md: revert io stats accounting

commit ad3fc798800fb7ca04c1dfc439dba946818048d8 upstream.

The commit 41d2d848e5c0 ("md: improve io stats accounting") could cause
double fault problem per the report [1], and also it is not correct to
change ->bi_end_io if md don't own it, so let's revert it.

And io stats accounting will be replemented in later commits.

[1]. https://lore.kernel.org/linux-raid/3bf04253-3fad-434a-63a7-20214e38cf26@gmail.com/T/#t

Fixes: 41d2d848e5c0 ("md: improve io stats accounting")
Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Signed-off-by: Song Liu <song@kernel.org>
[GM: backport to 5.10-stable]
Signed-off-by: Guillaume Morin <guillaume@morinfr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2069b16..cc38765 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -459,34 +459,12 @@ check_suspended:
 }
 EXPORT_SYMBOL(md_handle_request);
 
-struct md_io {
-       struct mddev *mddev;
-       bio_end_io_t *orig_bi_end_io;
-       void *orig_bi_private;
-       unsigned long start_time;
-       struct hd_struct *part;
-};
-
-static void md_end_io(struct bio *bio)
-{
-       struct md_io *md_io = bio->bi_private;
-       struct mddev *mddev = md_io->mddev;
-
-       part_end_io_acct(md_io->part, bio, md_io->start_time);
-
-       bio->bi_end_io = md_io->orig_bi_end_io;
-       bio->bi_private = md_io->orig_bi_private;
-
-       mempool_free(md_io, &mddev->md_io_pool);
-
-       if (bio->bi_end_io)
-               bio->bi_end_io(bio);
-}
-
 static blk_qc_t md_submit_bio(struct bio *bio)
 {
        const int rw = bio_data_dir(bio);
+       const int sgrp = op_stat_group(bio_op(bio));
        struct mddev *mddev = bio->bi_disk->private_data;
+       unsigned int sectors;
 
        if (mddev == NULL || mddev->pers == NULL) {
                bio_io_error(bio);
@@ -507,26 +485,21 @@ static blk_qc_t md_submit_bio(struct bio *bio)
                return BLK_QC_T_NONE;
        }
 
-       if (bio->bi_end_io != md_end_io) {
-               struct md_io *md_io;
-
-               md_io = mempool_alloc(&mddev->md_io_pool, GFP_NOIO);
-               md_io->mddev = mddev;
-               md_io->orig_bi_end_io = bio->bi_end_io;
-               md_io->orig_bi_private = bio->bi_private;
-
-               bio->bi_end_io = md_end_io;
-               bio->bi_private = md_io;
-
-               md_io->start_time = part_start_io_acct(mddev->gendisk,
-                                                      &md_io->part, bio);
-       }
-
+       /*
+        * save the sectors now since our bio can
+        * go away inside make_request
+        */
+       sectors = bio_sectors(bio);
        /* bio could be mergeable after passing to underlayer */
        bio->bi_opf &= ~REQ_NOMERGE;
 
        md_handle_request(mddev, bio);
 
+       part_stat_lock();
+       part_stat_inc(&mddev->gendisk->part0, ios[sgrp]);
+       part_stat_add(&mddev->gendisk->part0, sectors[sgrp], sectors);
+       part_stat_unlock();
+
        return BLK_QC_T_NONE;
 }
 
@@ -5636,7 +5609,6 @@ static void md_free(struct kobject *ko)
 
        bioset_exit(&mddev->bio_set);
        bioset_exit(&mddev->sync_set);
-       mempool_exit(&mddev->md_io_pool);
        kfree(mddev);
 }
 
@@ -5732,11 +5704,6 @@ static int md_alloc(dev_t dev, char *name)
                 */
                mddev->hold_active = UNTIL_STOP;
 
-       error = mempool_init_kmalloc_pool(&mddev->md_io_pool, BIO_POOL_SIZE,
-                                         sizeof(struct md_io));
-       if (error)
-               goto abort;
-
        error = -ENOMEM;
        mddev->queue = blk_alloc_queue(NUMA_NO_NODE);
        if (!mddev->queue)

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 2175a5a..c94811c 100644 (file)
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -487,7 +487,6 @@ struct mddev {
        struct bio_set                  sync_set; /* for sync operations like
                                                   * metadata and bitmap writes
                                                   */
-       mempool_t                       md_io_pool;
 
        /* Generic flush handling.
         * The last to finish preflush schedules a worker to submit