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SUNRPC: Fix the recent bv_offset fix

Message ID 169322843904.10891.2463559234906066461.stgit@bazille.1015granger.net (mailing list archive)
State New, archived
Headers show
Series SUNRPC: Fix the recent bv_offset fix | expand

Commit Message

Chuck Lever Aug. 28, 2023, 1:14 p.m. UTC 
From: Chuck Lever <chuck.lever@oracle.com>

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 <mlevitsky@redhat.com>
Fixes: c96e2a695e00 ("sunrpc: set the bv_offset of first bvec in svc_tcp_sendmsg")
Tested-by: Maxim Levitsky <mlevitsky@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/svcsock.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

The plan is to put this first in the nfsd-next pull request so that
it can back-ported immediately to 6.5.y.
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Patch

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 2eb8df44f894..589020ed909d 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -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,