Re: [PATCH 5/13] ext4: use zero_user_page

Andreas Dilger
2007-04-11T04:14:34Z

On Apr 10, 2007 20:36 -0700, Nate Diller wrote:
> Use zero_user_page() instead of open-coding it.
>
> Signed-off-by: Nate Diller <nate.diller@gmail.com>

> To: Andrew Morton <akpm@osdl.org>,
> Alexander Viro <viro@zeniv.linux.org.uk>
>Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org

Would have been better to CC the filesystem maintainers directly
(which was one of the reasons Andrew wanted per-fs patches so they
can be Ack/Nack independently.

Looks good in any case,

Signed-off-by: Andreas Dilger <adilger@clusterfs.com>

> diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ext4/inode.c linux-2.6.21-rc6-mm1-test/fs/ext4/inode.c
> --- linux-2.6.21-rc6-mm1/fs/ext4/inode.c 2007-04-10 17:15:04.000000000 -0700
> +++ linux-2.6.21-rc6-mm1-test/fs/ext4/inode.c 2007-04-10 18:33:04.000000000 -0700
> @@ -1791,7 +1791,6 @@ int ext4_block_truncate_page(handle_t *h
> struct inode *inode = mapping->host;
> struct buffer_head *bh;
> int err = 0;
> - void *kaddr;
>
> if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) &&
> test_opt(inode->i_sb, EXTENTS) &&
> @@ -1808,10 +1807,7 @@ int ext4_block_truncate_page(handle_t *h
> */
> if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
> ext4_should_writeback_data(inode) && PageUptodate(page)) {
> - 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);
> set_page_dirty(page);
> goto unlock;
> }
> @@ -1864,11 +1860,7 @@ int ext4_block_truncate_page(handle_t *h
> 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);
> BUFFER_TRACE(bh, "zeroed end of block");
>
> err = 0;
> diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ext4/writeback.c linux-2.6.21-rc6-mm1-test/fs/ext4/writeback.c
> --- linux-2.6.21-rc6-mm1/fs/ext4/writeback.c 2007-04-10 18:05:52.000000000 -0700
> +++ linux-2.6.21-rc6-mm1-test/fs/ext4/writeback.c 2007-04-10 18:33:04.000000000 -0700
> @@ -961,7 +961,6 @@ int ext4_wb_writepage(struct page *page,
> loff_t i_size = i_size_read(inode);
> pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
> unsigned offset;
> - void *kaddr;
>
> wb_debug("writepage %lu from inode %lu\n", page->index, inode->i_ino);
>
> @@ -1011,10 +1010,7 @@ int ext4_wb_writepage(struct page *page,
> * 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);
> return ext4_wb_write_single_page(page, wbc);
> }
>
> @@ -1065,7 +1061,6 @@ int ext4_wb_block_truncate_page(handle_t
> struct inode *inode = mapping->host;
> struct buffer_head bh, *bhw = &bh;
> unsigned blocksize, length;
> - void *kaddr;
> int err = 0;
>
> wb_debug("partial truncate from %lu on page %lu from inode %lu\n",
> @@ -1104,10 +1099,7 @@ int ext4_wb_block_truncate_page(handle_t
> }
> }
>
> - 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);
> SetPageUptodate(page);
> __set_page_dirty_nobuffers(page);
>
> -
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Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.