fs: kill block_prepare_write

__block_write_begin and block_prepare_write are identical except for slightly
different calling conventions.  Convert all callers to the __block_write_begin
calling conventions and drop block_prepare_write.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index caa7583..4dcb880 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -22,8 +22,6 @@
 
 int reiserfs_commit_write(struct file *f, struct page *page,
 			  unsigned from, unsigned to);
-int reiserfs_prepare_write(struct file *f, struct page *page,
-			   unsigned from, unsigned to);
 
 void reiserfs_evict_inode(struct inode *inode)
 {
@@ -165,7 +163,7 @@
 ** but tail is still sitting in a direct item, and we can't write to
 ** it.  So, look through this page, and check all the mapped buffers
 ** to make sure they have valid block numbers.  Any that don't need
-** to be unmapped, so that block_prepare_write will correctly call
+** to be unmapped, so that __block_write_begin will correctly call
 ** reiserfs_get_block to convert the tail into an unformatted node
 */
 static inline void fix_tail_page_for_writing(struct page *page)
@@ -439,13 +437,13 @@
 }
 
 /* special version of get_block that is only used by grab_tail_page right
-** now.  It is sent to block_prepare_write, and when you try to get a
+** now.  It is sent to __block_write_begin, and when you try to get a
 ** block past the end of the file (or a block from a hole) it returns
-** -ENOENT instead of a valid buffer.  block_prepare_write expects to
+** -ENOENT instead of a valid buffer.  __block_write_begin expects to
 ** be able to do i/o on the buffers returned, unless an error value
 ** is also returned.
 **
-** So, this allows block_prepare_write to be used for reading a single block
+** So, this allows __block_write_begin to be used for reading a single block
 ** in a page.  Where it does not produce a valid page for holes, or past the
 ** end of the file.  This turns out to be exactly what we need for reading
 ** tails for conversion.
@@ -558,11 +556,12 @@
 	 **
 	 ** We must fix the tail page for writing because it might have buffers
 	 ** that are mapped, but have a block number of 0.  This indicates tail
-	 ** data that has been read directly into the page, and block_prepare_write
-	 ** won't trigger a get_block in this case.
+	 ** data that has been read directly into the page, and
+	 ** __block_write_begin won't trigger a get_block in this case.
 	 */
 	fix_tail_page_for_writing(tail_page);
-	retval = reiserfs_prepare_write(NULL, tail_page, tail_start, tail_end);
+	retval = __reiserfs_write_begin(tail_page, tail_start,
+				      tail_end - tail_start);
 	if (retval)
 		goto unlock;
 
@@ -2033,7 +2032,7 @@
 	/* start within the page of the last block in the file */
 	start = (offset / blocksize) * blocksize;
 
-	error = block_prepare_write(page, start, offset,
+	error = __block_write_begin(page, start, offset - start,
 				    reiserfs_get_block_create_0);
 	if (error)
 		goto unlock;
@@ -2628,8 +2627,7 @@
 	return ret;
 }
 
-int reiserfs_prepare_write(struct file *f, struct page *page,
-			   unsigned from, unsigned to)
+int __reiserfs_write_begin(struct page *page, unsigned from, unsigned len)
 {
 	struct inode *inode = page->mapping->host;
 	int ret;
@@ -2650,7 +2648,7 @@
 		th->t_refcount++;
 	}
 
-	ret = block_prepare_write(page, from, to, reiserfs_get_block);
+	ret = __block_write_begin(page, from, len, reiserfs_get_block);
 	if (ret && reiserfs_transaction_running(inode->i_sb)) {
 		struct reiserfs_transaction_handle *th = current->journal_info;
 		/* this gets a little ugly.  If reiserfs_get_block returned an