Merge tag '6.4-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs fixes from Steve French:
 "smb3 client fixes, mostly DFS or reconnect related:

   - Two DFS connection sharing fixes

   - DFS refresh fix

   - Reconnect fix

   - Two potential use after free fixes

   - Also print prefix patch in mount debug msg

   - Two small cleanup fixes"

* tag '6.4-rc-smb3-client-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: Remove unneeded semicolon
  cifs: fix sharing of DFS connections
  cifs: avoid potential races when handling multiple dfs tcons
  cifs: protect access of TCP_Server_Info::{origin,leaf}_fullpath
  cifs: fix potential race when tree connecting ipc
  cifs: fix potential use-after-free bugs in TCP_Server_Info::hostname
  cifs: print smb3_fs_context::source when mounting
  cifs: protect session status check in smb2_reconnect()
  SMB3.1.1: correct definition for app_instance_id create contexts

fs/cifs/cifs_debug.c

@@ -280,8 +280,10 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 		seq_printf(m, "\n%d) ConnectionId: 0x%llx ",
 			c, server->conn_id);
 
+		spin_lock(&server->srv_lock);
 		if (server->hostname)
 			seq_printf(m, "Hostname: %s ", server->hostname);
+		spin_unlock(&server->srv_lock);
 #ifdef CONFIG_CIFS_SMB_DIRECT
 		if (!server->rdma)
 			goto skip_rdma;
@@ -623,10 +625,13 @@ static int cifs_stats_proc_show(struct seq_file *m, void *v)
 				server->fastest_cmd[j],
 				server->slowest_cmd[j]);
 		for (j = 0; j < NUMBER_OF_SMB2_COMMANDS; j++)
-			if (atomic_read(&server->smb2slowcmd[j]))
+			if (atomic_read(&server->smb2slowcmd[j])) {
+				spin_lock(&server->srv_lock);
 				seq_printf(m, "  %d slow responses from %s for command %d\n",
 					atomic_read(&server->smb2slowcmd[j]),
 					server->hostname, j);
+				spin_unlock(&server->srv_lock);
+			}
 #endif /* STATS2 */
 		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
 			list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {

fs/cifs/cifs_debug.h

@@ -81,19 +81,19 @@ do {									\
 
 #define cifs_server_dbg_func(ratefunc, type, fmt, ...)			\
 do {									\
-	const char *sn = "";						\
-	if (server && server->hostname)					\
-		sn = server->hostname;					\
+	spin_lock(&server->srv_lock);					\
 	if ((type) & FYI && cifsFYI & CIFS_INFO) {			\
 		pr_debug_ ## ratefunc("%s: \\\\%s " fmt,		\
-				      __FILE__, sn, ##__VA_ARGS__);	\
+				      __FILE__, server->hostname,	\
+				      ##__VA_ARGS__);			\
 	} else if ((type) & VFS) {					\
 		pr_err_ ## ratefunc("VFS: \\\\%s " fmt,			\
-				    sn, ##__VA_ARGS__);			\
+				    server->hostname, ##__VA_ARGS__);	\
 	} else if ((type) & NOISY && (NOISY != 0)) {			\
 		pr_debug_ ## ratefunc("\\\\%s " fmt,			\
-				      sn, ##__VA_ARGS__);		\
+				      server->hostname, ##__VA_ARGS__);	\
 	}								\
+	spin_unlock(&server->srv_lock);					\
 } while (0)
 
 #define cifs_server_dbg(type, fmt, ...)					\

fs/cifs/cifsfs.c

@@ -874,14 +874,12 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
 	struct cifs_mnt_data mnt_data;
 	struct dentry *root;
 
-	/*
-	 * Prints in Kernel / CIFS log the attempted mount operation
-	 *	If CIFS_DEBUG && cifs_FYI
-	 */
-	if (cifsFYI)
-		cifs_dbg(FYI, "Devname: %s flags: %d\n", old_ctx->UNC, flags);
-	else
-		cifs_info("Attempting to mount %s\n", old_ctx->UNC);
+	if (cifsFYI) {
+		cifs_dbg(FYI, "%s: devname=%s flags=0x%x\n", __func__,
+			 old_ctx->source, flags);
+	} else {
+		cifs_info("Attempting to mount %s\n", old_ctx->source);
+	}
 
 	cifs_sb = kzalloc(sizeof(struct cifs_sb_info), GFP_KERNEL);
 	if (cifs_sb == NULL) {

