On Fri, 2011-03-18 at 20:03 -0700, Allison Henderson wrote:
> This patch adds routines needed to zero out the
> unblock aligned data of the hole.
>
> The existing ext4_block_truncate_page routine that
> is used to zero out unblock aligned data from truncate
> has been modified to accept a length parameter, and
> renamed to ext4_block_zero_page_range.
>
> The function can now be used to zero out the
> head of a block, the tail of a block, or the middle
> of a block. The existing ext4_block_truncate_page
> has now become a wrapper to this function
>
> Signed-off-by: Allison Henderson <achender@xxxxxxxxxx>
Reviewed-by: Mingming Cao <cmm@xxxxxxxxxx>
> ---
> :100644 100644 3aa0b72... c722e31... M fs/ext4/ext4.h
> :100644 100644 67e7a3c... 78c5bc4... M fs/ext4/inode.c
> fs/ext4/ext4.h | 2 ++
> fs/ext4/inode.c | 33 +++++++++++++++++++++++++++++++--
> 2 files changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 3aa0b72..c722e31 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1738,6 +1738,8 @@ extern int ext4_writepage_trans_blocks(struct
> inode *);
> extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
> extern int ext4_block_truncate_page(handle_t *handle,
> struct address_space *mapping, loff_t from);
> +extern int ext4_block_zero_page_range(handle_t *handle,
> + struct address_space *mapping, loff_t from, loff_t length);
> extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct
> vm_fault *vmf);
> extern qsize_t *ext4_get_reserved_space(struct inode *inode);
> extern void ext4_da_update_reserve_space(struct inode *inode,
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 67e7a3c..78c5bc4 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3907,9 +3907,30 @@ void ext4_set_aops(struct inode *inode)
> int ext4_block_truncate_page(handle_t *handle,
> struct address_space *mapping, loff_t from)
> {
> + unsigned offset = from & (PAGE_CACHE_SIZE-1);
> + unsigned length;
> + unsigned blocksize;
> + struct inode *inode = mapping->host;
> +
> + blocksize = inode->i_sb->s_blocksize;
> + length = blocksize - (offset & (blocksize - 1));
> +
> + return ext4_block_zero_page_range(handle, mapping, from, length);
> +}
> +
> +/*
> + * ext4_block_zero_page_range() zeros out a mapping of length 'length'
> + * starting from file offset 'from'. The range to be zero'd must
> + * be contained with in one block. If the specified range exceeds
> + * the end of the block it will be shortened to end of the block
> + * that cooresponds to 'from'
> + */
> +int ext4_block_zero_page_range(handle_t *handle,
> + struct address_space *mapping, loff_t from, loff_t length)
> +{
> ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
> unsigned offset = from & (PAGE_CACHE_SIZE-1);
> - unsigned blocksize, length, pos;
> + unsigned blocksize, max, pos;
> ext4_lblk_t iblock;
> struct inode *inode = mapping->host;
> struct buffer_head *bh;
> @@ -3922,7 +3943,15 @@ int ext4_block_truncate_page(handle_t *handle,
> return -EINVAL;
>
> blocksize = inode->i_sb->s_blocksize;
> - length = blocksize - (offset & (blocksize - 1));
> + max = blocksize - (offset & (blocksize - 1));
> +
> + /*
> + * correct length if it does not fall between
> + * 'from' and the end of the block
> + */
> + if (length > max || length < 0)
> + length = max;
> +
> iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
>
> if (!page_has_buffers(page))
--
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