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gfs2: Another gfs2_find_jhead fix 

On filesystems with a block size smaller than the page size,
gfs2_find_jhead can split a page across two bios (for example, when
blocks are not allocated consecutively).  When that happens, the first
bio that completes will unlock the page in its bi_end_io handler even
though the page hasn't been read completely yet.  Fix that by using a
chained bio for the rest of the page.

While at it, clean up the sector calculation logic in
gfs2_log_alloc_bio.  In gfs2_find_jhead, simplify the disk block and
offset calculation logic and fix a variable name.

Fixes: f4686c26ec ("gfs2: read journal in large chunks")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2019-12-08 13:12:49 +00:00
parent 887352fb5f
commit eed0f953b9
1 changed files with 45 additions and 25 deletions
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70
fs/gfs2/lops.c
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@ -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 >> 9);
bio->bi_iter.bi_sector = blkno << (sb->s_blocksize_bits - 9);
bio_set_dev(bio, sb->s_bdev);
bio->bi_end_io = end_io;
bio->bi_private = sdp;
@ -472,6 +472,20 @@ static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,
put_page(page); /* Once more for find_or_create_page */
}
static struct bio *gfs2_chain_bio(struct bio *prev, unsigned int nr_iovecs)
{
struct bio *new;
new = bio_alloc(GFP_NOIO, nr_iovecs);
bio_copy_dev(new, prev);
new->bi_iter.bi_sector = bio_end_sector(prev);
new->bi_opf = prev->bi_opf;
new->bi_write_hint = prev->bi_write_hint;
bio_chain(new, prev);
submit_bio(prev);
return new;
}
/**
* gfs2_find_jhead - find the head of a log
* @jd: The journal descriptor
@ -488,15 +502,15 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head,
struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
struct address_space *mapping = jd->jd_inode->i_mapping;
unsigned int block = 0, blocks_submitted = 0, blocks_read = 0;
unsigned int bsize = sdp->sd_sb.sb_bsize;
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 readhead_blocks = BIO_MAX_PAGES << shift;
unsigned int readahead_blocks = BIO_MAX_PAGES << shift;
struct gfs2_journal_extent *je;
int sz, ret = 0;
struct bio *bio = NULL;
struct page *page = NULL;
bool done = false;
bool bio_chained = false, done = false;
errseq_t since;
memset(head, 0, sizeof(*head));
@ -505,9 +519,9 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head,
since = filemap_sample_wb_err(mapping);
list_for_each_entry(je, &jd->extent_list, list) {
for (; block < je->lblock + je->blocks; block++) {
u64 dblock;
u64 dblock = je->dblock;
for (; block < je->lblock + je->blocks; block++, dblock++) {
if (!page) {
page = find_or_create_page(mapping,
block >> shift, GFP_NOFS);
@ -516,35 +530,41 @@ int gfs2_find_jhead(struct gfs2_jdesc *jd, struct gfs2_log_header_host *head,
done = true;
goto out;
}
off = 0;
}
if (!bio || (bio_chained && !off)) {
/* start new bio */
} else {
sz = bio_add_page(bio, page, bsize, off);
if (sz == bsize)
goto block_added;
if (off) {
unsigned int blocks =
(PAGE_SIZE - off) >> bsize_shift;
bio = gfs2_chain_bio(bio, blocks);
bio_chained = true;
goto add_block_to_new_bio;
}
}
if (bio) {
unsigned int off;
off = (block << bsize_shift) & ~PAGE_MASK;
sz = bio_add_page(bio, page, bsize, off);
if (sz == bsize) { /* block added */
if (off + bsize == PAGE_SIZE) {
page = NULL;
goto page_added;
}
continue;
}
blocks_submitted = block + 1;
submit_bio(bio);
bio = NULL;
}
dblock = je->dblock + (block - je->lblock);
bio = gfs2_log_alloc_bio(sdp, dblock, gfs2_end_log_read);
bio->bi_opf = REQ_OP_READ;
sz = bio_add_page(bio, page, bsize, 0);
gfs2_assert_warn(sdp, sz == bsize);
if (bsize == PAGE_SIZE)
bio_chained = false;
add_block_to_new_bio:
sz = bio_add_page(bio, page, bsize, off);
BUG_ON(sz != bsize);
block_added:
off += bsize;
if (off == PAGE_SIZE)
page = NULL;
page_added:
if (blocks_submitted < blocks_read + readhead_blocks) {
if (blocks_submitted < blocks_read + readahead_blocks) {
/* Keep at least one bio in flight */
continue;
}