From fac55a2a6164dd9562119aa0f5848d5afb08cb55 Mon Sep 17 00:00:00 2001
From: "Paulo Alcantara (SUSE)" <pc@cjr.nz>
Date: Thu, 20 Feb 2020 19:49:34 -0300
Subject: [PATCH] cifs: handle prefix paths in reconnect
Patch-mainline: Not yet, in for-next branch
References: bsc#1144333
For the case where we have a DFS path like below and we're currently
connected to targetA:
//dfsroot/link -> //targetA/share/foo, //targetB/share/bar
after failover, we should make sure to update cifs_sb->prepath so the
next operations will use the new prefix path "/bar".
Besides, in order to simplify the use of different prefix paths,
enforce CIFS_MOUNT_USE_PREFIX_PATH for DFS mounts so we don't have to
revalidate the root dentry every time we set a new prefix path.
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
fs/cifs/cifsproto.h | 5 +++
fs/cifs/cifssmb.c | 19 +++++++++---
fs/cifs/connect.c | 63 +++++++---------------------------------
fs/cifs/dfs_cache.c | 38 ++++++++++++++++++++++++
fs/cifs/dfs_cache.h | 4 ++
fs/cifs/misc.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/cifs/smb2pdu.c | 19 +++++++++---
7 files changed, 169 insertions(+), 59 deletions(-)
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -594,6 +594,11 @@ int smb2_parse_query_directory(struct ci
int resp_buftype,
struct cifs_search_info *srch_inf);
+struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server);
+void cifs_put_tcp_super(struct super_block *sb);
+int update_super_prepath(struct cifs_tcon *tcon, const char *prefix,
+ size_t prefix_len);
+
#ifdef CONFIG_CIFS_DFS_UPCALL
static inline int get_dfs_path(const unsigned int xid, struct cifs_ses *ses,
const char *old_path,
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -162,9 +162,18 @@ static int __cifs_reconnect_tcon(const s
for (it = dfs_cache_get_tgt_iterator(&tl); it;
it = dfs_cache_get_next_tgt(&tl, it)) {
- const char *tgt = dfs_cache_get_tgt_name(it);
+ const char *share, *prefix;
+ size_t share_len, prefix_len;
- extract_unc_hostname(tgt, &dfs_host, &dfs_host_len);
+ rc = dfs_cache_get_tgt_share(it, &share, &share_len, &prefix,
+ &prefix_len);
+ if (rc) {
+ cifs_dbg(VFS, "%s: failed to parse target share %d\n",
+ __func__, rc);
+ continue;
+ }
+
+ extract_unc_hostname(share, &dfs_host, &dfs_host_len);
if (dfs_host_len != tcp_host_len
|| strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) {
@@ -175,11 +184,13 @@ static int __cifs_reconnect_tcon(const s
continue;
}
- scnprintf(tree, MAX_TREE_SIZE, "\\%s", tgt);
+ scnprintf(tree, MAX_TREE_SIZE, "\\%.*s", (int)share_len, share);
rc = CIFSTCon(0, tcon->ses, tree, tcon, nlsc);
- if (!rc)
+ if (!rc) {
+ rc = update_super_prepath(tcon, prefix, prefix_len);
break;
+ }
if (rc == -EREMOTE)
break;
}
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -57,7 +57,6 @@
#include "smb2proto.h"
#include "smbdirect.h"
#include "dns_resolve.h"
-#include "cifsfs.h"
#ifdef CONFIG_CIFS_DFS_UPCALL
#include "dfs_cache.h"
#endif
@@ -384,54 +383,7 @@ static inline int reconn_set_ipaddr(stru
#endif
#ifdef CONFIG_CIFS_DFS_UPCALL
-struct super_cb_data {
- struct TCP_Server_Info *server;
- struct super_block *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->sb)
- return;
-
- cifs_sb = CIFS_SB(sb);
- tcon = cifs_sb_master_tcon(cifs_sb);
- if (tcon->ses->server == d->server)
- d->sb = sb;
-}
-
-static struct super_block *get_tcp_super(struct TCP_Server_Info *server)
-{
- struct super_cb_data d = {
- .server = server,
- .sb = NULL,
- };
-
- iterate_supers_type(&cifs_fs_type, super_cb, &d);
-
- if (unlikely(!d.sb))
- return ERR_PTR(-ENOENT);
- /*
- * Grab an active reference in order to prevent automounts (DFS links)
- * of expiring and then freeing up our cifs superblock pointer while
- * we're doing failover.
