提交 ad2a722f 编写于 作者: B Boaz Harrosh 提交者: Al Viro

libfs: Open code simple_commit_write into only user

* simple_commit_write was only called by simple_write_end.
  Open coding it makes it tiny bit less heavy on the arithmetic and
  much more readable.

* While at it use zero_user() for clearing a partial page.
* While at it add a docbook comment for simple_write_end.
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
上级 4b1ae27a
...@@ -370,40 +370,51 @@ int simple_write_begin(struct file *file, struct address_space *mapping, ...@@ -370,40 +370,51 @@ int simple_write_begin(struct file *file, struct address_space *mapping,
return simple_prepare_write(file, page, from, from+len); return simple_prepare_write(file, page, from, from+len);
} }
static int simple_commit_write(struct file *file, struct page *page, /**
unsigned from, unsigned to) * simple_write_end - .write_end helper for non-block-device FSes
{ * @available: See .write_end of address_space_operations
struct inode *inode = page->mapping->host; * @file: "
loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; * @mapping: "
* @pos: "
if (!PageUptodate(page)) * @len: "
SetPageUptodate(page); * @copied: "
/* * @page: "
* No need to use i_size_read() here, the i_size * @fsdata: "
* cannot change under us because we hold the i_mutex. *
*/ * simple_write_end does the minimum needed for updating a page after writing is
if (pos > inode->i_size) * done. It has the same API signature as the .write_end of
i_size_write(inode, pos); * address_space_operations vector. So it can just be set onto .write_end for
set_page_dirty(page); * FSes that don't need any other processing. i_mutex is assumed to be held.
return 0; * Block based filesystems should use generic_write_end().
} * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
* is not called, so a filesystem that actually does store data in .write_inode
* should extend on what's done here with a call to mark_inode_dirty() in the
* case that i_size has changed.
*/
int simple_write_end(struct file *file, struct address_space *mapping, int simple_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied, loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata) struct page *page, void *fsdata)
{ {
unsigned from = pos & (PAGE_CACHE_SIZE - 1); struct inode *inode = page->mapping->host;
loff_t last_pos = pos + copied;
/* zero the stale part of the page if we did a short copy */ /* zero the stale part of the page if we did a short copy */
if (copied < len) { if (copied < len) {
void *kaddr = kmap_atomic(page, KM_USER0); unsigned from = pos & (PAGE_CACHE_SIZE - 1);
memset(kaddr + from + copied, 0, len - copied);
flush_dcache_page(page); zero_user(page, from + copied, len - copied);
kunmap_atomic(kaddr, KM_USER0);
} }
simple_commit_write(file, page, from, from+copied); if (!PageUptodate(page))
SetPageUptodate(page);
/*
* No need to use i_size_read() here, the i_size
* cannot change under us because we hold the i_mutex.
*/
if (last_pos > inode->i_size)
i_size_write(inode, last_pos);
set_page_dirty(page);
unlock_page(page); unlock_page(page);
page_cache_release(page); page_cache_release(page);
......
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