git: 34256484aff2 - main - Revert "nfsd: cut the Linux NFSv4.1/4.2 some slack w.r.t. RFC5661"

[Rick Macklem]

The branch main has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=34256484aff285f460a98c089b030228448fe19f

commit 34256484aff285f460a98c089b030228448fe19f
Author:     Rick Macklem <rmacklem at FreeBSD.org>
AuthorDate: 2021-04-15 21:08:40 +0000
Commit:     Rick Macklem <rmacklem at FreeBSD.org>
CommitDate: 2021-04-15 21:08:40 +0000

    Revert "nfsd: cut the Linux NFSv4.1/4.2 some slack w.r.t. RFC5661"
    
    This reverts commit 9edaceca8165e2864267547311daf145bb520270.
    
    It turns out that the Linux client intentionally does an NFSv4.1
    RPC with only a Sequence operation in it and with "seqid + 1"
    for the slot.  This is used to re-synchronize the slot's seqid
    and the client expects the NFS4ERR_SEQ_MISORDERED error reply.
    
    As such, revert the patch, so that the server remains RFC5661
    compliant.
---
 sys/fs/nfs/nfs_commonsubs.c | 23 +++--------------------
 1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/sys/fs/nfs/nfs_commonsubs.c b/sys/fs/nfs/nfs_commonsubs.c
index d7009b1e0ca4..4afa4c2d9ab4 100644
--- a/sys/fs/nfs/nfs_commonsubs.c
+++ b/sys/fs/nfs/nfs_commonsubs.c
@@ -98,11 +98,6 @@ int nfs_maxcopyrange = 10 * 1024 * 1024;
 SYSCTL_INT(_vfs_nfs, OID_AUTO, maxcopyrange, CTLFLAG_RW,
     &nfs_maxcopyrange, 0, "Max size of a Copy so RPC times reasonable");
 
-static int nfs_allowskip_sessionseq = 1;
-SYSCTL_INT(_vfs_nfs, OID_AUTO, linuxseqsesshack, CTLFLAG_RW,
-    &nfs_allowskip_sessionseq, 0, "Allow client to skip ahead one seq# for"
-    " session slot");
-
 /*
  * This array of structures indicates, for V4:
  * retfh - which of 3 types of calling args are used
@@ -4619,7 +4614,7 @@ nfsmout:
  * Handle an NFSv4.1 Sequence request for the session.
  * If reply != NULL, use it to return the cached reply, as required.
  * The client gets a cached reply via this call for callbacks, however the
- * server gets a cached reply via the nfsv4_seqsess_cacherep() call.
+ * server gets a cached reply via the nfsv4_seqsess_cachereply() call.
  */
 int
 nfsv4_seqsession(uint32_t seqid, uint32_t slotid, uint32_t highslot,
@@ -4653,24 +4648,12 @@ nfsv4_seqsession(uint32_t seqid, uint32_t slotid, uint32_t highslot,
 		} else
 			/* No reply cached, so just do it. */
 			slots[slotid].nfssl_inprog = 1;
-	} else if (slots[slotid].nfssl_seq + 1 == seqid ||
-	    (slots[slotid].nfssl_seq + 2 == seqid &&
-	     nfs_allowskip_sessionseq != 0)) {
-		/*
-		 * Allowing the seqid to be ahead by 2 is technically
-		 * a violation of RFC5661, but it seems harmless to do
-		 * and avoids returning NFSERR_SEQMISORDERED to a
-		 * slightly broken Linux NFSv4.1/4.2 client.
-		 * If the RPCs are really out of order, one with a
-		 * lower seqid will be subsequently received and that
-		 * one will get a NFSERR_SEQMISORDERED reply.
-		 * Can be disabled by setting vfs.nfs.linuxseqsesshack to 0.
-		 */
+	} else if ((slots[slotid].nfssl_seq + 1) == seqid) {
 		if (slots[slotid].nfssl_reply != NULL)
 			m_freem(slots[slotid].nfssl_reply);
 		slots[slotid].nfssl_reply = NULL;
 		slots[slotid].nfssl_inprog = 1;
-		slots[slotid].nfssl_seq = seqid;
+		slots[slotid].nfssl_seq++;
 	} else
 		error = NFSERR_SEQMISORDERED;
 	return (error);