dm ioctl: filter the returned values according to name or uuid prefix

If we set non-empty param->name or param->uuid on the DM_LIST_DEVICES_CMD
ioctl, the set values are considered filter prefixes. The ioctl will only
return entries with matching name or uuid prefix.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 0812ac6..2209cbc 100644 (file)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -540,6 +540,30 @@ static void *get_result_buffer(struct dm_ioctl *param, size_t param_size,
        return ((void *) param) + param->data_start;
 }
 
+static bool filter_device(struct hash_cell *hc, const char *pfx_name, const char *pfx_uuid)
+{
+       const char *val;
+       size_t val_len, pfx_len;
+
+       val = hc->name;
+       val_len = strlen(val);
+       pfx_len = strnlen(pfx_name, DM_NAME_LEN);
+       if (pfx_len > val_len)
+               return false;
+       if (memcmp(val, pfx_name, pfx_len))
+               return false;
+
+       val = hc->uuid ? hc->uuid : "";
+       val_len = strlen(val);
+       pfx_len = strnlen(pfx_uuid, DM_UUID_LEN);
+       if (pfx_len > val_len)
+               return false;
+       if (memcmp(val, pfx_uuid, pfx_len))
+               return false;
+
+       return true;
+}
+
 static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_size)
 {
        struct rb_node *n;
@@ -557,6 +581,8 @@ static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_
         */
        for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
                hc = container_of(n, struct hash_cell, name_node);
+               if (!filter_device(hc, param->name, param->uuid))
+                       continue;
                needed += align_val(offsetof(struct dm_name_list, name) + strlen(hc->name) + 1);
                needed += align_val(sizeof(uint32_t) * 2);
                if (param->flags & DM_UUID_FLAG && hc->uuid)
@@ -581,6 +607,8 @@ static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_
        for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
                void *uuid_ptr;
                hc = container_of(n, struct hash_cell, name_node);
+               if (!filter_device(hc, param->name, param->uuid))
+                       continue;
                if (old_nl)
                        old_nl->next = (uint32_t) ((void *) nl -
                                                   (void *) old_nl);