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authorJoe Thornber <ejt@redhat.com>2013-10-31 13:55:49 -0400
committerMike Snitzer <snitzer@redhat.com>2013-11-11 11:37:45 -0500
commitf494a9c6b1b6dd9a9f21bbb75d9210d478eeb498 (patch)
treee57197b7d38e7c6b2d718681fd70540ccc9a831e /drivers/md/dm-cache-metadata.c
parentc9d28d5d09a0fd5f02f1321c8e18ff7d9f92270b (diff)
dm cache: cache shrinking support
Allow a cache to shrink if the blocks being removed from the cache are not dirty. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-cache-metadata.c')
-rw-r--r--drivers/md/dm-cache-metadata.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 2262b4e57a28..062b83ed3e84 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -667,19 +667,85 @@ void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
667 kfree(cmd); 667 kfree(cmd);
668} 668}
669 669
670/*
671 * Checks that the given cache block is either unmapped or clean.
672 */
673static int block_unmapped_or_clean(struct dm_cache_metadata *cmd, dm_cblock_t b,
674 bool *result)
675{
676 int r;
677 __le64 value;
678 dm_oblock_t ob;
679 unsigned flags;
680
681 r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
682 if (r) {
683 DMERR("block_unmapped_or_clean failed");
684 return r;
685 }
686
687 unpack_value(value, &ob, &flags);
688 *result = !((flags & M_VALID) && (flags & M_DIRTY));
689
690 return 0;
691}
692
693static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
694 dm_cblock_t begin, dm_cblock_t end,
695 bool *result)
696{
697 int r;
698 *result = true;
699
700 while (begin != end) {
701 r = block_unmapped_or_clean(cmd, begin, result);
702 if (r)
703 return r;
704
705 if (!*result) {
706 DMERR("cache block %llu is dirty",
707 (unsigned long long) from_cblock(begin));
708 return 0;
709 }
710
711 begin = to_cblock(from_cblock(begin) + 1);
712 }
713
714 return 0;
715}
716
670int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size) 717int dm_cache_resize(struct dm_cache_metadata *cmd, dm_cblock_t new_cache_size)
671{ 718{
672 int r; 719 int r;
720 bool clean;
673 __le64 null_mapping = pack_value(0, 0); 721 __le64 null_mapping = pack_value(0, 0);
674 722
675 down_write(&cmd->root_lock); 723 down_write(&cmd->root_lock);
676 __dm_bless_for_disk(&null_mapping); 724 __dm_bless_for_disk(&null_mapping);
725
726 if (from_cblock(new_cache_size) < from_cblock(cmd->cache_blocks)) {
727 r = blocks_are_unmapped_or_clean(cmd, new_cache_size, cmd->cache_blocks, &clean);
728 if (r) {
729 __dm_unbless_for_disk(&null_mapping);
730 goto out;
731 }
732
733 if (!clean) {
734 DMERR("unable to shrink cache due to dirty blocks");
735 r = -EINVAL;
736 __dm_unbless_for_disk(&null_mapping);
737 goto out;
738 }
739 }
740
677 r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks), 741 r = dm_array_resize(&cmd->info, cmd->root, from_cblock(cmd->cache_blocks),
678 from_cblock(new_cache_size), 742 from_cblock(new_cache_size),
679 &null_mapping, &cmd->root); 743 &null_mapping, &cmd->root);
680 if (!r) 744 if (!r)
681 cmd->cache_blocks = new_cache_size; 745 cmd->cache_blocks = new_cache_size;
682 cmd->changed = true; 746 cmd->changed = true;
747
748out:
683 up_write(&cmd->root_lock); 749 up_write(&cmd->root_lock);
684 750
685 return r; 751 return r;