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rbd: increase maximum snapshot name length

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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>
This commit is contained in:
Alex Elder 2012-07-03 16:01:19 -05:00
parent db2388b6ee
commit d4b125e9eb
1 changed files with 11 additions and 5 deletions
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16
drivers/block/rbd.c
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@ -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
@ -2063,7 +2066,7 @@ static int rbd_register_snap_dev(struct rbd_snap *snap,
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);
@ -2797,8 +2800,13 @@ static char *rbd_add_parse_args(struct rbd_device *rbd_dev,
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;
@ -2809,8 +2817,6 @@ static char *rbd_add_parse_args(struct rbd_device *rbd_dev,
memcpy(snap_name, buf, len);
*(snap_name + len) = '\0';
dout(" SNAP_NAME is <%s>, len is %zd\n", snap_name, len);
return snap_name;
out_err: