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authorDavid Howells <dhowells@redhat.com>2018-02-06 06:26:30 +0000
committerDavid Howells <dhowells@redhat.com>2018-02-06 14:43:37 +0000
commit4d673da14533b32fe8d3125b5b7be4fea14e39a8 (patch)
treed0780b5603a48614696e7e9afebe5b61552c6cd1 /net/dns_resolver
parentafs: Rearrange afs_select_fileserver() a little (diff)
downloadlinux-dev-4d673da14533b32fe8d3125b5b7be4fea14e39a8.tar.xz
linux-dev-4d673da14533b32fe8d3125b5b7be4fea14e39a8.zip
afs: Support the AFS dynamic root
Support the AFS dynamic root which is a pseudo-volume that doesn't connect to any server resource, but rather is just a root directory that dynamically creates mountpoint directories where the name of such a directory is the name of the cell. Such a mount can be created thus: mount -t afs none /afs -o dyn Dynamic root superblocks aren't shared except by bind mounts and propagation. Cell root volumes can then be mounted by referring to them by name, e.g.: ls /afs/grand.central.org/ ls /afs/.grand.central.org/ The kernel will upcall to consult the DNS if the address wasn't supplied directly. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'net/dns_resolver')
-rw-r--r--net/dns_resolver/dns_query.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
index af781010753b..49da67034f29 100644
--- a/net/dns_resolver/dns_query.c
+++ b/net/dns_resolver/dns_query.c
@@ -52,11 +52,11 @@
* @name: Name to look up
* @namelen: Length of name
* @options: Request options (or NULL if no options)
- * @_result: Where to place the returned data.
+ * @_result: Where to place the returned data (or NULL)
* @_expiry: Where to store the result expiry time (or NULL)
*
- * The data will be returned in the pointer at *result, and the caller is
- * responsible for freeing it.
+ * The data will be returned in the pointer at *result, if provided, and the
+ * caller is responsible for freeing it.
*
* The description should be of the form "[<query_type>:]<domain_name>", and
* the options need to be appropriate for the query type requested. If no
@@ -81,7 +81,7 @@ int dns_query(const char *type, const char *name, size_t namelen,
kenter("%s,%*.*s,%zu,%s",
type, (int)namelen, (int)namelen, name, namelen, options);
- if (!name || namelen == 0 || !_result)
+ if (!name || namelen == 0)
return -EINVAL;
/* construct the query key description as "[<type>:]<name>" */
@@ -146,13 +146,15 @@ int dns_query(const char *type, const char *name, size_t namelen,
upayload = user_key_payload_locked(rkey);
len = upayload->datalen;
- ret = -ENOMEM;
- *_result = kmalloc(len + 1, GFP_KERNEL);
- if (!*_result)
- goto put;
+ if (_result) {
+ ret = -ENOMEM;
+ *_result = kmalloc(len + 1, GFP_KERNEL);
+ if (!*_result)
+ goto put;
- memcpy(*_result, upayload->data, len);
- (*_result)[len] = '\0';
+ memcpy(*_result, upayload->data, len);
+ (*_result)[len] = '\0';
+ }
if (_expiry)
*_expiry = rkey->expiry;