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From:   Christoph Hellwig <hch@lst.de>
To:     Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc:     linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org,
        darrick.wong@oracle.com, hch@lst.de, david@fromorbit.com,
        riteshh@linux.ibm.com, Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 02/15] iomap: Use a IOMAP_COW/srcmap for a
 read-modify-write I/O
Message-ID: <20190902163104.GB6263@lst.de>
References: <20190901200836.14959-1-rgoldwyn@suse.de> <20190901200836.14959-3-rgoldwyn@suse.de>
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On Sun, Sep 01, 2019 at 03:08:23PM -0500, Goldwyn Rodrigues wrote:
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -37,6 +37,7 @@ struct vm_fault;
>  #define IOMAP_MAPPED	0x03	/* blocks allocated at @addr */
>  #define IOMAP_UNWRITTEN	0x04	/* blocks allocated at @addr in unwritten state */
>  #define IOMAP_INLINE	0x05	/* data inline in the inode */
> +#define IOMAP_COW	0x06	/* copy data from srcmap before writing */

I don't think IOMAP_COW can be a type - it is a flag given that we
can do COW operations that allocate normal written extents (e.g. for
direct I/O or DAX) and for delayed allocations.