fs/cifs/cifsglob.h

@@ -736,17 +736,23 @@ struct TCP_Server_Info {
 #endif
 	struct mutex refpath_lock; /* protects leaf_fullpath */
 	/*
-	 * Canonical DFS full paths that were used to chase referrals in mount and reconnect.
+	 * origin_fullpath: Canonical copy of smb3_fs_context::source.
+	 *                  It is used for matching existing DFS tcons.
 	 *
-	 * origin_fullpath: first or original referral path
-	 * leaf_fullpath: last referral path (might be changed due to nested links in reconnect)
+	 * leaf_fullpath: Canonical DFS referral path related to this
+	 *                connection.
+	 *                It is used in DFS cache refresher, reconnect and may
+	 *                change due to nested DFS links.
 	 *
-	 * current_fullpath: pointer to either origin_fullpath or leaf_fullpath
-	 * NOTE: cannot be accessed outside cifs_reconnect() and smb2_reconnect()
+	 * Both protected by @refpath_lock and @srv_lock.  The @refpath_lock is
+	 * mosly used for not requiring a copy of @leaf_fullpath when getting
+	 * cached or new DFS referrals (which might also sleep during I/O).
+	 * While @srv_lock is held for making string and NULL comparions against
+	 * both fields as in mount(2) and cache refresh.
 	 *
-	 * format: \\HOST\SHARE\[OPTIONAL PATH]
+	 * format: \\HOST\SHARE[\OPTIONAL PATH]
 	 */
-	char *origin_fullpath, *leaf_fullpath, *current_fullpath;
+	char *origin_fullpath, *leaf_fullpath;
 };
 
 static inline bool is_smb1(struct TCP_Server_Info *server)
@@ -1232,8 +1238,8 @@ struct cifs_tcon {
 	struct cached_fids *cfids;
 	/* BB add field for back pointer to sb struct(s)? */
 #ifdef CONFIG_CIFS_DFS_UPCALL
-	struct list_head ulist; /* cache update list */
 	struct list_head dfs_ses_list;
+	struct delayed_work dfs_cache_work;
 #endif
 	struct delayed_work	query_interfaces; /* query interfaces workqueue job */
 };
@@ -1750,7 +1756,6 @@ struct cifs_mount_ctx {
 	struct TCP_Server_Info *server;
 	struct cifs_ses *ses;
 	struct cifs_tcon *tcon;
-	char *origin_fullpath, *leaf_fullpath;
 	struct list_head dfs_ses_list;
 };
 

fs/cifs/cifsproto.h

@@ -8,6 +8,7 @@
 #ifndef _CIFSPROTO_H
 #define _CIFSPROTO_H
 #include <linux/nls.h>
+#include <linux/ctype.h>
 #include "trace.h"
 #ifdef CONFIG_CIFS_DFS_UPCALL
 #include "dfs_cache.h"
@@ -572,7 +573,7 @@ extern int E_md4hash(const unsigned char *passwd, unsigned char *p16,
 extern struct TCP_Server_Info *
 cifs_find_tcp_session(struct smb3_fs_context *ctx);
 
-extern void cifs_put_smb_ses(struct cifs_ses *ses);
+void __cifs_put_smb_ses(struct cifs_ses *ses);
 
 extern struct cifs_ses *
 cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx);
@@ -696,4 +697,45 @@ struct super_block *cifs_get_tcon_super(struct cifs_tcon *tcon);
 void cifs_put_tcon_super(struct super_block *sb);
 int cifs_wait_for_server_reconnect(struct TCP_Server_Info *server, bool retry);
 
+/* Put references of @ses and @ses->dfs_root_ses */
+static inline void cifs_put_smb_ses(struct cifs_ses *ses)
+{
+	struct cifs_ses *rses = ses->dfs_root_ses;
+
+	__cifs_put_smb_ses(ses);
+	if (rses)
+		__cifs_put_smb_ses(rses);
+}
+
+/* Get an active reference of @ses and @ses->dfs_root_ses.
+ *
+ * NOTE: make sure to call this function when incrementing reference count of
+ * @ses to ensure that any DFS root session attached to it (@ses->dfs_root_ses)
+ * will also get its reference count incremented.
+ *
+ * cifs_put_smb_ses() will put both references, so call it when you're done.
+ */
+static inline void cifs_smb_ses_inc_refcount(struct cifs_ses *ses)
+{
+	lockdep_assert_held(&cifs_tcp_ses_lock);
+
+	ses->ses_count++;
+	if (ses->dfs_root_ses)
+		ses->dfs_root_ses->ses_count++;
+}
+
+static inline bool dfs_src_pathname_equal(const char *s1, const char *s2)
+{
+	if (strlen(s1) != strlen(s2))
+		return false;
+	for (; *s1; s1++, s2++) {
+		if (*s1 == '/' || *s1 == '\\') {
+			if (*s2 != '/' && *s2 != '\\')
+				return false;
+		} else if (tolower(*s1) != tolower(*s2))
+			return false;
+	}
+	return true;
+}
+
 #endif			/* _CIFSPROTO_H */

fs/cifs/dfs.c

@@ -99,7 +99,7 @@ static int get_session(struct cifs_mount_ctx *mnt_ctx, const char *full_path)
 	return rc;
 }
 
