[PATCH v2 06/14] jbd2: replace ll_rw_block()

Zhang Yi
2022-09-01T13:26:50Z

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.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
fs/jbd2/journal.c | 15 ++++++---------
fs/jbd2/recovery.c | 16 ++++++++++------
2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 6350d3857c89..140b070471c0 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1893,19 +1893,16 @@ 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)) {
- printk(KERN_ERR
- "JBD2: IO error reading journal superblock\n");
- goto out;
- }
+ err = bh_read(bh, 0);
+ if (err < 0) {
+ printk(KERN_ERR
+ "JBD2: IO error reading journal superblock\n");
+ goto out;
}

if (buffer_verified(bh))
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index f548479615c6..1f878c315b03 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -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);
--
2.31.1