[PATCH 10/17] btrfs: remove stripe boundary calculation for compressed I/O

Christoph Hellwig
2022-09-01T07:44:08Z

From: Qu Wenruo <wqu@suse.com>

Stop looking at the stripe boundary in alloc_compressed_bio() now that
that btrfs_submit_bio can split bios, open code the now trivial code
from alloc_compressed_bio() in btrfs_submit_compressed_read and stop
maintaining the pending_ios count for reads as there is always just
a single bio now.

Signed-off-by: Qu Wenruo <wqu@suse.com>
[hch: remove more cruft in btrfs_submit_compressed_read]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/btrfs/compression.c | 131 +++++++++++------------------------------
1 file changed, 34 insertions(+), 97 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 1f10f86e70557..5e8b75b030ace 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -136,12 +136,15 @@ static int compression_decompress(int type, struct list_head *ws,

static int btrfs_decompress_bio(struct compressed_bio *cb);

-static void finish_compressed_bio_read(struct compressed_bio *cb)
+static void end_compressed_bio_read(struct btrfs_bio *bbio)
{
+ struct compressed_bio *cb = bbio->private;
unsigned int index;
struct page *page;

- if (cb->status == BLK_STS_OK)
+ if (bbio->bio.bi_status)
+ cb->status = bbio->bio.bi_status;
+ else
cb->status = errno_to_blk_status(btrfs_decompress_bio(cb));

/* Release the compressed pages */
@@ -157,17 +160,6 @@ static void finish_compressed_bio_read(struct compressed_bio *cb)
/* Finally free the cb struct */
kfree(cb->compressed_pages);
kfree(cb);
-}
-
-static void end_compressed_bio_read(struct btrfs_bio *bbio)
-{
- struct compressed_bio *cb = bbio->private;
-
- if (bbio->bio.bi_status)
- cb->status = bbio->bio.bi_status;
-
- if (refcount_dec_and_test(&cb->pending_ios))
- finish_compressed_bio_read(cb);
bio_put(&bbio->bio);
}

@@ -286,42 +278,30 @@ static void end_compressed_bio_write(struct btrfs_bio *bbio)
* from or written to.
* @endio_func: The endio function to call after the IO for compressed data
* is finished.
- * @next_stripe_start: Return value of logical bytenr of where next stripe starts.
- * Let the caller know to only fill the bio up to the stripe
- * boundary.
*/
-
-
static struct bio *alloc_compressed_bio(struct compressed_bio *cb, u64 disk_bytenr,
blk_opf_t opf,
- btrfs_bio_end_io_t endio_func,
- u64 *next_stripe_start)
+ btrfs_bio_end_io_t endio_func)
{
- struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
- struct btrfs_io_geometry geom;
- struct extent_map *em;
struct bio *bio;
- int ret;

bio = btrfs_bio_alloc(BIO_MAX_VECS, opf, cb->inode, endio_func, cb);
bio->bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;

- em = btrfs_get_chunk_map(fs_info, disk_bytenr, fs_info->sectorsize);
- if (IS_ERR(em)) {
- bio_put(bio);
- return ERR_CAST(em);
- }
+ if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
+ struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
+ struct extent_map *em;

- if (bio_op(bio) == REQ_OP_ZONE_APPEND)
- bio_set_dev(bio, em->map_lookup->stripes[0].dev->bdev);
+ em = btrfs_get_chunk_map(fs_info, disk_bytenr,
+ fs_info->sectorsize);
+ if (IS_ERR(em)) {
+ bio_put(bio);
+ return ERR_CAST(em);
+ }

- ret = btrfs_get_io_geometry(fs_info, em, btrfs_op(bio), disk_bytenr, &geom);
- free_extent_map(em);
- if (ret < 0) {
- bio_put(bio);
- return ERR_PTR(ret);
+ bio_set_dev(bio, em->map_lookup->stripes[0].dev->bdev);
+ free_extent_map(em);
}
- *next_stripe_start = disk_bytenr + geom.len;
refcount_inc(&cb->pending_ios);
return bio;
}
@@ -348,7 +328,6 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
struct bio *bio = NULL;
struct compressed_bio *cb;
u64 cur_disk_bytenr = disk_start;
- u64 next_stripe_start;
blk_status_t ret = BLK_STS_OK;
const bool use_append = btrfs_use_zone_append(inode, disk_start);
const enum req_op bio_op = REQ_BTRFS_ONE_ORDERED |
@@ -384,8 +363,7 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
/* Allocate new bio if submitted or not yet allocated */
if (!bio) {
bio = alloc_compressed_bio(cb, cur_disk_bytenr,
- bio_op | write_flags, end_compressed_bio_write,
- &next_stripe_start);
+ bio_op | write_flags, end_compressed_bio_write);
if (IS_ERR(bio)) {
ret = errno_to_blk_status(PTR_ERR(bio));
break;
@@ -393,20 +371,12 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
if (blkcg_css)
bio->bi_opf |= REQ_CGROUP_PUNT;
}
- /*
- * We should never reach next_stripe_start start as we will
- * submit comp_bio when reach the boundary immediately.
- */
- ASSERT(cur_disk_bytenr != next_stripe_start);
-
/*
* We have various limits on the real read size:
- * - stripe boundary
* - page boundary
* - compressed length boundary
*/
- real_size = min_t(u64, U32_MAX, next_stripe_start - cur_disk_bytenr);
- real_size = min_t(u64, real_size, PAGE_SIZE - offset_in_page(offset));
+ real_size = min_t(u64, U32_MAX, PAGE_SIZE - offset_in_page(offset));
real_size = min_t(u64, real_size, compressed_len - offset);
ASSERT(IS_ALIGNED(real_size, fs_info->sectorsize));