-static int get_root_smb_session(struct cifs_mount_ctx *mnt_ctx)
+static int add_root_smb_session(struct cifs_mount_ctx *mnt_ctx)
 {
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
 	struct dfs_root_ses *root_ses;
@@ -127,7 +127,7 @@ static int get_dfs_conn(struct cifs_mount_ctx *mnt_ctx, const char *ref_path, co
 {
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
 	struct dfs_info3_param ref = {};
-	bool is_refsrv = false;
+	bool is_refsrv;
 	int rc, rc2;
 
 	rc = dfs_cache_get_tgt_referral(ref_path + 1, tit, &ref);
@@ -157,8 +157,10 @@ static int get_dfs_conn(struct cifs_mount_ctx *mnt_ctx, const char *ref_path, co
 		rc = cifs_is_path_remote(mnt_ctx);
 	}
 
+	dfs_cache_noreq_update_tgthint(ref_path + 1, tit);
+
 	if (rc == -EREMOTE && is_refsrv) {
-		rc2 = get_root_smb_session(mnt_ctx);
+		rc2 = add_root_smb_session(mnt_ctx);
 		if (rc2)
 			rc = rc2;
 	}
@@ -248,16 +250,19 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 		tcon = mnt_ctx->tcon;
 
 		mutex_lock(&server->refpath_lock);
+		spin_lock(&server->srv_lock);
 		if (!server->origin_fullpath) {
 			server->origin_fullpath = origin_fullpath;
-			server->current_fullpath = server->leaf_fullpath;
 			origin_fullpath = NULL;
 		}
+		spin_unlock(&server->srv_lock);
 		mutex_unlock(&server->refpath_lock);
 
 		if (list_empty(&tcon->dfs_ses_list)) {
 			list_replace_init(&mnt_ctx->dfs_ses_list,
 					  &tcon->dfs_ses_list);
+			queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,
+					   dfs_cache_get_ttl() * HZ);
 		} else {
 			dfs_put_root_smb_sessions(&mnt_ctx->dfs_ses_list);
 		}
@@ -272,15 +277,21 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx)
 
 int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
 {
-	struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb;
 	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
+	struct cifs_ses *ses;
+	char *source = ctx->source;
+	bool nodfs = ctx->nodfs;
 	int rc;
 
 	*isdfs = false;
-
+	/* Temporarily set @ctx->source to NULL as we're not matching DFS
+	 * superblocks yet.  See cifs_match_super() and match_server().
+	 */
+	ctx->source = NULL;
 	rc = get_session(mnt_ctx, NULL);
 	if (rc)
-		return rc;
+		goto out;
+
 	ctx->dfs_root_ses = mnt_ctx->ses;
 	/*
 	 * If called with 'nodfs' mount option, then skip DFS resolving.  Otherwise unconditionally
@@ -289,23 +300,41 @@ int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx, bool *isdfs)
 	 * Skip prefix path to provide support for DFS referrals from w2k8 servers which don't seem
 	 * to respond with PATH_NOT_COVERED to requests that include the prefix.
 	 */
-	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) ||
-	    dfs_get_referral(mnt_ctx, ctx->UNC + 1, NULL, NULL)) {
+	if (!nodfs) {
+		rc = dfs_get_referral(mnt_ctx, ctx->UNC + 1, NULL, NULL);
+		if (rc) {
+			if (rc != -ENOENT && rc != -EOPNOTSUPP)
+				goto out;
+			nodfs = true;
+		}
+	}
+	if (nodfs) {
 		rc = cifs_mount_get_tcon(mnt_ctx);
-		if (rc)
-			return rc;
-
-		rc = cifs_is_path_remote(mnt_ctx);
-		if (!rc || rc != -EREMOTE)
-			return rc;
+		if (!rc)
+			rc = cifs_is_path_remote(mnt_ctx);
+		goto out;
 	}
 
 	*isdfs = true;
-	rc = get_root_smb_session(mnt_ctx);
-	if (rc)
-		return rc;
-
-	return __dfs_mount_share(mnt_ctx);
+	/*
+	 * Prevent DFS root session of being put in the first call to
+	 * cifs_mount_put_conns().  If another DFS root server was not found
+	 * while chasing the referrals (@ctx->dfs_root_ses == @ses), then we
+	 * can safely put extra refcount of @ses.
+	 */
+	ses = mnt_ctx->ses;
+	mnt_ctx->ses = NULL;
+	mnt_ctx->server = NULL;
+	rc = __dfs_mount_share(mnt_ctx);
+	if (ses == ctx->dfs_root_ses)
+		cifs_put_smb_ses(ses);
+out:
+	/*
+	 * Restore previous value of @ctx->source so DFS superblock can be
+	 * matched in cifs_match_super().
+	 */
+	ctx->source = source;
+	return rc;
 }
 
