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fs: convert core functions to zero_user_page

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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.

[[email protected]: fix a few things]
Signed-off-by: Nate Diller <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Nate Diller 2007-05-09 02:35:07 -07:00 • committed by Linus Torvalds
commit 01f2705daf
7 changed files with 42 additions and 81 deletions
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7
mm/filemap_xip.c
View file

@ -434,7 +434,6 @@ xip_truncate_page(struct address_space *mapping, loff_t from)
unsigned blocksize;
unsigned length;
struct page *page;
void *kaddr;
BUG_ON(!mapping->a_ops->get_xip_page);
@ -458,11 +457,7 @@ xip_truncate_page(struct address_space *mapping, loff_t from)
else
return PTR_ERR(page);
}
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + offset, 0, length);
kunmap_atomic(kaddr, KM_USER0);
flush_dcache_page(page);
zero_user_page(page, offset, length, KM_USER0);
return 0;
}
EXPORT_SYMBOL_GPL(xip_truncate_page);

3
mm/truncate.c
View file

@ -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 @@ void do_invalidatepage(struct page *page, unsigned long offset)
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);
}