| Message ID | 1403145775-22641-7-git-send-email-miaox@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Thu, Jun 19, 2014 at 10:42:54AM +0800, Miao Xie wrote: > The deadlock happened when we mount degraded filesystem, the reproduced > steps are following: > # mkfs.btrfs -f -m raid1 -d raid1 <dev0> <dev1> > # echo 1 > /sys/block/`basename <dev0>`/device/delete > # mount -o degraded <dev1> <mnt> > > The reason was that the counter -- bi_remaining was wrong. If the missing > or unwriteable device was the last device in the mapping array, we would > not submit the original bio, so we shouldn't increase bi_remaining of it > in btrfs_end_bio(), or we would skip the final endio handle. > > Fix this problem by adding a flag into btrfs bio structure. If we submit > the original bio, we will set the flag, and we increase bi_remaining counter, > or we don't. > > Though there is another way to fix it -- decrease bi_remaining counter of the > original bio when we make sure the original bio is not submitted, this method > need add more check and is easy to make mistake. Happen to look at this problem, looks good to me. Reviewed-by: Liu Bo <bo.li.liu@oracle.com> -liubo > > Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> > --- > fs/btrfs/volumes.c | 7 ++++++- > fs/btrfs/volumes.h | 3 +++ > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 31f9036..4ca3c92 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -5415,8 +5415,12 @@ static void btrfs_end_bio(struct bio *bio, int err) > set_bit(BIO_UPTODATE, &bio->bi_flags); > err = 0; > } > + > + if (likely(bbio->flags & BTRFS_BIO_ORIG_BIO_SUBMITTED)) > + bio_endio_nodec(bio, err); > + else > + bio_endio(bio, err); > kfree(bbio); > - bio_endio_nodec(bio, err); > } else if (!is_orig_bio) { > bio_put(bio); > } > @@ -5671,6 +5675,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio, > BUG_ON(!bio); /* -ENOMEM */ > } else { > bio = first_bio; > + bbio->flags |= BTRFS_BIO_ORIG_BIO_SUBMITTED; > } > > submit_stripe_bio(root, bbio, bio, > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h > index 1a15bbe..2aaa00c 100644 > --- a/fs/btrfs/volumes.h > +++ b/fs/btrfs/volumes.h > @@ -190,11 +190,14 @@ struct btrfs_bio_stripe { > struct btrfs_bio; > typedef void (btrfs_bio_end_io_t) (struct btrfs_bio *bio, int err); > > +#define BTRFS_BIO_ORIG_BIO_SUBMITTED 0x1 > + > struct btrfs_bio { > atomic_t stripes_pending; > struct btrfs_fs_info *fs_info; > bio_end_io_t *end_io; > struct bio *orig_bio; > + unsigned long flags; > void *private; > atomic_t error; > int max_errors; > -- > 1.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 31f9036..4ca3c92 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -5415,8 +5415,12 @@ static void btrfs_end_bio(struct bio *bio, int err) set_bit(BIO_UPTODATE, &bio->bi_flags); err = 0; } + + if (likely(bbio->flags & BTRFS_BIO_ORIG_BIO_SUBMITTED)) + bio_endio_nodec(bio, err); + else + bio_endio(bio, err); kfree(bbio); - bio_endio_nodec(bio, err); } else if (!is_orig_bio) { bio_put(bio); } @@ -5671,6 +5675,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio, BUG_ON(!bio); /* -ENOMEM */ } else { bio = first_bio; + bbio->flags |= BTRFS_BIO_ORIG_BIO_SUBMITTED; } submit_stripe_bio(root, bbio, bio, diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 1a15bbe..2aaa00c 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -190,11 +190,14 @@ struct btrfs_bio_stripe { struct btrfs_bio; typedef void (btrfs_bio_end_io_t) (struct btrfs_bio *bio, int err); +#define BTRFS_BIO_ORIG_BIO_SUBMITTED 0x1 + struct btrfs_bio { atomic_t stripes_pending; struct btrfs_fs_info *fs_info; bio_end_io_t *end_io; struct bio *orig_bio; + unsigned long flags; void *private; atomic_t error; int max_errors;
The deadlock happened when we mount degraded filesystem, the reproduced steps are following: # mkfs.btrfs -f -m raid1 -d raid1 <dev0> <dev1> # echo 1 > /sys/block/`basename <dev0>`/device/delete # mount -o degraded <dev1> <mnt> The reason was that the counter -- bi_remaining was wrong. If the missing or unwriteable device was the last device in the mapping array, we would not submit the original bio, so we shouldn't increase bi_remaining of it in btrfs_end_bio(), or we would skip the final endio handle. Fix this problem by adding a flag into btrfs bio structure. If we submit the original bio, we will set the flag, and we increase bi_remaining counter, or we don't. Though there is another way to fix it -- decrease bi_remaining counter of the original bio when we make sure the original bio is not submitted, this method need add more check and is easy to make mistake. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> --- fs/btrfs/volumes.c | 7 ++++++- fs/btrfs/volumes.h | 3 +++ 2 files changed, 9 insertions(+), 1 deletion(-)