 /* Update dfs referral path of superblock */
@@ -342,10 +371,11 @@ static int update_server_fullpath(struct TCP_Server_Info *server, struct cifs_sb
 		rc = PTR_ERR(npath);
 	} else {
 		mutex_lock(&server->refpath_lock);
+		spin_lock(&server->srv_lock);
 		kfree(server->leaf_fullpath);
 		server->leaf_fullpath = npath;
+		spin_unlock(&server->srv_lock);
 		mutex_unlock(&server->refpath_lock);
-		server->current_fullpath = server->leaf_fullpath;
 	}
 	return rc;
 }
@@ -374,6 +404,54 @@ static int target_share_matches_server(struct TCP_Server_Info *server, char *sha
 	return rc;
 }
 
+static void __tree_connect_ipc(const unsigned int xid, char *tree,
+			       struct cifs_sb_info *cifs_sb,
+			       struct cifs_ses *ses)
+{
+	struct TCP_Server_Info *server = ses->server;
+	struct cifs_tcon *tcon = ses->tcon_ipc;
+	int rc;
+
+	spin_lock(&ses->ses_lock);
+	spin_lock(&ses->chan_lock);
+	if (cifs_chan_needs_reconnect(ses, server) ||
+	    ses->ses_status != SES_GOOD) {
+		spin_unlock(&ses->chan_lock);
+		spin_unlock(&ses->ses_lock);
+		cifs_server_dbg(FYI, "%s: skipping ipc reconnect due to disconnected ses\n",
+				__func__);
+		return;
+	}
+	spin_unlock(&ses->chan_lock);
+	spin_unlock(&ses->ses_lock);
+
+	cifs_server_lock(server);
+	scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
+	cifs_server_unlock(server);
+
+	rc = server->ops->tree_connect(xid, ses, tree, tcon,
+				       cifs_sb->local_nls);
+	cifs_server_dbg(FYI, "%s: tree_reconnect %s: %d\n", __func__, tree, rc);
+	spin_lock(&tcon->tc_lock);
+	if (rc) {
+		tcon->status = TID_NEED_TCON;
+	} else {
+		tcon->status = TID_GOOD;
+		tcon->need_reconnect = false;
+	}
+	spin_unlock(&tcon->tc_lock);
+}
+
+static void tree_connect_ipc(const unsigned int xid, char *tree,
+			     struct cifs_sb_info *cifs_sb,
+			     struct cifs_tcon *tcon)
+{
+	struct cifs_ses *ses = tcon->ses;
+
+	__tree_connect_ipc(xid, tree, cifs_sb, ses);
+	__tree_connect_ipc(xid, tree, cifs_sb, CIFS_DFS_ROOT_SES(ses));
+}
+
 static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
 				     struct cifs_sb_info *cifs_sb, char *tree, bool islink,
 				     struct dfs_cache_tgt_list *tl)
@@ -382,7 +460,6 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
 	struct TCP_Server_Info *server = tcon->ses->server;
 	const struct smb_version_operations *ops = server->ops;
 	struct cifs_ses *root_ses = CIFS_DFS_ROOT_SES(tcon->ses);
-	struct cifs_tcon *ipc = root_ses->tcon_ipc;
 	char *share = NULL, *prefix = NULL;
 	struct dfs_cache_tgt_iterator *tit;
 	bool target_match;
@@ -403,7 +480,7 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
 		share = prefix = NULL;
 
 		/* Check if share matches with tcp ses */
-		rc = dfs_cache_get_tgt_share(server->current_fullpath + 1, tit, &share, &prefix);
+		rc = dfs_cache_get_tgt_share(server->leaf_fullpath + 1, tit, &share, &prefix);
 		if (rc) {
 			cifs_dbg(VFS, "%s: failed to parse target share: %d\n", __func__, rc);
 			break;
@@ -417,19 +494,15 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
 			continue;
 		}
 
-		dfs_cache_noreq_update_tgthint(server->current_fullpath + 1, tit);
-
-		if (ipc->need_reconnect) {
-			scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
-			rc = ops->tree_connect(xid, ipc->ses, tree, ipc, cifs_sb->local_nls);
-			cifs_dbg(FYI, "%s: reconnect ipc: %d\n", __func__, rc);
-		}
+		dfs_cache_noreq_update_tgthint(server->leaf_fullpath + 1, tit);
+		tree_connect_ipc(xid, tree, cifs_sb, tcon);
 
 		scnprintf(tree, MAX_TREE_SIZE, "\\%s", share);
 		if (!islink) {
 			rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls);
 			break;
 		}
+
 		/*
 		 * If no dfs referrals were returned from link target, then just do a TREE_CONNECT
 		 * to it.  Otherwise, cache the dfs referral and then mark current tcp ses for
@@ -539,8 +612,8 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
 	cifs_sb = CIFS_SB(sb);
 
