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 15/15] xfs: Use the new iomap infrastructure for CoW
Date: Fri, 6 Sep 2019 18:55:07 +0200 [thread overview]
Message-ID: <20190906165507.GA12842@lst.de> (raw)
In-Reply-To: <20190905150650.21089-16-rgoldwyn@suse.de>
On Thu, Sep 05, 2019 at 10:06:50AM -0500, Goldwyn Rodrigues wrote:
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 8321733c16c3..13495d8a1ee2 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1006,7 +1006,10 @@ xfs_file_iomap_begin(
> */
> if (directio || imap.br_startblock == HOLESTARTBLOCK)
> imap = cmap;
> + else
> + xfs_bmbt_to_iomap(ip, srcmap, &cmap, false);
>
> + iomap->flags |= IOMAP_F_COW;
I don't think this is correct. We should only set IOMAP_F_COW
when we actually fill out the srcmap. Which is a very good agument
for Darrick's suggestion to check for a non-emptry srcmap.
Also this is missing the actually interesting part in
xfs_file_iomap_begin_delay.
I ended up spending the better half of the day trying to implement
that and did run into a few bugs in the core iomap changes, mostly
due to a confusion which iomap to use. So I ended up reworking those
a bit to:
a) check srcmap->type to see if there is a valid srcmap
b) set the srcmap pointer to iomap so that it doesn't need to
be special cased all over
c) fixed up a few more places to use the srcmap
This now at least survives xfstests -g quick on a 4k xfs file system
for. Here is my current tree:
http://git.infradead.org/users/hch/xfs.git/shortlog/refs/heads/xfs-cow-iomap
next prev parent reply other threads:[~2019-09-06 16:55 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
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 [this message]
2019-09-06 23:28 ` Dave Chinner
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