6 files changed, 42 insertions, 29 deletions
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 90f292b..404c19c 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -354,6 +354,15 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
 		file->f_path.dentry->d_name.name,
 		mapping->host->i_ino, len, (long long) pos);
 
+	/*
+	 * Prevent starvation issues if someone is doing a consistency
+	 * sync-to-disk
+	 */
+	ret = wait_on_bit(&NFS_I(mapping->host)->flags, NFS_INO_FLUSHING,
+			nfs_wait_bit_killable, TASK_KILLABLE);
+	if (ret)
+		return ret;
+
 	page = grab_cache_page_write_begin(mapping, index, flags);
 	if (!page)
 		return -ENOMEM;
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 00f116c..c40adc5 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -66,6 +66,18 @@ nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
 }
 
 /**
+ * nfs_wait_bit_killable - helper for functions that are sleeping on bit locks
+ * @word: long word containing the bit lock
+ */
+int nfs_wait_bit_killable(void *word)
+{
+	if (fatal_signal_pending(current))
+		return -ERESTARTSYS;
+	schedule();
+	return 0;
+}
+
+/**
  * nfs_compat_user_ino64 - returns the user-visible inode number
  * @fileid: 64-bit fileid
  *
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 340ede8..a55e69a 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -165,6 +165,7 @@ extern void nfs_clear_inode(struct inode *);
 extern void nfs4_clear_inode(struct inode *);
 #endif
 void nfs_zap_acl_cache(struct inode *inode);
+extern int nfs_wait_bit_killable(void *word);
 
 /* super.c */
 void nfs_parse_ip_address(char *, size_t, struct sockaddr *, size_t *);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 101f5f4..95f171e 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -193,14 +193,6 @@ static void nfs4_setup_readdir(u64 cookie, __be32 *verifier, struct dentry *dent
 	kunmap_atomic(start, KM_USER0);
 }
 
-static int nfs4_wait_bit_killable(void *word)
-{
-	if (fatal_signal_pending(current))
-		return -ERESTARTSYS;
-	schedule();
-	return 0;
-}
-
 static int nfs4_wait_clnt_recover(struct nfs_client *clp)
 {
 	int res;
@@ -208,7 +200,7 @@ static int nfs4_wait_clnt_recover(struct nfs_client *clp)
 	might_sleep();
 
 	res = wait_on_bit(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING,
-			nfs4_wait_bit_killable, TASK_KILLABLE);
+			nfs_wait_bit_killable, TASK_KILLABLE);
 	return res;
 }
 
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 7f07920..e297593 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -176,17 +176,6 @@ void nfs_release_request(struct nfs_page *req)
 	kref_put(&req->wb_kref, nfs_free_request);
 }
 
-static int nfs_wait_bit_killable(void *word)
-{
-	int ret = 0;
-
-	if (fatal_signal_pending(current))
-		ret = -ERESTARTSYS;
-	else
-		schedule();
-	return ret;
-}
-
 /**
  * nfs_wait_on_request - Wait for a request to complete.
  * @req: request to wait upon.
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 1a99993..36fd35e 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -313,19 +313,34 @@ static int nfs_writepages_callback(struct page *page, struct writeback_control *
 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
 	struct inode *inode = mapping->host;
+	unsigned long *bitlock = &NFS_I(inode)->flags;
 	struct nfs_pageio_descriptor pgio;
 	int err;
 
+	/* Stop dirtying of new pages while we sync */
+	err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
+			nfs_wait_bit_killable, TASK_KILLABLE);
+	if (err)
+		goto out_err;
+
 	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 
 	nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
 	err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 	nfs_pageio_complete(&pgio);
+
+	clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
+	smp_mb__after_clear_bit();
+	wake_up_bit(bitlock, NFS_INO_FLUSHING);
+
 	if (err < 0)
-		return err;
-	if (pgio.pg_error < 0)
-		return pgio.pg_error;
+		goto out_err;
+	err = pgio.pg_error;
+	if (err < 0)
+		goto out_err;
 	return 0;
+out_err:
+	return err;
 }
 
 /*
@@ -1432,18 +1447,13 @@ static int nfs_write_mapping(struct address_space *mapping, int how)
 {
 	struct writeback_control wbc = {
 		.bdi = mapping->backing_dev_info,
-		.sync_mode = WB_SYNC_NONE,
+		.sync_mode = WB_SYNC_ALL,
 		.nr_to_write = LONG_MAX,
 		.range_start = 0,
 		.range_end = LLONG_MAX,
 		.for_writepages = 1,
 	};
-	int ret;
 
-	ret = __nfs_write_mapping(mapping, &wbc, how);
-	if (ret < 0)
-		return ret;
-	wbc.sync_mode = WB_SYNC_ALL;
 	return __nfs_write_mapping(mapping, &wbc, how);
 }