NFS client bugfixes for Linux 3.8

- Fix a permissions problem when opening NFSv4 files that only have the
   exec bit set.
 - Fix a couple of typos in pNFS (inverted logic), and the mount parsing
   (missing pointer dereference).
 - Work around a series of deadlock issues due to workqueues using
   struct work_struct pointer address comparisons in the re-entrancy
   tests. Ensure that we don't free struct work_struct prematurely if
   our work function involves waiting for completion of other work
   items (e.g. by calling rpc_shutdown_client).
 - Revert the part of commit 168e4b3 that is causing unnecessary warnings
   to be issued in the nfsd callback code.
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Merge tag 'nfs-for-3.8-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client bugfixes from Trond Myklebust:

 - Fix a permissions problem when opening NFSv4 files that only have the
   exec bit set.

 - Fix a couple of typos in pNFS (inverted logic), and the mount parsing
   (missing pointer dereference).

 - Work around a series of deadlock issues due to workqueues using
   struct work_struct pointer address comparisons in the re-entrancy
   tests.  Ensure that we don't free struct work_struct prematurely if
   our work function involves waiting for completion of other work items
   (e.g. by calling rpc_shutdown_client).

 - Revert the part of commit 168e4b3 that is causing unnecessary
   warnings to be issued in the nfsd callback code.

* tag 'nfs-for-3.8-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  nfs: avoid dereferencing null pointer in initiate_bulk_draining
  SUNRPC: Partial revert of commit 168e4b39d1
  NFS: Ensure that we free the rpc_task after read and write cleanups are done
  SUNRPC: Ensure that we free the rpc_task after cleanups are done
  nfs: fix null checking in nfs_get_option_str()
  pnfs: Increase the refcount when LAYOUTGET fails the first time
  NFS: Fix access to suid/sgid executables

fs/nfs/callback_proc.c

@@ -206,7 +206,7 @@ static u32 initiate_bulk_draining(struct nfs_client *clp,
 
 		list_for_each_entry(lo, &server->layouts, plh_layouts) {
 			ino = igrab(lo->plh_inode);
-			if (ino)
+			if (!ino)
 				continue;
 			spin_lock(&ino->i_lock);
 			/* Is this layout in the process of being freed? */

fs/nfs/dir.c

@@ -2153,12 +2153,16 @@ static int nfs_open_permission_mask(int openflags)
 {
 	int mask = 0;
 
-	if ((openflags & O_ACCMODE) != O_WRONLY)
-		mask |= MAY_READ;
-	if ((openflags & O_ACCMODE) != O_RDONLY)
-		mask |= MAY_WRITE;
-	if (openflags & __FMODE_EXEC)
-		mask |= MAY_EXEC;
+	if (openflags & __FMODE_EXEC) {
+		/* ONLY check exec rights */
+		mask = MAY_EXEC;
+	} else {
+		if ((openflags & O_ACCMODE) != O_WRONLY)
+			mask |= MAY_READ;
+		if ((openflags & O_ACCMODE) != O_RDONLY)
+			mask |= MAY_WRITE;
+	}
+
 	return mask;
 }
 

fs/nfs/nfs4proc.c

@@ -1626,7 +1626,8 @@ static int _nfs4_recover_proc_open(struct nfs4_opendata *data)
 
 static int nfs4_opendata_access(struct rpc_cred *cred,
 				struct nfs4_opendata *opendata,
-				struct nfs4_state *state, fmode_t fmode)
+				struct nfs4_state *state, fmode_t fmode,
+				int openflags)
 {
 	struct nfs_access_entry cache;
 	u32 mask;
@@ -1638,11 +1639,14 @@ static int nfs4_opendata_access(struct rpc_cred *cred,
 
 	mask = 0;
 	/* don't check MAY_WRITE - a newly created file may not have
-	 * write mode bits, but POSIX allows the creating process to write */
-	if (fmode & FMODE_READ)
-		mask |= MAY_READ;
-	if (fmode & FMODE_EXEC)
-		mask |= MAY_EXEC;
+	 * write mode bits, but POSIX allows the creating process to write.
+	 * use openflags to check for exec, because fmode won't
+	 * always have FMODE_EXEC set when file open for exec. */
+	if (openflags & __FMODE_EXEC) {
+		/* ONLY check for exec rights */
+		mask = MAY_EXEC;
+	} else if (fmode & FMODE_READ)
+		mask = MAY_READ;
 
 	cache.cred = cred;
 	cache.jiffies = jiffies;
@@ -1896,7 +1900,7 @@ static int _nfs4_do_open(struct inode *dir,
 	if (server->caps & NFS_CAP_POSIX_LOCK)
 		set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);
 
