From a564e23f0f99759f453dbefcb9160dec6d99df96 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Wed, 8 Jul 2020 14:25:41 +0200
Subject: [PATCH] md: switch to ->check_events for media change notifications
Git-commit: a564e23f0f99759f453dbefcb9160dec6d99df96
Patch-mainline: v5.9-rc1
References: jsc#SLE-13984

md is the last driver using the legacy media_changed method.  Switch
it over to (not so) new ->clear_events approach, which also removes the
need for the ->revalidate_disk method.

(Coly Li: rebase the patch from Documentation/filesystems/locking.rst to
 Documentation/filesystems/Locking)

Signed-off-by: Christoph Hellwig <hch@lst.de>
[axboe: remove unused 'bdops' variable in disk_clear_events()]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>

---
 Documentation/filesystems/Locking |    4 +---
 block/genhd.c                     |    8 +-------
 drivers/md/md.c                   |   19 ++++++++-----------
 include/linux/blkdev.h            |    2 --
 4 files changed, 10 insertions(+), 23 deletions(-)

--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -392,7 +392,6 @@ prototypes:
 	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	int (*direct_access) (struct block_device *, sector_t, void **,
 				unsigned long *);
-	int (*media_changed) (struct gendisk *);
 	void (*unlock_native_capacity) (struct gendisk *);
 	int (*revalidate_disk) (struct gendisk *);
 	int (*getgeo)(struct block_device *, struct hd_geometry *);
@@ -405,13 +404,12 @@ release:		yes
 ioctl:			no
 compat_ioctl:		no
 direct_access:		no
-media_changed:		no
 unlock_native_capacity:	no
 revalidate_disk:	no
 getgeo:			no
 swap_slot_free_notify:	no	(see below)
 
-media_changed, unlock_native_capacity and revalidate_disk are called only from
+unlock_native_capacity and revalidate_disk are called only from
 check_disk_change().
 
 swap_slot_free_notify is called with swap_lock and sometimes the page lock
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1823,18 +1823,12 @@ void disk_flush_events(struct gendisk *d
  */
 unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
 {
-	const struct block_device_operations *bdops = disk->fops;
 	struct disk_events *ev = disk->ev;
 	unsigned int pending;
 	unsigned int clearing = mask;
 
-	if (!ev) {
-		/* for drivers still using the old ->media_changed method */
-		if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
-		    bdops->media_changed && bdops->media_changed(disk))
-			return DISK_EVENT_MEDIA_CHANGE;
+	if (!ev)
 		return 0;
-	}
 
 	disk_block_events(disk);
 
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5666,6 +5666,7 @@ static int md_alloc(dev_t dev, char *nam
 	 * remove it now.
 	 */
 	disk->flags |= GENHD_FL_EXT_DEVT;
+	disk->events |= DISK_EVENT_MEDIA_CHANGE;
 	mddev->gendisk = disk;
 	/* As soon as we call add_disk(), another thread could get
 	 * through to md_open, so make sure it doesn't get too far
@@ -7802,20 +7803,17 @@ static void md_release(struct gendisk *d
 	mddev_put(mddev);
 }
 
-static int md_media_changed(struct gendisk *disk)
-{
-	struct mddev *mddev = disk->private_data;
-
-	return mddev->changed;
-}
-
-static int md_revalidate(struct gendisk *disk)
+static unsigned int md_check_events(struct gendisk *disk, unsigned int clearing)
 {
 	struct mddev *mddev = disk->private_data;
+	unsigned int ret = 0;
 
+	if (mddev->changed)
+		ret = DISK_EVENT_MEDIA_CHANGE;
 	mddev->changed = 0;
-	return 0;
+	return ret;
 }
+
 static const struct block_device_operations md_fops =
 {
 	.owner		= THIS_MODULE,
@@ -7826,8 +7824,7 @@ static const struct block_device_operati
 	.compat_ioctl	= md_compat_ioctl,
 #endif
 	.getgeo		= md_getgeo,
-	.media_changed  = md_media_changed,
-	.revalidate_disk= md_revalidate,
+	.check_events	= md_check_events,
 };
 
 static int md_thread(void *arg)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1701,8 +1701,6 @@ struct block_device_operations {
 	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	unsigned int (*check_events) (struct gendisk *disk,
 				      unsigned int clearing);
-	/* ->media_changed() is DEPRECATED, use ->check_events() instead */
-	int (*media_changed) (struct gendisk *);
 	void (*unlock_native_capacity) (struct gendisk *);
 	int (*revalidate_disk) (struct gendisk *);
 	int (*getgeo)(struct block_device *, struct hd_geometry *);