diff options
| author | Shyam Prasad N <sprasad@microsoft.com> | 2021-05-18 15:05:50 +0000 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2021-07-14 10:06:03 -0500 |
| commit | 506c1da44fee32ba1d3a70413289ad58c772bba6 (patch) | |
| tree | 519eb1c02f57990884daec5513bdb6e62032585f /fs/cifs/dns_resolve.c | |
| parent | e73f0f0ee7541171d89f2e2491130c7771ba58d3 (diff) | |
cifs: use the expiry output of dns_query to schedule next resolution
We recently fixed DNS resolution of the server hostname during reconnect.
However, server IP address may change, even when the old one continues
to server (although sub-optimally).
We should schedule the next DNS resolution based on the TTL of
the DNS record used for the last resolution. This way, we resolve the
server hostname again when a DNS record expires.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Cc: <stable@vger.kernel.org> # v5.11+
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/dns_resolve.c')
| -rw-r--r-- | fs/cifs/dns_resolve.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/fs/cifs/dns_resolve.c b/fs/cifs/dns_resolve.c index d15b82d569ef..8c616aaeb7c4 100644 --- a/fs/cifs/dns_resolve.c +++ b/fs/cifs/dns_resolve.c @@ -24,6 +24,7 @@ * dns_resolve_server_name_to_ip - Resolve UNC server name to ip address. * @unc: UNC path specifying the server (with '/' as delimiter) * @ip_addr: Where to return the IP address. + * @expiry: Where to return the expiry time for the dns record. * * The IP address will be returned in string form, and the caller is * responsible for freeing it. @@ -31,7 +32,7 @@ * Returns length of result on success, -ve on error. */ int -dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) +dns_resolve_server_name_to_ip(const char *unc, char **ip_addr, time64_t *expiry) { struct sockaddr_storage ss; const char *hostname, *sep; @@ -66,13 +67,14 @@ dns_resolve_server_name_to_ip(const char *unc, char **ip_addr) /* Perform the upcall */ rc = dns_query(current->nsproxy->net_ns, NULL, hostname, len, - NULL, ip_addr, NULL, false); + NULL, ip_addr, expiry, false); if (rc < 0) cifs_dbg(FYI, "%s: unable to resolve: %*.*s\n", __func__, len, len, hostname); else - cifs_dbg(FYI, "%s: resolved: %*.*s to %s\n", - __func__, len, len, hostname, *ip_addr); + cifs_dbg(FYI, "%s: resolved: %*.*s to %s expiry %llu\n", + __func__, len, len, hostname, *ip_addr, + expiry ? (*expiry) : 0); return rc; name_is_IP_address: |