@@ -421,9 +391,6 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
submit = true;

cur_disk_bytenr += added;
- /* Reached stripe boundary */
- if (cur_disk_bytenr == next_stripe_start)
- submit = true;

/* Finished the range */
if (cur_disk_bytenr == disk_start + compressed_len)
@@ -613,10 +580,9 @@ void btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
struct extent_map_tree *em_tree;
struct compressed_bio *cb;
unsigned int compressed_len;
- struct bio *comp_bio = NULL;
+ struct bio *comp_bio;
const u64 disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
u64 cur_disk_byte = disk_bytenr;
- u64 next_stripe_start;
u64 file_offset;
u64 em_len;
u64 em_start;
@@ -681,37 +647,23 @@ void 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(BIO_MAX_VECS, REQ_OP_READ, cb->inode,
+ end_compressed_bio_read, cb);
+ comp_bio->bi_iter.bi_sector = cur_disk_byte >> SECTOR_SHIFT;
+
while (cur_disk_byte < disk_bytenr + compressed_len) {
u64 offset = cur_disk_byte - disk_bytenr;
unsigned int index = offset >> PAGE_SHIFT;
unsigned int real_size;
unsigned int added;
struct page *page = cb->compressed_pages[index];
- bool submit = false;

- /* Allocate new bio if submitted or not yet allocated */
- if (!comp_bio) {
- comp_bio = alloc_compressed_bio(cb, cur_disk_byte,
- REQ_OP_READ, end_compressed_bio_read,
- &next_stripe_start);
- if (IS_ERR(comp_bio)) {
- cb->status = errno_to_blk_status(PTR_ERR(comp_bio));
- break;
- }
- }
- /*
- * We should never reach next_stripe_start start as we will
- * submit comp_bio when reach the boundary immediately.
- */
- ASSERT(cur_disk_byte != next_stripe_start);
/*
* We have various limit on the real read size:
- * - stripe boundary
* - page boundary
* - compressed length boundary
*/
- real_size = min_t(u64, U32_MAX, next_stripe_start - cur_disk_byte);
- real_size = min_t(u64, real_size, PAGE_SIZE - offset_in_page(offset));
+ real_size = min_t(u64, U32_MAX, PAGE_SIZE - offset_in_page(offset));
real_size = min_t(u64, real_size, compressed_len - offset);
ASSERT(IS_ALIGNED(real_size, fs_info->sectorsize));

@@ -722,32 +674,17 @@ void btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
*/
ASSERT(added == real_size);
cur_disk_byte += added;
-
- /* Reached stripe boundary, need to submit */
- if (cur_disk_byte == next_stripe_start)
- submit = true;
-
- /* Has finished the range, need to submit */
- if (cur_disk_byte == disk_bytenr + compressed_len)
- submit = true;
-
- if (submit) {
- /*
- * Save the initial offset of this chunk, as there
- * is no direct correlation between compressed pages and
- * the original file offset. The field is only used for
- * priting error messages.
- */
- btrfs_bio(comp_bio)->file_offset = file_offset;
-
- ASSERT(comp_bio->bi_iter.bi_size);
- btrfs_submit_bio(fs_info, comp_bio, mirror_num);
- comp_bio = NULL;
- }
}

- if (refcount_dec_and_test(&cb->pending_ios))
- finish_compressed_bio_read(cb);
+ /*
+ * Just stash the initial offset of this chunk, as there is no direct
+ * correlation between compressed pages and the original file offset.
+ * The field is only used for priting error messages anyway.
+ */
+ btrfs_bio(comp_bio)->file_offset = file_offset;
+
+ ASSERT(comp_bio->bi_iter.bi_size);
+ btrfs_submit_bio(fs_info, comp_bio, mirror_num);
return;

fail:
--
2.30.2