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From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
	axboe@fb.com, Matias Bjorling <mb@lightnvm.io>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH 01/10] block: don't decrement nr_phys_segments for physically contigous segments
Date: Tue, 14 May 2019 16:32:31 +0200	[thread overview]
Message-ID: <20190514143231.GA14556@lst.de> (raw)
In-Reply-To: <20190514143102.GA14401@lst.de>

On Tue, May 14, 2019 at 04:31:02PM +0200, Christoph Hellwig wrote:
> On Tue, May 14, 2019 at 10:27:17PM +0800, Ming Lei wrote:
> > I am wondering if it can be done easily, given mkfs is userspace
> > which only calls write syscall on block device. Or could you share
> > something about how to fix the stupid things?
> 
> mkfs.ext4 at least uses buffered I/O on the block device.  And the
> block device uses the really old buffer head based address_space ops,
> which will submit one bio per buffer_head, that is per logic block.
> mkfs probably writes much larger sizes than that..

As a first step we could try something like that patch below.  Although
the mpage ops still aren't exactly optimal:


diff --git a/fs/block_dev.c b/fs/block_dev.c
index bded2ee3788d..b2ee74f1c669 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -608,12 +608,12 @@ EXPORT_SYMBOL(thaw_bdev);
 
 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
 {
-	return block_write_full_page(page, blkdev_get_block, wbc);
+	return mpage_writepage(page, blkdev_get_block, wbc);
 }
 
 static int blkdev_readpage(struct file * file, struct page * page)
 {
-	return block_read_full_page(page, blkdev_get_block);
+	return mpage_readpage(page, blkdev_get_block);
 }
 
 static int blkdev_readpages(struct file *file, struct address_space *mapping,
@@ -1984,7 +1984,7 @@ static int blkdev_releasepage(struct page *page, gfp_t wait)
 static int blkdev_writepages(struct address_space *mapping,
 			     struct writeback_control *wbc)
 {
-	return generic_writepages(mapping, wbc);
+	return mpage_writepages(mapping, wbc, blkdev_get_block);
 }
 
 static const struct address_space_operations def_blk_aops = {

  reply	other threads:[~2019-05-14 14:32 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-13  6:37 fix nr_phys_segments vs iterators accounting Christoph Hellwig
2019-05-13  6:37 ` [PATCH 01/10] block: don't decrement nr_phys_segments for physically contigous segments Christoph Hellwig
2019-05-13  9:45   ` Ming Lei
2019-05-13 12:03     ` Christoph Hellwig
2019-05-13 12:37       ` Christoph Hellwig
2019-05-14  4:36       ` Ming Lei
2019-05-14  5:14         ` Christoph Hellwig
2019-05-14  9:05           ` Ming Lei
2019-05-14 13:51             ` Christoph Hellwig
2019-05-14 13:57               ` Hannes Reinecke
2019-05-14 14:27               ` Ming Lei
2019-05-14 14:31                 ` Christoph Hellwig
2019-05-14 14:32                   ` Christoph Hellwig [this message]
2019-05-13  6:37 ` [PATCH 02/10] block: force an unlimited segment size on queues with a virt boundary Christoph Hellwig
2019-05-15  8:19   ` Ming Lei
2019-05-13  6:37 ` [PATCH 03/10] block: remove the segment size check in bio_will_gap Christoph Hellwig
2019-05-15  8:34   ` Ming Lei
2019-05-13  6:37 ` [PATCH 04/10] block: remove the bi_seg_{front,back}_size fields in struct bio Christoph Hellwig
2019-05-13  6:37 ` [PATCH 05/10] block: initialize the write priority in blk_rq_bio_prep Christoph Hellwig
2019-05-13 15:04   ` Chaitanya Kulkarni
2019-05-13  6:37 ` [PATCH 06/10] block: remove blk_init_request_from_bio Christoph Hellwig
2019-05-13  6:37 ` [PATCH 07/10] block: remove the bi_phys_segments field in struct bio Christoph Hellwig
2019-05-13  6:37 ` [PATCH 08/10] block: simplify blk_recalc_rq_segments Christoph Hellwig
2019-05-13  6:37 ` [PATCH 09/10] block: untangle the end of blk_bio_segment_split Christoph Hellwig
2019-05-13  6:37 ` [PATCH 10/10] block: mark blk_rq_bio_prep as inline Christoph Hellwig
2019-05-13 14:57   ` Chaitanya Kulkarni
     [not found] ` <CGME20190513063855epcas5p33ef8c4c0a0055bd0b66eadc859796f0f@epcms2p6>
2019-05-13  7:34   ` [PATCH 05/10] block: initialize the write priority in blk_rq_bio_prep Minwoo Im

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