- */
- cifs_sb_active(d.sb);
- return d.sb;
-}
-
-static inline void put_tcp_super(struct super_block *sb)
-{
- if (!IS_ERR_OR_NULL(sb))
- cifs_sb_deactive(sb);
-}
-
static void reconn_inval_dfs_target(struct TCP_Server_Info *server,
struct cifs_sb_info *cifs_sb,
struct dfs_cache_tgt_list *tgt_list,
@@ -503,7 +455,7 @@ cifs_reconnect(struct TCP_Server_Info *s
server->nr_targets = 1;
#ifdef CONFIG_CIFS_DFS_UPCALL
spin_unlock(&GlobalMid_Lock);
- sb = get_tcp_super(server);
+ sb = cifs_get_tcp_super(server);
if (IS_ERR(sb)) {
rc = PTR_ERR(sb);
cifs_dbg(FYI, "%s: will not do DFS failover: rc = %d\n",
@@ -530,7 +482,7 @@ cifs_reconnect(struct TCP_Server_Info *s
spin_unlock(&GlobalMid_Lock);
#ifdef CONFIG_CIFS_DFS_UPCALL
dfs_cache_free_tgts(&tgt_list);
- put_tcp_super(sb);
+ cifs_put_tcp_super(sb);
#endif
return rc;
} else
@@ -661,7 +613,7 @@ cifs_reconnect(struct TCP_Server_Info *s
}
- put_tcp_super(sb);
+ cifs_put_tcp_super(sb);
#endif
if (server->tcpStatus == CifsNeedNegotiate)
mod_delayed_work(cifsiod_wq, &server->echo, 0);
@@ -4927,6 +4879,15 @@ int cifs_mount(struct cifs_sb_info *cifs
* dentry revalidation to think the dentry are stale (ESTALE).
*/
cifs_autodisable_serverino(cifs_sb);
+ /*
+ * Force the use of prefix path to support failover on DFS paths that
+ * resolve to targets that have different prefix paths.
+ */
+ cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
+ kfree(cifs_sb->prepath);
+ cifs_sb->prepath = vol->prepath;
+ vol->prepath = NULL;
+
out:
free_xid(xid);
return mount_setup_tlink(cifs_sb, ses, tcon);
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -1257,6 +1257,44 @@ void dfs_cache_del_vol(const char *fullp
kref_put(&vi->refcnt, vol_release);
}
+/**
+ * dfs_cache_get_tgt_share - parse a DFS target
+ *
+ * @it: DFS target iterator.
+ * @share: tree name.
+ * @share_len: length of tree name.
+ * @prefix: prefix path.
+ * @prefix_len: length of prefix path.
+ *
+ * Return zero if target was parsed correctly, otherwise non-zero.
