Fix truncate(2) mtime and ctime handling

On Linux, ftruncate(2) always changes the file timestamps, even if the file size is not changed. However, in case of a successfull truncate(2), the timestamps are updated only if the file size changes. This translates to the VFS calling the ZFS Posix Layer "setattr" function (zpl_setattr) with ATTR_MTIME and ATTR_CTIME unconditionally set on the iattr mask only when doing a ftruncate(2), while the truncate(2) is left to the filesystem implementation to be dealt with. This behaviour is consistent with POSIX:2004/SUSv3 specifications where there's no explicit requirement for file size changes to update the timestamps only for ftruncate(2): http://pubs.opengroup.org/onlinepubs/009695399/functions/truncate.html http://pubs.opengroup.org/onlinepubs/009695399/functions/ftruncate.html This has been later updated in POSIX:2008/SUSv4 where, for both truncate(2)/ftruncate(2), there's no mention of this size change requirement: http://austingroupbugs.net/view.php?id=489 http://pubs.opengroup.org/onlinepubs/9699919799/functions/truncate.html http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html Unfortunately the Linux VFS is still calling into the ZPL without ATTR_MTIME/ATTR_CTIME set in the truncate(2) case: we fix this by explicitly updating the timestamps when detecting the ATTR_SIZE bit, which is always set in do_truncate(), on the iattr mask. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: loli10K <ezomori.nozomu@gmail.com> Closes #6811 Closes #6819
2026-06-01 11:44:16 +03:00 · 2017-11-13 18:24:26 +01:00
parent 13042a6ccd
commit 99834d1950
7 changed files with 221 additions and 4 deletions
@@ -0,0 +1,74 @@
+#!/bin/ksh -p
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright 2017, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/truncate/truncate.cfg
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/include/math.shlib
+
+#
+# DESCRIPTION:
+# Ensure both truncate(2)/ftruncate(2) update target file mtime/ctime attributes
+#
+# STRATEGY:
+# 1. Create a file
+# 2. Truncate the file
+# 3. Verify both mtime/ctime are updated
+# 4. Rinse and repeat for both truncate(2) and ftruncate(2) with various sizes
+#
+
+verify_runnable "both"
+
+function verify_truncate # <filename> <filesize> <option>
+{
+	typeset filename="$1"
+	typeset -i size="$2"
+	typeset option="$3"
+
+	log_must mkfile $sizeavg $filename # always start with $sizeavg
+	typeset -i timestm="$(stat -c %Y $filename)"
+	typeset -i timestc="$(stat -c %Z $filename)"
+	log_must sleep 1
+	log_must $STF_SUITE/tests/functional/truncate/truncate_test -s $size $filename $option
+	verify_eq $size "$(stat -c %s $filename)" "size"
+	verify_ne $timestm "$(stat -c %Y $filename)" "mtime"
+	verify_ne $timestc "$(stat -c %Z $filename)" "ctime"
+	log_must rm -f $filename
+}
+
+function cleanup
+{
+	[[ -f $truncfile ]] && rm -f $truncfile
+}
+
+log_assert "Ensure both truncate(2)/ftruncate(2) update target file timestamps"
+log_onexit cleanup
+
+truncfile="$TESTDIR/truncate.$$"
+sizemin="123"
+sizeavg="$((256*1024))"
+sizemax="$((1024*1024))"
+
+# truncate(2)
+verify_truncate $truncfile $sizemin ""
+verify_truncate $truncfile $sizeavg ""
+verify_truncate $truncfile $sizemax ""
+
+# ftruncate(2)
+verify_truncate $truncfile $sizemin "-f"
+verify_truncate $truncfile $sizeavg "-f"
+verify_truncate $truncfile $sizemax "-f"
+
+log_pass "Successful truncation correctly update timestamps"