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Re: RFC: pwritev2 regression test for invalid flags
- From: Jon Derrick <jonathan dot derrick at intel dot com>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, GNU C Library <libc-alpha at sourceware dot org>, Christoph Hellwig <hch at infradead dot org>
- Cc: Stephen Bates <sbates at raithlin dot com>, "linux-block at vger dot kernel dot org" <linux-block at vger dot kernel dot org>, Christoph Hellwig <hch at lst dot de>, Jens Axboe <axboe at fb dot com>
- Date: Thu, 1 Jun 2017 11:52:25 -0600
- Subject: Re: RFC: pwritev2 regression test for invalid flags
- Authentication-results: sourceware.org; auth=none
- References: <a5987ece-5351-346b-21fd-5a3e0092229e@linaro.org>
Hi Zanella,
On 06/15/2017 04:10 PM, Adhemerval Zanella wrote:
> After the issue with LO_HI_LONG definition on x86_64-linux-gnu, I planed to add
> this patch to check the above patch for correct check for invalid flags (which
> would also have show this issue with LO_HI_LONG being used on p{read,write}v2).
>
> However it seems to trigger what I think it is a kernel bug on version that
> provides p{read,write}v, where preadv2 does fails with EOPNOTSUPP but
> pwritev2 does not. For instance, on x86_64-linux-gnu-x32 and i686-linux-gnu
> (4.10.0-21-generic/x86_64):
It looks like the issue is that you are going through the compat_writev
path, which for some reason discards the flags parameter.
Can you apply the patch below to your kernel?
diff --git a/fs/read_write.c b/fs/read_write.c
index c4f88af..f77eb22 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1210,7 +1210,7 @@ static size_t compat_writev(struct file *file,
if (!(file->f_mode & FMODE_CAN_WRITE))
goto out;
- ret = compat_do_readv_writev(WRITE, file, vec, vlen, pos, 0);
+ ret = compat_do_readv_writev(WRITE, file, vec, vlen, pos, flags);
out:
if (ret > 0)