Merge tag 'kvm-ppc-fixes-4.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-block.git] / block / genhd.c

diff --git a/block/genhd.c b/block/genhd.c
index 88a53c188cb7338e74a9a55a44d8d0e5a2a758da..9656f9e9f99e20af13f1e175aba15f9447d9ef87 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -547,7 +547,7 @@ static int exact_lock(dev_t devt, void *data)
 {
        struct gendisk *p = data;
 
-       if (!get_disk(p))
+       if (!get_disk_and_module(p))
                return -1;
        return 0;
 }
@@ -717,6 +717,11 @@ void del_gendisk(struct gendisk *disk)
        blk_integrity_del(disk);
        disk_del_events(disk);
 
+       /*
+        * Block lookups of the disk until all bdevs are unhashed and the
+        * disk is marked as dead (GENHD_FL_UP cleared).
+        */
+       down_write(&disk->lookup_sem);
        /* invalidate stuff */
        disk_part_iter_init(&piter, disk,
                             DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
@@ -731,6 +736,7 @@ void del_gendisk(struct gendisk *disk)
        bdev_unhash_inode(disk_devt(disk));
        set_capacity(disk, 0);
        disk->flags &= ~GENHD_FL_UP;
+       up_write(&disk->lookup_sem);
 
        if (!(disk->flags & GENHD_FL_HIDDEN))
                sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
@@ -809,16 +815,28 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
 
                spin_lock_bh(&ext_devt_lock);
                part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
-               if (part && get_disk(part_to_disk(part))) {
+               if (part && get_disk_and_module(part_to_disk(part))) {
                        *partno = part->partno;
                        disk = part_to_disk(part);
                }
                spin_unlock_bh(&ext_devt_lock);
        }
 
-       if (disk && unlikely(disk->flags & GENHD_FL_HIDDEN)) {
-               put_disk(disk);
+       if (!disk)
+               return NULL;
+
+       /*
+        * Synchronize with del_gendisk() to not return disk that is being
+        * destroyed.
+        */
+       down_read(&disk->lookup_sem);
+       if (unlikely((disk->flags & GENHD_FL_HIDDEN) ||
+                    !(disk->flags & GENHD_FL_UP))) {
+               up_read(&disk->lookup_sem);
+               put_disk_and_module(disk);
                disk = NULL;
+       } else {
+               up_read(&disk->lookup_sem);
        }
        return disk;
 }
@@ -1418,6 +1436,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
                        kfree(disk);
                        return NULL;
                }
+               init_rwsem(&disk->lookup_sem);
                disk->node_id = node_id;
                if (disk_expand_part_tbl(disk, 0)) {
                        free_part_stats(&disk->part0);
@@ -1453,7 +1472,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
 }
 EXPORT_SYMBOL(__alloc_disk_node);
 
-struct kobject *get_disk(struct gendisk *disk)
+struct kobject *get_disk_and_module(struct gendisk *disk)
 {
        struct module *owner;
        struct kobject *kobj;
@@ -1471,17 +1490,30 @@ struct kobject *get_disk(struct gendisk *disk)
        return kobj;
 
 }
-
-EXPORT_SYMBOL(get_disk);
+EXPORT_SYMBOL(get_disk_and_module);
 
 void put_disk(struct gendisk *disk)
 {
        if (disk)
                kobject_put(&disk_to_dev(disk)->kobj);
 }
-
 EXPORT_SYMBOL(put_disk);
 
+/*
+ * This is a counterpart of get_disk_and_module() and thus also of
+ * get_gendisk().
+ */
+void put_disk_and_module(struct gendisk *disk)
+{
+       if (disk) {
+               struct module *owner = disk->fops->owner;
+
+               put_disk(disk);
+               module_put(owner);
+       }
+}
+EXPORT_SYMBOL(put_disk_and_module);
+
 static void set_disk_ro_uevent(struct gendisk *gd, int ro)
 {
        char event[] = "DISK_RO=1";