On Thu, Oct 31, 2013 at 04:18:33PM -0500, Eric Sandeen wrote:
> commit
> ec22ba8e ext4: disable merging of uninitialized extents
>
> ensured that if either extent under consideration is uninit,
> we decline to merge, and ext4_can_extents_be_merged() returns false.
>
> So there is no need for the caller to then test whether the
> extent under consideration is unitialized; if it were, we
> wouldn't have gotten that far.
>
> The comments were also inaccurate; ext4_can_extents_be_merged()
> no longer XORs the states, it fails if *either* is uninit.
>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Looks good to me.
Reviewed-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
Thanks,
- Zheng
> ---
>
> Disclaimer: compile-tested only.
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index de6d467..35f65cf 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -1715,7 +1715,6 @@ static int ext4_ext_try_to_merge_right(struct inode *inode,
> struct ext4_extent_header *eh;
> unsigned int depth, len;
> int merge_done = 0;
> - int uninitialized = 0;
>
> depth = ext_depth(inode);
> BUG_ON(path[depth].p_hdr == NULL);
> @@ -1725,12 +1724,8 @@ static int ext4_ext_try_to_merge_right(struct inode *inode,
> if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
> break;
> /* merge with next extent! */
> - if (ext4_ext_is_uninitialized(ex))
> - uninitialized = 1;
> ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
> + ext4_ext_get_actual_len(ex + 1));
> - if (uninitialized)
> - ext4_ext_mark_uninitialized(ex);
>
> if (ex + 1 < EXT_LAST_EXTENT(eh)) {
> len = (EXT_LAST_EXTENT(eh) - ex - 1)
> @@ -1885,7 +1880,6 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
> struct ext4_ext_path *npath = NULL;
> int depth, len, err;
> ext4_lblk_t next;
> - unsigned uninitialized = 0;
> int mb_flags = 0;
>
> if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
> @@ -1937,18 +1931,8 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
> if (err)
> return err;
>
> - /*
> - * ext4_can_extents_be_merged should have checked
> - * that either both extents are uninitialized, or
> - * both aren't. Thus we need to check only one of
> - * them here.
> - */
> - if (ext4_ext_is_uninitialized(ex))
> - uninitialized = 1;
> ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
> + ext4_ext_get_actual_len(newext));
> - if (uninitialized)
> - ext4_ext_mark_uninitialized(ex);
> eh = path[depth].p_hdr;
> nearex = ex;
> goto merge;
> @@ -1971,20 +1955,10 @@ prepend:
> if (err)
> return err;
>
> - /*
> - * ext4_can_extents_be_merged should have checked
> - * that either both extents are uninitialized, or
> - * both aren't. Thus we need to check only one of
> - * them here.
> - */
> - if (ext4_ext_is_uninitialized(ex))
> - uninitialized = 1;
> ex->ee_block = newext->ee_block;
> ext4_ext_store_pblock(ex, ext4_ext_pblock(newext));
> ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
> + ext4_ext_get_actual_len(newext));
> - if (uninitialized)
> - ext4_ext_mark_uninitialized(ex);
> eh = path[depth].p_hdr;
> nearex = ex;
> goto merge;
>
>
> --
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