[PATCH] blockdev.c: check driver layer errors (4d7dd8fd) · Commits · 戴 / test

Check driver layer errors. Fix from: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com> In blockdevc-check-errors.patch, add_bd_holder() is modified to return error values when some of its operation failed. Among them, it returns -EEXIST when a given bd_holder object already exists in the list. However, in this case, the function completed its work successfully and need no action by its caller other than freeing unused bd_holder object. So I think it's better to return success after freeing by itself. Otherwise, bd_claim-ing with same claim pointer will fail. Typically, lvresize will fails with following message: device-mapper: reload ioctl failed: Invalid argument and you'll see messages like below in kernel log: device-mapper: table: 254:13: linear: dm-linear: Device lookup failed device-mapper: ioctl: error adding target to table Similarly, it should not add bd_holder to the list if either one of symlinking fails. I don't have a test case for this to happen but it should cause dereference of freed pointer. If a matching bd_holder is found in bd_holder_list, add_bd_holder() completes its job by just incrementing the reference count. In this case, it should be considered as success but it used to return 'fail' to let the caller free temporary bd_holder. Fixed it to return success and free given object by itself. Also, if either one of symlinking fails, the bd_holder should not be added to the list so that it can be discarded later. Otherwise, the caller will free bd_holder which is in the list. Signed-off-by:

Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

fs/block_dev.c

+22 −12

Original line number	Diff line number	Diff line
		@@ -543,11 +543,11 @@ static struct kobject bdev_get_holder(struct block_device bdev)
		return kobject_get(bdev->bd_disk->holder_dir);
		}

		static void add_symlink(struct kobject from, struct kobject to)
		static int add_symlink(struct kobject from, struct kobject to)
		{
		if (!from \|\| !to)
		return;
		sysfs_create_link(from, to, kobject_name(to));
		return 0;
		return sysfs_create_link(from, to, kobject_name(to));
		}

		static void del_symlink(struct kobject from, struct kobject to)
		@@ -648,30 +648,38 @@ static void free_bd_holder(struct bd_holder *bo)
		* If there is no matching entry with @bo in @bdev->bd_holder_list,
		* add @bo to the list, create symlinks.
		*
		* Returns 1 if @bo was added to the list.
		* Returns 0 if @bo wasn't used by any reason and should be freed.
		* Returns 0 if symlinks are created or already there.
		* Returns -ve if something fails and @bo can be freed.
		*/
		static int add_bd_holder(struct block_device bdev, struct bd_holder bo)
		{
		struct bd_holder *tmp;
		int ret;

		if (!bo)
		return 0;
		return -EINVAL;

		list_for_each_entry(tmp, &bdev->bd_holder_list, list) {
		if (tmp->sdir == bo->sdir) {
		tmp->count++;
		/* We've already done what we need to do here. */
		free_bd_holder(bo);
		return 0;
		}
		}

		if (!bd_holder_grab_dirs(bdev, bo))
		return 0;
		return -EBUSY;

		add_symlink(bo->sdir, bo->sdev);
		add_symlink(bo->hdir, bo->hdev);
		ret = add_symlink(bo->sdir, bo->sdev);
		if (ret == 0) {
		ret = add_symlink(bo->hdir, bo->hdev);
		if (ret)
		del_symlink(bo->sdir, bo->sdev);
		}
		if (ret == 0)
		list_add_tail(&bo->list, &bdev->bd_holder_list);
		return 1;
		return ret;
		}

		/**
		@@ -741,7 +749,9 @@ static int bd_claim_by_kobject(struct block_device bdev, void holder,

		mutex_lock_nested(&bdev->bd_mutex, BD_MUTEX_PARTITION);
		res = bd_claim(bdev, holder);
		if (res \|\| !add_bd_holder(bdev, bo))
		if (res == 0)
		res = add_bd_holder(bdev, bo);
		if (res)
		free_bd_holder(bo);
		mutex_unlock(&bdev->bd_mutex);

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