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SUNRPC: Fix the recent bv_offset fix

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Jeff confirmed his original fix addressed his pynfs test failure,
but this same bug also impacted qemu: accessing qcow2 virtual disks
using direct I/O was failing. Jeff's fix missed that you have to
shorten the bio_vec element by the same amount as you increased
the page offset.

Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Fixes: c96e2a695e ("sunrpc: set the bv_offset of first bvec in svc_tcp_sendmsg")
Tested-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2023-08-28 09:23:00 -04:00
parent 2dde18cd1d
commit f16ff1cafb
1 changed files with 3 additions and 1 deletions
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4
net/sunrpc/svcsock.c
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@ -1244,8 +1244,10 @@ static int svc_tcp_sendmsg(struct socket *sock, struct xdr_buf *xdr,
if (ret != head->iov_len)
goto out;
if (xdr_buf_pagecount(xdr))
if (xdr_buf_pagecount(xdr)) {
xdr->bvec[0].bv_offset = offset_in_page(xdr->page_base);
xdr->bvec[0].bv_len -= offset_in_page(xdr->page_base);
}
msg.msg_flags = MSG_SPLICE_PAGES;
iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, xdr->bvec,