It turns out that when extending an existing bio, gfs2_find_jhead fails to check if the block number is consecutive, which leads to incorrect reads for fragmented journals.

In addition, limit the maximum bio size to an arbitrary value of 2 megabytes: since commit 07173c3ec276 ("block: enable multipage bvecs"), if we just keep adding pages until bio_add_page fails, bios will grow much larger than useful, which pins more memory than necessary with barely any additional performance gains.

Fixes: f4686c26ecc3 ("gfs2: read journal in large chunks") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Andreas Gruenbacher agruenba@redhat.com --- fs/gfs2/lops.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c index 5ea96757afc4..48b54ec1c793 100644 --- a/fs/gfs2/lops.c +++ b/fs/gfs2/lops.c @@ -263,7 +263,7 @@ static struct bio *gfs2_log_alloc_bio(struct gfs2_sbd *sdp, u64 blkno, struct super_block *sb = sdp->sd_vfs; struct bio *bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);

- bio->bi_iter.bi_sector = blkno << (sb->s_blocksize_bits - 9); + bio->bi_iter.bi_sector = blkno << sdp->sd_fsb2bb_shift; bio_set_dev(bio, sb->s_bdev); bio->bi_end_io = end_io; bio->bi_private = sdp; @@ -509,7 +509,7 @@ 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 readahead_blocks = BIO_MAX_PAGES << shift; + unsigned int max_bio_size = 2 * 1024 * 1024; struct gfs2_journal_extent *je; int sz, ret = 0; struct bio *bio = NULL; @@ -537,12 +537,17 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head, off = 0; }

- if (!bio || (bio_chained && !off)) { + if (!bio || (bio_chained && !off) || + bio->bi_iter.bi_size >= max_bio_size) { /* start new bio */ } else { - sz = bio_add_page(bio, page, bsize, off); - if (sz == bsize) - goto block_added; + sector_t sector = dblock << sdp->sd_fsb2bb_shift; + + if (bio_end_sector(bio) == sector) { + sz = bio_add_page(bio, page, bsize, off); + if (sz == bsize) + goto block_added; + } if (off) { unsigned int blocks = (PAGE_SIZE - off) >> bsize_shift; @@ -568,7 +573,7 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head, off += bsize; if (off == PAGE_SIZE) page = NULL; - if (blocks_submitted < blocks_read + readahead_blocks) { + if (blocks_submitted < 2 * max_bio_size >> bsize_shift) { /* Keep at least one bio in flight */ continue; }

base-commit: fbe051ea4adf66950e2f23e71ace8eeb4e0e1c73 prerequisite-patch-id: f37202c2597b647c19a42736cfec807040560d9b