On Tue, Sep 25, 2012 at 02:51:54PM +0200, Jens Axboe wrote:
> On 09/24/2012 06:56 AM, NeilBrown wrote:
> >
> > Hi Jens,
> > this patch has been sitting in my -next tree for a little while and I was
> > hoping for it to go in for the next merge window.
> > It simply allows bio_split() to be used on bios without a payload, such as
> > 'discard'.
> > Are you happy with it going in though my 'md' tree, or would you rather
> > take
> > it though your 'block' tree?
>
> It should go through my tree, especially since we've got conflicts with
> other changes. In other words, your patch does not apply to for-3.7/core
> as-is...
>
> Shaohua, could you resend an updated variant?
Here is the one applied to for-3.7/core
Subject: block: makes bio_split support bio without data
discard bio hasn't data attached. We hit a BUG_ON with such bio. This makes
bio_split works for such bio.
Signed-off-by: Shaohua Li <s...@fusionio.com>
Signed-off-by: NeilBrown <ne...@suse.de>
---
fs/bio.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
Index: linux/fs/bio.c
===================================================================
--- linux.orig/fs/bio.c 2012-09-28 15:09:38.000000000 +0800
+++ linux/fs/bio.c 2012-09-28 15:25:38.955252846 +0800
@@ -1475,7 +1475,7 @@ struct bio_pair *bio_split(struct bio *b
trace_block_split(bdev_get_queue(bi->bi_bdev), bi,
bi->bi_sector + first_sectors);
- BUG_ON(bi->bi_vcnt != 1);
+ BUG_ON(bi->bi_vcnt != 1 && bi->bi_vcnt != 0);
BUG_ON(bi->bi_idx != 0);
atomic_set(&bp->cnt, 3);
bp->error = 0;
@@ -1485,20 +1485,22 @@ struct bio_pair *bio_split(struct bio *b
bp->bio2.bi_size -= first_sectors << 9;
bp->bio1.bi_size = first_sectors << 9;
- bp->bv1 = bi->bi_io_vec[0];
- bp->bv2 = bi->bi_io_vec[0];
+ if (bi->bi_vcnt != 0) {
+ bp->bv1 = bi->bi_io_vec[0];
+ bp->bv2 = bi->bi_io_vec[0];
+
+ if (bio_is_rw(bi)) {
+ bp->bv2.bv_offset += first_sectors << 9;
+ bp->bv2.bv_len -= first_sectors << 9;
+ bp->bv1.bv_len = first_sectors << 9;
+ }
- if (bio_is_rw(bi)) {
- bp->bv2.bv_offset += first_sectors << 9;
- bp->bv2.bv_len -= first_sectors << 9;
- bp->bv1.bv_len = first_sectors << 9;
- }
-
- bp->bio1.bi_io_vec = &bp->bv1;
- bp->bio2.bi_io_vec = &bp->bv2;
+ bp->bio1.bi_io_vec = &bp->bv1;
+ bp->bio2.bi_io_vec = &bp->bv2;
- bp->bio1.bi_max_vecs = 1;
- bp->bio2.bi_max_vecs = 1;
+ bp->bio1.bi_max_vecs = 1;
+ bp->bio2.bi_max_vecs = 1;
+ }
bp->bio1.bi_end_io = bio_pair_end_1;
bp->bio2.bi_end_io = bio_pair_end_2;
--
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