NFS bugfixes for Linux 3.7

- Fix a bunch of deadlock situations:
   * State recovery can deadlock if we fail to release sequence ids before
     scheduling the recovery thread.
   * Calling deactivate_super() from an RPC workqueue thread can deadlock
     because of the call to rpc_shutdown_client.
 - Display the device name correctly in /proc/*/mounts
 - Fix a number of incorrect error return values:
   * When NFSv3 mounts fail due to a timeout.
   * On NFSv4.1 backchannel setup failure
   * On NFSv4 open access checks
 - pnfs_find_alloc_layout() must check the layout pointer for NULL
 - Fix a regression in the legacy DNS resolved
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Merge tag 'nfs-for-3.7-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client bugfixes from Trond Myklebust:

 - Fix a bunch of deadlock situations:
   * State recovery can deadlock if we fail to release sequence ids
     before scheduling the recovery thread.
   * Calling deactivate_super() from an RPC workqueue thread can
     deadlock because of the call to rpc_shutdown_client.

 - Display the device name correctly in /proc/*/mounts

 - Fix a number of incorrect error return values:
   * When NFSv3 mounts fail due to a timeout.
   * On NFSv4.1 backchannel setup failure
   * On NFSv4 open access checks

 - pnfs_find_alloc_layout() must check the layout pointer for NULL

 - Fix a regression in the legacy DNS resolved

* tag 'nfs-for-3.7-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS4: nfs4_opendata_access should return errno
  NFSv4: Initialise the NFSv4.1 slot table highest_used_slotid correctly
  SUNRPC: return proper errno from backchannel_rqst
  NFS: add nfs_sb_deactive_async to avoid deadlock
  nfs: Show original device name verbatim in /proc/*/mount{s,info}
  nfsv3: Make v3 mounts fail with ETIMEDOUTs instead EIO on mountd timeouts
  nfs: Check whether a layout pointer is NULL before free it
  NFS: fix bug in legacy DNS resolver.
  NFSv4: nfs4_locku_done must release the sequence id
  NFSv4.1: We must release the sequence id when we fail to get a session slot
  NFS: Wait for session recovery to finish before returning

fs/nfs/dns_resolve.c

@@ -217,7 +217,7 @@ static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
 {
 	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
 	struct nfs_dns_ent key, *item;
-	unsigned long ttl;
+	unsigned int ttl;
 	ssize_t len;
 	int ret = -EINVAL;
 
@@ -240,7 +240,8 @@ static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
 	key.namelen = len;
 	memset(&key.h, 0, sizeof(key.h));
 
-	ttl = get_expiry(&buf);
+	if (get_uint(&buf, &ttl) < 0)
+		goto out;
 	if (ttl == 0)
 		goto out;
 	key.h.expiry_time = ttl + seconds_since_boot();

fs/nfs/inode.c

@@ -685,7 +685,10 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)
 	if (ctx->cred != NULL)
 		put_rpccred(ctx->cred);
 	dput(ctx->dentry);
-	nfs_sb_deactive(sb);
+	if (is_sync)
+		nfs_sb_deactive(sb);
+	else
+		nfs_sb_deactive_async(sb);
 	kfree(ctx->mdsthreshold);
 	kfree(ctx);
 }

fs/nfs/internal.h

@@ -351,10 +351,12 @@ extern int __init register_nfs_fs(void);
 extern void __exit unregister_nfs_fs(void);
 extern void nfs_sb_active(struct super_block *sb);
 extern void nfs_sb_deactive(struct super_block *sb);
+extern void nfs_sb_deactive_async(struct super_block *sb);
 
 /* namespace.c */
+#define NFS_PATH_CANONICAL 1
 extern char *nfs_path(char **p, struct dentry *dentry,
-		      char *buffer, ssize_t buflen);
+		      char *buffer, ssize_t buflen, unsigned flags);
 extern struct vfsmount *nfs_d_automount(struct path *path);
 struct vfsmount *nfs_submount(struct nfs_server *, struct dentry *,
 			      struct nfs_fh *, struct nfs_fattr *);
@@ -498,7 +500,7 @@ static inline char *nfs_devname(struct dentry *dentry,
 				char *buffer, ssize_t buflen)
 {
 	char *dummy;
-	return nfs_path(&dummy, dentry, buffer, buflen);
+	return nfs_path(&dummy, dentry, buffer, buflen, NFS_PATH_CANONICAL);
 }
 
