Commit cd88a4fd authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David Sterba
Browse files

btrfs: use a separate end_io handler for extent_buffer writing 



Now that we always use a single bio to write an extent_buffer, the buffer
can be passed to the end_io handler as private data.  This allows
to simplify the metadata write end I/O handler, and merge the subpage
end_io handler into the main one.

Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent b51e6b4b

fs/btrfs/extent_io.c

+26 −100
Original line number Diff line number Diff line
@@ -1614,13 +1614,6 @@ void wait_on_extent_buffer_writeback(struct extent_buffer *eb) 
		       TASK_UNINTERRUPTIBLE);

}



static void end_extent_buffer_writeback(struct extent_buffer *eb)

{

	clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);

	smp_mb__after_atomic();

	wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);

}



/*

 * Lock extent buffer status and pages for writeback.

 *
@@ -1664,13 +1657,11 @@ static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *e 
	return ret;

}



static void set_btree_ioerr(struct page *page, struct extent_buffer *eb)

static void set_btree_ioerr(struct extent_buffer *eb)

{

	struct btrfs_fs_info *fs_info = eb->fs_info;



	btrfs_page_set_error(fs_info, page, eb->start, eb->len);

	if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))

		return;

	set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);



	/*

	 * A read may stumble upon this buffer later, make sure that it gets an
@@ -1684,7 +1675,7 @@ static void set_btree_ioerr(struct page *page, struct extent_buffer *eb) 
	 * return a 0 because we are readonly if we don't modify the err seq for

	 * the superblock.

	 */

	mapping_set_error(page->mapping, -EIO);

	mapping_set_error(eb->fs_info->btree_inode->i_mapping, -EIO);



	/*

	 * If writeback for a btree extent that doesn't belong to a log tree
@@ -1759,102 +1750,38 @@ static struct extent_buffer *find_extent_buffer_nolock( 
	return NULL;

}



/*

 * The endio function for subpage extent buffer write.

 *

 * Unlike end_bio_extent_buffer_writepage(), we only call end_page_writeback()

 * after all extent buffers in the page has finished their writeback.

 */

static void end_bio_subpage_eb_writepage(struct btrfs_bio *bbio)

static void extent_buffer_write_end_io(struct btrfs_bio *bbio)

{

	struct bio *bio = &bbio->bio;

	struct btrfs_fs_info *fs_info;

	struct bio_vec *bvec;

	struct extent_buffer *eb = bbio->private;

	struct btrfs_fs_info *fs_info = eb->fs_info;

	bool uptodate = !bbio->bio.bi_status;

	struct bvec_iter_all iter_all;

	struct bio_vec *bvec;

	u32 bio_offset = 0;



	fs_info = btrfs_sb(bio_first_page_all(bio)->mapping->host->i_sb);

	ASSERT(fs_info->nodesize < PAGE_SIZE);

	if (!uptodate)

		set_btree_ioerr(eb);



	ASSERT(!bio_flagged(bio, BIO_CLONED));

	bio_for_each_segment_all(bvec, bio, iter_all) {

	bio_for_each_segment_all(bvec, &bbio->bio, iter_all) {

		u64 start = eb->start + bio_offset;

		struct page *page = bvec->bv_page;

		u64 bvec_start = page_offset(page) + bvec->bv_offset;

		u64 bvec_end = bvec_start + bvec->bv_len - 1;

		u64 cur_bytenr = bvec_start;

		u32 len = bvec->bv_len;



		ASSERT(IS_ALIGNED(bvec->bv_len, fs_info->nodesize));



		/* Iterate through all extent buffers in the range */

		while (cur_bytenr <= bvec_end) {

			struct extent_buffer *eb;

			int done;



			/*

			 * Here we can't use find_extent_buffer(), as it may

			 * try to lock eb->refs_lock, which is not safe in endio

			 * context.

			 */

			eb = find_extent_buffer_nolock(fs_info, cur_bytenr);

			ASSERT(eb);



			cur_bytenr = eb->start + eb->len;



			ASSERT(test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags));

			done = atomic_dec_and_test(&eb->io_pages);

			ASSERT(done);



			if (bio->bi_status ||

			    test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {

				btrfs_page_clear_uptodate(fs_info, page,

							  eb->start, eb->len);

				set_btree_ioerr(page, eb);

			}

		atomic_dec(&eb->io_pages);



			btrfs_subpage_clear_writeback(fs_info, page, eb->start,

						      eb->len);

			end_extent_buffer_writeback(eb);

			/*

			 * free_extent_buffer() will grab spinlock which is not

			 * safe in endio context. Thus here we manually dec

			 * the ref.

			 */

			atomic_dec(&eb->refs);

		}

	}

	bio_put(bio);

		if (!uptodate) {

			btrfs_page_clear_uptodate(fs_info, page, start, len);

			btrfs_page_set_error(fs_info, page, start, len);

		}



static void end_bio_extent_buffer_writepage(struct btrfs_bio *bbio)

{

	struct bio *bio = &bbio->bio;

	struct bio_vec *bvec;

	struct extent_buffer *eb;

	int done;

	struct bvec_iter_all iter_all;



	ASSERT(!bio_flagged(bio, BIO_CLONED));

	bio_for_each_segment_all(bvec, bio, iter_all) {

		struct page *page = bvec->bv_page;



		eb = (struct extent_buffer *)page->private;

		BUG_ON(!eb);

		done = atomic_dec_and_test(&eb->io_pages);



		if (bio->bi_status ||

		    test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) {

			ClearPageUptodate(page);

			set_btree_ioerr(page, eb);

		btrfs_page_clear_writeback(fs_info, page, start, len);

		bio_offset += len;

	}



		end_page_writeback(page);



		if (!done)

			continue;



		end_extent_buffer_writeback(eb);

	}

	clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);

	smp_mb__after_atomic();

	wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);



	bio_put(bio);

	bio_put(&bbio->bio);

}



static void prepare_eb_write(struct extent_buffer *eb)
@@ -1912,7 +1839,7 @@ static void write_one_subpage_eb(struct extent_buffer *eb, 


	bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,

			       REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc),

			       eb->fs_info, end_bio_subpage_eb_writepage, NULL);

			       eb->fs_info, extent_buffer_write_end_io, eb);

	bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;

	bbio->inode = BTRFS_I(eb->fs_info->btree_inode);

	bbio->file_offset = eb->start;
@@ -1939,8 +1866,7 @@ static noinline_for_stack void write_one_eb(struct extent_buffer *eb, 


	bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,

			       REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc),

			       eb->fs_info, end_bio_extent_buffer_writepage,

			       NULL);

			       eb->fs_info, extent_buffer_write_end_io, eb);

	bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;

	bio_set_dev(&bbio->bio, eb->fs_info->fs_devices->latest_dev->bdev);

	wbc_init_bio(wbc, &bbio->bio);