 	/* If it is not dfs or there was no cached dfs referral, then reconnect to same share */
-	if (!server->current_fullpath ||
-	    dfs_cache_noreq_find(server->current_fullpath + 1, &ref, &tl)) {
+	if (!server->leaf_fullpath ||
+	    dfs_cache_noreq_find(server->leaf_fullpath + 1, &ref, &tl)) {
 		rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, cifs_sb->local_nls);
 		goto out;
 	}

fs/cifs/dfs.h

@@ -43,8 +43,12 @@ static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
 	size_t len;
 	char *s;
 
-	if (unlikely(!server->origin_fullpath))
+	spin_lock(&server->srv_lock);
+	if (unlikely(!server->origin_fullpath)) {
+		spin_unlock(&server->srv_lock);
 		return ERR_PTR(-EREMOTE);
+	}
+	spin_unlock(&server->srv_lock);
 
 	s = dentry_path_raw(dentry, page, PATH_MAX);
 	if (IS_ERR(s))
@@ -53,13 +57,18 @@ static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
 	if (!s[1])
 		s++;
 
+	spin_lock(&server->srv_lock);
 	len = strlen(server->origin_fullpath);
-	if (s < (char *)page + len)
+	if (s < (char *)page + len) {
+		spin_unlock(&server->srv_lock);
 		return ERR_PTR(-ENAMETOOLONG);
+	}
 
 	s -= len;
 	memcpy(s, server->origin_fullpath, len);
+	spin_unlock(&server->srv_lock);
 	convert_delimiter(s, '/');
+
 	return s;
 }
 

fs/cifs/dfs_cache.c

@@ -20,12 +20,14 @@
 #include "cifs_unicode.h"
 #include "smb2glob.h"
 #include "dns_resolve.h"
+#include "dfs.h"
 
 #include "dfs_cache.h"
 
-#define CACHE_HTABLE_SIZE 32
-#define CACHE_MAX_ENTRIES 64
-#define CACHE_MIN_TTL 120 /* 2 minutes */
+#define CACHE_HTABLE_SIZE	32
+#define CACHE_MAX_ENTRIES	64
+#define CACHE_MIN_TTL		120 /* 2 minutes */
+#define CACHE_DEFAULT_TTL	300 /* 5 minutes */
 
 #define IS_DFS_INTERLINK(v) (((v) & DFSREF_REFERRAL_SERVER) && !((v) & DFSREF_STORAGE_SERVER))
 
@@ -50,10 +52,9 @@ struct cache_entry {
 };
 
 static struct kmem_cache *cache_slab __read_mostly;
-static struct workqueue_struct *dfscache_wq __read_mostly;
+struct workqueue_struct *dfscache_wq;
 
-static int cache_ttl;
-static DEFINE_SPINLOCK(cache_ttl_lock);
+atomic_t dfs_cache_ttl;
 
 static struct nls_table *cache_cp;
 
@@ -65,10 +66,6 @@ static atomic_t cache_count;
 static struct hlist_head cache_htable[CACHE_HTABLE_SIZE];
 static DECLARE_RWSEM(htable_rw_lock);
 
-static void refresh_cache_worker(struct work_struct *work);
-
-static DECLARE_DELAYED_WORK(refresh_task, refresh_cache_worker);
-
 /**
  * dfs_cache_canonical_path - get a canonical DFS path
  *
@@ -290,7 +287,9 @@ int dfs_cache_init(void)
 	int rc;
 	int i;
 
-	dfscache_wq = alloc_workqueue("cifs-dfscache", WQ_FREEZABLE | WQ_UNBOUND, 1);
+	dfscache_wq = alloc_workqueue("cifs-dfscache",
+				      WQ_UNBOUND|WQ_FREEZABLE|WQ_MEM_RECLAIM,
+				      0);
 	if (!dfscache_wq)
 		return -ENOMEM;
 
@@ -306,6 +305,7 @@ int dfs_cache_init(void)
 		INIT_HLIST_HEAD(&cache_htable[i]);
 
 	atomic_set(&cache_count, 0);
+	atomic_set(&dfs_cache_ttl, CACHE_DEFAULT_TTL);
 	cache_cp = load_nls("utf8");
 	if (!cache_cp)
 		cache_cp = load_nls_default();
@@ -480,6 +480,7 @@ static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs,
 	int rc;
 	struct cache_entry *ce;
 	unsigned int hash;
+	int ttl;
 
 	WARN_ON(!rwsem_is_locked(&htable_rw_lock));
 
@@ -496,15 +497,8 @@ static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs,
 	if (IS_ERR(ce))
 		return ce;
 
