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authorJun'ichi Nomura <j-nomura@ce.jp.nec.com>2006-03-27 04:17:57 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-27 11:45:00 -0500
commit641dc636b0475582e48584340b774bd1e90d40d9 (patch)
tree75c839cebd81a8ec4fae6c0cc35a387da160cfbe /fs
parent100873687d81d4ce7b1299b447d33e87ba1e9583 (diff)
[PATCH] dm/md dependency tree in sysfs: bd_claim_by_kobject
Adding bd_claim_by_kobject() function which takes kobject as additional signature of holder device and creates sysfs symlinks between holder device and claimed device. bd_release_from_kobject() is a counterpart of bd_claim_by_kobject. Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/block_dev.c297
1 files changed, 297 insertions, 0 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 5983d42df015..3f36df7e037c 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -266,6 +266,9 @@ static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
266 mutex_init(&bdev->bd_mount_mutex); 266 mutex_init(&bdev->bd_mount_mutex);
267 INIT_LIST_HEAD(&bdev->bd_inodes); 267 INIT_LIST_HEAD(&bdev->bd_inodes);
268 INIT_LIST_HEAD(&bdev->bd_list); 268 INIT_LIST_HEAD(&bdev->bd_list);
269#ifdef CONFIG_SYSFS
270 INIT_LIST_HEAD(&bdev->bd_holder_list);
271#endif
269 inode_init_once(&ei->vfs_inode); 272 inode_init_once(&ei->vfs_inode);
270 } 273 }
271} 274}
@@ -490,6 +493,300 @@ void bd_release(struct block_device *bdev)
490 493
491EXPORT_SYMBOL(bd_release); 494EXPORT_SYMBOL(bd_release);
492 495
496#ifdef CONFIG_SYSFS
497/*
498 * Functions for bd_claim_by_kobject / bd_release_from_kobject
499 *
500 * If a kobject is passed to bd_claim_by_kobject()
501 * and the kobject has a parent directory,
502 * following symlinks are created:
503 * o from the kobject to the claimed bdev
504 * o from "holders" directory of the bdev to the parent of the kobject
505 * bd_release_from_kobject() removes these symlinks.
506 *
507 * Example:
508 * If /dev/dm-0 maps to /dev/sda, kobject corresponding to
509 * /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
510 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
511 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
512 */
513
514static struct kobject *bdev_get_kobj(struct block_device *bdev)
515{
516 if (bdev->bd_contains != bdev)
517 return kobject_get(&bdev->bd_part->kobj);
518 else
519 return kobject_get(&bdev->bd_disk->kobj);
520}
521
522static struct kobject *bdev_get_holder(struct block_device *bdev)
523{
524 if (bdev->bd_contains != bdev)
525 return kobject_get(bdev->bd_part->holder_dir);
526 else
527 return kobject_get(bdev->bd_disk->holder_dir);
528}
529
530static void add_symlink(struct kobject *from, struct kobject *to)
531{
532 if (!from || !to)
533 return;
534 sysfs_create_link(from, to, kobject_name(to));
535}
536
537static void del_symlink(struct kobject *from, struct kobject *to)
538{
539 if (!from || !to)
540 return;
541 sysfs_remove_link(from, kobject_name(to));
542}
543
544/*
545 * 'struct bd_holder' contains pointers to kobjects symlinked by
546 * bd_claim_by_kobject.
547 * It's connected to bd_holder_list which is protected by bdev->bd_sem.
548 */
549struct bd_holder {
550 struct list_head list; /* chain of holders of the bdev */
551 int count; /* references from the holder */
552 struct kobject *sdir; /* holder object, e.g. "/block/dm-0/slaves" */
553 struct kobject *hdev; /* e.g. "/block/dm-0" */
554 struct kobject *hdir; /* e.g. "/block/sda/holders" */
555 struct kobject *sdev; /* e.g. "/block/sda" */
556};
557
558/*
559 * Get references of related kobjects at once.
560 * Returns 1 on success. 0 on failure.
561 *
562 * Should call bd_holder_release_dirs() after successful use.
563 */
564static int bd_holder_grab_dirs(struct block_device *bdev,
565 struct bd_holder *bo)
566{
567 if (!bdev || !bo)
568 return 0;
569
570 bo->sdir = kobject_get(bo->sdir);
571 if (!bo->sdir)
572 return 0;
573
574 bo->hdev = kobject_get(bo->sdir->parent);
575 if (!bo->hdev)
576 goto fail_put_sdir;
577
578 bo->sdev = bdev_get_kobj(bdev);
579 if (!bo->sdev)
580 goto fail_put_hdev;
581
582 bo->hdir = bdev_get_holder(bdev);
583 if (!bo->hdir)
584 goto fail_put_sdev;
585
586 return 1;
587
588fail_put_sdev:
589 kobject_put(bo->sdev);
590fail_put_hdev:
591 kobject_put(bo->hdev);
592fail_put_sdir:
593 kobject_put(bo->sdir);
594
595 return 0;
596}
597
598/* Put references of related kobjects at once. */
599static void bd_holder_release_dirs(struct bd_holder *bo)
600{
601 kobject_put(bo->hdir);
602 kobject_put(bo->sdev);
603 kobject_put(bo->hdev);
604 kobject_put(bo->sdir);
605}
606
607static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
608{
609 struct bd_holder *bo;
610
611 bo = kzalloc(sizeof(*bo), GFP_KERNEL);
612 if (!bo)
613 return NULL;
614
615 bo->count = 1;
616 bo->sdir = kobj;
617
618 return bo;
619}
620
621static void free_bd_holder(struct bd_holder *bo)
622{
623 kfree(bo);
624}
625
626/**
627 * add_bd_holder - create sysfs symlinks for bd_claim() relationship
628 *
629 * @bdev: block device to be bd_claimed
630 * @bo: preallocated and initialized by alloc_bd_holder()
631 *
632 * If there is no matching entry with @bo in @bdev->bd_holder_list,
633 * add @bo to the list, create symlinks.
