[ 208/221] rbd: increase maximum snapshot name length

Greg Kroah-Hartman
2013-01-15T22:40:54Z

From: Alex Elder <elder@inktank.com>

(cherry picked from commit d4b125e9eb43babd14538ba61718e3db71a98d29)

Change RBD_MAX_SNAP_NAME_LEN to be based on NAME_MAX. That is a
practical limit for the length of a snapshot name (based on the
presence of a directory using the name under /sys/bus/rbd to
represent the snapshot).

The /sys entry is created by prefixing it with "snap_"; define that
prefix symbolically, and take its length into account in defining
the snapshot name length limit.

Enforce the limit in rbd_add_parse_args(). Also delete a dout()
call in that function that was not meant to be committed.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/rbd.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -61,7 +61,10 @@

#define RBD_MINORS_PER_MAJOR 256 /* max minors per blkdev */

-#define RBD_MAX_SNAP_NAME_LEN 32
+#define RBD_SNAP_DEV_NAME_PREFIX "snap_"
+#define RBD_MAX_SNAP_NAME_LEN \
+ (NAME_MAX - (sizeof (RBD_SNAP_DEV_NAME_PREFIX) - 1))
+
#define RBD_MAX_SNAP_COUNT 510 /* allows max snapc to fit in 4KB */
#define RBD_MAX_OPT_LEN 1024

@@ -2073,7 +2076,7 @@ static int rbd_register_snap_dev(struct
dev->type = &rbd_snap_device_type;
dev->parent = parent;
dev->release = rbd_snap_dev_release;
- dev_set_name(dev, "snap_%s", snap->name);
+ dev_set_name(dev, "%s%s", RBD_SNAP_DEV_NAME_PREFIX, snap->name);
dout("%s: registering device for snapshot %s\n", __func__, snap->name);

ret = device_register(dev);
@@ -2766,8 +2769,13 @@ static char *rbd_add_parse_args(struct r
if (!rbd_dev->image_name)
goto out_err;

- /* Snapshot name is optional */
+ /* Snapshot name is optional; default is to use "head" */
+
len = next_token(&buf);
+ if (len > RBD_MAX_SNAP_NAME_LEN) {
+ err_ptr = ERR_PTR(-ENAMETOOLONG);
+ goto out_err;
+ }
if (!len) {
buf = RBD_SNAP_HEAD_NAME; /* No snapshot supplied */
len = sizeof (RBD_SNAP_HEAD_NAME) - 1;
@@ -2778,8 +2786,6 @@ static char *rbd_add_parse_args(struct r
memcpy(snap_name, buf, len);
*(snap_name + len) = '\0';

-dout(" SNAP_NAME is <%s>, len is %zd\n", snap_name, len);
-
return snap_name;