-	spin_lock(&cache_ttl_lock);
-	if (!cache_ttl) {
-		cache_ttl = ce->ttl;
-		queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
-	} else {
-		cache_ttl = min_t(int, cache_ttl, ce->ttl);
-		mod_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
-	}
-	spin_unlock(&cache_ttl_lock);
+	ttl = min_t(int, atomic_read(&dfs_cache_ttl), ce->ttl);
+	atomic_set(&dfs_cache_ttl, ttl);
 
 	hlist_add_head(&ce->hlist, &cache_htable[hash]);
 	dump_ce(ce);
@@ -616,7 +610,6 @@ static struct cache_entry *lookup_cache_entry(const char *path)
  */
 void dfs_cache_destroy(void)
 {
-	cancel_delayed_work_sync(&refresh_task);
 	unload_nls(cache_cp);
 	flush_cache_ents();
 	kmem_cache_destroy(cache_slab);
@@ -1142,6 +1135,7 @@ static bool target_share_equal(struct TCP_Server_Info *server, const char *s1, c
  * target shares in @refs.
  */
 static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server,
+					 const char *path,
 					 struct dfs_cache_tgt_list *old_tl,
 					 struct dfs_cache_tgt_list *new_tl)
 {
@@ -1153,8 +1147,10 @@ static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server,
 		     nit = dfs_cache_get_next_tgt(new_tl, nit)) {
 			if (target_share_equal(server,
 					       dfs_cache_get_tgt_name(oit),
-					       dfs_cache_get_tgt_name(nit)))
+					       dfs_cache_get_tgt_name(nit))) {
+				dfs_cache_noreq_update_tgthint(path, nit);
 				return;
+			}
 		}
 	}
 
@@ -1162,13 +1158,28 @@ static void mark_for_reconnect_if_needed(struct TCP_Server_Info *server,
 	cifs_signal_cifsd_for_reconnect(server, true);
 }
 
+static bool is_ses_good(struct cifs_ses *ses)
+{
+	struct TCP_Server_Info *server = ses->server;
+	struct cifs_tcon *tcon = ses->tcon_ipc;
+	bool ret;
+
+	spin_lock(&ses->ses_lock);
+	spin_lock(&ses->chan_lock);
+	ret = !cifs_chan_needs_reconnect(ses, server) &&
+		ses->ses_status == SES_GOOD &&
+		!tcon->need_reconnect;
+	spin_unlock(&ses->chan_lock);
+	spin_unlock(&ses->ses_lock);
+	return ret;
+}
+
 /* Refresh dfs referral of tcon and mark it for reconnect if needed */
-static int __refresh_tcon(const char *path, struct cifs_tcon *tcon, bool force_refresh)
+static int __refresh_tcon(const char *path, struct cifs_ses *ses, bool force_refresh)
 {
 	struct dfs_cache_tgt_list old_tl = DFS_CACHE_TGT_LIST_INIT(old_tl);
 	struct dfs_cache_tgt_list new_tl = DFS_CACHE_TGT_LIST_INIT(new_tl);
-	struct cifs_ses *ses = CIFS_DFS_ROOT_SES(tcon->ses);
-	struct cifs_tcon *ipc = ses->tcon_ipc;
+	struct TCP_Server_Info *server = ses->server;
 	bool needs_refresh = false;
 	struct cache_entry *ce;
 	unsigned int xid;
@@ -1190,20 +1201,19 @@ static int __refresh_tcon(const char *path, struct cifs_tcon *tcon, bool force_r
 		goto out;
 	}
 
-	spin_lock(&ipc->tc_lock);
-	if (ipc->status != TID_GOOD) {
-		spin_unlock(&ipc->tc_lock);
-		cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n", __func__);
+	ses = CIFS_DFS_ROOT_SES(ses);
+	if (!is_ses_good(ses)) {
+		cifs_dbg(FYI, "%s: skip cache refresh due to disconnected ipc\n",
+			 __func__);
 		goto out;
 	}
-	spin_unlock(&ipc->tc_lock);
 
 	ce = cache_refresh_path(xid, ses, path, true);
 	if (!IS_ERR(ce)) {
 		rc = get_targets(ce, &new_tl);
 		up_read(&htable_rw_lock);
 		cifs_dbg(FYI, "%s: get_targets: %d\n", __func__, rc);
-		mark_for_reconnect_if_needed(tcon->ses->server, &old_tl, &new_tl);
+		mark_for_reconnect_if_needed(server, path, &old_tl, &new_tl);
 	}
 
 out:
@@ -1216,10 +1226,11 @@ static int __refresh_tcon(const char *path, struct cifs_tcon *tcon, bool force_r
 static int refresh_tcon(struct cifs_tcon *tcon, bool force_refresh)
 {
 	struct TCP_Server_Info *server = tcon->ses->server;
+	struct cifs_ses *ses = tcon->ses;
 
 	mutex_lock(&server->refpath_lock);
 	if (server->leaf_fullpath)
-		__refresh_tcon(server->leaf_fullpath + 1, tcon, force_refresh);
+		__refresh_tcon(server->leaf_fullpath + 1, ses, force_refresh);
 	mutex_unlock(&server->refpath_lock);
 	return 0;
 }
@@ -1263,56 +1274,32 @@ int dfs_cache_remount_fs(struct cifs_sb_info *cifs_sb)
 	return refresh_tcon(tcon, true);
 }
 
