Commit 9ff7ddd3 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David Sterba
Browse files

btrfs: do not allocate a btrfs_bio for low-level bios 



The bios submitted from btrfs_map_bio don't really interact with the
rest of btrfs and the only btrfs_bio member actually used in the
low-level bios is the pointer to the btrfs_io_context used for endio
handler.

Use a union in struct btrfs_io_stripe that allows the endio handler to
find the btrfs_io_context and remove the spurious ->device assignment
so that a plain fs_bio_set bio can be used for the low-level bios
allocated inside btrfs_map_bio.

Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent a316a259

fs/btrfs/extent_io.c

+0 −13
Original line number Diff line number Diff line
@@ -3203,19 +3203,6 @@ struct bio *btrfs_bio_alloc(unsigned int nr_iovecs) 
	return bio;

}



struct bio *btrfs_bio_clone(struct block_device *bdev, struct bio *bio)

{

	struct btrfs_bio *bbio;

	struct bio *new;



	/* Bio allocation backed by a bioset does not fail */

	new = bio_alloc_clone(bdev, bio, GFP_NOFS, &btrfs_bioset);

	bbio = btrfs_bio(new);

	btrfs_bio_init(bbio);

	bbio->iter = bio->bi_iter;

	return new;

}



struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size)

{

	struct bio *bio;

fs/btrfs/extent_io.h

+0 −1
Original line number Diff line number Diff line
@@ -247,7 +247,6 @@ void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end, 


int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array);

struct bio *btrfs_bio_alloc(unsigned int nr_iovecs);

struct bio *btrfs_bio_clone(struct block_device *bdev, struct bio *bio);

struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size);



void end_extent_writepage(struct page *page, int err, u64 start, u64 end);

fs/btrfs/volumes.c

+9 −10
Original line number Diff line number Diff line
@@ -6661,23 +6661,21 @@ static void btrfs_end_bioc(struct btrfs_io_context *bioc, bool async) 


static void btrfs_end_bio(struct bio *bio)

{

	struct btrfs_io_context *bioc = bio->bi_private;

	struct btrfs_io_stripe *stripe = bio->bi_private;

	struct btrfs_io_context *bioc = stripe->bioc;



	if (bio->bi_status) {

		atomic_inc(&bioc->error);

		if (bio->bi_status == BLK_STS_IOERR ||

		    bio->bi_status == BLK_STS_TARGET) {

			struct btrfs_device *dev = btrfs_bio(bio)->device;



			ASSERT(dev->bdev);

			if (btrfs_op(bio) == BTRFS_MAP_WRITE)

				btrfs_dev_stat_inc_and_print(dev,

				btrfs_dev_stat_inc_and_print(stripe->dev,

						BTRFS_DEV_STAT_WRITE_ERRS);

			else if (!(bio->bi_opf & REQ_RAHEAD))

				btrfs_dev_stat_inc_and_print(dev,

				btrfs_dev_stat_inc_and_print(stripe->dev,

						BTRFS_DEV_STAT_READ_ERRS);

			if (bio->bi_opf & REQ_PREFLUSH)

				btrfs_dev_stat_inc_and_print(dev,

				btrfs_dev_stat_inc_and_print(stripe->dev,

						BTRFS_DEV_STAT_FLUSH_ERRS);

		}

	}
@@ -6709,14 +6707,15 @@ static void submit_stripe_bio(struct btrfs_io_context *bioc, 
	}



	if (clone) {

		bio = btrfs_bio_clone(dev->bdev, orig_bio);

		bio = bio_alloc_clone(dev->bdev, orig_bio, GFP_NOFS, &fs_bio_set);

	} else {

		bio = orig_bio;

		bio_set_dev(bio, dev->bdev);

		btrfs_bio(bio)->device = dev;

	}



	bio->bi_private = bioc;

	btrfs_bio(bio)->device = dev;

	bioc->stripes[dev_nr].bioc = bioc;

	bio->bi_private = &bioc->stripes[dev_nr];

	bio->bi_end_io = btrfs_end_bio;

	bio->bi_iter.bi_sector = physical >> 9;

	/*

fs/btrfs/volumes.h

+6 −1
Original line number Diff line number Diff line
@@ -412,7 +412,12 @@ static inline void btrfs_bio_free_csum(struct btrfs_bio *bbio) 


struct btrfs_io_stripe {

	struct btrfs_device *dev;

	union {

		/* Block mapping */

		u64 physical;

		/* For the endio handler */

		struct btrfs_io_context *bioc;

	};

	u64 length; /* only used for discard mappings */

};