[PATCH 1/1] loop: Fix occasional uevent drop

* [PATCH 1/1] loop: Fix occasional uevent drop
@ 2020-11-11 18:08 ` Petr Vorel
  0 siblings, 0 replies; 6+ messages in thread
From: Petr Vorel @ 2020-11-11 18:08 UTC (permalink / raw)
  To: linux-block
  Cc: Petr Vorel, Christoph Hellwig, Josef Bacik, Jens Axboe,
	Martijn Coenen, Johannes Thumshirn, Hannes Reinecke, ltp

716ad0986cbd caused to occasional drop of loop device uevent, which was
no longer triggered in loop_set_size() but in a different part of code.

Bug is reproducible with LTP test uevent01 [1]:

i=0; while true; do
    i=$((i+1)); echo "== $i =="
    lsmod |grep -q loop && rmmod -f loop
    ./uevent01 || break
done

Put back triggering through code called in loop_set_size().

Fix required to add yet another parameter to
set_capacity_revalidate_and_notify().

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/uevents/uevent01.c

Fixes: 716ad0986cbd ("loop: Switch to set_capacity_revalidate_and_notify")
Reported-by: <ltp@lists.linux.it>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
Hi,

original bug looks to be a rice (usually ~ 10 loops is enough),
so this might just covers another problems).

Kind regards,
Petr

 block/genhd.c                | 6 ++++--
 drivers/block/loop.c         | 2 +-
 drivers/block/virtio_blk.c   | 2 +-
 drivers/block/xen-blkfront.c | 2 +-
 drivers/nvme/host/core.c     | 2 +-
 drivers/scsi/sd.c            | 4 ++--
 include/linux/genhd.h        | 2 +-
 7 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 0a273211fec2..3092910945c0 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -47,10 +47,10 @@ static void disk_release_events(struct gendisk *disk);
 
 /*
  * Set disk capacity and notify if the size is not currently
- * zero and will not be set to zero
+ * zero and will not be set to zero or not explicitly forced.
  */
 void set_capacity_revalidate_and_notify(struct gendisk *disk, sector_t size,
-					bool update_bdev)
+					bool update_bdev, bool force_notify)
 {
 	sector_t capacity = get_capacity(disk);
 
@@ -62,6 +62,8 @@ void set_capacity_revalidate_and_notify(struct gendisk *disk, sector_t size,
 		char *envp[] = { "RESIZE=1", NULL };
 
 		kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+	} else if (force_notify) {
+		kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
 	}
 }
 
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index cb1191d6e945..7233f3482447 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -255,7 +255,7 @@ static void loop_set_size(struct loop_device *lo, loff_t size)
 
 	bd_set_nr_sectors(bdev, size);
 
-	set_capacity_revalidate_and_notify(lo->lo_disk, size, false);
+	set_capacity_revalidate_and_notify(lo->lo_disk, size, false, true);
 }
 
 static inline int
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index a314b9382442..93e56e2ba15c 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -470,7 +470,7 @@ static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
 		   cap_str_10,
 		   cap_str_2);
 
-	set_capacity_revalidate_and_notify(vblk->disk, capacity, true);
+	set_capacity_revalidate_and_notify(vblk->disk, capacity, true, false);
 }
 
 static void virtblk_config_changed_work(struct work_struct *work)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 48629d3433b4..5b5795a612cc 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -2370,7 +2370,7 @@ static void blkfront_connect(struct blkfront_info *info)
 			return;
 		printk(KERN_INFO "Setting capacity to %Lu\n",
 		       sectors);
-		set_capacity_revalidate_and_notify(info->gd, sectors, true);
+		set_capacity_revalidate_and_notify(info->gd, sectors, true, false);
 
 		return;
 	case BLKIF_STATE_SUSPENDED:
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 40ca71b29bb9..ca7ebd0b9668 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2053,7 +2053,7 @@ static void nvme_update_disk_info(struct gendisk *disk,
 			capacity = 0;
 	}
 
-	set_capacity_revalidate_and_notify(disk, capacity, false);
+	set_capacity_revalidate_and_notify(disk, capacity, false, false);
 
 	nvme_config_discard(disk, ns);
 	nvme_config_write_zeroes(disk, ns);
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 656bcf4940d6..81503e99e937 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3266,7 +3266,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	sdkp->first_scan = 0;
 
 	set_capacity_revalidate_and_notify(disk,
-		logical_to_sectors(sdp, sdkp->capacity), false);
+		logical_to_sectors(sdp, sdkp->capacity), false, false);
 	sd_config_write_same(sdkp);
 	kfree(buffer);
 
@@ -3276,7 +3276,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	 * capacity to 0.
 	 */
 	if (sd_zbc_revalidate_zones(sdkp))
-		set_capacity_revalidate_and_notify(disk, 0, false);
+		set_capacity_revalidate_and_notify(disk, 0, false, false);
 
  out:
 	return 0;
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 38f23d757013..6656e7931379 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -316,7 +316,7 @@ extern void disk_block_events(struct gendisk *disk);
 extern void disk_unblock_events(struct gendisk *disk);
 extern void disk_flush_events(struct gendisk *disk, unsigned int mask);
 void set_capacity_revalidate_and_notify(struct gendisk *disk, sector_t size,
-		bool update_bdev);
+		bool update_bdev, bool force_notify);
 
 /* drivers/char/random.c */
 extern void add_disk_randomness(struct gendisk *disk) __latent_entropy;
-- 
2.29.2


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