Fix regression in SMB3 time handling
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Message ID CAH2r5mtrUgvc+mr04oeq9wQcmxUOSM-6PwBzL7XQ_Q9Z5V-BUw@mail.gmail.com
State New
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Series
  • Fix regression in SMB3 time handling
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Commit Message

Steve French Oct. 9, 2019, 1:26 a.m. UTC
Fixes xfstest 258 which regressed due to a recent change to add min/max time

Patch
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From ff93aba3e671bbde7d46a9b6e6af1136142e31e5 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Tue, 8 Oct 2019 00:27:14 -0500
Subject: [PATCH 1/3] smb3: Fix regression in time handling

Fixes: cb7a69e60590 ("cifs: Initialize filesystem timestamp ranges")

Only very old servers (e.g. OS/2 and DOS) did not support
DCE TIME (100 nanosecond granularity).  Fix the checks used
to set minimum and maximum times.

CC: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
---
 fs/cifs/cifsfs.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 2e9c7f493f99..45330b32f1bb 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -169,18 +169,26 @@  cifs_read_super(struct super_block *sb)
 	else
 		sb->s_maxbytes = MAX_NON_LFS;
 
-	/* BB FIXME fix time_gran to be larger for LANMAN sessions */
-	sb->s_time_gran = 100;
-
-	if (tcon->unix_ext) {
-		ts = cifs_NTtimeToUnix(0);
+	/* Some very old servers like DOS and OS/2 used 2 second granularity */
+	if ((tcon->ses->server->vals->protocol_id == SMB10_PROT_ID) &&
+	    ((tcon->ses->capabilities &
+	      tcon->ses->server->vals->cap_nt_find) == 0) &&
+	    !tcon->unix_ext) {
+		sb->s_time_gran = 2000000000; /* 2 seconds */
+		ts = cnvrtDosUnixTm(cpu_to_le16(SMB_DATE_MIN), 0, 0);
 		sb->s_time_min = ts.tv_sec;
-		ts = cifs_NTtimeToUnix(cpu_to_le64(S64_MAX));
+		ts = cnvrtDosUnixTm(cpu_to_le16(SMB_DATE_MAX),
+				    cpu_to_le16(SMB_TIME_MAX), 0);
 		sb->s_time_max = ts.tv_sec;
 	} else {
-		ts = cnvrtDosUnixTm(cpu_to_le16(SMB_DATE_MIN), 0, 0);
+		/*
+		 * Almost every server, including all SMB2+, uses DCE TIME
+		 * ie 100 nanosecond units, since 1601.  See MS-DTYP and MS-FSCC
+		 */
+		sb->s_time_gran = 100;
+		ts = cifs_NTtimeToUnix(0);
 		sb->s_time_min = ts.tv_sec;
-		ts = cnvrtDosUnixTm(cpu_to_le16(SMB_DATE_MAX), cpu_to_le16(SMB_TIME_MAX), 0);
+		ts = cifs_NTtimeToUnix(cpu_to_le64(S64_MAX));
 		sb->s_time_max = ts.tv_sec;
 	}
 
-- 
2.20.1