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Fix lseek(SEEK_DATA/SEEK_HOLE) mmap consistency

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When using lseek(2) to report data/holes memory mapped regions of
the file were ignored.  This could result in incorrect results.
To handle this zfs_holey_common() was updated to asynchronously
writeback any dirty mmap(2) regions prior to reporting holes.

Additionally, while not strictly required, the dn_struct_rwlock is
now held over the dirty check to prevent the dnode structure from
changing.  This ensures that a clean dnode can't be dirtied before
the data/hole is located.  The range lock is now also taken to
ensure the call cannot race with zfs_write().

Furthermore, the code was refactored to provide a dnode_is_dirty()
helper function which checks the dnode for any dirty records to
determine its dirtiness.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Rich Ercolani <rincebrain@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #11900
Closes #12724
This commit is contained in:
Brian Behlendorf
2021-11-07 13:27:44 -08:00
committed by Tony Hutter
parent 5bf81fea2f
commit 664d487a5d
18 changed files with 305 additions and 32 deletions
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tests/zfs-tests/tests/functional/mmap/Makefile.am
+2 -1
View File
@@ -4,7 +4,8 @@ dist_pkgdata_SCRIPTS = \
cleanup.ksh \
mmap_read_001_pos.ksh \
mmap_write_001_pos.ksh \
mmap_libaio_001_pos.ksh
mmap_libaio_001_pos.ksh \
mmap_seek_001_pos.ksh
dist_pkgdata_DATA = \
mmap.cfg
tests/zfs-tests/tests/functional/mmap/mmap_seek_001_pos.ksh
Executable
+67
View File
@@ -0,0 +1,67 @@
#!/bin/ksh -p
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
#
# Copyright (c) 2021 by Lawrence Livermore National Security, LLC.
#
. $STF_SUITE/include/libtest.shlib
. $STF_SUITE/tests/functional/mmap/mmap.cfg
#
# DESCRIPTION:
# lseek() data/holes for an mmap()'d file.
#
# STRATEGY:
# 1. Enable compression and hole reporting for dirty files.
# 2. Call mmap_seek binary test case for various record sizes.
#
verify_runnable "global"
function cleanup
{
log_must zfs set compression=off $TESTPOOL/$TESTFS
log_must zfs set recordsize=128k $TESTPOOL/$TESTFS
log_must rm -f $TESTDIR/test-mmap-file
log_must set_tunable64 DMU_OFFSET_NEXT_SYNC $dmu_offset_next_sync
}
log_assert "lseek() data/holes for an mmap()'d file."
log_onexit cleanup
# Enable hole reporting for dirty files.
typeset dmu_offset_next_sync=$(get_tunable DMU_OFFSET_NEXT_SYNC)
log_must set_tunable64 DMU_OFFSET_NEXT_SYNC 1
# Compression must be enabled to convert zero'd blocks to holes.
# This behavior is checked by the mmap_seek test.
log_must zfs set compression=on $TESTPOOL/$TESTFS
for bs in 4096 8192 16384 32768 65536 131072; do
log_must zfs set recordsize=$bs $TESTPOOL/$TESTFS
log_must mmap_seek $TESTDIR/test-mmap-file $((1024*1024)) $bs
log_must rm $TESTDIR/test-mmap-file
done
log_pass "lseek() data/holes for an mmap()'d file succeeded."