btrfs: split the bio submission path into a separate file

The code used by btrfs_submit_bio only interacts with the rest of
volumes.c through __btrfs_map_block (which itself is a more generic
version of two exported helpers) and does not really have anything
to do with volumes.c.  Create a new bio.c file and a bio.h header
going along with it for the btrfs_bio-based storage layer, which
will grow even more going forward.

Also update the file with my copyright notice given that a large
part of the moved code was written or rewritten by me.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 5 insertions, 291 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e51fd5f1042a..acab20f2863d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5,12 +5,9 @@
 
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
-#include <linux/bio.h>
 #include <linux/slab.h>
-#include <linux/blkdev.h>
 #include <linux/ratelimit.h>
 #include <linux/kthread.h>
-#include <linux/raid/pq.h>
 #include <linux/semaphore.h>
 #include <linux/uuid.h>
 #include <linux/list_sort.h>
@@ -23,8 +20,6 @@
 #include "print-tree.h"
 #include "volumes.h"
 #include "raid56.h"
-#include "async-thread.h"
-#include "check-integrity.h"
 #include "rcu-string.h"
 #include "dev-replace.h"
 #include "sysfs.h"
@@ -41,8 +36,6 @@
 #include "scrub.h"
 #include "super.h"
 
-static struct bio_set btrfs_bioset;
-
 #define BTRFS_BLOCK_GROUP_STRIPE_MASK	(BTRFS_BLOCK_GROUP_RAID0 | \
 					 BTRFS_BLOCK_GROUP_RAID10 | \
 					 BTRFS_BLOCK_GROUP_RAID56_MASK)
@@ -255,11 +248,6 @@ out_overflow:;
 static int init_first_rw_device(struct btrfs_trans_handle *trans);
 static int btrfs_relocate_sys_chunks(struct btrfs_fs_info *fs_info);
 static void btrfs_dev_stat_print_on_load(struct btrfs_device *device);
-static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
-			     enum btrfs_map_op op, u64 logical, u64 *length,
-			     struct btrfs_io_context **bioc_ret,
-			     struct btrfs_io_stripe *smap,
-			     int *mirror_num_ret, int need_raid_map);
 
 /*
  * Device locking
@@ -6364,11 +6352,11 @@ static void set_io_stripe(struct btrfs_io_stripe *dst, const struct map_lookup *
 			stripe_offset + stripe_nr * map->stripe_len;
 }
 
-static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
-			     enum btrfs_map_op op, u64 logical, u64 *length,
-			     struct btrfs_io_context **bioc_ret,
-			     struct btrfs_io_stripe *smap,
-			     int *mirror_num_ret, int need_raid_map)
+int __btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
+		      u64 logical, u64 *length,
+		      struct btrfs_io_context **bioc_ret,
+		      struct btrfs_io_stripe *smap, int *mirror_num_ret,
+		      int need_raid_map)
 {
 	struct extent_map *em;
 	struct map_lookup *map;
@@ -6651,266 +6639,6 @@ int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 				 NULL, NULL, 1);
 }
 
