Commit a39da514 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David Sterba
Browse files

btrfs: limit write bios to a single ordered extent 



Currently buffered writeback bios are allowed to span multiple
ordered_extents, although that basically never actually happens since
commit 4a445b7b ("btrfs: don't merge pages into bio if their page
offset is not contiguous").

Supporting bios than span ordered_extents complicates the file
checksumming code, and prevents us from adding an ordered_extent pointer
to the btrfs_bio structure.  Use the existing code to limit a bio to
single ordered_extent for zoned device writes for all writes.

This allows to remove the REQ_BTRFS_ONE_ORDERED flags, and the
handling of multiple ordered_extents in btrfs_csum_one_bio.

Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent c731cd0b

fs/btrfs/bio.c

+0 −3
Original line number Diff line number Diff line
@@ -457,9 +457,6 @@ static void btrfs_submit_mirrored_bio(struct btrfs_io_context *bioc, int dev_nr) 
static void __btrfs_submit_bio(struct bio *bio, struct btrfs_io_context *bioc,

			       struct btrfs_io_stripe *smap, int mirror_num)

{

	/* Do not leak our private flag into the block layer. */

	bio->bi_opf &= ~REQ_BTRFS_ONE_ORDERED;



	if (!bioc) {

		/* Single mirror read/write fast path. */

		btrfs_bio(bio)->mirror_num = mirror_num;

fs/btrfs/bio.h

+0 −3
Original line number Diff line number Diff line
@@ -102,9 +102,6 @@ static inline void btrfs_bio_end_io(struct btrfs_bio *bbio, blk_status_t status) 
	bbio->end_io(bbio);

}



/* Bio only refers to one ordered extent. */

#define REQ_BTRFS_ONE_ORDERED			REQ_DRV



/* Submit using blkcg_punt_bio_submit. */

#define REQ_BTRFS_CGROUP_PUNT			REQ_FS_PRIVATE

fs/btrfs/compression.c

+0 −2
Original line number Diff line number Diff line
@@ -293,8 +293,6 @@ void btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start, 
	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&

	       IS_ALIGNED(len, fs_info->sectorsize));



	write_flags |= REQ_BTRFS_ONE_ORDERED;



	cb = alloc_compressed_bio(inode, start, REQ_OP_WRITE | write_flags,

				  end_compressed_bio_write);

	cb->start = start;

fs/btrfs/extent_io.c

+2 −9
Original line number Diff line number Diff line
@@ -826,13 +826,8 @@ static void alloc_new_bio(struct btrfs_inode *inode, 
	bio_ctrl->bbio = bbio;

	bio_ctrl->len_to_oe_boundary = U32_MAX;



	/*

	 * Limit the extent to the ordered boundary for Zone Append.

	 * Compressed bios aren't submitted directly, so it doesn't apply to

	 * them.

	 */

	if (bio_ctrl->compress_type == BTRFS_COMPRESS_NONE &&

	    btrfs_use_zone_append(bbio)) {

	/* Limit data write bios to the ordered boundary. */

	if (bio_ctrl->wbc) {

		struct btrfs_ordered_extent *ordered;



		ordered = btrfs_lookup_ordered_extent(inode, file_offset);
@@ -842,9 +837,7 @@ static void alloc_new_bio(struct btrfs_inode *inode, 
					ordered->disk_num_bytes - file_offset);

			btrfs_put_ordered_extent(ordered);

		}

	}



	if (bio_ctrl->wbc) {

		/*

		 * Pick the last added device to support cgroup writeback.  For

		 * multi-device file systems this means blk-cgroup policies have

fs/btrfs/file-item.c

+0 −38
Original line number Diff line number Diff line
@@ -733,8 +733,6 @@ blk_status_t btrfs_csum_one_bio(struct btrfs_bio *bbio) 
	struct bio_vec bvec;

	int index;

	unsigned int blockcount;

	unsigned long total_bytes = 0;

	unsigned long this_sum_bytes = 0;

	int i;

	unsigned nofs_flag;
@@ -776,34 +774,6 @@ blk_status_t btrfs_csum_one_bio(struct btrfs_bio *bbio) 
						 - 1);



		for (i = 0; i < blockcount; i++) {

			if (!(bio->bi_opf & REQ_BTRFS_ONE_ORDERED) &&

			    !in_range(offset, ordered->file_offset,

				      ordered->num_bytes)) {

				unsigned long bytes_left;



				sums->len = this_sum_bytes;

				this_sum_bytes = 0;

				btrfs_add_ordered_sum(ordered, sums);

				btrfs_put_ordered_extent(ordered);



				bytes_left = bio->bi_iter.bi_size - total_bytes;



				nofs_flag = memalloc_nofs_save();

				sums = kvzalloc(btrfs_ordered_sum_size(fs_info,

						      bytes_left), GFP_KERNEL);

				memalloc_nofs_restore(nofs_flag);

				if (!sums)

					return BLK_STS_RESOURCE;



				sums->len = bytes_left;

				ordered = btrfs_lookup_ordered_extent(inode,

								offset);

				ASSERT(ordered); /* Logic error */

				sums->logical = (bio->bi_iter.bi_sector << SECTOR_SHIFT)

					+ total_bytes;

				index = 0;

			}



			data = bvec_kmap_local(&bvec);

			crypto_shash_digest(shash,

					    data + (i * fs_info->sectorsize),
@@ -812,18 +782,10 @@ blk_status_t btrfs_csum_one_bio(struct btrfs_bio *bbio) 
			kunmap_local(data);

			index += fs_info->csum_size;

			offset += fs_info->sectorsize;

			this_sum_bytes += fs_info->sectorsize;

			total_bytes += fs_info->sectorsize;

		}



	}

	this_sum_bytes = 0;



	/*

	 * The ->sums assignment is for zoned writes, where a bio never spans

	 * ordered extents and is only done unconditionally because that's cheaper

	 * than a branch.

	 */

	bbio->sums = sums;

	btrfs_add_ordered_sum(ordered, sums);

	btrfs_put_ordered_extent(ordered);