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-rw-r--r--block/genhd.c48
1 files changed, 40 insertions, 8 deletions
diff --git a/block/genhd.c b/block/genhd.c
index 88a53c188cb7..9656f9e9f99e 100644
--- 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";