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>

1 files changed, 5 insertions, 6 deletions

diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c
index f042eec464c2..4068f485cfd6 100644
--- a/fs/sysv/itree.c
+++ b/fs/sysv/itree.c
@@ -459,12 +459,10 @@ static int sysv_readpage(struct file *file, struct page *page)
         return block_read_full_page(page,get_block);
 }
 
-int __sysv_write_begin(struct file *file, struct address_space *mapping,
-                        loff_t pos, unsigned len, unsigned flags,
-                        struct page **pagep, void **fsdata)
+int sysv_prepare_chunk(struct page *page, loff_t pos, unsigned len)
 {
-        return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
-                                get_block);
+        return block_write_begin_newtrunc(NULL, page->mapping, pos, len, 0,
+                                          &page, NULL, get_block);
 }
 
 static int sysv_write_begin(struct file *file, struct address_space *mapping,
@@ -472,7 +470,8 @@ static int sysv_write_begin(struct file *file, struct address_space *mapping,
                         struct page **pagep, void **fsdata)
 {
         *pagep = NULL;
-        return __sysv_write_begin(file, mapping, pos, len, flags, pagep, fsdata);
+        return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
+                                get_block);
 }
 
 static sector_t sysv_bmap(struct address_space *mapping, sector_t block)