 /*

fs/nfs/mount_clnt.c

@@ -181,7 +181,7 @@ int nfs_mount(struct nfs_mount_request *info)
 	else
 		msg.rpc_proc = &mnt_clnt->cl_procinfo[MOUNTPROC_MNT];
 
-	status = rpc_call_sync(mnt_clnt, &msg, 0);
+	status = rpc_call_sync(mnt_clnt, &msg, RPC_TASK_SOFT|RPC_TASK_TIMEOUT);
 	rpc_shutdown_client(mnt_clnt);
 
 	if (status < 0)

fs/nfs/namespace.c

@@ -33,6 +33,7 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
  * @dentry - pointer to dentry
  * @buffer - result buffer
  * @buflen - length of buffer
+ * @flags - options (see below)
  *
  * Helper function for constructing the server pathname
  * by arbitrary hashed dentry.
@@ -40,8 +41,14 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
  * This is mainly for use in figuring out the path on the
  * server side when automounting on top of an existing partition
  * and in generating /proc/mounts and friends.
+ *
+ * Supported flags:
+ * NFS_PATH_CANONICAL: ensure there is exactly one slash after
+ *		       the original device (export) name
+ *		       (if unset, the original name is returned verbatim)
  */
-char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen)
+char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
+	       unsigned flags)
 {
 	char *end;
 	int namelen;
@@ -74,7 +81,7 @@ rename_retry:
 		rcu_read_unlock();
 		goto rename_retry;
 	}
-	if (*end != '/') {
+	if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
 		if (--buflen < 0) {
 			spin_unlock(&dentry->d_lock);
 			rcu_read_unlock();
@@ -91,9 +98,11 @@ rename_retry:
 		return end;
 	}
 	namelen = strlen(base);
-	/* Strip off excess slashes in base string */
-	while (namelen > 0 && base[namelen - 1] == '/')
-		namelen--;
+	if (flags & NFS_PATH_CANONICAL) {
+		/* Strip off excess slashes in base string */
+		while (namelen > 0 && base[namelen - 1] == '/')
+			namelen--;
+	}
 	buflen -= namelen;
 	if (buflen < 0) {
 		spin_unlock(&dentry->d_lock);

fs/nfs/nfs4namespace.c

@@ -81,7 +81,8 @@ static char *nfs_path_component(const char *nfspath, const char *end)
 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
 {
 	char *limit;
-	char *path = nfs_path(&limit, dentry, buffer, buflen);
+	char *path = nfs_path(&limit, dentry, buffer, buflen,
+			      NFS_PATH_CANONICAL);
 	if (!IS_ERR(path)) {
 		char *path_component = nfs_path_component(path, limit);
 		if (path_component)

fs/nfs/nfs4proc.c

@@ -339,8 +339,7 @@ static int nfs4_handle_exception(struct nfs_server *server, int errorcode, struc
 			dprintk("%s ERROR: %d Reset session\n", __func__,
 				errorcode);
 			nfs4_schedule_session_recovery(clp->cl_session, errorcode);
-			exception->retry = 1;
-			break;
+			goto wait_on_recovery;
 #endif /* defined(CONFIG_NFS_V4_1) */
 		case -NFS4ERR_FILE_OPEN:
 			if (exception->timeout > HZ) {
@@ -1572,9 +1571,11 @@ static void nfs4_open_prepare(struct rpc_task *task, void *calldata)
 	data->timestamp = jiffies;
 	if (nfs4_setup_sequence(data->o_arg.server,
 				&data->o_arg.seq_args,
-				&data->o_res.seq_res, task))
-		return;
-	rpc_call_start(task);
+				&data->o_res.seq_res,
+				task) != 0)
+		nfs_release_seqid(data->o_arg.seqid);
+	else
+		rpc_call_start(task);
 	return;
 unlock_no_action:
 	rcu_read_unlock();
@@ -1748,7 +1749,7 @@ static int nfs4_opendata_access(struct rpc_cred *cred,
 
