4.4-stable review patch. If anyone has any objections, please let me know.
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From: Paulo Alcantara paulo@paulo.ac
commit 28eb24ff75c5ac130eb326b3b4d0dcecfc0f427d upstream.
In case a hostname resolves to a different IP address (e.g. long running mounts), make sure to resolve it every time prior to calling generic_ip_connect() in reconnect.
Suggested-by: Steve French stfrench@microsoft.com Signed-off-by: Paulo Alcantara palcantara@suse.de Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Pavel Shilovsky pshilov@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/connect.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+)
--- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -48,6 +48,7 @@ #include "cifs_unicode.h" #include "cifs_debug.h" #include "cifs_fs_sb.h" +#include "dns_resolve.h" #include "ntlmssp.h" #include "nterr.h" #include "rfc1002pdu.h" @@ -304,6 +305,53 @@ static int cifs_setup_volume_info(struct const char *devname);
/* + * Resolve hostname and set ip addr in tcp ses. Useful for hostnames that may + * get their ip addresses changed at some point. + * + * This should be called with server->srv_mutex held. + */ +#ifdef CONFIG_CIFS_DFS_UPCALL +static int reconn_set_ipaddr(struct TCP_Server_Info *server) +{ + int rc; + int len; + char *unc, *ipaddr = NULL; + + if (!server->hostname) + return -EINVAL; + + len = strlen(server->hostname) + 3; + + unc = kmalloc(len, GFP_KERNEL); + if (!unc) { + cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__); + return -ENOMEM; + } + snprintf(unc, len, "\\%s", server->hostname); + + rc = dns_resolve_server_name_to_ip(unc, &ipaddr); + kfree(unc); + + if (rc < 0) { + cifs_dbg(FYI, "%s: failed to resolve server part of %s to IP: %d\n", + __func__, server->hostname, rc); + return rc; + } + + rc = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr, + strlen(ipaddr)); + kfree(ipaddr); + + return !rc ? -1 : 0; +} +#else +static inline int reconn_set_ipaddr(struct TCP_Server_Info *server) +{ + return 0; +} +#endif + +/* * cifs tcp session reconnection * * mark tcp session as reconnecting so temporarily locked @@ -400,6 +448,11 @@ cifs_reconnect(struct TCP_Server_Info *s rc = generic_ip_connect(server); if (rc) { cifs_dbg(FYI, "reconnect error %d\n", rc); + rc = reconn_set_ipaddr(server); + if (rc) { + cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n", + __func__, rc); + } mutex_unlock(&server->srv_mutex); msleep(3000); } else {