-/*
- * Worker that will refresh DFS cache from all active mounts based on lowest TTL value
- * from a DFS referral.
- */
-static void refresh_cache_worker(struct work_struct *work)
+/* Refresh all DFS referrals related to DFS tcon */
+void dfs_cache_refresh(struct work_struct *work)
 {
 	struct TCP_Server_Info *server;
-	struct cifs_tcon *tcon, *ntcon;
-	struct list_head tcons;
+	struct dfs_root_ses *rses;
+	struct cifs_tcon *tcon;
 	struct cifs_ses *ses;
 
-	INIT_LIST_HEAD(&tcons);
-
-	spin_lock(&cifs_tcp_ses_lock);
-	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
-		if (!server->leaf_fullpath)
-			continue;
-
-		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
-			if (ses->tcon_ipc) {
-				ses->ses_count++;
-				list_add_tail(&ses->tcon_ipc->ulist, &tcons);
-			}
-			list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
-				if (!tcon->ipc) {
-					tcon->tc_count++;
-					list_add_tail(&tcon->ulist, &tcons);
-				}
-			}
-		}
-	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	tcon = container_of(work, struct cifs_tcon, dfs_cache_work.work);
+	ses = tcon->ses;
+	server = ses->server;
 
-	list_for_each_entry_safe(tcon, ntcon, &tcons, ulist) {
-		struct TCP_Server_Info *server = tcon->ses->server;
-
-		list_del_init(&tcon->ulist);
+	mutex_lock(&server->refpath_lock);
+	if (server->leaf_fullpath)
+		__refresh_tcon(server->leaf_fullpath + 1, ses, false);
+	mutex_unlock(&server->refpath_lock);
 
+	list_for_each_entry(rses, &tcon->dfs_ses_list, list) {
+		ses = rses->ses;
+		server = ses->server;
 		mutex_lock(&server->refpath_lock);
 		if (server->leaf_fullpath)
-			__refresh_tcon(server->leaf_fullpath + 1, tcon, false);
+			__refresh_tcon(server->leaf_fullpath + 1, ses, false);
 		mutex_unlock(&server->refpath_lock);
-
-		if (tcon->ipc)
-			cifs_put_smb_ses(tcon->ses);
-		else
-			cifs_put_tcon(tcon);
 	}
 
-	spin_lock(&cache_ttl_lock);
-	queue_delayed_work(dfscache_wq, &refresh_task, cache_ttl * HZ);
-	spin_unlock(&cache_ttl_lock);
+	queue_delayed_work(dfscache_wq, &tcon->dfs_cache_work,
+			   atomic_read(&dfs_cache_ttl) * HZ);
 }

fs/cifs/dfs_cache.h

@@ -13,6 +13,9 @@
 #include <linux/uuid.h>
 #include "cifsglob.h"
 
+extern struct workqueue_struct *dfscache_wq;
+extern atomic_t dfs_cache_ttl;
+
 #define DFS_CACHE_TGT_LIST_INIT(var) { .tl_numtgts = 0, .tl_list = LIST_HEAD_INIT((var).tl_list), }
 
 struct dfs_cache_tgt_list {
@@ -42,6 +45,7 @@ int dfs_cache_get_tgt_share(char *path, const struct dfs_cache_tgt_iterator *it,
 			    char **prefix);
 char *dfs_cache_canonical_path(const char *path, const struct nls_table *cp, int remap);
 int dfs_cache_remount_fs(struct cifs_sb_info *cifs_sb);
+void dfs_cache_refresh(struct work_struct *work);
 
 static inline struct dfs_cache_tgt_iterator *
 dfs_cache_get_next_tgt(struct dfs_cache_tgt_list *tl,
@@ -89,4 +93,9 @@ dfs_cache_get_nr_tgts(const struct dfs_cache_tgt_list *tl)
 	return tl ? tl->tl_numtgts : 0;
 }
 
+static inline int dfs_cache_get_ttl(void)
+{
+	return atomic_read(&dfs_cache_ttl);
+}
+
 #endif /* _CIFS_DFS_CACHE_H */

fs/cifs/ioctl.c

@@ -239,7 +239,7 @@ static int cifs_dump_full_key(struct cifs_tcon *tcon, struct smb3_full_key_debug
 					 * section, we need to make sure it won't be released
 					 * so increment its refcount
 					 */
-					ses->ses_count++;
+					cifs_smb_ses_inc_refcount(ses);
 					found = true;
 					goto search_end;
 				}

fs/cifs/sess.c

@@ -159,6 +159,7 @@ cifs_chan_is_iface_active(struct cifs_ses *ses,
 /* returns number of channels added */
 int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses)
 {
+	struct TCP_Server_Info *server = ses->server;
 	int old_chan_count, new_chan_count;
 	int left;
 	int rc = 0;
@@ -178,16 +179,16 @@ int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses)
 		return 0;
 	}
 