-/*
- * Initialize a btrfs_bio structure.  This skips the embedded bio itself as it
- * is already initialized by the block layer.
- */
-static inline void btrfs_bio_init(struct btrfs_bio *bbio,
-				  btrfs_bio_end_io_t end_io, void *private)
-{
-	memset(bbio, 0, offsetof(struct btrfs_bio, bio));
-	bbio->end_io = end_io;
-	bbio->private = private;
-}
-
-/*
- * Allocate a btrfs_bio structure.  The btrfs_bio is the main I/O container for
- * btrfs, and is used for all I/O submitted through btrfs_submit_bio.
- *
- * Just like the underlying bio_alloc_bioset it will not fail as it is backed by
- * a mempool.
- */
-struct bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf,
-			    btrfs_bio_end_io_t end_io, void *private)
-{
-	struct bio *bio;
-
-	bio = bio_alloc_bioset(NULL, nr_vecs, opf, GFP_NOFS, &btrfs_bioset);
-	btrfs_bio_init(btrfs_bio(bio), end_io, private);
-	return bio;
-}
-
-struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size,
-				    btrfs_bio_end_io_t end_io, void *private)
-{
-	struct bio *bio;
-	struct btrfs_bio *bbio;
-
-	ASSERT(offset <= UINT_MAX && size <= UINT_MAX);
-
-	bio = bio_alloc_clone(orig->bi_bdev, orig, GFP_NOFS, &btrfs_bioset);
-	bbio = btrfs_bio(bio);
-	btrfs_bio_init(bbio, end_io, private);
-
-	bio_trim(bio, offset >> 9, size >> 9);
-	bbio->iter = bio->bi_iter;
-	return bio;
-}
-
-static void btrfs_log_dev_io_error(struct bio *bio, struct btrfs_device *dev)
-{
-	if (!dev || !dev->bdev)
-		return;
-	if (bio->bi_status != BLK_STS_IOERR && bio->bi_status != BLK_STS_TARGET)
-		return;
-
-	if (btrfs_op(bio) == BTRFS_MAP_WRITE)
-		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
-	if (!(bio->bi_opf & REQ_RAHEAD))
-		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
-	if (bio->bi_opf & REQ_PREFLUSH)
-		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_FLUSH_ERRS);
-}
-
-static struct workqueue_struct *btrfs_end_io_wq(struct btrfs_fs_info *fs_info,
-						struct bio *bio)
-{
-	if (bio->bi_opf & REQ_META)
-		return fs_info->endio_meta_workers;
-	return fs_info->endio_workers;
-}
-
-static void btrfs_end_bio_work(struct work_struct *work)
-{
-	struct btrfs_bio *bbio =
-		container_of(work, struct btrfs_bio, end_io_work);
-
-	bbio->end_io(bbio);
-}
-
-static void btrfs_simple_end_io(struct bio *bio)
-{
-	struct btrfs_fs_info *fs_info = bio->bi_private;
-	struct btrfs_bio *bbio = btrfs_bio(bio);
-
-	btrfs_bio_counter_dec(fs_info);
-
-	if (bio->bi_status)
-		btrfs_log_dev_io_error(bio, bbio->device);
-
-	if (bio_op(bio) == REQ_OP_READ) {
-		INIT_WORK(&bbio->end_io_work, btrfs_end_bio_work);
-		queue_work(btrfs_end_io_wq(fs_info, bio), &bbio->end_io_work);
-	} else {
-		bbio->end_io(bbio);
-	}
-}
-
-static void btrfs_raid56_end_io(struct bio *bio)
-{
-	struct btrfs_io_context *bioc = bio->bi_private;
-	struct btrfs_bio *bbio = btrfs_bio(bio);
-
-	btrfs_bio_counter_dec(bioc->fs_info);
-	bbio->mirror_num = bioc->mirror_num;
-	bbio->end_io(bbio);
-
-	btrfs_put_bioc(bioc);
-}
-
-static void btrfs_orig_write_end_io(struct bio *bio)
-{
-	struct btrfs_io_stripe *stripe = bio->bi_private;
-	struct btrfs_io_context *bioc = stripe->bioc;
-	struct btrfs_bio *bbio = btrfs_bio(bio);
-
-	btrfs_bio_counter_dec(bioc->fs_info);
-
-	if (bio->bi_status) {
-		atomic_inc(&bioc->error);
-		btrfs_log_dev_io_error(bio, stripe->dev);
-	}
-
-	/*
-	 * Only send an error to the higher layers if it is beyond the tolerance
-	 * threshold.
-	 */
-	if (atomic_read(&bioc->error) > bioc->max_errors)
-		bio->bi_status = BLK_STS_IOERR;
-	else
-		bio->bi_status = BLK_STS_OK;
-
-	bbio->end_io(bbio);
-	btrfs_put_bioc(bioc);
-}
-
-static void btrfs_clone_write_end_io(struct bio *bio)
-{
-	struct btrfs_io_stripe *stripe = bio->bi_private;
-
-	if (bio->bi_status) {
-		atomic_inc(&stripe->bioc->error);
-		btrfs_log_dev_io_error(bio, stripe->dev);
-	}
-
-	/* Pass on control to the original bio this one was cloned from */
-	bio_endio(stripe->bioc->orig_bio);
-	bio_put(bio);
-}
-
