From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [rfc] weirdness in bio_map_user_iov()
Date: Wed, 21 Sep 2016 22:52:26 +0100 [thread overview]
Message-ID: <20160921215226.GU2356@ZenIV.linux.org.uk> (raw)
What happens if we feed it a 3-element iovec array, one page in each?
AFAICS, bio_add_pc_page() is called for each of those pages, even if
the previous calls have failed - break is only out of the inner loop.
Sure, failure due to exceeded request size means that everything after
that one will fail, but what of e.g.
/*
* If the queue doesn't support SG gaps and adding this
* offset would create a gap, disallow it.
*/
if (bvec_gap_to_prev(q, prev, offset))
return 0;
in there? Won't we risk having the first and the third pages added, with
the second one quietly skipped? Jens, looks like it had come from you
(by way of jejb). Am I missing something subtle here?
next reply other threads:[~2016-09-21 21:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 21:52 Al Viro [this message]
2016-09-23 21:47 ` [rfc] weirdness in bio_map_user_iov() Sagi Grimberg
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