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authorPaulo Alcantara <palcantara@suse.de>2018-11-14 17:13:25 -0200
committerSteve French <stfrench@microsoft.com>2018-12-28 10:13:11 -0600
commit93d5cb517db39e8af8d1292f9e785e4983b7f708 (patch)
treeda84893e19fdc2d854d5983b7d54b7b2ce552baa /fs/cifs/connect.c
parent4a367dc0443566f87d73f2cdb94703b0e1374315 (diff)
downloadlinux-93d5cb517db39e8af8d1292f9e785e4983b7f708.tar.bz2
cifs: Add support for failover in cifs_reconnect()
After failing to reconnect to original target, it will retry any target available from DFS cache. Signed-off-by: Paulo Alcantara <palcantara@suse.de> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/connect.c')
-rw-r--r--fs/cifs/connect.c189
1 files changed, 188 insertions, 1 deletions
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 658a0d191056..ef51cf748db7 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -57,6 +57,7 @@
#include "smb2proto.h"
#include "smbdirect.h"
#include "dns_resolve.h"
+#include "cifsfs.h"
#ifdef CONFIG_CIFS_DFS_UPCALL
#include "dfs_cache.h"
#endif
@@ -322,6 +323,116 @@ static void tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink);
static void cifs_prune_tlinks(struct work_struct *work);
static int cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
const char *devname, bool is_smb3);
+static char *extract_hostname(const char *unc);
+
+#ifdef CONFIG_CIFS_DFS_UPCALL
+struct super_cb_data {
+ struct TCP_Server_Info *server;
+ struct cifs_sb_info *cifs_sb;
+};
+
+/* These functions must be called with server->srv_mutex held */
+
+static void super_cb(struct super_block *sb, void *arg)
+{
+ struct super_cb_data *d = arg;
+ struct cifs_sb_info *cifs_sb;
+ struct cifs_tcon *tcon;
+
+ if (d->cifs_sb)
+ return;
+
+ cifs_sb = CIFS_SB(sb);
+ tcon = cifs_sb_master_tcon(cifs_sb);
+ if (tcon->ses->server == d->server)
+ d->cifs_sb = cifs_sb;
+}
+
+static inline struct cifs_sb_info *
+find_super_by_tcp(struct TCP_Server_Info *server)
+{
+ struct super_cb_data d = {
+ .server = server,
+ .cifs_sb = NULL,
+ };
+
+ iterate_supers_type(&cifs_fs_type, super_cb, &d);
+ return d.cifs_sb ? d.cifs_sb : ERR_PTR(-ENOENT);
+}
+
+static void reconn_inval_dfs_target(struct TCP_Server_Info *server,
+ struct cifs_sb_info *cifs_sb,
+ struct dfs_cache_tgt_list *tgt_list,
+ struct dfs_cache_tgt_iterator **tgt_it)
+{
+ const char *name;
+ int rc;
+ char *ipaddr = NULL;
+ char *unc;
+ int len;
+
+ if (!cifs_sb || !cifs_sb->origin_fullpath || !tgt_list ||
+ !server->nr_targets)
+ return;
+
+ if (!*tgt_it) {
+ *tgt_it = dfs_cache_get_tgt_iterator(tgt_list);
+ } else {
+ *tgt_it = dfs_cache_get_next_tgt(tgt_list, *tgt_it);
+ if (!*tgt_it)
+ *tgt_it = dfs_cache_get_tgt_iterator(tgt_list);
+ }
+
+ cifs_dbg(FYI, "%s: UNC: %s\n", __func__, cifs_sb->origin_fullpath);
+
+ name = dfs_cache_get_tgt_name(*tgt_it);
+
+ kfree(server->hostname);
+
+ server->hostname = extract_hostname(name);
+ if (!server->hostname) {
+ cifs_dbg(FYI, "%s: failed to extract hostname from target: %d\n",
+ __func__, -ENOMEM);
+ return;
+ }
+
+ len = strlen(server->hostname) + 3;
+
+ unc = kmalloc(len, GFP_KERNEL);
+ if (!unc) {
+ cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);
+ return;
+ }
+ 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 = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,
+ strlen(ipaddr));
+ kfree(ipaddr);
+
+ if (!rc) {
+ cifs_dbg(FYI, "%s: failed to get ipaddr out of hostname\n",
+ __func__);
+ }
+}
+
+static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
+ struct dfs_cache_tgt_list *tl,
+ struct dfs_cache_tgt_iterator **it)
+{
+ if (!cifs_sb->origin_fullpath)
+ return -EOPNOTSUPP;
+ return dfs_cache_noreq_find(cifs_sb->origin_fullpath + 1, NULL, tl);
+}
+#endif
/*
* cifs tcp session reconnection
@@ -340,8 +451,33 @@ cifs_reconnect(struct TCP_Server_Info *server)
