Commit 20be493b authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Even more gfs2_find_jhead fixes 



Fix several issues in the previous gfs2_find_jhead fix:
* When updating @blocks_submitted, @block refers to the first block block not
  submitted yet, not the last block submitted, so fix an off-by-one error.
* We want to ensure that @blocks_submitted is far enough ahead of @blocks_read
  to guarantee that there is in-flight I/O.  Otherwise, we'll eventually end up
  waiting for pages that haven't been submitted, yet.
* It's much easier to compare the number of blocks added with the number of
  blocks submitted to limit the maximum bio size.
* Even with bio chaining, we can keep adding blocks until we reach the maximum
  bio size, as long as we stop at a page boundary.  This simplifies the logic.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: default avatarBob Peterson <rpeterso@redhat.com>
parent 9cb1fd0e

fs/gfs2/lops.c

+5 −10
Original line number Diff line number Diff line
@@ -509,12 +509,12 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head, 
	unsigned int bsize = sdp->sd_sb.sb_bsize, off;

	unsigned int bsize_shift = sdp->sd_sb.sb_bsize_shift;

	unsigned int shift = PAGE_SHIFT - bsize_shift;

	unsigned int max_bio_size = 2 * 1024 * 1024;

	unsigned int max_blocks = 2 * 1024 * 1024 >> bsize_shift;

	struct gfs2_journal_extent *je;

	int sz, ret = 0;

	struct bio *bio = NULL;

	struct page *page = NULL;

	bool bio_chained = false, done = false;

	bool done = false;

	errseq_t since;



	memset(head, 0, sizeof(*head));
@@ -537,10 +537,7 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head, 
				off = 0;

			}



			if (!bio || (bio_chained && !off) ||

			    bio->bi_iter.bi_size >= max_bio_size) {

				/* start new bio */

			} else {

			if (bio && (off || block < blocks_submitted + max_blocks)) {

				sector_t sector = dblock << sdp->sd_fsb2bb_shift;



				if (bio_end_sector(bio) == sector) {
@@ -553,19 +550,17 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head, 
						(PAGE_SIZE - off) >> bsize_shift;



					bio = gfs2_chain_bio(bio, blocks);

					bio_chained = true;

					goto add_block_to_new_bio;

				}

			}



			if (bio) {

				blocks_submitted = block + 1;

				blocks_submitted = block;

				submit_bio(bio);

			}



			bio = gfs2_log_alloc_bio(sdp, dblock, gfs2_end_log_read);

			bio->bi_opf = REQ_OP_READ;

			bio_chained = false;

add_block_to_new_bio:

			sz = bio_add_page(bio, page, bsize, off);

			BUG_ON(sz != bsize);
@@ -573,7 +568,7 @@ block_added: 
			off += bsize;

			if (off == PAGE_SIZE)

				page = NULL;

			if (blocks_submitted < 2 * max_bio_size >> bsize_shift) {

			if (blocks_submitted <= blocks_read + max_blocks) {

				/* Keep at least one bio in flight */

				continue;

			}

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