From: zhangyi (F) yi.zhang@huawei.com
commit 211ad4b733037f66f9be0a79eade3da7ab11cbb8 upstream.
Currently, although we submit super bios in order (and super.nr_entries is incremented by each logged entry), submit_bio() is async so each super sector may not be written to log device in order and then the final nr_entries may be smaller than it should be.
This problem can be reproduced by the xfstests generic/455 with ext4:
QA output created by 455 -Silence is golden +mark 'end' does not exist
Fix this by serializing submission of super sectors to make sure each is written to the log disk in order.
Fixes: 0e9cebe724597 ("dm: add log writes target") Cc: stable@vger.kernel.org Signed-off-by: zhangyi (F) yi.zhang@huawei.com Suggested-by: Josef Bacik josef@toxicpanda.com Reviewed-by: Josef Bacik josef@toxicpanda.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/md/dm-log-writes.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-)
--- a/drivers/md/dm-log-writes.c +++ b/drivers/md/dm-log-writes.c @@ -60,6 +60,7 @@
#define WRITE_LOG_VERSION 1ULL #define WRITE_LOG_MAGIC 0x6a736677736872ULL +#define WRITE_LOG_SUPER_SECTOR 0
/* * The disk format for this is braindead simple. @@ -115,6 +116,7 @@ struct log_writes_c { struct list_head logging_blocks; wait_queue_head_t wait; struct task_struct *log_kthread; + struct completion super_done; };
struct pending_block { @@ -180,6 +182,14 @@ static void log_end_io(struct bio *bio) bio_put(bio); }
+static void log_end_super(struct bio *bio) +{ + struct log_writes_c *lc = bio->bi_private; + + complete(&lc->super_done); + log_end_io(bio); +} + /* * Meant to be called if there is an error, it will free all the pages * associated with the block. @@ -215,7 +225,8 @@ static int write_metadata(struct log_wri bio->bi_iter.bi_size = 0; bio->bi_iter.bi_sector = sector; bio_set_dev(bio, lc->logdev->bdev); - bio->bi_end_io = log_end_io; + bio->bi_end_io = (sector == WRITE_LOG_SUPER_SECTOR) ? + log_end_super : log_end_io; bio->bi_private = lc; bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
@@ -418,11 +429,18 @@ static int log_super(struct log_writes_c super.nr_entries = cpu_to_le64(lc->logged_entries); super.sectorsize = cpu_to_le32(lc->sectorsize);
- if (write_metadata(lc, &super, sizeof(super), NULL, 0, 0)) { + if (write_metadata(lc, &super, sizeof(super), NULL, 0, + WRITE_LOG_SUPER_SECTOR)) { DMERR("Couldn't write super"); return -1; }
+ /* + * Super sector should be writen in-order, otherwise the + * nr_entries could be rewritten incorrectly by an old bio. + */ + wait_for_completion_io(&lc->super_done); + return 0; }
@@ -531,6 +549,7 @@ static int log_writes_ctr(struct dm_targ INIT_LIST_HEAD(&lc->unflushed_blocks); INIT_LIST_HEAD(&lc->logging_blocks); init_waitqueue_head(&lc->wait); + init_completion(&lc->super_done); atomic_set(&lc->io_blocks, 0); atomic_set(&lc->pending_blocks, 0);