block: add a helper to raise a media changed event

Refactor disk_check_events() and move some code into disk_event_uevent().
Then add disk_force_media_change(), a helper which will be used by
devices to force issuing a DISK_EVENT_MEDIA_CHANGE event.

Co-developed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-6-mcroce@linux.microsoft.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/disk-events.c b/block/disk-events.c
index 04c52f3992eda4140e4e538767d9e4ef33568f90..7445b8ff2775f32dd16ef378a953e93ea7bc62fc 100644 (file)
--- a/block/disk-events.c
+++ b/block/disk-events.c
@@ -163,15 +163,31 @@ void disk_flush_events(struct gendisk *disk, unsigned int mask)
        spin_unlock_irq(&ev->lock);
 }
 
+/*
+ * Tell userland about new events.  Only the events listed in @disk->events are
+ * reported, and only if DISK_EVENT_FLAG_UEVENT is set.  Otherwise, events are
+ * processed internally but never get reported to userland.
+ */
+static void disk_event_uevent(struct gendisk *disk, unsigned int events)
+{
+       char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
+       int nr_events = 0, i;
+
+       for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
+               if (events & disk->events & (1 << i))
+                       envp[nr_events++] = disk_uevents[i];
+
+       if (nr_events)
+               kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+}
+
 static void disk_check_events(struct disk_events *ev,
                              unsigned int *clearing_ptr)
 {
        struct gendisk *disk = ev->disk;
-       char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
        unsigned int clearing = *clearing_ptr;
        unsigned int events;
        unsigned long intv;
-       int nr_events = 0, i;
 
        /* check events */
        events = disk->fops->check_events(disk, clearing);
@@ -193,19 +209,8 @@ static void disk_check_events(struct disk_events *ev,
        if (events & DISK_EVENT_MEDIA_CHANGE)
                inc_diskseq(disk);
 
-       /*
-        * Tell userland about new events.  Only the events listed in
-        * @disk->events are reported, and only if DISK_EVENT_FLAG_UEVENT
-        * is set. Otherwise, events are processed internally but never
-        * get reported to userland.
-        */
-       for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
-               if ((events & disk->events & (1 << i)) &&
-                   (disk->event_flags & DISK_EVENT_FLAG_UEVENT))
-                       envp[nr_events++] = disk_uevents[i];
-
-       if (nr_events)
-               kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+       if (disk->event_flags & DISK_EVENT_FLAG_UEVENT)
+               disk_event_uevent(disk, events);
 }
 
 /**
@@ -284,6 +289,32 @@ bool bdev_check_media_change(struct block_device *bdev)
 }
 EXPORT_SYMBOL(bdev_check_media_change);
 
+/**
+ * disk_force_media_change - force a media change event
+ * @disk: the disk which will raise the event
+ * @events: the events to raise
+ *
+ * Generate uevents for the disk. If DISK_EVENT_MEDIA_CHANGE is present,
+ * attempt to free all dentries and inodes and invalidates all block
+ * device page cache entries in that case.
+ *
+ * Returns %true if DISK_EVENT_MEDIA_CHANGE was raised, or %false if not.
+ */
+bool disk_force_media_change(struct gendisk *disk, unsigned int events)
+{
+       disk_event_uevent(disk, events);
+
+       if (!(events & DISK_EVENT_MEDIA_CHANGE))
+               return false;
+
+       if (__invalidate_device(disk->part0, true))
+               pr_warn("VFS: busy inodes on changed media %s\n",
+                       disk->disk_name);
+       set_bit(GD_NEED_PART_SCAN, &disk->state);
+       return true;
+}
+EXPORT_SYMBOL_GPL(disk_force_media_change);
+
 /*
  * Separate this part out so that a different pointer for clearing_ptr can be
  * passed in for disk_clear_events.

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 140c028845af07c45e5d000926d3be28928fc141..849486de81c660a0ead0833a7adc233ecc8e1357 100644 (file)
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -237,6 +237,7 @@ 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);
 bool set_capacity_and_notify(struct gendisk *disk, sector_t size);
+bool disk_force_media_change(struct gendisk *disk, unsigned int events);
 
 /* drivers/char/random.c */
 extern void add_disk_randomness(struct gendisk *disk) __latent_entropy;