[PATCH 03/23] btrfs: handle U64_MAX for shrink_delalloc

Josef Bacik
2020-07-21T14:22:45Z

Data allocations are going to want to pass in U64_MAX for flushing
space, adjust shrink_delalloc to handle this properly.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/space-info.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 10cae5b55235..78ad8f01785c 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -530,8 +530,19 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info, u64 to_reclaim,
int loops;

/* Calc the number of the pages we need flush for space reservation */
- items = calc_reclaim_items_nr(fs_info, to_reclaim);
- to_reclaim = items * EXTENT_SIZE_PER_ITEM;
+ if (to_reclaim == U64_MAX) {
+ items = U64_MAX;
+ } else {
+ /*
+ * to_reclaim is set to however much metadata we need to
+ * reclaim, but reclaiming that much data doesn't really track
+ * exactly, so increase the amount to reclaim by 2x in order to
+ * make sure we're flushing enough delalloc to hopefully reclaim
+ * some metadata reservations.
+ */
+ items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
+ to_reclaim = items * EXTENT_SIZE_PER_ITEM;
+ }

trans = (struct btrfs_trans_handle *)current->journal_info;
space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
@@ -742,7 +753,7 @@ static void flush_space(struct btrfs_fs_info *fs_info,
break;
case FLUSH_DELALLOC:
case FLUSH_DELALLOC_WAIT:
- shrink_delalloc(fs_info, num_bytes * 2,
+ shrink_delalloc(fs_info, num_bytes,
state == FLUSH_DELALLOC_WAIT);
break;
case FLUSH_DELAYED_REFS_NR:
--
2.24.1