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authorJosef Bacik <josef@toxicpanda.com>2021-11-09 18:12:02 +0300
committerDavid Sterba <dsterba@suse.com>2022-01-03 17:09:45 +0300
commit9cd8dcdc5e5c459bcd01a97c8c8d6bc2c8d73fdf (patch)
treebd42346a38f42f01d5216ee2e362043f69d3f85d /fs/btrfs/space-info.c
parent9f35f76d7df66507b698ac7298fb6c175a6aae7d (diff)
downloadlinux-9cd8dcdc5e5c459bcd01a97c8c8d6bc2c8d73fdf.tar.xz
btrfs: check for priority ticket granting before flushing
Since we're dropping locks before we enter the priority flushing loops we could have had our ticket granted before we got the space_info->lock. So add this check to avoid doing some extra flushing in the priority flushing cases. The case in priority_reclaim_metadata_space is an optimization. Think we came in to reserve, we didn't have the space, we added our ticket to the list. But at the same time somebody was waiting on the space_info lock to add space and do btrfs_try_granting_ticket(), so we drop the lock, get satisfied, come in to do our loop, and we have been satisfied. This is the priority reclaim path, so to_reclaim could be !0 still because we may have only satisfied the priority tickets and still left non priority tickets on the list. We would then have to_reclaim but ->bytes == 0. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> [ add note about the optimization ] Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/space-info.c')
-rw-r--r--fs/btrfs/space-info.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 9d6048f54097..dd6509795532 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -1264,7 +1264,13 @@ static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
spin_lock(&space_info->lock);
to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
- if (!to_reclaim) {
+ /*
+ * This is the priority reclaim path, so to_reclaim could be >0 still
+ * because we may have only satisified the priority tickets and still
+ * left non priority tickets on the list. We would then have
+ * to_reclaim but ->bytes == 0.
+ */
+ if (ticket->bytes == 0) {
spin_unlock(&space_info->lock);
return;
}
@@ -1297,6 +1303,13 @@ static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
struct reserve_ticket *ticket)
{
spin_lock(&space_info->lock);
+
+ /* We could have been granted before we got here. */
+ if (ticket->bytes == 0) {
+ spin_unlock(&space_info->lock);
+ return;
+ }
+
while (!space_info->full) {
spin_unlock(&space_info->lock);
flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);