Btrfs: wake up inode cache waiters sooner to reduce waiting time

If we need to start an inode caching thread, because none currently exists
on disk, we can wake up all waiters as soon as we mark the range starting
at root's highest objectid + 1 and ending at BTRFS_LAST_FREE_OBJECTID as
free, so that they don't need to wait for the caching thread to start and
do some progress. We follow the same approach within the caching thread,
since as soon as it finds a free range and marks it as free space in the
cache, it wakes up all waiters. So improve this by adding such a wakeup
call after marking that initial range as free space.

Fixes: a47d6b70e28040 ("Btrfs: setup free ino caching in a more asynchronous way")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index c692c8b6e3719978784cfe32bb24c8ea0c3ee7d6..86031cdfc3568c8390c1f6110359e7c4ea1c15ad 100644 (file)
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -176,6 +176,7 @@ static void start_caching(struct btrfs_root *root)
        if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
                __btrfs_add_free_space(fs_info, ctl, objectid,
                                       BTRFS_LAST_FREE_OBJECTID - objectid + 1);
+               wake_up(&root->ino_cache_wait);
        }
 
        tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",