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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
Download patch file Download diff file Expand all files Collapse all files

56
fs/buffer.c
View file

@ -1846,13 +1846,8 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
if (block_start >= to)
break;
if (buffer_new(bh)) {
void *kaddr;
clear_buffer_new(bh);
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr+block_start, 0, bh->b_size);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, block_start, bh->b_size, KM_USER0);
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
}
@ -1940,10 +1935,8 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
SetPageError(page);
}
if (!buffer_mapped(bh)) {
void *kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + i * blocksize, 0, blocksize);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, i * blocksize, blocksize,
KM_USER0);
if (!err)
set_buffer_uptodate(bh);
continue;
@ -2086,7 +2079,6 @@ int cont_prepare_write(struct page *page, unsigned offset,
long status;
unsigned zerofrom;
unsigned blocksize = 1 << inode->i_blkbits;
void *kaddr;
while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
status = -ENOMEM;
@ -2108,10 +2100,8 @@ int cont_prepare_write(struct page *page, unsigned offset,
PAGE_CACHE_SIZE, get_block);
if (status)
goto out_unmap;
kaddr = kmap_atomic(new_page, KM_USER0);
memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom);
flush_dcache_page(new_page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, zerofrom, PAGE_CACHE_SIZE - zerofrom,
KM_USER0);
generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
unlock_page(new_page);
page_cache_release(new_page);
@ -2138,10 +2128,7 @@ int cont_prepare_write(struct page *page, unsigned offset,
if (status)
goto out1;
if (zerofrom < offset) {
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr+zerofrom, 0, offset-zerofrom);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, zerofrom, offset - zerofrom, KM_USER0);
__block_commit_write(inode, page, zerofrom, offset);
}
return 0;
@ -2340,10 +2327,7 @@ failed:
* Error recovery is pretty slack. Clear the page and mark it dirty
* so we'll later zero out any blocks which _were_ allocated.
*/
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr, 0, PAGE_CACHE_SIZE);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
SetPageUptodate(page);
set_page_dirty(page);
return ret;
@ -2382,7 +2366,6 @@ int nobh_writepage(struct page *page, get_block_t *get_block,
loff_t i_size = i_size_read(inode);
const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
void *kaddr;
int ret;
/* Is the page fully inside i_size? */
@ -2413,10 +2396,7 @@ int nobh_writepage(struct page *page, get_block_t *get_block,
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
out:
ret = mpage_writepage(page, get_block, wbc);
if (ret == -EAGAIN)
@ -2437,7 +2417,6 @@ int nobh_truncate_page(struct address_space *mapping, loff_t from)
unsigned to;
struct page *page;
const struct address_space_operations *a_ops = mapping->a_ops;
char *kaddr;
int ret = 0;
if ((offset & (blocksize - 1)) == 0)
@ -2451,10 +2430,8 @@ int nobh_truncate_page(struct address_space *mapping, loff_t from)
to = (offset + blocksize) & ~(blocksize - 1);
ret = a_ops->prepare_write(NULL, page, offset, to);
if (ret == 0) {
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, offset, PAGE_CACHE_SIZE - offset,
KM_USER0);
/*
* It would be more correct to call aops->commit_write()
* here, but this is more efficient.
@ -2480,7 +2457,6 @@ int block_truncate_page(struct address_space *mapping,
struct inode *inode = mapping->host;
struct page *page;
struct buffer_head *bh;
void *kaddr;
int err;
blocksize = 1 << inode->i_blkbits;
@ -2534,11 +2510,7 @@ int block_truncate_page(struct address_space *mapping,
goto unlock;
}
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + offset, 0, length);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, offset, length, KM_USER0);
mark_buffer_dirty(bh);
err = 0;
@ -2559,7 +2531,6 @@ int block_write_full_page(struct page *page, get_block_t *get_block,
loff_t i_size = i_size_read(inode);
const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
void *kaddr;
/* Is the page fully inside i_size? */
if (page->index < end_index)
@ -2585,10 +2556,7 @@ int block_write_full_page(struct page *page, get_block_t *get_block,
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
return __block_write_full_page(inode, page, get_block, wbc);
}

8
fs/direct-io.c
View file

@ -867,7 +867,6 @@ static int do_direct_IO(struct dio *dio)
do_holes:
/* Handle holes */
if (!buffer_mapped(map_bh)) {
char *kaddr;
loff_t i_size_aligned;
/* AKPM: eargh, -ENOTBLK is a hack */
@ -888,11 +887,8 @@ do_holes:
page_cache_release(page);
goto out;
}
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + (block_in_page << blkbits),
0, 1 << blkbits);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, block_in_page << blkbits,
1 << blkbits, KM_USER0);
dio->block_in_file++;
block_in_page++;
goto next_block;

15
fs/mpage.c
View file

@ -284,11 +284,9 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
}
if (first_hole != blocks_per_page) {
char *kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + (first_hole << blkbits), 0,
PAGE_CACHE_SIZE - (first_hole << blkbits));
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, first_hole << blkbits,
PAGE_CACHE_SIZE - (first_hole << blkbits),
KM_USER0);
if (first_hole == 0) {
SetPageUptodate(page);
unlock_page(page);
@ -576,14 +574,11 @@ page_is_mapped:
* written out to the file."
*/
unsigned offset = i_size & (PAGE_CACHE_SIZE - 1);
char *kaddr;
if (page->index > end_index || !offset)
goto confused;
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
zero_user_page(page, offset, PAGE_CACHE_SIZE - offset,
KM_USER0);
}
/*