[PATCH 5.6 094/194] gfs2: More gfs2_find_jhead fixes

Greg Kroah-Hartman
2020-05-18T18:03:47Z

From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit aa83da7f47b26c9587bade6c4bc4736ffa308f0a ]

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>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 c090d5ad3f221..3a020bdc358cd 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -259,7 +259,7 @@ 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;
@@ -505,7 +505,7 @@ 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;
@@ -533,12 +533,17 @@ 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;
@@ -564,7 +569,7 @@ 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;
}
--
2.20.1