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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, linux-xfs@vger.kernel.org,
	Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 02/15] iomap: Read page from srcmap if IOMAP_F_COW is set
Date: Thu, 5 Sep 2019 18:37:56 +0200	[thread overview]
Message-ID: <20190905163756.GA22883@lst.de> (raw)
In-Reply-To: <20190905150650.21089-3-rgoldwyn@suse.de>

On Thu, Sep 05, 2019 at 10:06:37AM -0500, Goldwyn Rodrigues wrote:
> -	else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
> +	} else if (iomap->flags & IOMAP_F_COW) {
> +		if (WARN_ON_ONCE(iomap->flags & IOMAP_F_BUFFER_HEAD)) {
> +			status = -EIO;
> +			goto out_no_page;
> +		}
> +		if (WARN_ON_ONCE(srcmap->type == IOMAP_HOLE &&
> +				 srcmap->addr != IOMAP_NULL_ADDR)) {

Well, we want HOLES to have IOMAP_NULL_ADDR everywhere, so not sure
why the assert is just here.

> +			status = -EIO;
> +			goto out_no_page;
> +		}
> +		status = __iomap_write_begin(inode, pos, len, page, srcmap);
> +	} else if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
>  		status = __block_write_begin_int(page, pos, len, NULL, iomap);
> -	else
> +	} else {
>  		status = __iomap_write_begin(inode, pos, len, page, iomap);
> +	}

Maybe a good way to structure this is:

	if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
		if (WARN_ON_ONCE(iomap->flags & IOMAP_F_COW)) {
			status = -EIO;
			goto out_no_page;
		}
		status = __block_write_begin_int(page, pos, len, NULL, iomap);
	} else {
 		status = __iomap_write_begin(inode, pos, len, page,
				(iomap->flags & IOMAP_F_COW) ?  srcmap : iomap);
	}

  reply	other threads:[~2019-09-05 16:38 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05 15:06 [PATCH v4 0/15] CoW support for iomap Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 01/15] iomap: Use a srcmap for a read-modify-write I/O Goldwyn Rodrigues
2019-09-05 23:23   ` Darrick J. Wong
2019-09-05 15:06 ` [PATCH 02/15] iomap: Read page from srcmap if IOMAP_F_COW is set Goldwyn Rodrigues
2019-09-05 16:37   ` Christoph Hellwig [this message]
2019-09-05 20:28     ` Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 03/15] btrfs: Eliminate PagePrivate for btrfs data pages Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 04/15] btrfs: Add a simple buffered iomap write Goldwyn Rodrigues
2019-09-05 16:23   ` Christoph Hellwig
2019-09-05 20:42     ` Goldwyn Rodrigues
2019-09-06  5:54       ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 05/15] btrfs: Add CoW in iomap based writes Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 06/15] btrfs: remove buffered write code made unnecessary Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 07/15] fs: Export generic_file_buffered_read() Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 08/15] btrfs: basic direct read operation Goldwyn Rodrigues
2019-09-05 16:25   ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 09/15] btrfs: Carve out btrfs_get_extent_map_write() out of btrfs_get_blocks_write() Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 10/15] btrfs: Rename __endio_write_update_ordered() to btrfs_update_ordered_extent() Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 11/15] iomap: use a function pointer for dio submits Goldwyn Rodrigues
2019-09-05 16:27   ` Christoph Hellwig
2019-09-05 23:24     ` Darrick J. Wong
2019-09-05 15:06 ` [PATCH 12/15] btrfs: Use iomap_dio_rw for performing direct I/O writes Goldwyn Rodrigues
2019-09-05 16:31   ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 13/15] btrfs: Remove btrfs_dio_data and __btrfs_direct_write Goldwyn Rodrigues
2019-09-05 16:32   ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 14/15] btrfs: update inode size during bio completion Goldwyn Rodrigues
2019-09-05 16:33   ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 15/15] xfs: Use the new iomap infrastructure for CoW Goldwyn Rodrigues
2019-09-06 16:55   ` Christoph Hellwig
2019-09-06 23:28     ` Dave Chinner

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