Commit ba206a02 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
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btrfs: convert from readpages to readahead 



Implement the new readahead method in btrfs using the new
readahead_page_batch() function.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Gao Xiang <gaoxiang25@huawei.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Link: http://lkml.kernel.org/r/20200414150233.24495-18-willy@infradead.org


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d4388340

fs/btrfs/extent_io.c

+12 −31
Original line number Diff line number Diff line
@@ -4367,51 +4367,32 @@ int extent_writepages(struct address_space *mapping, 
	return ret;

}



int extent_readpages(struct address_space *mapping, struct list_head *pages,

		     unsigned nr_pages)

void extent_readahead(struct readahead_control *rac)

{

	struct bio *bio = NULL;

	unsigned long bio_flags = 0;

	struct page *pagepool[16];

	struct extent_map *em_cached = NULL;

	int nr = 0;

	u64 prev_em_start = (u64)-1;

	int nr;



	while (!list_empty(pages)) {

		u64 contig_end = 0;



		for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) {

			struct page *page = lru_to_page(pages);



			prefetchw(&page->flags);

			list_del(&page->lru);

			if (add_to_page_cache_lru(page, mapping, page->index,

						readahead_gfp_mask(mapping))) {

				put_page(page);

				break;

			}



			pagepool[nr++] = page;

			contig_end = page_offset(page) + PAGE_SIZE - 1;

		}



		if (nr) {

	while ((nr = readahead_page_batch(rac, pagepool))) {

		u64 contig_start = page_offset(pagepool[0]);

		u64 contig_end = page_offset(pagepool[nr - 1]) + PAGE_SIZE - 1;



		ASSERT(contig_start + nr * PAGE_SIZE - 1 == contig_end);



			contiguous_readpages(pagepool, nr, contig_start,

				     contig_end, &em_cached, &bio, &bio_flags,

				     &prev_em_start);

		}

		contiguous_readpages(pagepool, nr, contig_start, contig_end,

				&em_cached, &bio, &bio_flags, &prev_em_start);

	}



	if (em_cached)

		free_extent_map(em_cached);



	if (bio)

		return submit_one_bio(bio, 0, bio_flags);

	return 0;

	if (bio) {

		if (submit_one_bio(bio, 0, bio_flags))

			return;

	}

}



/*

fs/btrfs/extent_io.h

+1 −2
Original line number Diff line number Diff line
@@ -198,8 +198,7 @@ int extent_writepages(struct address_space *mapping, 
		      struct writeback_control *wbc);

int btree_write_cache_pages(struct address_space *mapping,

			    struct writeback_control *wbc);

int extent_readpages(struct address_space *mapping, struct list_head *pages,

		     unsigned nr_pages);

void extent_readahead(struct readahead_control *rac);

int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,

		__u64 start, __u64 len);

void set_page_extent_mapped(struct page *page);

fs/btrfs/inode.c

+7 −9
Original line number Diff line number Diff line
@@ -4856,8 +4856,8 @@ static void evict_inode_truncate_pages(struct inode *inode) 


	/*

	 * Keep looping until we have no more ranges in the io tree.

	 * We can have ongoing bios started by readpages (called from readahead)

	 * that have their endio callback (extent_io.c:end_bio_extent_readpage)

	 * We can have ongoing bios started by readahead that have

	 * their endio callback (extent_io.c:end_bio_extent_readpage)

	 * still in progress (unlocked the pages in the bio but did not yet

	 * unlocked the ranges in the io tree). Therefore this means some

	 * ranges can still be locked and eviction started because before
@@ -7050,11 +7050,11 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend, 
			 * for it to complete) and then invalidate the pages for

			 * this range (through invalidate_inode_pages2_range()),

			 * but that can lead us to a deadlock with a concurrent

			 * call to readpages() (a buffered read or a defrag call

			 * call to readahead (a buffered read or a defrag call

			 * triggered a readahead) on a page lock due to an

			 * ordered dio extent we created before but did not have

			 * yet a corresponding bio submitted (whence it can not

			 * complete), which makes readpages() wait for that

			 * complete), which makes readahead wait for that

			 * ordered extent to complete while holding a lock on

			 * that page.

			 */
@@ -8293,11 +8293,9 @@ static int btrfs_writepages(struct address_space *mapping, 
	return extent_writepages(mapping, wbc);

}



static int

btrfs_readpages(struct file *file, struct address_space *mapping,

		struct list_head *pages, unsigned nr_pages)

static void btrfs_readahead(struct readahead_control *rac)

{

	return extent_readpages(mapping, pages, nr_pages);

	extent_readahead(rac);

}



static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
@@ -10553,7 +10551,7 @@ static const struct address_space_operations btrfs_aops = { 
	.readpage	= btrfs_readpage,

	.writepage	= btrfs_writepage,

	.writepages	= btrfs_writepages,

	.readpages	= btrfs_readpages,

	.readahead	= btrfs_readahead,

	.direct_IO	= btrfs_direct_IO,

	.invalidatepage = btrfs_invalidatepage,

	.releasepage	= btrfs_releasepage,

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