Commit eed0f953 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

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: f4686c26 ("gfs2: read journal in large chunks")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 887352fb

fs/gfs2/lops.c

+44 −24
Original line number Diff line number Diff line
@@ -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) {

				unsigned int off;



				off = (block << bsize_shift) & ~PAGE_MASK;

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

				/* start new bio */

			} else {

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

				if (sz == bsize) { /* block added */

					if (off + bsize == PAGE_SIZE) {

						page = NULL;

						goto page_added;

				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;

				}

					continue;

			}



			if (bio) {

				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;

			}

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