634 *
635 * Returns 1 if @bo was added to the list.
636 * Returns 0 if @bo wasn't used by any reason and should be freed.
637 */
638static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
639{
640 struct bd_holder *tmp;
641
642 if (!bo)
643 return 0;
644
645 list_for_each_entry(tmp, &bdev->bd_holder_list, list) {
646 if (tmp->sdir == bo->sdir) {
647 tmp->count++;
648 return 0;
649 }
650 }
651
652 if (!bd_holder_grab_dirs(bdev, bo))
653 return 0;
654
655 add_symlink(bo->sdir, bo->sdev);
656 add_symlink(bo->hdir, bo->hdev);
657 list_add_tail(&bo->list, &bdev->bd_holder_list);
658 return 1;
659}
660
661/**
662 * del_bd_holder - delete sysfs symlinks for bd_claim() relationship
663 *
664 * @bdev: block device to be bd_claimed
665 * @kobj: holder's kobject
666 *
667 * If there is matching entry with @kobj in @bdev->bd_holder_list
668 * and no other bd_claim() from the same kobject,
669 * remove the struct bd_holder from the list, delete symlinks for it.
670 *
671 * Returns a pointer to the struct bd_holder when it's removed from the list
672 * and ready to be freed.
673 * Returns NULL if matching claim isn't found or there is other bd_claim()
674 * by the same kobject.
675 */
676static struct bd_holder *del_bd_holder(struct block_device *bdev,
677 struct kobject *kobj)
678{
679 struct bd_holder *bo;
680
681 list_for_each_entry(bo, &bdev->bd_holder_list, list) {
682 if (bo->sdir == kobj) {
683 bo->count--;
684 BUG_ON(bo->count < 0);
685 if (!bo->count) {
686 list_del(&bo->list);
687 del_symlink(bo->sdir, bo->sdev);
688 del_symlink(bo->hdir, bo->hdev);
689 bd_holder_release_dirs(bo);
690 return bo;
691 }
692 break;
693 }
694 }
695
696 return NULL;
697}
698
699/**
700 * bd_claim_by_kobject - bd_claim() with additional kobject signature
701 *
702 * @bdev: block device to be claimed
703 * @holder: holder's signature
704 * @kobj: holder's kobject
705 *
706 * Do bd_claim() and if it succeeds, create sysfs symlinks between
707 * the bdev and the holder's kobject.
708 * Use bd_release_from_kobject() when relesing the claimed bdev.
709 *
710 * Returns 0 on success. (same as bd_claim())
711 * Returns errno on failure.
712 */
713static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
714 struct kobject *kobj)
715{
716 int res;
717 struct bd_holder *bo;
718
719 if (!kobj)
720 return -EINVAL;
721
722 bo = alloc_bd_holder(kobj);
723 if (!bo)
724 return -ENOMEM;
725
726 down(&bdev->bd_sem);
727 res = bd_claim(bdev, holder);
728 if (res || !add_bd_holder(bdev, bo))
729 free_bd_holder(bo);
730 up(&bdev->bd_sem);
731
732 return res;
733}
734
735/**
736 * bd_release_from_kobject - bd_release() with additional kobject signature
737 *
738 * @bdev: block device to be released
739 * @kobj: holder's kobject
740 *
741 * Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
742 */
743static void bd_release_from_kobject(struct block_device *bdev,
744 struct kobject *kobj)
745{
746 struct bd_holder *bo;
747
748 if (!kobj)
749 return;
750
751 down(&bdev->bd_sem);
752 bd_release(bdev);
753 if ((bo = del_bd_holder(bdev, kobj)))
754 free_bd_holder(bo);
755 up(&bdev->bd_sem);
756}
757
758/**
759 * bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
760 *
761 * @bdev: block device to be claimed
762 * @holder: holder's signature
763 * @disk: holder's gendisk
764 *
765 * Call bd_claim_by_kobject() with getting @disk->slave_dir.
766 */
767int bd_claim_by_disk(struct block_device *bdev, void *holder,
768 struct gendisk *disk)
769{
770 return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
771}
772EXPORT_SYMBOL_GPL(bd_claim_by_disk);
773
774/**
775 * bd_release_from_disk - wrapper function for bd_release_from_kobject()
776 *
777 * @bdev: block device to be claimed
778 * @disk: holder's gendisk
779 *
780 * Call bd_release_from_kobject() and put @disk->slave_dir.
781 */
782void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
783{
784 bd_release_from_kobject(bdev, disk->slave_dir);
785 kobject_put(disk->slave_dir);
786}
787EXPORT_SYMBOL_GPL(bd_release_from_disk);
788#endif
789
493/* 790/*
494 * Tries to open block device by device number. Use it ONLY if you 791 * Tries to open block device by device number. Use it ONLY if you
495 * really do not have anything better - i.e. when you are behind a 792 * really do not have anything better - i.e. when you are behind a