Re: [PATCH 06/11] rbd: add read_only rbd map option

[Alex Elder <elder@inktank.com>]

On 08/30/2012 12:29 PM, Yehuda Sadeh wrote:
> On Fri, Aug 24, 2012 at 9:34 AM, Alex Elder <elder@inktank.com> wrote:
>> Add the ability to map an rbd image read-only, by specifying either
>> "read_only" or "ro" as an option on the rbd "command line."
>>
>> Signed-off-by: Alex Elder <elder@inktank.com>
>> ---
>>  drivers/block/rbd.c |   22 ++++++++++++++++++----
>>  1 file changed, 18 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
>> index b40f553..5e22bb5 100644
>> --- a/drivers/block/rbd.c
>> +++ b/drivers/block/rbd.c
>> @@ -69,7 +69,8 @@
>>  #define DEV_NAME_LEN           32
>>  #define MAX_INT_FORMAT_WIDTH   ((5 * sizeof (int)) / 2 + 1)
>>
>> -#define RBD_NOTIFY_TIMEOUT_DEFAULT 10
>> +#define RBD_NOTIFY_TIMEOUT_DEFAULT     10
>> +#define RBD_READ_ONLY_DEFAULT          false
>>
>>  /*
>>   * block device image metadata (in-memory version)
>> @@ -91,6 +92,7 @@ struct rbd_image_header {
>>
>>  struct rbd_options {
>>         int     notify_timeout;
>> +       bool    read_only;
>>  };
>>
>>  /*
>> @@ -176,7 +178,7 @@ struct rbd_device {
>>         u64                     snap_id;        /* current snapshot id */
>>         /* whether the snap_id this device reads from still exists */
>>         bool                    snap_exists;
>> -       int                     read_only;
>> +       bool                    read_only;
>>
>>         struct list_head        node;
>>
>> @@ -351,12 +353,18 @@ enum {
>>         /* int args above */
>>         Opt_last_string,
>>         /* string args above */
>> +       Opt_read_only,
>> +       /* Boolean args above */
>> +       Opt_last_bool,
>>  };
>>
>>  static match_table_t rbd_opts_tokens = {
>>         {Opt_notify_timeout, "notify_timeout=%d"},
>>         /* int args above */
>>         /* string args above */
>> +       {Opt_read_only, "read_only"},
>> +       {Opt_read_only, "ro"},          /* Alternate spelling */
>> +       /* Boolean args above */
>>         {-1, NULL}
>>  };
>>
>> @@ -381,6 +389,8 @@ static int parse_rbd_opts_token(char *c, void *private)
>>         } else if (token > Opt_last_int && token < Opt_last_string) {
>>                 dout("got string token %d val %s\n", token,
>>                      argstr[0].from);
>> +       } else if (token > Opt_last_string && token < Opt_last_bool) {
>> +               dout("got Boolean token %d\n", token);
>>         } else {
>>                 dout("got token %d\n", token);
>>         }
>> @@ -389,6 +399,9 @@ static int parse_rbd_opts_token(char *c, void *private)
>>         case Opt_notify_timeout:
>>                 rbd_opts->notify_timeout = intval;
>>                 break;
>> +       case Opt_read_only:
>> +               rbd_opts->read_only = !rbd_opts->read_only;
> 
> should this be a flip-flop? better have "rw" and "read_write" options
> instead, or just set it to true here.

Yes I think you have a good point.  I'll set it to true.  I'll also
add a "rw" option while I'm at it; the mount command offers both and
I do prefer offering both.

					-Alex


>> +               break;
>>         default:
>>                 BUG_ON(token);
>>         }
>> @@ -407,6 +420,7 @@ static int rbd_get_client(struct rbd_device
>> *rbd_dev, const char *mon_addr,
>>         struct rbd_client *rbdc;
>>
>>         rbd_opts->notify_timeout = RBD_NOTIFY_TIMEOUT_DEFAULT;
>> +       rbd_opts->read_only = RBD_READ_ONLY_DEFAULT;
>>
>>         ceph_opts = ceph_parse_options(options, mon_addr,
>>                                         mon_addr + mon_addr_len,
>> @@ -613,7 +627,7 @@ static int rbd_header_set_snap(struct rbd_device
>> *rbd_dev, u64 *size)
>>                     sizeof (RBD_SNAP_HEAD_NAME))) {
>>                 rbd_dev->snap_id = CEPH_NOSNAP;
>>                 rbd_dev->snap_exists = false;
>> -               rbd_dev->read_only = 0;
>> +               rbd_dev->read_only = rbd_dev->rbd_opts.read_only;
>>                 if (size)
>>                         *size = rbd_dev->header.image_size;
>>         } else {
>> @@ -625,7 +639,7 @@ static int rbd_header_set_snap(struct rbd_device
>> *rbd_dev, u64 *size)
>>                         goto done;
>>                 rbd_dev->snap_id = snap_id;
>>                 rbd_dev->snap_exists = true;
>> -               rbd_dev->read_only = 1;
>> +               rbd_dev->read_only = true;      /* No choice for snapshots */
>>         }
>>
>>         ret = 0;
>> --
>> 1.7.9.5
>>
>> --
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> 
>