Re: [PATCH 4/4] block: Optionally snapshot page contents to provide stable pages during write
From: Zheng Liu <hidden>
Date: 2012-12-16 16:13:36
Also in:
linux-fsdevel, lkml
On Thu, Dec 13, 2012 at 12:08:11AM -0800, Darrick J. Wong wrote:
quoted hunk ↗ jump to hunk
diff --git a/mm/bounce.c b/mm/bounce.c index 0420867..fa11935 100644 --- a/mm/bounce.c +++ b/mm/bounce.c@@ -178,6 +178,38 @@ static void bounce_end_io_read_isa(struct bio *bio, int err) __bounce_end_io_read(bio, isa_page_pool, err); } +#ifdef CONFIG_NEED_BOUNCE_POOL +static int might_snapshot_stable_page_write(struct bio **bio_orig) +{ + return bio_data_dir(*bio_orig) == WRITE; +} + +static int should_snapshot_stable_pages(struct page *page, int rw) +{ + struct backing_dev_info *bdi; + struct address_space *mapping = page_mapping(page); + + if (!mapping) + return 0; + bdi = mapping->backing_dev_info; + if (!bdi_cap_stable_pages_required(bdi)) + return 0; + + return mapping->host->i_sb->s_flags & MS_SNAP_STABLE && + rw == WRITE; +} +#else +static int might_snapshot_stable_page_write(struct bio **bio_orig) +{ + return 0; +} + +static int should_snapshot_static_pages(struct page *page, int rw)
^^^^^^
It should be _stable_.
Regards,
- Zhengquoted hunk ↗ jump to hunk
+{ + return 0; +} +#endif /* CONFIG_NEED_BOUNCE_POOL */ + static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, mempool_t *pool) {@@ -192,7 +224,8 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig, /* * is destination page below bounce pfn? */ - if (page_to_pfn(page) <= queue_bounce_pfn(q)) + if (page_to_pfn(page) <= queue_bounce_pfn(q) && + !should_snapshot_stable_pages(page, rw)) continue; /*@@ -284,7 +317,8 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) * don't waste time iterating over bio segments */ if (!(q->bounce_gfp & GFP_DMA)) { - if (queue_bounce_pfn(q) >= blk_max_pfn) + if (queue_bounce_pfn(q) >= blk_max_pfn && + !might_snapshot_stable_page_write(bio_orig)) return; pool = page_pool; } else {