Commit 8c004d1f authored by Zhang Yi's avatar Zhang Yi Committed by Andrew Morton
Browse files

jbd2: replace ll_rw_block() 

ll_rw_block() is not safe for the sync read path because it cannot
guarantee that submitting read IO if the buffer has been locked. We
could get false positive EIO after wait_on_buffer() if the buffer has
been locked by others. So stop using ll_rw_block() in
journal_get_superblock(). We also switch to new bh_readahead_batch()
for the buffer array readahead path.

Link: https://lkml.kernel.org/r/20220901133505.2510834-7-yi.zhang@huawei.com


Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarTheodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 0ed48061

fs/jbd2/journal.c

+6 −9
Original line number Diff line number Diff line
@@ -1893,20 +1893,17 @@ static int journal_get_superblock(journal_t *journal) 
{

	struct buffer_head *bh;

	journal_superblock_t *sb;

	int err = -EIO;

	int err;



	bh = journal->j_sb_buffer;



	J_ASSERT(bh != NULL);

	if (!buffer_uptodate(bh)) {

		ll_rw_block(REQ_OP_READ, 1, &bh);

		wait_on_buffer(bh);

		if (!buffer_uptodate(bh)) {

	err = bh_read(bh, 0);

	if (err < 0) {

		printk(KERN_ERR

			"JBD2: IO error reading journal superblock\n");

		goto out;

	}

	}



	if (buffer_verified(bh))

		return 0;

fs/jbd2/recovery.c

+10 −6
Original line number Diff line number Diff line
@@ -100,7 +100,7 @@ static int do_readahead(journal_t *journal, unsigned int start) 
		if (!buffer_uptodate(bh) && !buffer_locked(bh)) {

			bufs[nbufs++] = bh;

			if (nbufs == MAXBUF) {

				ll_rw_block(REQ_OP_READ, nbufs, bufs);

				bh_readahead_batch(nbufs, bufs, 0);

				journal_brelse_array(bufs, nbufs);

				nbufs = 0;

			}
@@ -109,7 +109,7 @@ static int do_readahead(journal_t *journal, unsigned int start) 
	}



	if (nbufs)

		ll_rw_block(REQ_OP_READ, nbufs, bufs);

		bh_readahead_batch(nbufs, bufs, 0);

	err = 0;



failed:
@@ -152,9 +152,14 @@ static int jread(struct buffer_head **bhp, journal_t *journal, 
		return -ENOMEM;



	if (!buffer_uptodate(bh)) {

		/* If this is a brand new buffer, start readahead.

                   Otherwise, we assume we are already reading it.  */

		if (!buffer_req(bh))

		/*

		 * If this is a brand new buffer, start readahead.

		 * Otherwise, we assume we are already reading it.

		 */

		bool need_readahead = !buffer_req(bh);



		bh_read_nowait(bh, 0);

		if (need_readahead)

			do_readahead(journal, offset);

		wait_on_buffer(bh);

	}
@@ -687,7 +692,6 @@ static int do_one_pass(journal_t *journal, 
					mark_buffer_dirty(nbh);

					BUFFER_TRACE(nbh, "marking uptodate");

					++info->nr_replays;

					/* ll_rw_block(WRITE, 1, &nbh); */

					unlock_buffer(nbh);

					brelse(obh);

					brelse(nbh);