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Date:      Tue, 24 Apr 2018 20:21:59 +0000 (UTC)
From:      Rick Macklem <rmacklem@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-projects@freebsd.org
Subject:   svn commit: r332969 - projects/pnfs-planb-server/sys/fs/nfsserver
Message-ID:  <201804242021.w3OKLxtw028972@repo.freebsd.org>
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Author: rmacklem
Date: Tue Apr 24 20:21:59 2018
New Revision: 332969
URL: https://svnweb.freebsd.org/changeset/base/332969

Log:
  Add a sysctl called vfs.nfsd.flexlinuxhack which can be set non-zero to
  work around a Linux Flexible File Layout driver bug that causes it to
  use the synthetic user/group for "tightly coupled" servers like this one.

Modified:
  projects/pnfs-planb-server/sys/fs/nfsserver/nfs_nfsdstate.c

Modified: projects/pnfs-planb-server/sys/fs/nfsserver/nfs_nfsdstate.c
==============================================================================
--- projects/pnfs-planb-server/sys/fs/nfsserver/nfs_nfsdstate.c	Tue Apr 24 20:05:45 2018	(r332968)
+++ projects/pnfs-planb-server/sys/fs/nfsserver/nfs_nfsdstate.c	Tue Apr 24 20:21:59 2018	(r332969)
@@ -105,6 +105,11 @@ SYSCTL_INT(_vfs_nfsd, OID_AUTO, pnfsstrictatime, CTLFL
     &nfsrv_pnfsatime, 0,
     "For pNFS service, do Getattr ops to keep atime up-to-date");
 
+int	nfsrv_flexlinuxhack = 0;
+SYSCTL_INT(_vfs_nfsd, OID_AUTO, flexlinuxhack, CTLFLAG_RW,
+    &nfsrv_flexlinuxhack, 0,
+    "For Linux clients, hack around Flex File Layout bug");
+
 /*
  * Hash lists for nfs V4.
  */
@@ -6432,13 +6437,15 @@ nfsrv_filelayout(struct nfsrv_descript *nd, int iomode
 }
 
 #define	FLEX_OWNERID	"999"
+#define	FLEX_UID0	"0"
 /*
  * Generate a Flex File Layout.
  * The FLEX_OWNERID can be any string of 3 decimal digits. Although this
  * string goes on the wire, it isn't supposed to be used by the client,
  * since this server uses tight coupling.
- * The Linux Flexible File Layout client driver doesn't like a Null string
- * for these.
+ * Although not recommended by the spec., if vfs.nfsd.flexlinuxhack=1 use
+ * a string of "0". This works around the Linux Flex File Layout driver bug
+ * which uses the synthetic uid/gid strings for the "tightly coupled" case.
  */
 static struct nfslayout *
 nfsrv_flexlayout(struct nfsrv_descript *nd, int iomode, int mirrorcnt,
@@ -6480,10 +6487,19 @@ nfsrv_flexlayout(struct nfsrv_descript *nd, int iomode
 		NFSBCOPY(dsfhp, tl, sizeof(*dsfhp));
 		tl += (NFSM_RNDUP(NFSX_V4PNFSFH) / NFSX_UNSIGNED);
 		dsfhp++;
-		*tl++ = txdr_unsigned(strlen(FLEX_OWNERID));	/* Any uid. */
-		NFSBCOPY(FLEX_OWNERID, tl++, NFSX_UNSIGNED);
-		*tl++ = txdr_unsigned(strlen(FLEX_OWNERID));	/* Any gid. */
-		NFSBCOPY(FLEX_OWNERID, tl++, NFSX_UNSIGNED);
+		if (nfsrv_flexlinuxhack != 0) {
+			*tl++ = txdr_unsigned(strlen(FLEX_UID0));
+			*tl = 0;		/* 0 pad string. */
+			NFSBCOPY(FLEX_UID0, tl++, strlen(FLEX_UID0));
+			*tl++ = txdr_unsigned(strlen(FLEX_UID0));
+			*tl = 0;		/* 0 pad string. */
+			NFSBCOPY(FLEX_UID0, tl++, strlen(FLEX_UID0));
+		} else {
+			*tl++ = txdr_unsigned(strlen(FLEX_OWNERID));
+			NFSBCOPY(FLEX_OWNERID, tl++, NFSX_UNSIGNED);
+			*tl++ = txdr_unsigned(strlen(FLEX_OWNERID));
+			NFSBCOPY(FLEX_OWNERID, tl++, NFSX_UNSIGNED);
+		}
 	}
 	*tl++ = txdr_unsigned(0);		/* ff_flags. */
 	*tl = txdr_unsigned(60);		/* Status interval hint. */

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