NFSv4/flexfiles: Fix layout merge mirror check.

jira LE-4603
Rebuild_History Non-Buildable kernel-5.14.0-570.58.1.el9_6
commit-author Jonathan Curley <jcurley@purestorage.com>
commit dd2fa82

Typo in ff_lseg_match_mirrors makes the diff ineffective. This results
in merge happening all the time. Merge happening all the time is
problematic because it marks lsegs invalid. Marking lsegs invalid
causes all outstanding IO to get restarted with EAGAIN and connections
to get closed.

Closing connections constantly triggers race conditions in the RDMA
implementation...

Fixes: 660d1eb ("pNFS/flexfile: Don't merge layout segments if the mirrors don't match")
	Signed-off-by: Jonathan Curley <jcurley@purestorage.com>
	Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
(cherry picked from commit dd2fa82)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -276,7 +276,7 @@ ff_lseg_match_mirrors(struct pnfs_layout_segment *l1,
 		struct pnfs_layout_segment *l2)
 {
 	const struct nfs4_ff_layout_segment *fl1 = FF_LAYOUT_LSEG(l1);
-	const struct nfs4_ff_layout_segment *fl2 = FF_LAYOUT_LSEG(l1);
+	const struct nfs4_ff_layout_segment *fl2 = FF_LAYOUT_LSEG(l2);
 	u32 i;
 
 	if (fl1->mirror_array_cnt != fl2->mirror_array_cnt)