-	if (ses->server->dialect < SMB30_PROT_ID) {
+	if (server->dialect < SMB30_PROT_ID) {
 		spin_unlock(&ses->chan_lock);
 		cifs_dbg(VFS, "multichannel is not supported on this protocol version, use 3.0 or above\n");
 		return 0;
 	}
 
-	if (!(ses->server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
+	if (!(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
 		ses->chan_max = 1;
 		spin_unlock(&ses->chan_lock);
-		cifs_dbg(VFS, "server %s does not support multichannel\n", ses->server->hostname);
+		cifs_server_dbg(VFS, "no multichannel support\n");
 		return 0;
 	}
 	spin_unlock(&ses->chan_lock);

fs/cifs/smb2pdu.c

@@ -175,8 +175,17 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		}
 	}
 	spin_unlock(&tcon->tc_lock);
-	if ((!tcon->ses) || (tcon->ses->ses_status == SES_EXITING) ||
-	    (!tcon->ses->server) || !server)
+
+	ses = tcon->ses;
+	if (!ses)
+		return -EIO;
+	spin_lock(&ses->ses_lock);
+	if (ses->ses_status == SES_EXITING) {
+		spin_unlock(&ses->ses_lock);
+		return -EIO;
+	}
+	spin_unlock(&ses->ses_lock);
+	if (!ses->server || !server)
 		return -EIO;
 
 	spin_lock(&server->srv_lock);
@@ -204,8 +213,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	if (rc)
 		return rc;
 
-	ses = tcon->ses;
-
 	spin_lock(&ses->chan_lock);
 	if (!cifs_chan_needs_reconnect(ses, server) && !tcon->need_reconnect) {
 		spin_unlock(&ses->chan_lock);
@@ -3794,7 +3801,7 @@ void smb2_reconnect_server(struct work_struct *work)
 		if (ses->tcon_ipc && ses->tcon_ipc->need_reconnect) {
 			list_add_tail(&ses->tcon_ipc->rlist, &tmp_list);
 			tcon_selected = tcon_exist = true;
-			ses->ses_count++;
+			cifs_smb_ses_inc_refcount(ses);
 		}
 		/*
 		 * handle the case where channel needs to reconnect
@@ -3805,7 +3812,7 @@ void smb2_reconnect_server(struct work_struct *work)
 		if (!tcon_selected && cifs_chan_needs_reconnect(ses, server)) {
 			list_add_tail(&ses->rlist, &tmp_ses_list);
 			ses_exist = true;
-			ses->ses_count++;
+			cifs_smb_ses_inc_refcount(ses);
 		}
 		spin_unlock(&ses->chan_lock);
 	}
@@ -4130,7 +4137,7 @@ smb2_readv_callback(struct mid_q_entry *mid)
 	if (rdata->got_bytes) {
 		rqst.rq_iter	  = rdata->iter;
 		rqst.rq_iter_size = iov_iter_count(&rdata->iter);
-	};
+	}
 
 	WARN_ONCE(rdata->server != mid->server,
 		  "rdata server %p != mid server %p",

fs/ksmbd/smb2pdu.h

@@ -83,22 +83,6 @@ struct create_durable_reconn_v2_req {
 	__le32 Flags;
 } __packed;
 
-struct create_app_inst_id {
-	struct create_context ccontext;
-	__u8 Name[8];
-	__u8 Reserved[8];
-	__u8 AppInstanceId[16];
-} __packed;
-
-struct create_app_inst_id_vers {
-	struct create_context ccontext;
-	__u8 Name[8];
-	__u8 Reserved[2];
-	__u8 Padding[4];
-	__le64 AppInstanceVersionHigh;
-	__le64 AppInstanceVersionLow;
-} __packed;
-
 struct create_alloc_size_req {
 	struct create_context ccontext;
 	__u8   Name[8];

fs/smbfs_common/smb2pdu.h

@@ -1250,6 +1250,26 @@ struct create_disk_id_rsp {
 	__u8  Reserved[16];
 } __packed;
 
+/* See MS-SMB2 2.2.13.2.13 */
+struct create_app_inst_id {
+	struct create_context ccontext;
+	__u8 Name[16];
+	__le32 StructureSize; /* Must be 20 */
+	__u16 Reserved;
+	__u8 AppInstanceId[16];
+} __packed;
+
+/* See MS-SMB2 2.2.13.2.15 */
+struct create_app_inst_id_vers {
+	struct create_context ccontext;
+	__u8 Name[16];
+	__le32 StructureSize; /* Must be 24 */
+	__u16 Reserved;
+	__u32 Padding;
+	__le64 AppInstanceVersionHigh;
+	__le64 AppInstanceVersionLow;
+} __packed;
+
 /* See MS-SMB2 2.2.31 and 2.2.32 */
 struct smb2_ioctl_req {
 	struct smb2_hdr hdr;