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Date:   Wed, 8 Mar 2023 15:33:30 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Cc:     "hch@infradead.org" <hch@infradead.org>,
        Qu Wenruo <quwenruo.btrfs@gmx.com>,
        David Sterba <dsterba@suse.cz>,
        "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
        Josef Bacik <josef@toxicpanda.com>,
        Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v7 04/13] btrfs: add support for inserting raid stripe
 extents
Message-ID: <20230308143330.GB14929@lst.de>
References: <94293952cdc120b46edf82672af874b0877e1e83.1677750131.git.johannes.thumshirn@wdc.com> <3e2d5ede-fb00-3aa8-e55e-d088b8df9e60@gmx.com> <b5bfe1a9-51dc-2a94-5ebd-4673b896d5ea@wdc.com> <6eabe69c-3abe-255b-797f-7917cd6a33cd@gmx.com> <7bd4ce91-58e6-f68b-6d69-3f9deff39ff5@wdc.com> <ZACsVI3mfprrj4j6@infradead.org> <bde5197e-7313-5017-ffbf-a528559c38cb@wdc.com> <48acd511-7f69-4c42-44ea-a39973d57c98@gmx.com> <ZAIBQ0hzLTjOIYcr@infradead.org> <e9e7820b-9cf3-8361-cf3c-e4d59baa5b21@wdc.com>
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On Wed, Mar 08, 2023 at 09:11:54AM +0000, Johannes Thumshirn wrote:
> @@ -393,10 +378,12 @@ static void btrfs_orig_write_end_io(struct bio *bio)
>                 stripe->physical = bio->bi_iter.bi_sector << SECTOR_SHIFT;
>  
>         if (btrfs_need_stripe_tree_update(bioc->fs_info, bioc->map_type)) {
> +               struct btrfs_ordered_extent *oe;
> +
> +               oe = btrfs_lookup_ordered_extent(bbio->inode, bbio->file_offset);
> +               btrfs_get_bioc(bioc);
> +               oe->bioc = bioc;
> +               btrfs_put_ordered_extent(oe);


> +       } else if (ordered_extent->bioc) {
> +               ret = btrfs_add_ordered_stripe(ordered_extent->bioc);
> +               btrfs_put_bioc(ordered_extent->bioc);
> +               if (ret)
> +                       goto out;

Given that btrfs_add_ordered_stripe only really builds the
btrfs_ordered_stripe structure and inserts it into the tree,
can't we just allocate the btrfs_ordered_stripe structure
in the end_io handler and have the ordered_extent point to it?

Also if you don't to split the ordered_extent for each bio,
you could instead have a list of btrfs_ordered_stripes in the
ordered_extent and then process all of them in the ordered_extent
completion handling.