linux-kernel - Re: [PATCH v11 2/9] block: Add copy offload support infrastructure

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Message-ID: <CAFL455nMtKbDt1HeN6D2WPB2JjOYq2z1=RagmmuhmQ33eL2Bfw@mail.gmail.com>
Date:   Tue, 30 May 2023 13:29:12 +0200
From:   Maurizio Lombardi <mlombard@...hat.com>
To:     Nitesh Shetty <nj.shetty@...sung.com>
Cc:     Jens Axboe <axboe@...nel.dk>, Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...nel.org>, dm-devel@...hat.com,
        Keith Busch <kbusch@...nel.org>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        James Smart <james.smart@...adcom.com>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        James.Bottomley@...senpartnership.com, bvanassche@....org,
        hare@...e.de, ming.lei@...hat.com, dlemoal@...nel.org,
        anuj20.g@...sung.com, joshi.k@...sung.com, nitheshshetty@...il.com,
        gost.dev@...sung.com, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v11 2/9] block: Add copy offload support infrastructure

po 22. 5. 2023 v 13:17 odesílatel Nitesh Shetty <nj.shetty@...sung.com> napsal:
>
> +static int __blkdev_copy_offload(struct block_device *bdev_in, loff_t pos_in,
> +               struct block_device *bdev_out, loff_t pos_out, size_t len,
> +               cio_iodone_t endio, void *private, gfp_t gfp_mask)
> +{
> +       struct cio *cio;
> +       struct copy_ctx *ctx;
> +       struct bio *read_bio, *write_bio;
> +       struct page *token;
> +       sector_t copy_len;
> +       sector_t rem, max_copy_len;
> +
> +       cio = kzalloc(sizeof(struct cio), GFP_KERNEL);
> +       if (!cio)
> +               return -ENOMEM;
> +       atomic_set(&cio->refcount, 0);
> +       cio->waiter = current;
> +       cio->endio = endio;
> +       cio->private = private;
> +
> +       max_copy_len = min(bdev_max_copy_sectors(bdev_in),
> +                       bdev_max_copy_sectors(bdev_out)) << SECTOR_SHIFT;
> +
> +       cio->pos_in = pos_in;
> +       cio->pos_out = pos_out;
> +       /* If there is a error, comp_len will be set to least successfully
> +        * completed copied length
> +        */
> +       cio->comp_len = len;
> +       for (rem = len; rem > 0; rem -= copy_len) {
> +               copy_len = min(rem, max_copy_len);
> +
> +               token = alloc_page(gfp_mask);
> +               if (unlikely(!token))
> +                       goto err_token;

[...]

> +err_token:
> +       cio->comp_len = min_t(sector_t, cio->comp_len, (len - rem));
> +       if (!atomic_read(&cio->refcount))
> +               return -ENOMEM;
> +       /* Wait for submitted IOs to complete */
> +       return blkdev_copy_wait_completion(cio);
> +}

Suppose the first call to "token = alloc_page()" fails (and
cio->refcount == 0), isn't "cio" going to be leaked here?

Maurizio