-	status = nfs4_opendata_access(cred, opendata, state, fmode);
+	status = nfs4_opendata_access(cred, opendata, state, fmode, flags);
 	if (status != 0)
 		goto err_opendata_put;
 

fs/nfs/pnfs.c

@@ -254,7 +254,7 @@ static void
 pnfs_layout_set_fail_bit(struct pnfs_layout_hdr *lo, int fail_bit)
 {
 	lo->plh_retry_timestamp = jiffies;
-	if (test_and_set_bit(fail_bit, &lo->plh_flags))
+	if (!test_and_set_bit(fail_bit, &lo->plh_flags))
 		atomic_inc(&lo->plh_refcount);
 }
 

fs/nfs/read.c

@@ -91,12 +91,16 @@ void nfs_readdata_release(struct nfs_read_data *rdata)
 	put_nfs_open_context(rdata->args.context);
 	if (rdata->pages.pagevec != rdata->pages.page_array)
 		kfree(rdata->pages.pagevec);
-	if (rdata != &read_header->rpc_data)
-		kfree(rdata);
-	else
+	if (rdata == &read_header->rpc_data) {
 		rdata->header = NULL;
+		rdata = NULL;
+	}
 	if (atomic_dec_and_test(&hdr->refcnt))
 		hdr->completion_ops->completion(hdr);
+	/* Note: we only free the rpc_task after callbacks are done.
+	 * See the comment in rpc_free_task() for why
+	 */
+	kfree(rdata);
 }
 EXPORT_SYMBOL_GPL(nfs_readdata_release);
 

fs/nfs/super.c

@@ -1152,7 +1152,7 @@ static int nfs_get_option_str(substring_t args[], char **option)
 {
 	kfree(*option);
 	*option = match_strdup(args);
-	return !option;
+	return !*option;
 }
 
 static int nfs_get_option_ul(substring_t args[], unsigned long *option)

fs/nfs/write.c

@@ -126,12 +126,16 @@ void nfs_writedata_release(struct nfs_write_data *wdata)
 	put_nfs_open_context(wdata->args.context);
 	if (wdata->pages.pagevec != wdata->pages.page_array)
 		kfree(wdata->pages.pagevec);
-	if (wdata != &write_header->rpc_data)
-		kfree(wdata);
-	else
+	if (wdata == &write_header->rpc_data) {
 		wdata->header = NULL;
+		wdata = NULL;
+	}
 	if (atomic_dec_and_test(&hdr->refcnt))
 		hdr->completion_ops->completion(hdr);
+	/* Note: we only free the rpc_task after callbacks are done.
+	 * See the comment in rpc_free_task() for why
+	 */
+	kfree(wdata);
 }
 EXPORT_SYMBOL_GPL(nfs_writedata_release);
 

net/sunrpc/clnt.c

@@ -610,11 +610,6 @@ EXPORT_SYMBOL_GPL(rpc_killall_tasks);
  */
 void rpc_shutdown_client(struct rpc_clnt *clnt)
 {
-	/*
-	 * To avoid deadlock, never call rpc_shutdown_client from a
-	 * workqueue context!
-	 */
-	WARN_ON_ONCE(current->flags & PF_WQ_WORKER);
 	might_sleep();
 
 	dprintk_rcu("RPC:       shutting down %s client for %s\n",

net/sunrpc/sched.c

@@ -934,16 +934,35 @@ struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
 	return task;
 }
 
+/*
+ * rpc_free_task - release rpc task and perform cleanups
+ *
+ * Note that we free up the rpc_task _after_ rpc_release_calldata()
+ * in order to work around a workqueue dependency issue.
+ *
+ * Tejun Heo states:
+ * "Workqueue currently considers two work items to be the same if they're
+ * on the same address and won't execute them concurrently - ie. it
+ * makes a work item which is queued again while being executed wait
+ * for the previous execution to complete.
+ *
+ * If a work function frees the work item, and then waits for an event
+ * which should be performed by another work item and *that* work item
+ * recycles the freed work item, it can create a false dependency loop.
+ * There really is no reliable way to detect this short of verifying
+ * every memory free."
+ *
+ */
 static void rpc_free_task(struct rpc_task *task)
 {
-	const struct rpc_call_ops *tk_ops = task->tk_ops;
-	void *calldata = task->tk_calldata;
+	unsigned short tk_flags = task->tk_flags;
 
-	if (task->tk_flags & RPC_TASK_DYNAMIC) {
+	rpc_release_calldata(task->tk_ops, task->tk_calldata);
+
+	if (tk_flags & RPC_TASK_DYNAMIC) {
 		dprintk("RPC: %5u freeing task\n", task->tk_pid);
 		mempool_free(task, rpc_task_mempool);
 	}
-	rpc_release_calldata(tk_ops, calldata);
 }
 
 static void rpc_async_release(struct work_struct *work)