block: remove management of bi_remaining when restoring original bi_end_io
Commitc4cf5261("bio: skip atomic inc/dec of ->bi_remaining for non-chains") regressed all existing callers that followed this pattern: 1) saving a bio's original bi_end_io 2) wiring up an intermediate bi_end_io 3) restoring the original bi_end_io from intermediate bi_end_io 4) calling bio_endio() to execute the restored original bi_end_io The regression was due to BIO_CHAIN only ever getting set if bio_inc_remaining() is called. For the above pattern it isn't set until step 3 above (step 2 would've needed to establish BIO_CHAIN). As such the first bio_endio(), in step 2 above, never decremented __bi_remaining before calling the intermediate bi_end_io -- leaving __bi_remaining with the value 1 instead of 0. When bio_inc_remaining() occurred during step 3 it brought it to a value of 2. When the second bio_endio() was called, in step 4 above, it should've called the original bi_end_io but it didn't because there was an extra reference that wasn't dropped (due to atomic operations being optimized away since BIO_CHAIN wasn't set upfront). Fix this issue by removing the __bi_remaining management complexity for all callers that use the above pattern -- bio_chain() is the only interface that _needs_ to be concerned with __bi_remaining. For the above pattern callers just expect the bi_end_io they set to get called! Remove bio_endio_nodec() and also remove all bio_inc_remaining() calls that aren't associated with the bio_chain() interface. Also, the bio_inc_remaining() interface has been moved local to bio.c. Fixes:c4cf5261("bio: skip atomic inc/dec of ->bi_remaining for non-chains") Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Mike Snitzer
Jens Axboe
Родитель
b04a5636a6
Коммит
326e1dbb57
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@ -361,7 +361,7 @@ static void bio_integrity_verify_fn(struct work_struct *work)
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/* Restore original bio completion handler */
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bio->bi_end_io = bip->bip_end_io;
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bio_endio_nodec(bio, error);
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bio_endio(bio, error);
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}
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/**
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@ -388,7 +388,7 @@ void bio_integrity_endio(struct bio *bio, int error)
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*/
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if (error) {
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bio->bi_end_io = bip->bip_end_io;
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bio_endio_nodec(bio, error);
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bio_endio(bio, error);
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return;
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}
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35
block/bio.c
35
block/bio.c
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@ -303,6 +303,17 @@ static void bio_chain_endio(struct bio *bio, int error)
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bio_put(bio);
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}
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/*
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* Increment chain count for the bio. Make sure the CHAIN flag update
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* is visible before the raised count.
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*/
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static inline void bio_inc_remaining(struct bio *bio)
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{
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bio->bi_flags |= (1 << BIO_CHAIN);
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smp_mb__before_atomic();
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atomic_inc(&bio->__bi_remaining);
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}
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/**
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* bio_chain - chain bio completions
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* @bio: the target bio
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@ -1756,8 +1767,10 @@ static inline bool bio_remaining_done(struct bio *bio)
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BUG_ON(atomic_read(&bio->__bi_remaining) <= 0);
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if (atomic_dec_and_test(&bio->__bi_remaining))
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if (atomic_dec_and_test(&bio->__bi_remaining)) {
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clear_bit(BIO_CHAIN, &bio->bi_flags);
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return true;
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}
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return false;
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}
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@ -1808,26 +1821,6 @@ void bio_endio(struct bio *bio, int error)
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}
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EXPORT_SYMBOL(bio_endio);
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/**
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* bio_endio_nodec - end I/O on a bio, without decrementing bi_remaining
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* @bio: bio
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* @error: error, if any
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*
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* For code that has saved and restored bi_end_io; thing hard before using this
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* function, probably you should've cloned the entire bio.
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**/
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void bio_endio_nodec(struct bio *bio, int error)
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{
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/*
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* If it's not flagged as a chain, we are not going to dec the count
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*/
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if (bio_flagged(bio, BIO_CHAIN))
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bio_inc_remaining(bio);
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bio_endio(bio, error);
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}
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EXPORT_SYMBOL(bio_endio_nodec);
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/**
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* bio_split - split a bio
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* @bio: bio to split
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@ -55,7 +55,7 @@ static void bch_bio_submit_split_done(struct closure *cl)
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s->bio->bi_end_io = s->bi_end_io;
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s->bio->bi_private = s->bi_private;
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bio_endio_nodec(s->bio, 0);
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bio_endio(s->bio, 0);
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closure_debug_destroy(&s->cl);
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mempool_free(s, s->p->bio_split_hook);
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@ -86,12 +86,6 @@ static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
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{
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bio->bi_end_io = h->bi_end_io;
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bio->bi_private = h->bi_private;
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/*
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* Must bump bi_remaining to allow bio to complete with
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* restored bi_end_io.
