performed immediately.
*/
- redirty_tail(inode, wb);
+ redirty_tail_locked(inode, wb);
}
} else if (inode->i_state & I_DIRTY) {
/*
@@ -1341,7 +1353,7 @@ static void requeue_inode(struct inode *
* such as delayed allocation during submission or metadata
* updates after data IO completion.
*/
- redirty_tail(inode, wb);
+ redirty_tail_locked(inode, wb);
} else if (inode->i_state & I_DIRTY_TIME) {
inode->dirtied_when = jiffies;
inode_io_list_move_locked(inode, wb, &wb->b_dirty_time);
@@ -1588,8 +1600,8 @@ static long writeback_sb_inodes(struct s
*/
spin_lock(&inode->i_lock);
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
+ redirty_tail_locked(inode, wb);
spin_unlock(&inode->i_lock);
- redirty_tail(inode, wb);
continue;
}
if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) {