On Tue, Nov 08, 2016 at 12:08:12PM +0100, Jan Kara wrote:
> Currently mapping of blocks for DAX writes happen with
> EXT4_GET_BLOCKS_PRE_IO flag set. That has a result that each
> ext4_map_blocks() call creates a separate written extent, although it
> could be merged to the neighboring extents in the extent tree. The
> reason for using this flag is that in case the extent is unwritten, we
> need to convert it to written one and zero it out. However this "convert
> mapped range to written" operation is already implemented by
> ext4_map_blocks() for the case of data writes into unwritten extent. So
> just use flags for that mode of operation, simplify the code, and avoid
> unnecessary split extents.
>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
The code that this patch modifies was just introduced in the previous patch.
Is there a reason to keep both patches, or would it be cleaner just to squash
them and have one patch that introduces the code as you intend for it to end
up?
> ---
> fs/ext4/inode.c | 17 -----------------
> 1 file changed, 17 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index a7079cab645a..3192ec0768d4 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3351,7 +3351,6 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> return PTR_ERR(handle);
>
> ret = ext4_map_blocks(handle, inode, &map,
> - EXT4_GET_BLOCKS_PRE_IO |
> EXT4_GET_BLOCKS_CREATE_ZERO);
> if (ret < 0) {
> ext4_journal_stop(handle);
> @@ -3360,22 +3359,6 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> goto retry;
> return ret;
> }
> - /* For DAX writes we need to zero out unwritten extents */
> - if (map.m_flags & EXT4_MAP_UNWRITTEN) {
> - /*
> - * We are protected by i_mmap_sem or i_rwsem so we know
> - * block cannot go away from under us even though we
> - * dropped i_data_sem. Convert extent to written and
> - * write zeros there.
> - */
> - ret = ext4_map_blocks(handle, inode, &map,
> - EXT4_GET_BLOCKS_CONVERT |
> - EXT4_GET_BLOCKS_CREATE_ZERO);
> - if (ret < 0) {
> - ext4_journal_stop(handle);
> - return ret;
> - }
> - }
>
> /*
> * If we added blocks beyond i_size we need to make sure they
> --
> 2.6.6
>
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