 	/* even though OPEN succeeded, access is denied. Close the file */
 	nfs4_close_state(state, fmode);
-	return -NFS4ERR_ACCESS;
+	return -EACCES;
 }
 
 /*
@@ -2196,7 +2197,7 @@ static void nfs4_free_closedata(void *data)
 	nfs4_put_open_state(calldata->state);
 	nfs_free_seqid(calldata->arg.seqid);
 	nfs4_put_state_owner(sp);
-	nfs_sb_deactive(sb);
+	nfs_sb_deactive_async(sb);
 	kfree(calldata);
 }
 
@@ -2296,9 +2297,10 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
 	if (nfs4_setup_sequence(NFS_SERVER(inode),
 				&calldata->arg.seq_args,
 				&calldata->res.seq_res,
-				task))
-		goto out;
-	rpc_call_start(task);
+				task) != 0)
+		nfs_release_seqid(calldata->arg.seqid);
+	else
+		rpc_call_start(task);
 out:
 	dprintk("%s: done!\n", __func__);
 }
@@ -4529,6 +4531,7 @@ static void nfs4_locku_done(struct rpc_task *task, void *data)
 			if (nfs4_async_handle_error(task, calldata->server, NULL) == -EAGAIN)
 				rpc_restart_call_prepare(task);
 	}
+	nfs_release_seqid(calldata->arg.seqid);
 }
 
 static void nfs4_locku_prepare(struct rpc_task *task, void *data)
@@ -4545,9 +4548,11 @@ static void nfs4_locku_prepare(struct rpc_task *task, void *data)
 	calldata->timestamp = jiffies;
 	if (nfs4_setup_sequence(calldata->server,
 				&calldata->arg.seq_args,
-				&calldata->res.seq_res, task))
-		return;
-	rpc_call_start(task);
+				&calldata->res.seq_res,
+				task) != 0)
+		nfs_release_seqid(calldata->arg.seqid);
+	else
+		rpc_call_start(task);
 }
 
 static const struct rpc_call_ops nfs4_locku_ops = {
@@ -4692,7 +4697,7 @@ static void nfs4_lock_prepare(struct rpc_task *task, void *calldata)
 	/* Do we need to do an open_to_lock_owner? */
 	if (!(data->arg.lock_seqid->sequence->flags & NFS_SEQID_CONFIRMED)) {
 		if (nfs_wait_on_sequence(data->arg.open_seqid, task) != 0)
-			return;
+			goto out_release_lock_seqid;
 		data->arg.open_stateid = &state->stateid;
 		data->arg.new_lock_owner = 1;
 		data->res.open_seqid = data->arg.open_seqid;
@@ -4701,10 +4706,15 @@ static void nfs4_lock_prepare(struct rpc_task *task, void *calldata)
 	data->timestamp = jiffies;
 	if (nfs4_setup_sequence(data->server,
 				&data->arg.seq_args,
-				&data->res.seq_res, task))
+				&data->res.seq_res,
+				task) == 0) {
+		rpc_call_start(task);
 		return;
-	rpc_call_start(task);
-	dprintk("%s: done!, ret = %d\n", __func__, data->rpc_status);
+	}
+	nfs_release_seqid(data->arg.open_seqid);
+out_release_lock_seqid:
+	nfs_release_seqid(data->arg.lock_seqid);
+	dprintk("%s: done!, ret = %d\n", __func__, task->tk_status);
 }
 
