Re: [PATCH 01/19] iomap: better document the IOMAP_F_* flags

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On Mon, Sep 09, 2019 at 08:27:04PM +0200, Christoph Hellwig wrote:
> The documentation for IOMAP_F_* is a bit disorganized, and doesn't
> mention the fact that most flags are set by the file system and consumed
> by the iomap core, while IOMAP_F_SIZE_CHANGED is set by the core and
> consumed by the file system.
> 
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Wooooooo,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>

--D

> ---
>  include/linux/iomap.h | 31 +++++++++++++++++++++++--------
>  1 file changed, 23 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index e79af6b28410..8adcc8dd4498 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -30,21 +30,36 @@ struct vm_fault;
>  #define IOMAP_INLINE	0x05	/* data inline in the inode */
>  
>  /*
> - * Flags for all iomap mappings:
> + * Flags reported by the file system from iomap_begin:
> + *
> + * IOMAP_F_NEW indicates that the blocks have been newly allocated and need
> + * zeroing for areas that no data is copied to.
>   *
>   * IOMAP_F_DIRTY indicates the inode has uncommitted metadata needed to access
>   * written data and requires fdatasync to commit them to persistent storage.
> + *
> + * IOMAP_F_SHARED indicates that the blocks are shared, and will need to be
> + * unshared as part a write.
> + *
> + * IOMAP_F_MERGED indicates that the iomap contains the merge of multiple block
> + * mappings.
> + *
> + * IOMAP_F_BUFFER_HEAD indicates that the file system requires the use of
> + * buffer heads for this mapping.
>   */
> -#define IOMAP_F_NEW		0x01	/* blocks have been newly allocated */
> -#define IOMAP_F_DIRTY		0x02	/* uncommitted metadata */
> -#define IOMAP_F_BUFFER_HEAD	0x04	/* file system requires buffer heads */
> -#define IOMAP_F_SIZE_CHANGED	0x08	/* file size has changed */
> +#define IOMAP_F_NEW		0x01
> +#define IOMAP_F_DIRTY		0x02
> +#define IOMAP_F_SHARED		0x04
> +#define IOMAP_F_MERGED		0x08
> +#define IOMAP_F_BUFFER_HEAD	0x10
>  
>  /*
> - * Flags that only need to be reported for IOMAP_REPORT requests:
> + * Flags set by the core iomap code during operations:
> + *
> + * IOMAP_F_SIZE_CHANGED indicates to the iomap_end method that the file size
> + * has changed as the result of this write operation.
>   */
> -#define IOMAP_F_MERGED		0x10	/* contains multiple blocks/extents */
> -#define IOMAP_F_SHARED		0x20	/* block shared with another file */
> +#define IOMAP_F_SIZE_CHANGED	0x100
>  
>  /*
>   * Flags from 0x1000 up are for file system specific usage:
> -- 
> 2.20.1
> 



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