rbd: return snap name from rbd_add_parse_args()

This is the first of two patches aimed at isolating the code that
sets the mapping information into a single spot.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 37 insertions, 35 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 4377a8302fc3..1a64ba294a76 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2477,28 +2477,31 @@ static inline char *dup_token(const char **buf, size_t *lenp)
 }
 
 /*
- * This fills in the pool_name, image_name, image_name_len, snap_name,
- * rbd_dev, rbd_md_name, and name fields of the given rbd_dev, based
- * on the list of monitor addresses and other options provided via
- * /sys/bus/rbd/add.
+ * This fills in the pool_name, image_name, image_name_len, rbd_dev,
+ * rbd_md_name, and name fields of the given rbd_dev, based on the
+ * list of monitor addresses and other options provided via
+ * /sys/bus/rbd/add.  Returns a pointer to a dynamically-allocated
+ * copy of the snapshot name to map if successful, or a
+ * pointer-coded error otherwise.
  *
  * Note: rbd_dev is assumed to have been initially zero-filled.
  */
-static int rbd_add_parse_args(struct rbd_device *rbd_dev,
-                              const char *buf,
-                              const char **mon_addrs,
-                              size_t *mon_addrs_size,
-                              char *options,
-                             size_t options_size)
+static char *rbd_add_parse_args(struct rbd_device *rbd_dev,
+                                const char *buf,
+                                const char **mon_addrs,
+                                size_t *mon_addrs_size,
+                                char *options,
+                                size_t options_size)
 {
         size_t len;
-        int ret;
+        char *err_ptr = ERR_PTR(-EINVAL);
+        char *snap_name;
 
         /* The first four tokens are required */
 
         len = next_token(&buf);
         if (!len)
-                return -EINVAL;
+                return err_ptr;
         *mon_addrs_size = len + 1;
         *mon_addrs = buf;
 
@@ -2506,9 +2509,9 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
 
         len = copy_token(&buf, options, options_size);
         if (!len || len >= options_size)
-                return -EINVAL;
+                return err_ptr;
 
-        ret = -ENOMEM;
+        err_ptr = ERR_PTR(-ENOMEM);
         rbd_dev->pool_name = dup_token(&buf, NULL);
         if (!rbd_dev->pool_name)
                 goto out_err;
@@ -2526,26 +2529,21 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
                 goto out_err;
         sprintf(rbd_dev->header_name, "%s%s", rbd_dev->image_name, RBD_SUFFIX);
 
-        /*
-         * The snapshot name is optional.  If none is is supplied,
-         * we use the default value.
-         */
-        rbd_dev->mapping.snap_name = dup_token(&buf, &len);
-        if (!rbd_dev->mapping.snap_name)
-                goto out_err;
+        /* Snapshot name is optional */
+        len = next_token(&buf);
         if (!len) {
-                /* Replace the empty name with the default */
-                kfree(rbd_dev->mapping.snap_name);
-                rbd_dev->mapping.snap_name
-                        = kmalloc(sizeof (RBD_SNAP_HEAD_NAME), GFP_KERNEL);
-                if (!rbd_dev->mapping.snap_name)
-                        goto out_err;
-
-                memcpy(rbd_dev->mapping.snap_name, RBD_SNAP_HEAD_NAME,
-                        sizeof (RBD_SNAP_HEAD_NAME));
+                buf = RBD_SNAP_HEAD_NAME; /* No snapshot supplied */
+                len = sizeof (RBD_SNAP_HEAD_NAME) - 1;
         }
+        snap_name = kmalloc(len + 1, GFP_KERNEL);
+        if (!snap_name)
+                goto out_err;
+        memcpy(snap_name, buf, len);
+        *(snap_name + len) = '\0';
 
-        return 0;
+dout("    SNAP_NAME is <%s>, len is %zd\n", snap_name, len);
+
+        return snap_name;
 
 out_err:
         kfree(rbd_dev->header_name);
@@ -2556,7 +2554,7 @@ out_err:
         kfree(rbd_dev->pool_name);
         rbd_dev->pool_name = NULL;
 
-        return ret;
+        return err_ptr;
 }
 
 static ssize_t rbd_add(struct bus_type *bus,
@@ -2569,6 +2567,7 @@ static ssize_t rbd_add(struct bus_type *bus,
         size_t mon_addrs_size = 0;
         struct ceph_osd_client *osdc;
         int rc = -ENOMEM;
+        char *snap_name;
 
         if (!try_module_get(THIS_MODULE))
                 return -ENODEV;
@@ -2595,10 +2594,13 @@ static ssize_t rbd_add(struct bus_type *bus,
         sprintf(rbd_dev->name, "%s%d", RBD_DRV_NAME, rbd_dev->dev_id);
 
         /* parse add command */
-        rc = rbd_add_parse_args(rbd_dev, buf, &mon_addrs, &mon_addrs_size,
-                                options, count);
-        if (rc)
+        snap_name = rbd_add_parse_args(rbd_dev, buf,
+                                &mon_addrs, &mon_addrs_size, options, count);
+        if (IS_ERR(snap_name)) {
+                rc = PTR_ERR(snap_name);
                 goto err_put_id;
+        }
+        rbd_dev->mapping.snap_name = snap_name;
 
         rc = rbd_get_client(rbd_dev, mon_addrs, mon_addrs_size - 1, options);
         if (rc < 0)