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/include/linux/highmem.h b/include/linux/highmem.h
index a515eb0..b5f2ab4 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -94,17 +94,27 @@
/*
* Same but also flushes aliased cache contents to RAM.
+ *
+ * This must be a macro because KM_USER0 and friends aren't defined if
+ * !CONFIG_HIGHMEM
*/
-static inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
+#define zero_user_page(page, offset, size, km_type) \
+ do { \
+ void *kaddr; \
+ \
+ BUG_ON((offset) + (size) > PAGE_SIZE); \
+ \
+ kaddr = kmap_atomic(page, km_type); \
+ memset((char *)kaddr + (offset), 0, (size)); \
+ flush_dcache_page(page); \
+ kunmap_atomic(kaddr, (km_type)); \
+ } while (0)
+
+
+static inline void memclear_highpage_flush(struct page *page,
+ unsigned int offset, unsigned int size)
{
- void *kaddr;
-
- BUG_ON(offset + size > PAGE_SIZE);
-
- kaddr = kmap_atomic(page, KM_USER0);
- memset((char *)kaddr + offset, 0, size);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, offset, size, KM_USER0);
}
#ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE