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

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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: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Christoph Hellwig 2022-05-26 09:36:42 +02:00 committed by David Sterba
parent a316a25991
commit 9ff7ddd3c7
4 changed files with 15 additions and 25 deletions
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13
fs/btrfs/extent_io.c
View file

@ -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;

1
fs/btrfs/extent_io.h
View file

@ -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);

19
fs/btrfs/volumes.c
View file

@ -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;
/*

7
fs/btrfs/volumes.h
View file

@ -412,7 +412,12 @@ static inline void btrfs_bio_free_csum(struct btrfs_bio *bbio)
struct btrfs_io_stripe {
struct btrfs_device *dev;
u64 physical;
union {
/* Block mapping */
u64 physical;
/* For the endio handler */
struct btrfs_io_context *bioc;
};
u64 length; /* only used for discard mappings */
};