[PATCH v3 2/3] btrfs: remove btrfs_bio_alloc() helper

Qu Wenruo
2021-09-15T07:17:27Z

The helper btrfs_bio_alloc() is almost the same as btrfs_io_bio_alloc(),
except it's allocating using BIO_MAX_VECS as @nr_iovecs, and initialize
bio->bi_iter.bi_sector.

However the naming itself is not using "btrfs_io_bio" to indicate its
parameter is "strcut btrfs_io_bio" and can be easily confused with
"struct btrfs_bio".

Considering assigned bio->bi_iter.bi_sector is such a simple work and
there are already tons of call sites doing that manually, there is no
need to do that in a helper.

Remove btrfs_bio_alloc() helper, and enhance btrfs_io_bio_alloc()
function to provide a fail-safe value for its @nr_iovecs.

And then replace all btrfs_bio_alloc() callers with
btrfs_io_bio_alloc().

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/compression.c | 12 ++++++++----
fs/btrfs/extent_io.c | 33 +++++++++++++++------------------
fs/btrfs/extent_io.h | 1 -
3 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 7869ad12bc6e..2475dc0b1c22 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -418,7 +418,8 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
cb->orig_bio = NULL;
cb->nr_pages = nr_pages;

- bio = btrfs_bio_alloc(first_byte);
+ bio = btrfs_io_bio_alloc(0);
+ bio->bi_iter.bi_sector = first_byte >> SECTOR_SHIFT;
bio->bi_opf = bio_op | write_flags;
bio->bi_private = cb;
bio->bi_end_io = end_compressed_bio_write;
@@ -490,7 +491,8 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
bio_endio(bio);
}

- bio = btrfs_bio_alloc(first_byte);
+ bio = btrfs_io_bio_alloc(0);
+ bio->bi_iter.bi_sector = first_byte >> SECTOR_SHIFT;
bio->bi_opf = bio_op | write_flags;
bio->bi_private = cb;
bio->bi_end_io = end_compressed_bio_write;
@@ -748,7 +750,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
/* include any pages we added in add_ra-bio_pages */
cb->len = bio->bi_iter.bi_size;

- comp_bio = btrfs_bio_alloc(cur_disk_byte);
+ comp_bio = btrfs_io_bio_alloc(0);
+ comp_bio->bi_iter.bi_sector = cur_disk_byte >> SECTOR_SHIFT;
comp_bio->bi_opf = REQ_OP_READ;
comp_bio->bi_private = cb;
comp_bio->bi_end_io = end_compressed_bio_read;
@@ -806,7 +809,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
bio_endio(comp_bio);
}

- comp_bio = btrfs_bio_alloc(cur_disk_byte);
+ comp_bio = btrfs_io_bio_alloc(0);
+ comp_bio->bi_iter.bi_sector = cur_disk_byte >> SECTOR_SHIFT;
comp_bio->bi_opf = REQ_OP_READ;
comp_bio->bi_private = cb;
comp_bio->bi_end_io = end_compressed_bio_read;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 1aed03ef5f49..d3fcf7e8dc48 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3121,16 +3121,22 @@ static inline void btrfs_io_bio_init(struct btrfs_io_bio *btrfs_bio)
}

/*
- * The following helpers allocate a bio. As it's backed by a bioset, it'll
- * never fail. We're returning a bio right now but you can call btrfs_io_bio
- * for the appropriate container_of magic
+ * Allocate a btrfs_io_bio, with @nr_iovecs as maximum iovecs.
+ *
+ * If @nr_iovecs is 0, it will use BIO_MAX_VECS as @nr_iovces instead.
+ * This behavior is to provide a fail-safe default value.
+ *
+ * This helper uses bioset to allocate the bio, thus it's backed by mempool,
+ * and should not fail from process contexts.
*/
-struct bio *btrfs_bio_alloc(u64 first_byte)
+struct bio *btrfs_io_bio_alloc(unsigned int nr_iovecs)
{
struct bio *bio;

- bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_VECS, &btrfs_bioset);
- bio->bi_iter.bi_sector = first_byte >> 9;
+ ASSERT(nr_iovecs <= BIO_MAX_VECS);
+ if (nr_iovecs == 0)
+ nr_iovecs = BIO_MAX_VECS;
+ bio = bio_alloc_bioset(GFP_NOFS, nr_iovecs, &btrfs_bioset);
btrfs_io_bio_init(btrfs_io_bio(bio));
return bio;
}
@@ -3148,16 +3154,6 @@ struct bio *btrfs_bio_clone(struct bio *bio)
return new;
}

-struct bio *btrfs_io_bio_alloc(unsigned int nr_iovecs)
-{
- struct bio *bio;
-
- /* Bio allocation backed by a bioset does not fail */
- bio = bio_alloc_bioset(GFP_NOFS, nr_iovecs, &btrfs_bioset);
- btrfs_io_bio_init(btrfs_io_bio(bio));
- return bio;
-}
-
struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size)
{
struct bio *bio;
@@ -3307,14 +3303,15 @@ static int alloc_new_bio(struct btrfs_inode *inode,
struct bio *bio;
int ret;

+ bio = btrfs_io_bio_alloc(0);
/*
* For compressed page range, its disk_bytenr is always @disk_bytenr
* passed in, no matter if we have added any range into previous bio.
*/
if (bio_flags & EXTENT_BIO_COMPRESSED)
- bio = btrfs_bio_alloc(disk_bytenr);
+ bio->bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
else
- bio = btrfs_bio_alloc(disk_bytenr + offset);
+ bio->bi_iter.bi_sector = (disk_bytenr + offset) >> SECTOR_SHIFT;
bio_ctrl->bio = bio;
bio_ctrl->bio_flags = bio_flags;
bio->bi_end_io = end_io_func;
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index ba471f2063a7..81fa68eaa699 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -278,7 +278,6 @@ void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end);
void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
struct page *locked_page,
u32 bits_to_clear, unsigned long page_ops);
-struct bio *btrfs_bio_alloc(u64 first_byte);
struct bio *btrfs_io_bio_alloc(unsigned int nr_iovecs);
struct bio *btrfs_bio_clone(struct bio *bio);
struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size);
--
2.33.0