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gfs2: Even more gfs2_find_jhead fixes

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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: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2020-05-26 20:11:51 +02:00
parent 9cb1fd0efd
commit 20be493b78
1 changed files with 5 additions and 10 deletions
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15
fs/gfs2/lops.c
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@ -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;
}