 static void nfs4_recover_lock_prepare(struct rpc_task *task, void *calldata)
@@ -5667,7 +5677,7 @@ static void nfs4_add_and_init_slots(struct nfs4_slot_table *tbl,
 		tbl->slots = new;
 		tbl->max_slots = max_slots;
 	}
-	tbl->highest_used_slotid = -1;	/* no slot is currently used */
+	tbl->highest_used_slotid = NFS4_NO_SLOT;
 	for (i = 0; i < tbl->max_slots; i++)
 		tbl->slots[i].seq_nr = ivalue;
 	spin_unlock(&tbl->slot_tbl_lock);

fs/nfs/pnfs.c

@@ -925,8 +925,8 @@ pnfs_find_alloc_layout(struct inode *ino,
 	if (likely(nfsi->layout == NULL)) {	/* Won the race? */
 		nfsi->layout = new;
 		return new;
-	}
-	pnfs_free_layout_hdr(new);
+	} else if (new != NULL)
+		pnfs_free_layout_hdr(new);
 out_existing:
 	pnfs_get_layout_hdr(nfsi->layout);
 	return nfsi->layout;

fs/nfs/super.c

@@ -54,6 +54,7 @@
 #include <linux/parser.h>
 #include <linux/nsproxy.h>
 #include <linux/rcupdate.h>
+#include <linux/kthread.h>
 
 #include <asm/uaccess.h>
 
@@ -415,6 +416,54 @@ void nfs_sb_deactive(struct super_block *sb)
 }
 EXPORT_SYMBOL_GPL(nfs_sb_deactive);
 
+static int nfs_deactivate_super_async_work(void *ptr)
+{
+	struct super_block *sb = ptr;
+
+	deactivate_super(sb);
+	module_put_and_exit(0);
+	return 0;
+}
+
+/*
+ * same effect as deactivate_super, but will do final unmount in kthread
+ * context
+ */
+static void nfs_deactivate_super_async(struct super_block *sb)
+{
+	struct task_struct *task;
+	char buf[INET6_ADDRSTRLEN + 1];
+	struct nfs_server *server = NFS_SB(sb);
+	struct nfs_client *clp = server->nfs_client;
+
+	if (!atomic_add_unless(&sb->s_active, -1, 1)) {
+		rcu_read_lock();
+		snprintf(buf, sizeof(buf),
+			rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+		rcu_read_unlock();
+
+		__module_get(THIS_MODULE);
+		task = kthread_run(nfs_deactivate_super_async_work, sb,
+				"%s-deactivate-super", buf);
+		if (IS_ERR(task)) {
+			pr_err("%s: kthread_run: %ld\n",
+				__func__, PTR_ERR(task));
+			/* make synchronous call and hope for the best */
+			deactivate_super(sb);
+			module_put(THIS_MODULE);
+		}
+	}
+}
+
+void nfs_sb_deactive_async(struct super_block *sb)
+{
+	struct nfs_server *server = NFS_SB(sb);
+
+	if (atomic_dec_and_test(&server->active))
+		nfs_deactivate_super_async(sb);
+}
+EXPORT_SYMBOL_GPL(nfs_sb_deactive_async);
+
 /*
  * Deliver file system statistics to userspace
  */
@@ -771,7 +820,7 @@ int nfs_show_devname(struct seq_file *m, struct dentry *root)
 	int err = 0;
 	if (!page)
 		return -ENOMEM;
-	devname = nfs_path(&dummy, root, page, PAGE_SIZE);
+	devname = nfs_path(&dummy, root, page, PAGE_SIZE, 0);
 	if (IS_ERR(devname))
 		err = PTR_ERR(devname);
 	else

fs/nfs/unlink.c

@@ -95,7 +95,7 @@ static void nfs_async_unlink_release(void *calldata)
 
 	nfs_dec_sillycount(data->dir);
 	nfs_free_unlinkdata(data);
-	nfs_sb_deactive(sb);
+	nfs_sb_deactive_async(sb);
 }
 
 static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)

net/sunrpc/backchannel_rqst.c

@@ -172,7 +172,7 @@ out_free:
 		xprt_free_allocation(req);
 
 	dprintk("RPC:       setup backchannel transport failed\n");
-	return -1;
+	return -ENOMEM;
 }
 EXPORT_SYMBOL_GPL(xprt_setup_backchannel);