From 407d9efbc638a64f2c9857a6489807bbf02f56f3 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 24 May 2011 00:23:34 +0200
Subject: [PATCH] --- yaml --- r: 251682 b: refs/heads/master c:
 24da4fab5a617ecbf0f0c64e7ba7703383faa411 h: refs/heads/master v: v3

---
 [refs]                            |  2 +-
 trunk/fs/buffer.c                 | 37 +++++++++++++++++--------------
 trunk/include/linux/buffer_head.h | 14 ++++++++++++
 3 files changed, 35 insertions(+), 18 deletions(-)

diff --git a/[refs] b/[refs]
index 0f1abfda4cfb..cef91a9d3196 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7c6e984dfca8ff5b04d359a59b24f39a691b87d3
+refs/heads/master: 24da4fab5a617ecbf0f0c64e7ba7703383faa411
diff --git a/trunk/fs/buffer.c b/trunk/fs/buffer.c
index a08bb8e61c6f..f6ad8f9b8fa5 100644
--- a/trunk/fs/buffer.c
+++ b/trunk/fs/buffer.c
@@ -2332,23 +2332,22 @@ EXPORT_SYMBOL(block_commit_write);
  * beyond EOF, then the page is guaranteed safe against truncation until we
  * unlock the page.
  */
-int
-block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
-		   get_block_t get_block)
+int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+			 get_block_t get_block)
 {
 	struct page *page = vmf->page;
 	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
 	unsigned long end;
 	loff_t size;
-	int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
+	int ret;
 
 	lock_page(page);
 	size = i_size_read(inode);
 	if ((page->mapping != inode->i_mapping) ||
 	    (page_offset(page) > size)) {
-		/* page got truncated out from underneath us */
-		unlock_page(page);
-		goto out;
+		/* We overload EFAULT to mean page got truncated */
+		ret = -EFAULT;
+		goto out_unlock;
 	}
 
 	/* page is wholly or partially inside EOF */
@@ -2361,18 +2360,22 @@ block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
 	if (!ret)
 		ret = block_commit_write(page, 0, end);
 
-	if (unlikely(ret)) {
-		unlock_page(page);
-		if (ret == -ENOMEM)
-			ret = VM_FAULT_OOM;
-		else /* -ENOSPC, -EIO, etc */
-			ret = VM_FAULT_SIGBUS;
-	} else
-		ret = VM_FAULT_LOCKED;
-
-out:
+	if (unlikely(ret < 0))
+		goto out_unlock;
+	return 0;
+out_unlock:
+	unlock_page(page);
 	return ret;
 }
+EXPORT_SYMBOL(__block_page_mkwrite);
+
+int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+		   get_block_t get_block)
+{
+	int ret = __block_page_mkwrite(vma, vmf, get_block);
+
+	return block_page_mkwrite_return(ret);
+}
 EXPORT_SYMBOL(block_page_mkwrite);
 
 /*
diff --git a/trunk/include/linux/buffer_head.h b/trunk/include/linux/buffer_head.h
index f5df23561b96..2bf6a9136a94 100644
--- a/trunk/include/linux/buffer_head.h
+++ b/trunk/include/linux/buffer_head.h
@@ -217,8 +217,22 @@ int cont_write_begin(struct file *, struct address_space *, loff_t,
 			get_block_t *, loff_t *);
 int generic_cont_expand_simple(struct inode *inode, loff_t size);
 int block_commit_write(struct page *page, unsigned from, unsigned to);
+int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+				get_block_t get_block);
 int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
 				get_block_t get_block);
+/* Convert errno to return value from ->page_mkwrite() call */
+static inline int block_page_mkwrite_return(int err)
+{
+	if (err == 0)
+		return VM_FAULT_LOCKED;
+	if (err == -EFAULT)
+		return VM_FAULT_NOPAGE;
+	if (err == -ENOMEM)
+		return VM_FAULT_OOM;
+	/* -ENOSPC, -EDQUOT, -EIO ... */
+	return VM_FAULT_SIGBUS;
+}
 sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 int nobh_write_begin(struct address_space *, loff_t, unsigned, unsigned,