Commit 07166122 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: scrub: factor out parity scrub code into a helper 



The function scrub_raid56_parity_stripe() is handling the parity stripe
by the following steps:

- Scrub each data stripes
  And make sure everything is fine in each data stripe

- Cache the data stripe into the raid bio

- Use the cached raid bio to scrub the target parity stripe

Extract the last two steps into a new helper,
scrub_raid56_cached_parity(), as a cleanup and make the error handling
more straightforward.

With the following minor cleanups:

- Use on-stack bio structure
  The bio is always empty thus we do not need any bio vector nor the
  block device. Thus there is no need to allocate a bio, the on-stack
  one is more than enough to cut it.

- Remove the unnecessary btrfs_put_bioc() call if btrfs_map_block()
  failed
  If btrfs_map_block() is failed, @bioc_ret will not be touched thus
  there is no need to call btrfs_put_bioc() in this case.

- Use a proper out: tag to do the cleanup
  Now the error cleanup is much shorter and simpler, just
  btrfs_bio_counter_dec() and bio_uninit().

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent d435c513

fs/btrfs/scrub.c

+52 −41
Original line number Diff line number Diff line
@@ -2113,24 +2113,69 @@ static int should_cancel_scrub(const struct scrub_ctx *sctx) 
	return 0;

}



static int scrub_raid56_cached_parity(struct scrub_ctx *sctx,

				      struct btrfs_device *scrub_dev,

				      struct btrfs_chunk_map *map,

				      u64 full_stripe_start,

				      unsigned long *extent_bitmap)

{

	DECLARE_COMPLETION_ONSTACK(io_done);

	struct btrfs_fs_info *fs_info = sctx->fs_info;

	struct btrfs_io_context *bioc = NULL;

	struct btrfs_raid_bio *rbio;

	struct bio bio;

	const int data_stripes = nr_data_stripes(map);

	u64 length = btrfs_stripe_nr_to_offset(data_stripes);

	int ret;



	bio_init(&bio, NULL, NULL, 0, REQ_OP_READ);

	bio.bi_iter.bi_sector = full_stripe_start >> SECTOR_SHIFT;

	bio.bi_private = &io_done;

	bio.bi_end_io = raid56_scrub_wait_endio;



	btrfs_bio_counter_inc_blocked(fs_info);

	ret = btrfs_map_block(fs_info, BTRFS_MAP_WRITE, full_stripe_start,

			      &length, &bioc, NULL, NULL);

	if (ret < 0)

		goto out;

	/* For RAID56 write there must be an @bioc allocated. */

	ASSERT(bioc);

	rbio = raid56_parity_alloc_scrub_rbio(&bio, bioc, scrub_dev, extent_bitmap,

				BTRFS_STRIPE_LEN >> fs_info->sectorsize_bits);

	btrfs_put_bioc(bioc);

	if (!rbio) {

		ret = -ENOMEM;

		goto out;

	}

	/* Use the recovered stripes as cache to avoid read them from disk again. */

	for (int i = 0; i < data_stripes; i++) {

		struct scrub_stripe *stripe = &sctx->raid56_data_stripes[i];



		raid56_parity_cache_data_folios(rbio, stripe->folios,

				full_stripe_start + (i << BTRFS_STRIPE_LEN_SHIFT));

	}

	raid56_parity_submit_scrub_rbio(rbio);

	wait_for_completion_io(&io_done);

	ret = blk_status_to_errno(bio.bi_status);

out:

	btrfs_bio_counter_dec(fs_info);

	bio_uninit(&bio);

	return ret;

}



static int scrub_raid56_parity_stripe(struct scrub_ctx *sctx,

				      struct btrfs_device *scrub_dev,

				      struct btrfs_block_group *bg,

				      struct btrfs_chunk_map *map,

				      u64 full_stripe_start)

{

	DECLARE_COMPLETION_ONSTACK(io_done);

	struct btrfs_fs_info *fs_info = sctx->fs_info;

	struct btrfs_raid_bio *rbio;

	struct btrfs_io_context *bioc = NULL;

	struct btrfs_path extent_path = { 0 };

	struct btrfs_path csum_path = { 0 };

	struct bio *bio;

	struct scrub_stripe *stripe;

	bool all_empty = true;

	const int data_stripes = nr_data_stripes(map);

	unsigned long extent_bitmap = 0;

	u64 length = btrfs_stripe_nr_to_offset(data_stripes);

	int ret;



	ASSERT(sctx->raid56_data_stripes);
@@ -2252,42 +2297,8 @@ static int scrub_raid56_parity_stripe(struct scrub_ctx *sctx, 
	}



	/* Now we can check and regenerate the P/Q stripe. */

	bio = bio_alloc(NULL, 1, REQ_OP_READ, GFP_NOFS);

	bio->bi_iter.bi_sector = full_stripe_start >> SECTOR_SHIFT;

	bio->bi_private = &io_done;

	bio->bi_end_io = raid56_scrub_wait_endio;



	btrfs_bio_counter_inc_blocked(fs_info);

	ret = btrfs_map_block(fs_info, BTRFS_MAP_WRITE, full_stripe_start,

			      &length, &bioc, NULL, NULL);

	if (ret < 0) {

		bio_put(bio);

		btrfs_put_bioc(bioc);

		btrfs_bio_counter_dec(fs_info);

		goto out;

	}

	rbio = raid56_parity_alloc_scrub_rbio(bio, bioc, scrub_dev, &extent_bitmap,

				BTRFS_STRIPE_LEN >> fs_info->sectorsize_bits);

	btrfs_put_bioc(bioc);

	if (!rbio) {

		ret = -ENOMEM;

		bio_put(bio);

		btrfs_bio_counter_dec(fs_info);

		goto out;

	}

	/* Use the recovered stripes as cache to avoid read them from disk again. */

	for (int i = 0; i < data_stripes; i++) {

		stripe = &sctx->raid56_data_stripes[i];



		raid56_parity_cache_data_folios(rbio, stripe->folios,

				full_stripe_start + (i << BTRFS_STRIPE_LEN_SHIFT));

	}

	raid56_parity_submit_scrub_rbio(rbio);

	wait_for_completion_io(&io_done);

	ret = blk_status_to_errno(bio->bi_status);

	bio_put(bio);

	btrfs_bio_counter_dec(fs_info);



	ret = scrub_raid56_cached_parity(sctx, scrub_dev, map, full_stripe_start,

					 &extent_bitmap);

out:

	btrfs_release_path(&extent_path);

	btrfs_release_path(&csum_path);