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author | Mike Snitzer <snitzer@redhat.com> | 2015-05-22 09:14:03 -0400 |
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committer | Jens Axboe <axboe@fb.com> | 2015-05-22 08:58:55 -0600 |
commit | 326e1dbb57368087a36607aaebe9795b8d5453e5 (patch) | |
tree | bbc17b38188d4f2d45d255f1254d63494d37e1e4 /include | |
parent | b04a5636a665f5529fdf69ee7e5512156196f31c (diff) | |
download | linux-stable-326e1dbb57368087a36607aaebe9795b8d5453e5.tar.gz linux-stable-326e1dbb57368087a36607aaebe9795b8d5453e5.tar.bz2 linux-stable-326e1dbb57368087a36607aaebe9795b8d5453e5.zip |
block: remove management of bi_remaining when restoring original bi_end_io
Commit c4cf5261 ("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>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/bio.h | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h index 7486ea103f6e..f0291cf64cc5 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -427,7 +427,6 @@ static inline struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask) } extern void bio_endio(struct bio *, int); -extern void bio_endio_nodec(struct bio *, int); struct request_queue; extern int bio_phys_segments(struct request_queue *, struct bio *); @@ -659,17 +658,6 @@ static inline struct bio *bio_list_get(struct bio_list *bl) } /* - * Increment chain count for the bio. Make sure the CHAIN flag update - * is visible before the raised count. - */ -static inline void bio_inc_remaining(struct bio *bio) -{ - bio->bi_flags |= (1 << BIO_CHAIN); - smp_mb__before_atomic(); - atomic_inc(&bio->__bi_remaining); -} - -/* * bio_set is used to allow other portions of the IO system to * allocate their own private memory pools for bio and iovec structures. * These memory pools in turn all allocate from the bio_slab |