[Devel] [PATCH VZ9 v3 4/5] block/blk-cbt: add BLKCBTLIST ioctl

[Andrey Zhadchenko]

so user can query the list of active bitmaps.

https://virtuozzo.atlassian.net/browse/VSTOR-96269
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>

---
v2:
 - add abi version
 - remove total_count from struct blk_user_cbt_list

 block/blk-cbt.c         | 36 ++++++++++++++++++++++++++++++++++++
 block/ioctl.c           |  1 +
 include/uapi/linux/fs.h |  9 +++++++++
 3 files changed, 46 insertions(+)

diff --git a/block/blk-cbt.c b/block/blk-cbt.c
index 2543bf1e846c..5e5f224cf8f4 100644
--- a/block/blk-cbt.c
+++ b/block/blk-cbt.c
@@ -986,6 +986,40 @@ static int cbt_ioc_set(struct block_device *bdev, struct blk_user_cbt_info __use
 	return ret;
 }
 
+static int cbt_ioc_list(struct block_device *bdev, void __user *arg)
+{
+	void __user *name_ptr = (void *)((size_t)arg + sizeof(struct blk_user_cbt_list));
+	struct request_queue *q = bdev_get_queue(bdev);
+	struct blk_user_cbt_list lst;
+	struct cbt_info *cbt;
+	__u32 total = 0;
+
+	if (copy_from_user(&lst, arg, sizeof(lst)))
+		return -EFAULT;
+
+	if (!access_ok(name_ptr,
+		       lst.count * CBT_NAME_LENGTH))
+		return -EFAULT;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(cbt, &q->cbt_list, list) {
+		if (total < lst.count) {
+			if (copy_to_user(name_ptr, cbt->name, CBT_NAME_LENGTH))
+				return -EFAULT;
+			name_ptr = (void *)((size_t)name_ptr + CBT_NAME_LENGTH);
+		}
+		total++;
+	}
+	rcu_read_unlock();
+
+	lst.count = total;
+
+	if (copy_to_user(arg, &lst, sizeof(lst)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static int cbt_ioc_misc(struct block_device *bdev, void __user *arg)
 {
 	struct request_queue *q = bdev_get_queue(bdev);
@@ -1041,6 +1075,8 @@ int blk_cbt_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 		return cbt_ioc_set(bdev, ucbt_ioc, 0);
 	case BLKCBTMISC:
 		return cbt_ioc_misc(bdev, arg);
+	case BLKCBTLIST:
+		return cbt_ioc_list(bdev, arg);
 	default:
 		BUG();
 	}
diff --git a/block/ioctl.c b/block/ioctl.c
index b2d3dbe5bef5..6e76d55790ea 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -569,6 +569,7 @@ static int blkdev_common_ioctl(struct block_device *bdev, blk_mode_t mode,
 	case BLKCBTSET:
 	case BLKCBTCLR:
 	case BLKCBTMISC:
+	case BLKCBTLIST:
 		return blk_cbt_ioctl(bdev, cmd, (char __user *)arg);
 	default:
 		return -ENOIOCTLCMD;
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 2aaee5257477..3122e2783eda 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -174,12 +174,21 @@ struct blk_user_cbt_snap_create {
 	__u64 size;
 };
 
+struct blk_user_cbt_list {
+	__u32 version;		/* API version */
+	__u32 count;		/* Amount of name entries in names
+				 * in - available, out - filled
+				 */
+	__u8 names[0];		/* Array of CBT_NAME_LENGTH long names */
+};
+
 #define BLKCBTSTART _IOR(0x12,200, struct blk_user_cbt_info)
 #define BLKCBTSTOP _IOR(0x12, 201, struct blk_user_cbt_info)
 #define BLKCBTGET _IOWR(0x12,202,struct blk_user_cbt_info)
 #define BLKCBTSET _IOR(0x12,203,struct blk_user_cbt_info)
 #define BLKCBTCLR _IOR(0x12,204,struct blk_user_cbt_info)
 #define BLKCBTMISC _IOWR(0x12,205,struct blk_user_cbt_misc_info)
+#define BLKCBTLIST _IOWR(0x12, 206, struct blk_user_cbt_list)
 
 /*
  * Flags for the fsx_xflags field
-- 
2.39.3