-static void btrfs_submit_dev_bio(struct btrfs_device *dev, struct bio *bio)
-{
-	if (!dev || !dev->bdev ||
-	    test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) ||
-	    (btrfs_op(bio) == BTRFS_MAP_WRITE &&
-	     !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))) {
-		bio_io_error(bio);
-		return;
-	}
-
-	bio_set_dev(bio, dev->bdev);
-
-	/*
-	 * For zone append writing, bi_sector must point the beginning of the
-	 * zone
-	 */
-	if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
-		u64 physical = bio->bi_iter.bi_sector << SECTOR_SHIFT;
-
-		if (btrfs_dev_is_sequential(dev, physical)) {
-			u64 zone_start = round_down(physical,
-						    dev->fs_info->zone_size);
-
-			bio->bi_iter.bi_sector = zone_start >> SECTOR_SHIFT;
-		} else {
-			bio->bi_opf &= ~REQ_OP_ZONE_APPEND;
-			bio->bi_opf |= REQ_OP_WRITE;
-		}
-	}
-	btrfs_debug_in_rcu(dev->fs_info,
-	"%s: rw %d 0x%x, sector=%llu, dev=%lu (%s id %llu), size=%u",
-		__func__, bio_op(bio), bio->bi_opf, bio->bi_iter.bi_sector,
-		(unsigned long)dev->bdev->bd_dev, btrfs_dev_name(dev),
-		dev->devid, bio->bi_iter.bi_size);
-
-	btrfsic_check_bio(bio);
-	submit_bio(bio);
-}
-
-static void btrfs_submit_mirrored_bio(struct btrfs_io_context *bioc, int dev_nr)
-{
-	struct bio *orig_bio = bioc->orig_bio, *bio;
-
-	ASSERT(bio_op(orig_bio) != REQ_OP_READ);
-
-	/* Reuse the bio embedded into the btrfs_bio for the last mirror */
-	if (dev_nr == bioc->num_stripes - 1) {
-		bio = orig_bio;
-		bio->bi_end_io = btrfs_orig_write_end_io;
-	} else {
-		bio = bio_alloc_clone(NULL, orig_bio, GFP_NOFS, &fs_bio_set);
-		bio_inc_remaining(orig_bio);
-		bio->bi_end_io = btrfs_clone_write_end_io;
-	}
-
-	bio->bi_private = &bioc->stripes[dev_nr];
-	bio->bi_iter.bi_sector = bioc->stripes[dev_nr].physical >> SECTOR_SHIFT;
-	bioc->stripes[dev_nr].bioc = bioc;
-	btrfs_submit_dev_bio(bioc->stripes[dev_nr].dev, bio);
-}
-
-void btrfs_submit_bio(struct btrfs_fs_info *fs_info, struct bio *bio, int mirror_num)
-{
-	u64 logical = bio->bi_iter.bi_sector << 9;
-	u64 length = bio->bi_iter.bi_size;
-	u64 map_length = length;
-	struct btrfs_io_context *bioc = NULL;
-	struct btrfs_io_stripe smap;
-	int ret;
-
-	btrfs_bio_counter_inc_blocked(fs_info);
-	ret = __btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,
-				&bioc, &smap, &mirror_num, 1);
-	if (ret) {
-		btrfs_bio_counter_dec(fs_info);
-		btrfs_bio_end_io(btrfs_bio(bio), errno_to_blk_status(ret));
-		return;
-	}
-
-	if (map_length < length) {
-		btrfs_crit(fs_info,
-			   "mapping failed logical %llu bio len %llu len %llu",
-			   logical, length, map_length);
-		BUG();
-	}
-
-	if (!bioc) {
-		/* Single mirror read/write fast path */
-		btrfs_bio(bio)->mirror_num = mirror_num;
-		btrfs_bio(bio)->device = smap.dev;
-		bio->bi_iter.bi_sector = smap.physical >> SECTOR_SHIFT;
-		bio->bi_private = fs_info;
-		bio->bi_end_io = btrfs_simple_end_io;
-		btrfs_submit_dev_bio(smap.dev, bio);
-	} else if (bioc->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
-		/* Parity RAID write or read recovery */
-		bio->bi_private = bioc;
-		bio->bi_end_io = btrfs_raid56_end_io;
-		if (bio_op(bio) == REQ_OP_READ)
-			raid56_parity_recover(bio, bioc, mirror_num);
-		else
-			raid56_parity_write(bio, bioc);
-	} else {
-		/* Write to multiple mirrors */
-		int total_devs = bioc->num_stripes;
-		int dev_nr;
-
-		bioc->orig_bio = bio;
-		for (dev_nr = 0; dev_nr < total_devs; dev_nr++)
-			btrfs_submit_mirrored_bio(bioc, dev_nr);
-	}
-}
-
 static bool dev_args_match_fs_devices(const struct btrfs_dev_lookup_args *args,
 				      const struct btrfs_fs_devices *fs_devices)
 {
@@ -8440,17 +8168,3 @@ bool btrfs_repair_one_zone(struct btrfs_fs_info *fs_info, u64 logical)
 
 	return true;
 }
-
-int __init btrfs_bioset_init(void)
-{
-	if (bioset_init(&btrfs_bioset, BIO_POOL_SIZE,
-			offsetof(struct btrfs_bio, bio),
-			BIOSET_NEED_BVECS))
-		return -ENOMEM;
-	return 0;
-}
-
-void __cold btrfs_bioset_exit(void)
-{
-	bioset_exit(&btrfs_bioset);
-}