[Ocfs2-devel] [PATCH 5/6] Framework for version LVB

[Goldwyn Rodrigues]

On 11/03/2013 07:10 PM, Mark Fasheh wrote:
> On Fri, Oct 18, 2013 at 09:46:12AM -0500, Goldwyn Rodrigues wrote:
>> Use the native DLM locks for version control negotiation. Most
>> of the framework is taken from gfs2/lock_dlm.c
>>
>> Signed-off-by: Goldwyn Rodrigues <rgoldwyn at suse.com>
>> ---
>>   fs/ocfs2/stack_user.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 102 insertions(+)
>>
>> diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
>> index 5660e6d..f417d5e 100644
>> --- a/fs/ocfs2/stack_user.c
>> +++ b/fs/ocfs2/stack_user.c
>> @@ -118,6 +118,9 @@ struct ocfs2_live_connection {
>>   	enum ocfs2_connection_type	oc_type;
>>   	atomic_t                        oc_this_node;
>>   	int                             oc_our_slot;
>> +	struct dlm_lksb                 oc_version_lksb;
>> +	char                            oc_lvb[DLM_LVB_LEN];
>> +	struct completion               oc_sync_wait;
>>   };
>>
>>   struct ocfs2_control_private {
>> @@ -796,6 +799,105 @@ static int fs_protocol_compare(struct ocfs2_protocol_version *existing,
>>   	return 0;
>>   }
>>
>> +static int lvb_to_version(char *lvb, struct ocfs2_protocol_version *ver)
>> +{
>> +	struct ocfs2_protocol_version pv;
>> +	struct ocfs2_protocol_version *max =
>> +		&ocfs2_user_plugin.sp_max_proto;
>> +
>> +	memcpy(&pv, lvb, sizeof(struct ocfs2_protocol_version));
>> +	if ((pv.pv_major == LONG_MIN) || (pv.pv_major == LONG_MAX) ||
>> +	    (pv.pv_major > (u8)-1) || (pv.pv_major < 1))
>> +		return -ERANGE;
>> +	if ((pv.pv_minor == LONG_MIN) || (pv.pv_minor == LONG_MAX) ||
>> +	    (pv.pv_minor > (u8)-1) || (pv.pv_minor < 0))
>> +		return -ERANGE;
>> +	if ((pv.pv_major != max->pv_major) ||
>> +	    (pv.pv_minor > max->pv_minor))
>> +		return -EINVAL;
>> +	ver->pv_major = pv.pv_major;
>> +	ver->pv_minor = pv.pv_minor;
>> +	return 0;
>> +}
>
> I don't like that lvb_to_version() can return error - I would prefer that
> validation of the lvb contents happen _outside_ the conversion function.
> There should actually never be a reason to fail converting an lvb and any
> corruptions, etc should be caught afterwards.

Ok. Will do.

>
>
>> +static void version_to_lvb(struct ocfs2_protocol_version *ver, char *lvb)
>> +{
>> +	memcpy(lvb, ver, sizeof(struct ocfs2_protocol_version));
>> +}
>
> You'll need to account for mixed-endian clusters here and above. Look at
> ocfs_stuff_meta_lvb() and ocfs2_refresh_inode_from_lvb() to see what I'm
> talking about. Since the lvb goes over the network we chose a big-endian
> representation there.

ocfs2_protocol_version has two variables, pv_major and pv_minor both of 
which are u8 :) Perhaps I could put in a comment if you like.

>
>
>> +static void sync_wait_cb(void *arg)
>> +{
>> +	struct ocfs2_cluster_connection *conn = arg;
>> +	struct ocfs2_live_connection *lc = conn->cc_private;
>> +	complete(&lc->oc_sync_wait);
>> +}
>> +
>> +static int sync_unlock(struct ocfs2_cluster_connection *conn,
>> +		struct dlm_lksb *lksb, char *name)
>> +{
>> +	int error;
>> +	struct ocfs2_live_connection *lc = conn->cc_private;
>> +
>> +	error = dlm_unlock(conn->cc_lockspace, lksb->sb_lkid, 0, lksb, conn);
>> +	if (error) {
>> +		printk(KERN_ERR "%s lkid %x error %d\n",
>> +				name, lksb->sb_lkid, error);
>> +		return error;
>> +	}
>> +
>> +	wait_for_completion(&lc->oc_sync_wait);
>> +
>> +	if (lksb->sb_status != -DLM_EUNLOCK) {
>> +		printk(KERN_ERR "%s lkid %x status %d\n",
>> +				name, lksb->sb_lkid, lksb->sb_status);
>> +		return -1;
>> +	}
>> +	return 0;
>> +}
>> +
>> +static int sync_lock(struct ocfs2_cluster_connection *conn,
>> +		int mode, uint32_t flags,
>> +		struct dlm_lksb *lksb, char *name)
>> +{
>> +	int error, status;
>> +	struct ocfs2_live_connection *lc = conn->cc_private;
>> +
>> +	error = dlm_lock(conn->cc_lockspace, mode, lksb, flags,
>> +			name, strlen(name),
>> +			0, sync_wait_cb, conn, NULL);
>> +	if (error) {
>> +		printk(KERN_ERR "%s lkid %x flags %x mode %d error %d\n",
>> +				name, lksb->sb_lkid, flags, mode, error);
>> +		return error;
>> +	}
>> +
>> +	wait_for_completion(&lc->oc_sync_wait);
>> +
>> +	status = lksb->sb_status;
>> +
>> +	if (status && status != -EAGAIN) {
>> +		printk(KERN_ERR "%s lkid %x flags %x mode %d status %d\n",
>> +				name, lksb->sb_lkid, flags, mode, status);
>> +	}
>> +
>> +	return status;
>> +}
>> +
>> +
>> +static int version_lock(struct ocfs2_cluster_connection *conn, int mode,
>> +		int flags)
>> +{
>> +	struct ocfs2_live_connection *lc = conn->cc_private;
>> +	return sync_lock(conn, mode, flags,
>> +			&lc->oc_version_lksb, "version_lock");
>> +}
>
> #define	VERSION_LOCK_NAME	"version_lock"
>
> and take the "name" argument out of sync_lock().
> 	--Mark
>

Understood.


-- 
Goldwyn