[PATCH 0/2] rbd: support additional Boolean rbd_dev flags

[PATCH 0/2] rbd: support additional Boolean rbd_dev flags

[Alex Elder]

This series actually added another flag to the rbd_dev, but the
need for that went away.  Still, I thought these two changes
added value so I kept them.

					-Alex

[PATCH 1/2] rbd: define helpers for read_only flag

[Alex Elder]

In anticipation of replacing the "read_only" field with a "flags"
field, write some trivial wrapper routines for operating on the
read-only state of an rbd_device.

Change the variable name "dev" in rbd_header_set_snap() to be
"rbd_dev" to follow convention.

Signed-off-by: Alex Elder <elder@dreamhost.com>
---
  drivers/block/rbd.c |   35 ++++++++++++++++++++++++++---------
  1 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 229f974..e7b443a 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -187,6 +187,21 @@ struct rbd_device {
  	struct device		dev;
  };

+static inline bool rbd_dev_is_readonly(struct rbd_device *rbd_dev)
+{
+	return rbd_dev->read_only;
+}
+
+static inline void rbd_dev_set_readonly(struct rbd_device *rbd_dev)
+{
+	rbd_dev->read_only = true;
+}
+
+static inline void rbd_dev_clear_readonly(struct rbd_device *rbd_dev)
+{
+	rbd_dev->read_only = false;
+}
+
  static DEFINE_MUTEX(ctl_mutex);	  /* Serialize 
open/close/setup/teardown */

  static LIST_HEAD(rbd_dev_list);    /* devices */
@@ -245,12 +260,14 @@ static int __rbd_update_snaps(struct rbd_device 
*rbd_dev);
  static int rbd_open(struct block_device *bdev, fmode_t mode)
  {
  	struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
+	bool read_only;

  	rbd_get_dev(rbd_dev);

-	set_device_ro(bdev, rbd_dev->read_only);
+	read_only = rbd_dev_is_readonly(rbd_dev);
+	set_device_ro(bdev, read_only);

-	if ((mode & FMODE_WRITE) && rbd_dev->read_only)
+	if ((mode & FMODE_WRITE) && read_only)
  		return -EROFS;

  	return 0;
@@ -589,11 +606,11 @@ static int snap_by_name(struct rbd_image_header 
*header, const char *snap_name,
  	return -ENOENT;
  }

-static int rbd_header_set_snap(struct rbd_device *dev,
+static int rbd_header_set_snap(struct rbd_device *rbd_dev,
  			       const char *snap_name,
  			       u64 *size)
  {
-	struct rbd_image_header *header = &dev->header;
+	struct rbd_image_header *header = &rbd_dev->header;
  	struct ceph_snap_context *snapc = header->snapc;
  	int ret = -ENOENT;

@@ -604,8 +621,8 @@ static int rbd_header_set_snap(struct rbd_device *dev,
  			snapc->seq = header->snap_seq;
  		else
  			snapc->seq = 0;
-		dev->cur_snap = 0;
-		dev->read_only = 0;
+		rbd_dev->cur_snap = 0;
+		rbd_dev_clear_readonly(rbd_dev);
  		if (size)
  			*size = header->image_size;
  	} else {
@@ -613,8 +630,8 @@ static int rbd_header_set_snap(struct rbd_device *dev,
  		if (ret < 0)
  			goto done;

-		dev->cur_snap = header->total_snaps - ret;
-		dev->read_only = 1;
+		rbd_dev->cur_snap = header->total_snaps - ret;
+		rbd_dev_set_readonly(rbd_dev);
  	}

  	ret = 0;
@@ -1476,7 +1493,7 @@ static void rbd_rq_fn(struct request_queue *q)
  		size = blk_rq_bytes(rq);
  		ofs = blk_rq_pos(rq) * SECTOR_SIZE;
  		rq_bio = rq->bio;
-		if (do_write && rbd_dev->read_only) {
+		if (do_write && rbd_dev_is_readonly(rbd_dev)) {
  			__blk_end_request_all(rq, -EROFS);
  			continue;
  		}
-- 
1.7.5.4

[PATCH 2/2] rbd: convert to using flags field

[Alex Elder]

To allow having more than just read-only as Boolean state associated
with an rbd_device, replace the "read_only" field with a more
general "flags" field.  The non-atomic versions of bit operations
are fine for our purposes.

Signed-off-by: Alex Elder <elder@dreamhost.com>
---
  drivers/block/rbd.c |   14 ++++++++++----
  1 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index e7b443a..da38804 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -176,7 +176,8 @@ struct rbd_device {
  	char                    snap_name[RBD_MAX_SNAP_NAME_LEN];
  	u32 cur_snap;	/* index+1 of current snapshot within snap context
  			   0 - for the head */
-	int read_only;
+
+	unsigned long		flags;

  	struct list_head	node;

@@ -187,19 +188,24 @@ struct rbd_device {
  	struct device		dev;
  };

+/* Bit position definitions for the rbd_device->flags */
+enum {
+	RBD_DEV_FLAG_READ_ONLY,
+};
+
  static inline bool rbd_dev_is_readonly(struct rbd_device *rbd_dev)
  {
-	return rbd_dev->read_only;
+	return test_bit(RBD_DEV_FLAG_READ_ONLY, &rbd_dev->flags);
  }

  static inline void rbd_dev_set_readonly(struct rbd_device *rbd_dev)
  {
-	rbd_dev->read_only = true;
+	__set_bit(RBD_DEV_FLAG_READ_ONLY, &rbd_dev->flags);
  }

  static inline void rbd_dev_clear_readonly(struct rbd_device *rbd_dev)
  {
-	rbd_dev->read_only = false;
+	__clear_bit(RBD_DEV_FLAG_READ_ONLY, &rbd_dev->flags);
  }

  static DEFINE_MUTEX(ctl_mutex);	  /* Serialize 
open/close/setup/teardown */
-- 
1.7.5.4