+ */
+int dfs_cache_get_tgt_share(const struct dfs_cache_tgt_iterator *it,
+ const char **share, size_t *share_len,
+ const char **prefix, size_t *prefix_len)
+{
+ char *s, sep;
+
+ if (!it || !share || !share_len || !prefix || !prefix_len)
+ return -EINVAL;
+
+ sep = it->it_name[0];
+ if (sep != '\\' && sep != '/')
+ return -EINVAL;
+
+ s = strchr(it->it_name + 1, sep);
+ if (!s)
+ return -EINVAL;
+
+ s = strchrnul(s + 1, sep);
+
+ *share = it->it_name;
+ *share_len = s - it->it_name;
+ *prefix = *s ? s + 1 : s;
+ *prefix_len = &it->it_name[strlen(it->it_name)] - *prefix;
+
+ return 0;
+}
+
/* Get all tcons that are within a DFS namespace and can be refreshed */
static void get_tcons(struct TCP_Server_Info *server, struct list_head *head)
{
--- a/fs/cifs/dfs_cache.h
+++ b/fs/cifs/dfs_cache.h
@@ -49,6 +49,10 @@ extern int dfs_cache_update_vol(const ch
struct TCP_Server_Info *server);
extern void dfs_cache_del_vol(const char *fullpath);
+extern int dfs_cache_get_tgt_share(const struct dfs_cache_tgt_iterator *it,
+ const char **share, size_t *share_len,
+ const char **prefix, size_t *prefix_len);
+
static inline struct dfs_cache_tgt_iterator *
dfs_cache_get_next_tgt(struct dfs_cache_tgt_list *tl,
struct dfs_cache_tgt_iterator *it)
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -31,6 +31,7 @@
#include "nterr.h"
#include "cifs_unicode.h"
#include "smb2pdu.h"
+#include "cifsfs.h"
extern mempool_t *cifs_sm_req_poolp;
extern mempool_t *cifs_req_poolp;
@@ -1038,3 +1039,82 @@ int copy_path_name(char *dst, const char
name_len++;
return name_len;
}
+
+struct super_cb_data {
+ struct TCP_Server_Info *server;
+ struct super_block *sb;
+};
+
+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->sb)
+ return;
+
+ cifs_sb = CIFS_SB(sb);
+ tcon = cifs_sb_master_tcon(cifs_sb);
+ if (tcon->ses->server == d->server)
+ d->sb = sb;
+}
+
+struct super_block *cifs_get_tcp_super(struct TCP_Server_Info *server)
+{
+ struct super_cb_data d = {
+ .server = server,
+ .sb = NULL,
+ };
+
+ iterate_supers_type(&cifs_fs_type, super_cb, &d);
+
+ if (unlikely(!d.sb))
+ return ERR_PTR(-ENOENT);
+ /*
+ * Grab an active reference in order to prevent automounts (DFS links)
+ * of expiring and then freeing up our cifs superblock pointer while
+ * we're doing failover.
+ */
+ cifs_sb_active(d.sb);
+ return d.sb;
+}
+
+void cifs_put_tcp_super(struct super_block *sb)
+{
+ if (!IS_ERR_OR_NULL(sb))
+ cifs_sb_deactive(sb);
+}
+
+int update_super_prepath(struct cifs_tcon *tcon, const char *prefix,
+ size_t prefix_len)
+{
+ struct super_block *sb;
+ struct cifs_sb_info *cifs_sb;
+ int rc = 0;
+
+ sb = cifs_get_tcp_super(tcon->ses->server);
+ if (IS_ERR(sb))
+ return PTR_ERR(sb);
+
+ cifs_sb = CIFS_SB(sb);
+
+ kfree(cifs_sb->prepath);
+
+ if (*prefix && prefix_len) {
+ cifs_sb->prepath = kstrndup(prefix, prefix_len, GFP_ATOMIC);
+ if (!cifs_sb->prepath) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));
+ } else
+ cifs_sb->prepath = NULL;
+
+ cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
+
+out:
+ cifs_put_tcp_super(sb);
+ return rc;
+}
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -193,9 +193,18 @@ static int __smb2_reconnect(const struct
for (it = dfs_cache_get_tgt_iterator(&tl); it;
it = dfs_cache_get_next_tgt(&tl, it)) {
- const char *tgt = dfs_cache_get_tgt_name(it);
+ const char *share, *prefix;
+ size_t share_len, prefix_len;
- extract_unc_hostname(tgt, &dfs_host, &dfs_host_len);
+ rc = dfs_cache_get_tgt_share(it, &share, &share_len, &prefix,
+ &prefix_len);
+ if (rc) {
+ cifs_dbg(VFS, "%s: failed to parse target share %d\n",
+ __func__, rc);
+ continue;
+ }
+
+ extract_unc_hostname(share, &dfs_host, &dfs_host_len);
if (dfs_host_len != tcp_host_len
|| strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) {
@@ -206,11 +215,13 @@ static int __smb2_reconnect(const struct
continue;
}
- scnprintf(tree, MAX_TREE_SIZE, "\\%s", tgt);
+ scnprintf(tree, MAX_TREE_SIZE, "\\%.*s", (int)share_len, share);
rc = SMB2_tcon(0, tcon->ses, tree, tcon, nlsc);
- if (!rc)
+ if (!rc) {
+ rc = update_super_prepath(tcon, prefix, prefix_len);
break;
+ }
if (rc == -EREMOTE)
break;
}