From 4886ff7b50f6341539611a1503a6ad2e55b77c98 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 20 Mar 2023 10:12:49 +0800 Subject: btrfs: introduce a new helper to submit write bio for repair Both scrub and read-repair are utilizing a special repair writes that: - Only writes back to a single device Even for read-repair on RAID56, we only update the corrupted data stripe itself, not triggering the full RMW path. - Requires a valid @mirror_num For RAID56 case, only @mirror_num == 1 is valid. For non-RAID56 cases, we need @mirror_num to locate our stripe. - No data csum generation needed These two call sites still have some differences though: - Read-repair goes plain bio It doesn't need a full btrfs_bio, and goes submit_bio_wait(). - New scrub repair would go btrfs_bio To simplify both read and write path. So here this patch would: - Introduce a common helper, btrfs_map_repair_block() Due to the single device nature, we can use an on-stack btrfs_io_stripe to pass device and its physical bytenr. - Introduce a new interface, btrfs_submit_repair_bio(), for later scrub code This is for the incoming scrub code. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) (limited to 'fs/btrfs/volumes.c') diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index c201d72f798e..db6e15205be5 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -8019,3 +8019,76 @@ bool btrfs_repair_one_zone(struct btrfs_fs_info *fs_info, u64 logical) return true; } + +static void map_raid56_repair_block(struct btrfs_io_context *bioc, + struct btrfs_io_stripe *smap, + u64 logical) +{ + int data_stripes = nr_bioc_data_stripes(bioc); + int i; + + for (i = 0; i < data_stripes; i++) { + u64 stripe_start = bioc->full_stripe_logical + + (i << BTRFS_STRIPE_LEN_SHIFT); + + if (logical >= stripe_start && + logical < stripe_start + BTRFS_STRIPE_LEN) + break; + } + ASSERT(i < data_stripes); + smap->dev = bioc->stripes[i].dev; + smap->physical = bioc->stripes[i].physical + + ((logical - bioc->full_stripe_logical) & + BTRFS_STRIPE_LEN_MASK); +} + +/* + * Map a repair write into a single device. + * + * A repair write is triggered by read time repair or scrub, which would only + * update the contents of a single device. + * Not update any other mirrors nor go through RMW path. + * + * Callers should ensure: + * + * - Call btrfs_bio_counter_inc_blocked() first + * - The range does not cross stripe boundary + * - Has a valid @mirror_num passed in. + */ +int btrfs_map_repair_block(struct btrfs_fs_info *fs_info, + struct btrfs_io_stripe *smap, u64 logical, + u32 length, int mirror_num) +{ + struct btrfs_io_context *bioc = NULL; + u64 map_length = length; + int mirror_ret = mirror_num; + int ret; + + ASSERT(mirror_num > 0); + + ret = __btrfs_map_block(fs_info, BTRFS_MAP_WRITE, logical, &map_length, + &bioc, smap, &mirror_ret, true); + if (ret < 0) + return ret; + + /* The map range should not cross stripe boundary. */ + ASSERT(map_length >= length); + + /* Already mapped to single stripe. */ + if (!bioc) + goto out; + + /* Map the RAID56 multi-stripe writes to a single one. */ + if (bioc->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) { + map_raid56_repair_block(bioc, smap, logical); + goto out; + } + + ASSERT(mirror_num <= bioc->num_stripes); + smap->dev = bioc->stripes[mirror_num - 1].dev; + smap->physical = bioc->stripes[mirror_num - 1].physical; +out: + btrfs_put_bioc(bioc); + ASSERT(smap->dev); + return 0; +} -- cgit v1.2.3-73-gaa49b