Messages in this thread Patch in this message | | | Date | Thu, 29 May 2014 14:06:18 +0800 | From | Jet Chen <> | Subject | Re: [PATCH] bio: decrease bi_iter.bi_size by len in the fail path |
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On 05/29/2014 01:44 AM, Ming Lei wrote: > On Thu, May 29, 2014 at 1:21 AM, Maurizio Lombardi <mlombard@redhat.com> wrote: >> Hi Ming, >> >> On Thu, May 29, 2014 at 12:59:19AM +0800, Ming Lei wrote: >>> >>> Actually, the correct thing may be like what did in the >>> attached patch, as Maurizio discussed with me[1]. >>> >>> Very interestingly, I have reproduced the problem one time >>> with ext4/271 ext4/301 ext4/305, but won't with the attached >>> patch after running it for 3 rounds. >>> >>> [tom@localhost xfstests]$ sudo ./check ext4/271 ext4/301 ext4/305 >>> FSTYP -- ext4 >>> PLATFORM -- Linux/x86_64 localhost 3.15.0-rc7-next-20140527+ >>> MKFS_OPTIONS -- /dev/vdc >>> MOUNT_OPTIONS -- -o acl,user_xattr /dev/vdc /mnt/scratch >>> >>> ext4/271 1s ... 1s >>> ext4/301 31s ... 32s >>> ext4/305 181s ... 180s >>> Ran: ext4/271 ext4/301 ext4/305 >>> Passed all 3 tests >>> >>> Jet, could you test the attached patch? >>> >>> [1], https://lkml.org/lkml/2014/5/27/327 >> >> There is a little mistake in your patch, you removed bio->bi_iter.bi_size += len; >> after the "done" label, >> but be careful that at line 747 there is a "goto done"... bi_size should be incremented >> before jumping there. > > Good catch, thanks Maurizio. > > Jet, please test the attached patch in this mail and ignore previous > one. > > The story behind the patch should be like below: > > - one page is added in __bio_add_page() 'successfully', > and bio->bi_phys_segments is equal to queue_max_segments(q), > but it should have been rejected since the last vector isn't covered > > - next time, __bio_add_page() is called to add one page, but this > time blk_recount_segments() can figure out the actual physical > segments and find it is more than max segments, so failure is > triggered, but the bio->bi_phys_segments is updated with > max segments plus one > > - the oops is triggered and reported by Jet, :-) > > > Thanks, > This patch works, thanks.
Tested-by: Jet Chen <jet.chen@intel.com>
diff --git a/block/bio.c b/block/bio.c index 0443694..f9bae56 100644 --- a/block/bio.c +++ b/block/bio.c @@ -744,6 +744,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page } } + bio->bi_iter.bi_size += len; goto done; } } @@ -761,6 +762,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page bvec->bv_offset = offset; bio->bi_vcnt++; bio->bi_phys_segments++; + bio->bi_iter.bi_size += len; /* * Perform a recount if the number of segments is greater @@ -802,7 +804,6 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page bio->bi_flags &= ~(1 << BIO_SEG_VALID); done: - bio->bi_iter.bi_size += len; return len; failed: @@ -810,6 +811,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page bvec->bv_len = 0; bvec->bv_offset = 0; bio->bi_vcnt--; + bio->bi_iter.bi_size -= len; blk_recount_segments(q, bio); return 0; } | |