Commit 7d636676 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Darrick J. Wong
Browse files

iomap: Convert read_count to read_bytes_pending 



Instead of counting bio segments, count the number of bytes submitted.
This insulates us from the block layer's definition of what a 'same page'
is, which is not necessarily clear once THPs are involved.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 0a195b91

fs/iomap/buffered-io.c

+12 −29
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ 
 * to track sub-page uptodate status and I/O completions.

 */

struct iomap_page {

	atomic_t		read_count;

	atomic_t		read_bytes_pending;

	atomic_t		write_count;

	spinlock_t		uptodate_lock;

	unsigned long		uptodate[];
@@ -72,7 +72,7 @@ iomap_page_release(struct page *page) 


	if (!iop)

		return;

	WARN_ON_ONCE(atomic_read(&iop->read_count));

	WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending));

	WARN_ON_ONCE(atomic_read(&iop->write_count));

	WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) !=

			PageUptodate(page));
@@ -167,13 +167,6 @@ iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len) 
		SetPageUptodate(page);

}



static void

iomap_read_finish(struct iomap_page *iop, struct page *page)

{

	if (!iop || atomic_dec_and_test(&iop->read_count))

		unlock_page(page);

}



static void

iomap_read_page_end_io(struct bio_vec *bvec, int error)

{
@@ -187,7 +180,8 @@ iomap_read_page_end_io(struct bio_vec *bvec, int error) 
		iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);

	}



	iomap_read_finish(iop, page);

	if (!iop || atomic_sub_and_test(bvec->bv_len, &iop->read_bytes_pending))

		unlock_page(page);

}



static void
@@ -267,30 +261,19 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, 
	}



	ctx->cur_page_in_bio = true;

	if (iop)

		atomic_add(plen, &iop->read_bytes_pending);



	/*

	 * Try to merge into a previous segment if we can.

	 */

	/* Try to merge into a previous segment if we can */

	sector = iomap_sector(iomap, pos);

	if (ctx->bio && bio_end_sector(ctx->bio) == sector)

		is_contig = true;



	if (is_contig &&

	    __bio_try_merge_page(ctx->bio, page, plen, poff, &same_page)) {

		if (!same_page && iop)

			atomic_inc(&iop->read_count);

	if (ctx->bio && bio_end_sector(ctx->bio) == sector) {

		if (__bio_try_merge_page(ctx->bio, page, plen, poff,

				&same_page))

			goto done;

		is_contig = true;

	}



	/*

	 * If we start a new segment we need to increase the read count, and we

	 * need to do so before submitting any previous full bio to make sure

	 * that we don't prematurely unlock the page.

	 */

	if (iop)

		atomic_inc(&iop->read_count);



	if (!ctx->bio || !is_contig || bio_full(ctx->bio, plen)) {

	if (!is_contig || bio_full(ctx->bio, plen)) {

		gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);

		gfp_t orig_gfp = gfp;

		int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;

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