fs: convert core functions to zero_user_page
It's very common for file systems to need to zero part or all of a page,
the simplist way is just to use kmap_atomic() and memset(). There's
actually a library function in include/linux/highmem.h that does exactly
that, but it's confusingly named memclear_highpage_flush(), which is
descriptive of *how* it does the work rather than what the *purpose* is.
So this patchset renames the function to zero_user_page(), and calls it
from the various places that currently open code it.
This first patch introduces the new function call, and converts all the
core kernel callsites, both the open-coded ones and the old
memclear_highpage_flush() ones. Following this patch is a series of
conversions for each file system individually, per AKPM, and finally a
patch deprecating the old call. The diffstat below shows the entire
patchset.
[akpm@linux-foundation.org: fix a few things]
Signed-off-by: Nate Diller <nate.diller@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/truncate.c b/mm/truncate.c
index 0f4b6d1..4fbe1a2 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -12,6 +12,7 @@
#include <linux/swap.h>
#include <linux/module.h>
#include <linux/pagemap.h>
+#include <linux/highmem.h>
#include <linux/pagevec.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/buffer_head.h> /* grr. try_to_release_page,
@@ -46,7 +47,7 @@
static inline void truncate_partial_page(struct page *page, unsigned partial)
{
- memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
+ zero_user_page(page, partial, PAGE_CACHE_SIZE - partial, KM_USER0);
if (PagePrivate(page))
do_invalidatepage(page, partial);
}