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authorChristoph Lameter <clameter@sgi.com>2008-02-04 22:28:29 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:13 -0800
commiteebd2aa355692afaf9906f62118620f1a1c19dbb (patch)
tree207eead3a736963c3e50942038c463f2f611ccce /fs/buffer.c
parentb98348bdd08dc4ec11828aa98a78edde15c53cfa (diff)
Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user
Simplify page cache zeroing of segments of pages through 3 functions zero_user_segments(page, start1, end1, start2, end2) Zeros two segments of the page. It takes the position where to start and end the zeroing which avoids length calculations and makes code clearer. zero_user_segment(page, start, end) Same for a single segment. zero_user(page, start, length) Length variant for the case where we know the length. We remove the zero_user_page macro. Issues: 1. Its a macro. Inline functions are preferable. 2. The KM_USER0 macro is only defined for HIGHMEM. Having to treat this special case everywhere makes the code needlessly complex. The parameter for zeroing is always KM_USER0 except in one single case that we open code. Avoiding KM_USER0 makes a lot of code not having to be dealing with the special casing for HIGHMEM anymore. Dealing with kmap is only necessary for HIGHMEM configurations. In those configurations we use KM_USER0 like we do for a series of other functions defined in highmem.h. Since KM_USER0 is depends on HIGHMEM the existing zero_user_page function could not be a macro. zero_user_* functions introduced here can be be inline because that constant is not used when these functions are called. Also extract the flushing of the caches to be outside of the kmap. [akpm@linux-foundation.org: fix nfs and ntfs build] [akpm@linux-foundation.org: fix ntfs build some more] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: <linux-ext4@vger.kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Mark Fasheh <mark.fasheh@oracle.com> Cc: David Chinner <dgc@sgi.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/buffer.c')
-rw-r--r--fs/buffer.c44
1 files changed, 14 insertions, 30 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index 456c9ab7705b..1de921484eac 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1798,7 +1798,7 @@ void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
start = max(from, block_start);
size = min(to, block_end) - start;
- zero_user_page(page, start, size, KM_USER0);
+ zero_user(page, start, size);
set_buffer_uptodate(bh);
}
@@ -1861,19 +1861,10 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
mark_buffer_dirty(bh);
continue;
}
- if (block_end > to || block_start < from) {
- void *kaddr;
-
- kaddr = kmap_atomic(page, KM_USER0);
- if (block_end > to)
- memset(kaddr+to, 0,
- block_end-to);
- if (block_start < from)
- memset(kaddr+block_start,
- 0, from-block_start);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- }
+ if (block_end > to || block_start < from)
+ zero_user_segments(page,
+ to, block_end,
+ block_start, from);
continue;
}
}
@@ -2104,8 +2095,7 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
SetPageError(page);
}
if (!buffer_mapped(bh)) {
- zero_user_page(page, i * blocksize, blocksize,
- KM_USER0);
+ zero_user(page, i * blocksize, blocksize);
if (!err)
set_buffer_uptodate(bh);
continue;
@@ -2218,7 +2208,7 @@ int cont_expand_zero(struct file *file, struct address_space *mapping,
&page, &fsdata);
if (err)
goto out;
- zero_user_page(page, zerofrom, len, KM_USER0);
+ zero_user(page, zerofrom, len);
err = pagecache_write_end(file, mapping, curpos, len, len,
page, fsdata);
if (err < 0)
@@ -2245,7 +2235,7 @@ int cont_expand_zero(struct file *file, struct address_space *mapping,
&page, &fsdata);
if (err)
goto out;
- zero_user_page(page, zerofrom, len, KM_USER0);
+ zero_user(page, zerofrom, len);
err = pagecache_write_end(file, mapping, curpos, len, len,
page, fsdata);
if (err < 0)
@@ -2422,7 +2412,6 @@ int nobh_write_begin(struct file *file, struct address_space *mapping,
unsigned block_in_page;
unsigned block_start, block_end;
sector_t block_in_file;
- char *kaddr;
int nr_reads = 0;
int ret = 0;
int is_mapped_to_disk = 1;
@@ -2493,13 +2482,8 @@ int nobh_write_begin(struct file *file, struct address_space *mapping,
continue;
}
if (buffer_new(bh) || !buffer_mapped(bh)) {
- kaddr = kmap_atomic(page, KM_USER0);
- if (block_start < from)
- memset(kaddr+block_start, 0, from-block_start);
- if (block_end > to)
- memset(kaddr + to, 0, block_end - to);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_segments(page, block_start, from,
+ to, block_end);
continue;
}
if (buffer_uptodate(bh))
@@ -2636,7 +2620,7 @@ 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."
*/
- zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
+ zero_user_segment(page, offset, PAGE_CACHE_SIZE);
out:
ret = mpage_writepage(page, get_block, wbc);
if (ret == -EAGAIN)
@@ -2709,7 +2693,7 @@ has_buffers:
if (page_has_buffers(page))
goto has_buffers;
}
- zero_user_page(page, offset, length, KM_USER0);
+ zero_user(page, offset, length);
set_page_dirty(page);
err = 0;
@@ -2785,7 +2769,7 @@ int block_truncate_page(struct address_space *mapping,
goto unlock;
}
- zero_user_page(page, offset, length, KM_USER0);
+ zero_user(page, offset, length);
mark_buffer_dirty(bh);
err = 0;
@@ -2831,7 +2815,7 @@ 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."
*/
- zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
+ zero_user_segment(page, offset, PAGE_CACHE_SIZE);
return __block_write_full_page(inode, page, get_block, wbc);
}