* [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS [not found] <1477728600-12938-1-git-send-email-tom.leiming@gmail.com> @ 2016-10-29 8:08 ` Ming Lei 2016-10-31 15:36 ` Christoph Hellwig 0 siblings, 1 reply; 4+ messages in thread From: Ming Lei @ 2016-10-29 8:08 UTC (permalink / raw) To: Jens Axboe, linux-kernel Cc: linux-block, linux-fsdevel, Christoph Hellwig, Kirill A . Shutemov, Ming Lei, Chris Mason, Josef Bacik, David Sterba, open list:BTRFS FILE SYSTEM There are lots of direct access to .bi_vcnt & .bi_io_vec of bio, and it isn't ready to support multipage bvecs for BTRFS, so set NO_MP for these request queues. Signed-off-by: Ming Lei <tom.leiming@gmail.com> --- fs/btrfs/volumes.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 71a60cc01451..2e7237a3b84d 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1011,6 +1011,9 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices, if (blk_queue_discard(q)) device->can_discard = 1; + /* BTRFS isn't ready to support multipage bvecs */ + set_bit(QUEUE_FLAG_NO_MP, &q->queue_flags); + device->bdev = bdev; device->in_fs_metadata = 0; device->mode = flags; -- 2.7.4 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS 2016-10-29 8:08 ` [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS Ming Lei @ 2016-10-31 15:36 ` Christoph Hellwig 2016-10-31 17:58 ` Chris Mason 0 siblings, 1 reply; 4+ messages in thread From: Christoph Hellwig @ 2016-10-31 15:36 UTC (permalink / raw) To: Ming Lei Cc: Jens Axboe, linux-kernel, linux-block, linux-fsdevel, Christoph Hellwig, Kirill A . Shutemov, Chris Mason, Josef Bacik, David Sterba, open list:BTRFS FILE SYSTEM On Sat, Oct 29, 2016 at 04:08:25PM +0800, Ming Lei wrote: > There are lots of direct access to .bi_vcnt & .bi_io_vec > of bio, and it isn't ready to support multipage bvecs > for BTRFS, so set NO_MP for these request queues. For one bio is an I/O submitter, it has absolutely no business changing queue flags - if we need to stick to this limitation it simply needs a version of bio_add_page that doesn't create multi-page bvecs. Second I don't think making it multipage bvec aware is all that hard, and we should aim for doing the proper thing. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS 2016-10-31 15:36 ` Christoph Hellwig @ 2016-10-31 17:58 ` Chris Mason 2016-10-31 18:00 ` Christoph Hellwig 0 siblings, 1 reply; 4+ messages in thread From: Chris Mason @ 2016-10-31 17:58 UTC (permalink / raw) To: Christoph Hellwig Cc: Ming Lei, Jens Axboe, linux-kernel, linux-block, linux-fsdevel, Kirill A . Shutemov, Josef Bacik, David Sterba, open list:BTRFS FILE SYSTEM On Mon, Oct 31, 2016 at 08:36:44AM -0700, Christoph Hellwig wrote: >On Sat, Oct 29, 2016 at 04:08:25PM +0800, Ming Lei wrote: >> There are lots of direct access to .bi_vcnt & .bi_io_vec >> of bio, and it isn't ready to support multipage bvecs >> for BTRFS, so set NO_MP for these request queues. > >For one bio is an I/O submitter, it has absolutely no business changing >queue flags - if we need to stick to this limitation it simply needs >a version of bio_add_page that doesn't create multi-page bvecs. > >Second I don't think making it multipage bvec aware is all that hard, >and we should aim for doing the proper thing. Yeah, I'd rather make us less special. The direct access was a short term fix to adjust to the new bio interfaces, we should clean it up. -chris ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS 2016-10-31 17:58 ` Chris Mason @ 2016-10-31 18:00 ` Christoph Hellwig 0 siblings, 0 replies; 4+ messages in thread From: Christoph Hellwig @ 2016-10-31 18:00 UTC (permalink / raw) To: Chris Mason, Christoph Hellwig, Ming Lei, Jens Axboe, linux-kernel, linux-block, linux-fsdevel, Kirill A . Shutemov, Josef Bacik, David Sterba, open list:BTRFS FILE SYSTEM On Mon, Oct 31, 2016 at 11:58:29AM -0600, Chris Mason wrote: > Yeah, I'd rather make us less special. The direct access was a short term > fix to adjust to the new bio interfaces, we should clean it up. I've got patches for a few areas in progress, I'll send them your way once I've finished testing. There will be a few more areas left where I'll need a little help, though. ^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-10-29 8:08 ` [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS Ming Lei
2016-10-31 15:36 ` Christoph Hellwig
2016-10-31 17:58 ` Chris Mason
2016-10-31 18:00 ` Christoph Hellwig
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