struct cifs_tcon *tcon;
struct mid_q_entry *mid_entry;
struct list_head retry_list;
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ struct cifs_sb_info *cifs_sb;
+ struct dfs_cache_tgt_list tgt_list;
+ struct dfs_cache_tgt_iterator *tgt_it = NULL;
+#endif
spin_lock(&GlobalMid_Lock);
+ server->nr_targets = 1;
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ cifs_sb = find_super_by_tcp(server);
+ if (IS_ERR(cifs_sb)) {
+ rc = PTR_ERR(cifs_sb);
+ cifs_dbg(FYI, "%s: will not do DFS failover: rc = %d\n",
+ __func__, rc);
+ cifs_sb = NULL;
+ } else {
+ rc = reconn_setup_dfs_targets(cifs_sb, &tgt_list, &tgt_it);
+ if (rc) {
+ cifs_dbg(VFS, "%s: no target servers for DFS failover\n",
+ __func__);
+ } else {
+ server->nr_targets = dfs_cache_get_nr_tgts(&tgt_list);
+ }
+ }
+ cifs_dbg(FYI, "%s: will retry %d target(s)\n", __func__,
+ server->nr_targets);
+#endif
if (server->tcpStatus == CifsExiting) {
/* the demux thread will exit normally
next time through the loop */
@@ -415,14 +551,22 @@ cifs_reconnect(struct TCP_Server_Info *server)
do {
try_to_freeze();
- /* we should try only the port we connected to before */
mutex_lock(&server->srv_mutex);
+ /*
+ * Set up next DFS target server (if any) for reconnect. If DFS
+ * feature is disabled, then we will retry last server we
+ * connected to before.
+ */
if (cifs_rdma_enabled(server))
rc = smbd_reconnect(server);
else
rc = generic_ip_connect(server);
if (rc) {
cifs_dbg(FYI, "reconnect error %d\n", rc);
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ reconn_inval_dfs_target(server, cifs_sb, &tgt_list,
+ &tgt_it);
+#endif
mutex_unlock(&server->srv_mutex);
msleep(3000);
} else {
@@ -435,6 +579,22 @@ cifs_reconnect(struct TCP_Server_Info *server)
}
} while (server->tcpStatus == CifsNeedReconnect);
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ if (tgt_it) {
+ rc = dfs_cache_noreq_update_tgthint(cifs_sb->origin_fullpath + 1,
+ tgt_it);
+ if (rc) {
+ cifs_dbg(VFS, "%s: failed to update DFS target hint: rc = %d\n",
+ __func__, rc);
+ }
+ rc = dfs_cache_update_vol(cifs_sb->origin_fullpath, server);
+ if (rc) {
+ cifs_dbg(VFS, "%s: failed to update vol info in DFS cache: rc = %d\n",
+ __func__, rc);
+ }
+ }
+ dfs_cache_free_tgts(&tgt_list);
+#endif
if (server->tcpStatus == CifsNeedNegotiate)
mod_delayed_work(cifsiod_wq, &server->echo, 0);
@@ -2471,6 +2631,8 @@ smbd_connected:
}
tcp_ses->tcpStatus = CifsNeedNegotiate;
+ tcp_ses->nr_targets = 1;
+
/* thread spawned, put it on the list */
spin_lock(&cifs_tcp_ses_lock);
list_add(&tcp_ses->tcp_ses_list, &cifs_tcp_ses_list);
@@ -4303,6 +4465,12 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
goto error;
}
+ full_path = build_unc_path_to_root(vol, cifs_sb, true);
+ if (IS_ERR(full_path)) {
+ rc = PTR_ERR(full_path);
+ full_path = NULL;
+ goto error;
+ }
/*
* Perform an unconditional check for whether there are DFS
* referrals for this path without prefix, to provide support
@@ -4409,6 +4577,22 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
if (rc)
goto error;
+ spin_lock(&cifs_tcp_ses_lock);
+ if (!tcon->dfs_path) {
+ /* Save full path in new tcon to do failover when reconnecting tcons */
+ tcon->dfs_path = full_path;
+ full_path = NULL;
+ tcon->remap = cifs_remap(cifs_sb);
+ }
+ cifs_sb->origin_fullpath = kstrndup(tcon->dfs_path,
+ strlen(tcon->dfs_path), GFP_KERNEL);
+ if (!cifs_sb->origin_fullpath) {
+ spin_unlock(&cifs_tcp_ses_lock);
+ rc = -ENOMEM;
+ goto error;
+ }
+ spin_unlock(&cifs_tcp_ses_lock);
+
/*
* After reconnecting to a different server, unique ids won't
* match anymore, so we disable serverino. This prevents
@@ -4650,6 +4834,9 @@ cifs_umount(struct cifs_sb_info *cifs_sb)
kfree(cifs_sb->mountdata);
kfree(cifs_sb->prepath);
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ kfree(cifs_sb->origin_fullpath);
+#endif
call_rcu(&cifs_sb->rcu, delayed_free);
}