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dm log writes: make sure super sector log updates are written in order 

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: 0e9cebe724 ("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>
This commit is contained in:
zhangyi (F) 2019-06-05 21:27:08 +08:00 committed by Mike Snitzer
parent 10c9c8e7c0
commit 211ad4b733
1 changed files with 21 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/md/dm-log-writes.c
View File

@ -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_writes_c *lc, void *entry,
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 *lc)
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_target *ti, unsigned int argc, char **argv)
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);