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>
diff --git a/fs/buffer.c b/fs/buffer.c
index 14529ec..c319c49 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1833,9 +1833,10 @@
}
EXPORT_SYMBOL(page_zero_new_buffers);
-static int __block_prepare_write(struct inode *inode, struct page *page,
- unsigned from, unsigned to, get_block_t *get_block)
+int block_prepare_write(struct page *page, unsigned from, unsigned to,
+ get_block_t *get_block)
{
+ struct inode *inode = page->mapping->host;
unsigned block_start, block_end;
sector_t block;
int err = 0;
@@ -1908,10 +1909,13 @@
if (!buffer_uptodate(*wait_bh))
err = -EIO;
}
- if (unlikely(err))
+ if (unlikely(err)) {
page_zero_new_buffers(page, from, to);
+ ClearPageUptodate(page);
+ }
return err;
}
+EXPORT_SYMBOL(block_prepare_write);
static int __block_commit_write(struct inode *inode, struct page *page,
unsigned from, unsigned to)
@@ -1948,6 +1952,15 @@
return 0;
}
+int __block_write_begin(struct page *page, loff_t pos, unsigned len,
+ get_block_t *get_block)
+{
+ unsigned start = pos & (PAGE_CACHE_SIZE - 1);
+
+ return block_prepare_write(page, start, start + len, get_block);
+}
+EXPORT_SYMBOL(__block_write_begin);
+
/*
* Filesystems implementing the new truncate sequence should use the
* _newtrunc postfix variant which won't incorrectly call vmtruncate.
@@ -1958,41 +1971,22 @@
struct page **pagep, void **fsdata,
get_block_t *get_block)
{
- struct inode *inode = mapping->host;
- int status = 0;
+ pgoff_t index = pos >> PAGE_CACHE_SHIFT;
struct page *page;
- pgoff_t index;
- unsigned start, end;
- int ownpage = 0;
+ int status;
- index = pos >> PAGE_CACHE_SHIFT;
- start = pos & (PAGE_CACHE_SIZE - 1);
- end = start + len;
+ page = grab_cache_page_write_begin(mapping, index, flags);
+ if (!page)
+ return -ENOMEM;
- page = *pagep;
- if (page == NULL) {
- ownpage = 1;
- page = grab_cache_page_write_begin(mapping, index, flags);
- if (!page) {
- status = -ENOMEM;
- goto out;
- }
- *pagep = page;
- } else
- BUG_ON(!PageLocked(page));
-
- status = __block_prepare_write(inode, page, start, end, get_block);
+ status = __block_write_begin(page, pos, len, get_block);
if (unlikely(status)) {
- ClearPageUptodate(page);
-
- if (ownpage) {
- unlock_page(page);
- page_cache_release(page);
- *pagep = NULL;
- }
+ unlock_page(page);
+ page_cache_release(page);
+ page = NULL;
}
-out:
+ *pagep = page;
return status;
}
EXPORT_SYMBOL(block_write_begin_newtrunc);
@@ -2379,17 +2373,6 @@
}
EXPORT_SYMBOL(cont_write_begin);
-int block_prepare_write(struct page *page, unsigned from, unsigned to,
- get_block_t *get_block)
-{
- struct inode *inode = page->mapping->host;
- int err = __block_prepare_write(inode, page, from, to, get_block);
- if (err)
- ClearPageUptodate(page);
- return err;
-}
-EXPORT_SYMBOL(block_prepare_write);
-
int block_commit_write(struct page *page, unsigned from, unsigned to)
{
struct inode *inode = page->mapping->host;