btrfs: replace cleaner_delayed_iput_mutex with a waitqueue

The throttle path doesn't take cleaner_delayed_iput_mutex, which means
we could think we're done flushing iputs in the data space reservation
path when we could have a throttler doing an iput.  There's no real
reason to serialize the delayed iput flushing, so instead of taking the
cleaner_delayed_iput_mutex whenever we flush the delayed iputs just
replace it with an atomic counter and a waitqueue.  This removes the
short (or long depending on how big the inode is) window where we think
there are no more pending iputs when there really are some.

The waiting is killable as it could be indirectly called from user
operations like fallocate or zero-range. Such call sites should handle
the error but otherwise it's not necessary. Eg. flush_space just needs
to attempt to make space by waiting on iputs.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add killable comment and changelog parts ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2018-12-03 11:06:52 -05:00 committed by David Sterba
parent 3ece54e504
commit 034f784d7c
4 changed files with 35 additions and 9 deletions

View file

@ -1717,9 +1717,7 @@ static int cleaner_kthread(void *arg)
goto sleep;
}
mutex_lock(&fs_info->cleaner_delayed_iput_mutex);
btrfs_run_delayed_iputs(fs_info);
mutex_unlock(&fs_info->cleaner_delayed_iput_mutex);
again = btrfs_clean_one_deleted_snapshot(root);
mutex_unlock(&fs_info->cleaner_mutex);
@ -2676,7 +2674,6 @@ int open_ctree(struct super_block *sb,
mutex_init(&fs_info->delete_unused_bgs_mutex);
mutex_init(&fs_info->reloc_mutex);
mutex_init(&fs_info->delalloc_root_mutex);
mutex_init(&fs_info->cleaner_delayed_iput_mutex);
seqlock_init(&fs_info->profiles_lock);
INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
@ -2698,6 +2695,7 @@ int open_ctree(struct super_block *sb,
atomic_set(&fs_info->defrag_running, 0);
atomic_set(&fs_info->qgroup_op_seq, 0);
atomic_set(&fs_info->reada_works_cnt, 0);
atomic_set(&fs_info->nr_delayed_iputs, 0);
atomic64_set(&fs_info->tree_mod_seq, 0);
fs_info->sb = sb;
fs_info->max_inline = BTRFS_DEFAULT_MAX_INLINE;
@ -2775,6 +2773,7 @@ int open_ctree(struct super_block *sb,
init_waitqueue_head(&fs_info->transaction_wait);
init_waitqueue_head(&fs_info->transaction_blocked_wait);
init_waitqueue_head(&fs_info->async_submit_wait);
init_waitqueue_head(&fs_info->delayed_iputs_wait);
INIT_LIST_HEAD(&fs_info->pinned_chunks);