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writeback: Add asserts for adding freed inode to lists 

In the past we had several use-after-free issues with inodes getting
added to writeback lists after evict() removed them. These are painful
to debug so add some asserts to catch the problem earlier. The only
non-obvious change in the commit is that we need to tweak
redirty_tail_locked() to avoid triggering assertion in
inode_io_list_move_locked().

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221212113633.29181-1-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jan Kara 2022-12-12 12:36:33 +01:00 committed by Jens Axboe
parent eb7081409f
commit a9438b44bc
1 changed files with 14 additions and 1 deletions
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15
fs/fs-writeback.c
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@ -121,6 +121,7 @@ static bool inode_io_list_move_locked(struct inode *inode,
{
assert_spin_locked(&wb->list_lock);
assert_spin_locked(&inode->i_lock);
WARN_ON_ONCE(inode->i_state & I_FREEING);
list_move(&inode->i_io_list, head);
@ -280,6 +281,7 @@ static void inode_cgwb_move_to_attached(struct inode *inode,
{
assert_spin_locked(&wb->list_lock);
assert_spin_locked(&inode->i_lock);
WARN_ON_ONCE(inode->i_state & I_FREEING);
inode->i_state &= ~I_SYNC_QUEUED;
if (wb != &wb->bdi->wb)
@ -1129,6 +1131,7 @@ static void inode_cgwb_move_to_attached(struct inode *inode,
{
assert_spin_locked(&wb->list_lock);
assert_spin_locked(&inode->i_lock);
WARN_ON_ONCE(inode->i_state & I_FREEING);
inode->i_state &= ~I_SYNC_QUEUED;
list_del_init(&inode->i_io_list);
@ -1294,6 +1297,17 @@ static void redirty_tail_locked(struct inode *inode, struct bdi_writeback *wb)
{
assert_spin_locked(&inode->i_lock);
inode->i_state &= ~I_SYNC_QUEUED;
/*
* When the inode is being freed just don't bother with dirty list
* tracking. Flush worker will ignore this inode anyway and it will
* trigger assertions in inode_io_list_move_locked().
*/
if (inode->i_state & I_FREEING) {
list_del_init(&inode->i_io_list);
wb_io_lists_depopulated(wb);
return;
}
if (!list_empty(&wb->b_dirty)) {
struct inode *tail;
@ -1302,7 +1316,6 @@ static void redirty_tail_locked(struct inode *inode, struct bdi_writeback *wb)
inode->dirtied_when = jiffies;
}
inode_io_list_move_locked(inode, wb, &wb->b_dirty);
inode->i_state &= ~I_SYNC_QUEUED;
}
static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)