From 5faafc77f7de69147d1e818026b9a0cbf036a7b2 Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Tue, 13 Apr 2021 09:03:49 +0100 Subject: [PATCH] dm space maps: don't reset space map allocation cursor when committing Current commit code resets the place where the search for free blocks will begin back to the start of the metadata device. There are a couple of repercussions to this: - The first allocation after the commit is likely to take longer than normal as it searches for a free block in an area that is likely to have very few free blocks (if any). - Any free blocks it finds will have been recently freed. Reusing them means we have fewer old copies of the metadata to aid recovery from hardware error. Fix these issues by leaving the cursor alone, only resetting when the search hits the end of the metadata device. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/persistent-data/dm-space-map-disk.c | 9 ++++++++- drivers/md/persistent-data/dm-space-map-metadata.c | 9 ++++++++- 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/md/persistent-data/dm-space-map-disk.c b/drivers/md/persistent-data/dm-space-map-disk.c index 61f5690..4f8069b 100644 --- a/drivers/md/persistent-data/dm-space-map-disk.c +++ b/drivers/md/persistent-data/dm-space-map-disk.c @@ -171,6 +171,14 @@ static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b) * Any block we allocate has to be free in both the old and current ll. */ r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, smd->begin, smd->ll.nr_blocks, b); + if (r == -ENOSPC) { + /* + * There's no free block between smd->begin and the end of the metadata device. + * We search before smd->begin in case something has been freed. + */ + r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, 0, smd->begin, b); + } + if (r) return r; @@ -194,7 +202,6 @@ static int sm_disk_commit(struct dm_space_map *sm) return r; memcpy(&smd->old_ll, &smd->ll, sizeof(smd->old_ll)); - smd->begin = 0; smd->nr_allocated_this_transaction = 0; return 0; diff --git a/drivers/md/persistent-data/dm-space-map-metadata.c b/drivers/md/persistent-data/dm-space-map-metadata.c index 9e3c64e..da439ac 100644 --- a/drivers/md/persistent-data/dm-space-map-metadata.c +++ b/drivers/md/persistent-data/dm-space-map-metadata.c @@ -452,6 +452,14 @@ static int sm_metadata_new_block_(struct dm_space_map *sm, dm_block_t *b) * Any block we allocate has to be free in both the old and current ll. */ r = sm_ll_find_common_free_block(&smm->old_ll, &smm->ll, smm->begin, smm->ll.nr_blocks, b); + if (r == -ENOSPC) { + /* + * There's no free block between smm->begin and the end of the metadata device. + * We search before smm->begin in case something has been freed. + */ + r = sm_ll_find_common_free_block(&smm->old_ll, &smm->ll, 0, smm->begin, b); + } + if (r) return r; @@ -503,7 +511,6 @@ static int sm_metadata_commit(struct dm_space_map *sm) return r; memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll)); - smm->begin = 0; smm->allocated_this_transaction = 0; return 0; -- 2.7.4