introduce __block_write_begin

Split up the block_write_begin implementation - __block_write_begin is a new
trivial wrapper for block_prepare_write that always takes an already
allocated page and can be either called from block_write_begin or filesystem
code that already has a page allocated.  Remove the handling of already
allocated pages from block_write_begin after switching all callers that
do it to __block_write_begin.

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

1 files changed, 4 insertions, 7 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d6a7701018a6..3da3c9646e5e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1578,11 +1578,9 @@ retry:
         *pagep = page;
 
         if (ext4_should_dioread_nolock(inode))
-                ret = block_write_begin(file, mapping, pos, len, flags, pagep,
-                                fsdata, ext4_get_block_write);
+                ret = __block_write_begin(page, pos, len, ext4_get_block_write);
         else
-                ret = block_write_begin(file, mapping, pos, len, flags, pagep,
-                                fsdata, ext4_get_block);
+                ret = __block_write_begin(page, pos, len, ext4_get_block);
 
         if (!ret && ext4_should_journal_data(inode)) {
                 ret = walk_page_buffers(handle, page_buffers(page),
@@ -1593,7 +1591,7 @@ retry:
                 unlock_page(page);
                 page_cache_release(page);
                 /*
-                 * block_write_begin may have instantiated a few blocks
+                 * __block_write_begin may have instantiated a few blocks
                  * outside i_size.  Trim these off again. Don't need
                  * i_size_read because we hold i_mutex.
                  *
@@ -3185,8 +3183,7 @@ retry:
         }
         *pagep = page;
 
-        ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
-                                ext4_da_get_block_prep);
+        ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
         if (ret < 0) {
                 unlock_page(page);
                 ext4_journal_stop(handle);