linux-kernel - Re: [PATCH v20 13/32] ceph: Provide a splice-read stub

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Message-ID: <ef4cc431-4cc4-eb39-735d-0b3b3759abed@redhat.com>
Date:   Mon, 22 May 2023 09:53:28 +0800
From:   Xiubo Li <xiubli@...hat.com>
To:     David Howells <dhowells@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>, Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>, Jan Kara <jack@...e.cz>,
        Jeff Layton <jlayton@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Hillf Danton <hdanton@...a.com>,
        Christian Brauner <brauner@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Christoph Hellwig <hch@....de>,
        Ilya Dryomov <idryomov@...il.com>, ceph-devel@...r.kernel.org
Subject: Re: [PATCH v20 13/32] ceph: Provide a splice-read stub


On 5/19/23 17:24, David Howells wrote:
> Xiubo Li <xiubli@...hat.com> wrote:
>
>>> +	ret = ceph_get_caps(in, CEPH_CAP_FILE_RD, want, -1, &got);
>>> +	if (ret < 0) {
>>> +		ceph_end_io_read(inode);
>>> +		return ret;
>>> +	}
>>> +
>>> +	if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) == 0) {
>>> +		dout("splice_read/sync %p %llx.%llx %llu~%zu got cap refs on %s\n",
>>> +		     inode, ceph_vinop(inode), *ppos, len,
>>> +		     ceph_cap_string(got));
>>> +
>>> +		ceph_end_io_read(inode);
>>> +		return direct_splice_read(in, ppos, pipe, len, flags);
>> Shouldn't we release cap ref before returning here ?
> Ummm...  Even if we got no caps?

No, at least we have got the 'need' caps: CEPH_CAP_FILE_RD once here.

I saw you have updated this and will check it.

Thanks

- Xiubo

>
> David
>