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-rw-r--r--fs/block_dev.c93
1 files changed, 75 insertions, 18 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index fe3f59c14a02..333a7bb4cb9c 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -432,6 +432,9 @@ static void init_once(void *foo)
432 mutex_init(&bdev->bd_mutex); 432 mutex_init(&bdev->bd_mutex);
433 INIT_LIST_HEAD(&bdev->bd_inodes); 433 INIT_LIST_HEAD(&bdev->bd_inodes);
434 INIT_LIST_HEAD(&bdev->bd_list); 434 INIT_LIST_HEAD(&bdev->bd_list);
435#ifdef CONFIG_SYSFS
436 INIT_LIST_HEAD(&bdev->bd_holder_disks);
437#endif
435 inode_init_once(&ei->vfs_inode); 438 inode_init_once(&ei->vfs_inode);
436 /* Initialize mutex for freeze. */ 439 /* Initialize mutex for freeze. */
437 mutex_init(&bdev->bd_fsfreeze_mutex); 440 mutex_init(&bdev->bd_fsfreeze_mutex);
@@ -779,6 +782,23 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
779} 782}
780 783
781#ifdef CONFIG_SYSFS 784#ifdef CONFIG_SYSFS
785struct bd_holder_disk {
786 struct list_head list;
787 struct gendisk *disk;
788 int refcnt;
789};
790
791static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
792 struct gendisk *disk)
793{
794 struct bd_holder_disk *holder;
795
796 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
797 if (holder->disk == disk)
798 return holder;
799 return NULL;
800}
801
782static int add_symlink(struct kobject *from, struct kobject *to) 802static int add_symlink(struct kobject *from, struct kobject *to)
783{ 803{
784 return sysfs_create_link(from, to, kobject_name(to)); 804 return sysfs_create_link(from, to, kobject_name(to));
@@ -794,6 +814,8 @@ static void del_symlink(struct kobject *from, struct kobject *to)
794 * @bdev: the claimed slave bdev 814 * @bdev: the claimed slave bdev
795 * @disk: the holding disk 815 * @disk: the holding disk
796 * 816 *
817 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
818 *
797 * This functions creates the following sysfs symlinks. 819 * This functions creates the following sysfs symlinks.
798 * 820 *
799 * - from "slaves" directory of the holder @disk to the claimed @bdev 821 * - from "slaves" directory of the holder @disk to the claimed @bdev
@@ -817,47 +839,83 @@ static void del_symlink(struct kobject *from, struct kobject *to)
817 */ 839 */
818int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) 840int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
819{ 841{
842 struct bd_holder_disk *holder;
820 int ret = 0; 843 int ret = 0;
821 844
822 mutex_lock(&bdev->bd_mutex); 845 mutex_lock(&bdev->bd_mutex);
823 846
824 WARN_ON_ONCE(!bdev->bd_holder || bdev->bd_holder_disk); 847 WARN_ON_ONCE(!bdev->bd_holder);
825 848
826 /* FIXME: remove the following once add_disk() handles errors */ 849 /* FIXME: remove the following once add_disk() handles errors */
827 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir)) 850 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
828 goto out_unlock; 851 goto out_unlock;
829 852
830 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); 853 holder = bd_find_holder_disk(bdev, disk);
831 if (ret) 854 if (holder) {
855 holder->refcnt++;
832 goto out_unlock; 856 goto out_unlock;
857 }
833 858
834 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); 859 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
835 if (ret) { 860 if (!holder) {
836 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); 861 ret = -ENOMEM;
837 goto out_unlock; 862 goto out_unlock;
838 } 863 }
839 864
840 bdev->bd_holder_disk = disk; 865 INIT_LIST_HEAD(&holder->list);
866 holder->disk = disk;
867 holder->refcnt = 1;
868
869 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
870 if (ret)
871 goto out_free;
872
873 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
874 if (ret)
875 goto out_del;
876
877 list_add(&holder->list, &bdev->bd_holder_disks);
878 goto out_unlock;
879
880out_del:
881 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
882out_free:
883 kfree(holder);
841out_unlock: 884out_unlock:
842 mutex_unlock(&bdev->bd_mutex); 885 mutex_unlock(&bdev->bd_mutex);
843 return ret; 886 return ret;
844} 887}
845EXPORT_SYMBOL_GPL(bd_link_disk_holder); 888EXPORT_SYMBOL_GPL(bd_link_disk_holder);
846 889
847static void bd_unlink_disk_holder(struct block_device *bdev) 890/**
891 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
892 * @bdev: the calimed slave bdev
893 * @disk: the holding disk
894 *
895 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
896 *
897 * CONTEXT:
898 * Might sleep.
899 */
900void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
848{ 901{
849 struct gendisk *disk = bdev->bd_holder_disk; 902 struct bd_holder_disk *holder;
850 903
851 bdev->bd_holder_disk = NULL; 904 mutex_lock(&bdev->bd_mutex);
852 if (!disk)
853 return;
854 905
855 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); 906 holder = bd_find_holder_disk(bdev, disk);
856 del_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); 907
908 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
909 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
910 del_symlink(bdev->bd_part->holder_dir,
911 &disk_to_dev(disk)->kobj);
912 list_del_init(&holder->list);
913 kfree(holder);
914 }
915
916 mutex_unlock(&bdev->bd_mutex);
857} 917}
858#else 918EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
859static inline void bd_unlink_disk_holder(struct block_device *bdev)
860{ }
861#endif 919#endif
862 920
863/** 921/**
@@ -1380,7 +1438,6 @@ int blkdev_put(struct block_device *bdev, fmode_t mode)
1380 * unblock evpoll if it was a write holder. 1438 * unblock evpoll if it was a write holder.
1381 */ 1439 */
1382 if (bdev_free) { 1440 if (bdev_free) {
1383 bd_unlink_disk_holder(bdev);
1384 if (bdev->bd_write_holder) { 1441 if (bdev->bd_write_holder) {
1385 disk_unblock_events(bdev->bd_disk); 1442 disk_unblock_events(bdev->bd_disk);
1386 bdev->bd_write_holder = false; 1443 bdev->bd_write_holder = false;