Re: [PATCH v5 9/9] btrfs: implement RWF_ENCODED writes

[Josef Bacik <josef@toxicpanda.com>]

On 8/21/20 3:38 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> The implementation resembles direct I/O: we have to flush any ordered
> extents, invalidate the page cache, and do the io tree/delalloc/extent
> map/ordered extent dance. From there, we can reuse the compression code
> with a minor modification to distinguish the write from writeback. This
> also creates inline extents when possible.
> 
> Now that read and write are implemented, this also sets the
> FMODE_ENCODED_IO flag in btrfs_file_open().
> 
> Signed-off-by: Omar Sandoval <osandov@fb.com>
> ---
>   fs/btrfs/compression.c  |   7 +-
>   fs/btrfs/compression.h  |   6 +-
>   fs/btrfs/ctree.h        |   2 +
>   fs/btrfs/file.c         |  40 +++++--
>   fs/btrfs/inode.c        | 246 +++++++++++++++++++++++++++++++++++++++-
>   fs/btrfs/ordered-data.c |  12 +-
>   fs/btrfs/ordered-data.h |   2 +
>   7 files changed, 298 insertions(+), 17 deletions(-)
> 

<snip>

> +
> +	ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode), disk_num_bytes);
> +	if (ret)
> +		goto out_unlock;
> +	ret = btrfs_qgroup_reserve_data(BTRFS_I(inode), &data_reserved, start,
> +					num_bytes);
> +	if (ret)
> +		goto out_free_data_space;
> +	ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), num_bytes,
> +					      disk_num_bytes);
> +	if (ret)
> +		goto out_qgroup_free_data;

This can just be btrfs_delalloc_reserve_space() and that way the error handling 
is much cleaner.

<snip>
> +
> +out_free_reserved:
> +	btrfs_dec_block_group_reservations(fs_info, ins.objectid);
> +	btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
> +out_delalloc_release:
> +	btrfs_delalloc_release_extents(BTRFS_I(inode), num_bytes);
> +	btrfs_delalloc_release_metadata(BTRFS_I(inode), disk_num_bytes,
> +					ret < 0);

Likewise this can all just be btrfs_free_reserved_data_space().  Thanks,

Josef