clean up write_begin usage for directories in pagecache

For filesystem that implement directories in pagecache we call
block_write_begin with an already allocated page for this code, while the
normal regular file write path uses the default block_write_begin behaviour.

Get rid of the __foofs_write_begin helper and opencode the normal write_begin
call in foofs_write_begin, while adding a new foofs_prepare_chunk helper for
the directory code.  The added benefit is that foofs_prepare_chunk has
a much saner calling convention.

Note that the interruptible flag passed into block_write_begin is always
ignored if we already pass in a page (see next patch for details), and
we never were doing truncations of exessive blocks for this case either so we
can switch directly to block_write_begin_newtrunc.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 10 insertions, 18 deletions

diff --git a/fs/ufs/dir.c b/fs/ufs/dir.c
index ec78475..dbc9099 100644
--- a/fs/ufs/dir.c
+++ b/fs/ufs/dir.c
@@ -95,8 +95,7 @@ void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
 	int err;
 
 	lock_page(page);
-	err = __ufs_write_begin(NULL, page->mapping, pos, len,
-				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
+	err = ufs_prepare_chunk(page, pos, len);
 	BUG_ON(err);
 
 	de->d_ino = cpu_to_fs32(dir->i_sb, inode->i_ino);
@@ -381,8 +380,7 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
 got_it:
 	pos = page_offset(page) +
 			(char*)de - (char*)page_address(page);
-	err = __ufs_write_begin(NULL, page->mapping, pos, rec_len,
-				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
+	err = ufs_prepare_chunk(page, pos, rec_len);
 	if (err)
 		goto out_unlock;
 	if (de->d_ino) {
@@ -518,7 +516,6 @@ int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
 		     struct page * page)
 {
 	struct super_block *sb = inode->i_sb;
-	struct address_space *mapping = page->mapping;
 	char *kaddr = page_address(page);
 	unsigned from = ((char*)dir - kaddr) & ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
 	unsigned to = ((char*)dir - kaddr) + fs16_to_cpu(sb, dir->d_reclen);
@@ -549,8 +546,7 @@ int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
 
 	pos = page_offset(page) + from;
 	lock_page(page);
-	err = __ufs_write_begin(NULL, mapping, pos, to - from,
-				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
+	err = ufs_prepare_chunk(page, pos, to - from);
 	BUG_ON(err);
 	if (pde)
 		pde->d_reclen = cpu_to_fs16(sb, to - from);
@@ -577,8 +573,7 @@ int ufs_make_empty(struct inode * inode, struct inode *dir)
 	if (!page)
 		return -ENOMEM;
 
-	err = __ufs_write_begin(NULL, mapping, 0, chunk_size,
-				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
+	err = ufs_prepare_chunk(page, 0, chunk_size);
 	if (err) {
 		unlock_page(page);
 		goto fail;
diff --git a/fs/ufs/inode.c b/fs/ufs/inode.c
index 73fe773..a9555b1 100644
--- a/fs/ufs/inode.c
+++ b/fs/ufs/inode.c
@@ -558,12 +558,10 @@ static int ufs_readpage(struct file *file, struct page *page)
 	return block_read_full_page(page,ufs_getfrag_block);
 }
 
-int __ufs_write_begin(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned flags,
-			struct page **pagep, void **fsdata)
+int ufs_prepare_chunk(struct page *page, loff_t pos, unsigned len)
 {
-	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
-				ufs_getfrag_block);
+	return block_write_begin_newtrunc(NULL, page->mapping, pos, len, 0,
+					  &page, NULL, ufs_getfrag_block);
 }
 
 static int ufs_write_begin(struct file *file, struct address_space *mapping,
@@ -571,7 +569,8 @@ static int ufs_write_begin(struct file *file, struct address_space *mapping,
 			struct page **pagep, void **fsdata)
 {
 	*pagep = NULL;
-	return __ufs_write_begin(file, mapping, pos, len, flags, pagep, fsdata);
+	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+				ufs_getfrag_block);
 }
 
 static sector_t ufs_bmap(struct address_space *mapping, sector_t block)
diff --git a/fs/ufs/util.h b/fs/ufs/util.h
index 23ceed8..0466036 100644
--- a/fs/ufs/util.h
+++ b/fs/ufs/util.h
@@ -257,9 +257,7 @@ ufs_set_inode_gid(struct super_block *sb, struct ufs_inode *inode, u32 value)
 
 extern dev_t ufs_get_inode_dev(struct super_block *, struct ufs_inode_info *);
 extern void ufs_set_inode_dev(struct super_block *, struct ufs_inode_info *, dev_t);
-extern int __ufs_write_begin(struct file *file, struct address_space *mapping,
-		loff_t pos, unsigned len, unsigned flags,
-		struct page **pagep, void **fsdata);
+extern int ufs_prepare_chunk(struct page *page, loff_t pos, unsigned len);
 
 /*
  * These functions manipulate ufs buffers