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*/
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bio_inc_remaining(bio);
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}
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/*----------------------------------------------------------------*/
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@ -1254,8 +1254,6 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio, int error)
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dm_bio_restore(bd, bio);
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bio_record->details.bi_bdev = NULL;
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bio_inc_remaining(bio);
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queue_bio(ms, bio, rw);
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return DM_ENDIO_INCOMPLETE;
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}
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@ -1478,7 +1478,6 @@ out:
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if (full_bio) {
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full_bio->bi_end_io = pe->full_bio_end_io;
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full_bio->bi_private = pe->full_bio_private;
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bio_inc_remaining(full_bio);
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}
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increment_pending_exceptions_done_count();
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@ -793,10 +793,9 @@ static void inc_remap_and_issue_cell(struct thin_c *tc,
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static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
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{
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if (m->bio) {
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if (m->bio)
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m->bio->bi_end_io = m->saved_bi_end_io;
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bio_inc_remaining(m->bio);
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}
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cell_error(m->tc->pool, m->cell);
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list_del(&m->list);
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mempool_free(m, m->tc->pool->mapping_pool);
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@ -810,10 +809,8 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
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int r;
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bio = m->bio;
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if (bio) {
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if (bio)
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bio->bi_end_io = m->saved_bi_end_io;
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bio_inc_remaining(bio);
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}
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if (m->err) {
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cell_error(pool, m->cell);
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@ -459,7 +459,7 @@ static void verity_finish_io(struct dm_verity_io *io, int error)
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bio->bi_end_io = io->orig_bi_end_io;
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bio->bi_private = io->orig_bi_private;
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bio_endio_nodec(bio, error);
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bio_endio(bio, error);
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}
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static void verity_work(struct work_struct *w)
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@ -1745,7 +1745,7 @@ static void end_workqueue_fn(struct btrfs_work *work)
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bio->bi_private = end_io_wq->private;
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bio->bi_end_io = end_io_wq->end_io;
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kmem_cache_free(btrfs_end_io_wq_cache, end_io_wq);
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bio_endio_nodec(bio, error);
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bio_endio(bio, error);
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}
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static int cleaner_kthread(void *arg)
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@ -5585,10 +5585,10 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
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static inline void btrfs_end_bbio(struct btrfs_bio *bbio, struct bio *bio, int err)
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{
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if (likely(bbio->flags & BTRFS_BIO_ORIG_BIO_SUBMITTED))
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bio_endio_nodec(bio, err);
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else
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bio->bi_private = bbio->private;
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bio->bi_end_io = bbio->end_io;
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bio_endio(bio, err);
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btrfs_put_bbio(bbio);
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}
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@ -5632,8 +5632,6 @@ static void btrfs_end_bio(struct bio *bio, int err)
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bio = bbio->orig_bio;
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}
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bio->bi_private = bbio->private;
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bio->bi_end_io = bbio->end_io;
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btrfs_io_bio(bio)->mirror_num = bbio->mirror_num;
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/* only send an error to the higher layers if it is
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* beyond the tolerance of the btrfs bio
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@ -5815,8 +5813,6 @@ static void bbio_error(struct btrfs_bio *bbio, struct bio *bio, u64 logical)
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/* Shoud be the original bio. */
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WARN_ON(bio != bbio->orig_bio);
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bio->bi_private = bbio->private;
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bio->bi_end_io = bbio->end_io;
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btrfs_io_bio(bio)->mirror_num = bbio->mirror_num;
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bio->bi_iter.bi_sector = logical >> 9;
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@ -5897,10 +5893,8 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
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if (dev_nr < total_devs - 1) {
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bio = btrfs_bio_clone(first_bio, GFP_NOFS);
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BUG_ON(!bio); /* -ENOMEM */
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} else {
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} else
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bio = first_bio;
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bbio->flags |= BTRFS_BIO_ORIG_BIO_SUBMITTED;
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}
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submit_stripe_bio(root, bbio, bio,
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bbio->stripes[dev_nr].physical, dev_nr, rw,
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@ -292,8 +292,6 @@ struct btrfs_bio_stripe {
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struct btrfs_bio;
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typedef void (btrfs_bio_end_io_t) (struct btrfs_bio *bio, int err);
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#define BTRFS_BIO_ORIG_BIO_SUBMITTED (1 << 0)
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struct btrfs_bio {
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atomic_t refs;
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atomic_t stripes_pending;
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@ -427,7 +427,6 @@ static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
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}
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extern void bio_endio(struct bio *, int);
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extern void bio_endio_nodec(struct bio *, int);
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struct request_queue;
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extern int bio_phys_segments(struct request_queue *, struct bio *);
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@ -658,17 +657,6 @@ static inline struct bio *bio_list_get(struct bio_list *bl)
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return bio;
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}
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/*
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* Increment chain count for the bio. Make sure the CHAIN flag update
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* is visible before the raised count.
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*/
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static inline void bio_inc_remaining(struct bio *bio)
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{
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bio->bi_flags |= (1 << BIO_CHAIN);
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smp_mb__before_atomic();
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atomic_inc(&bio->__bi_remaining);
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}
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/*
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* bio_set is used to allow other portions of the IO system to
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* allocate their own private memory pools for bio and iovec structures.
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