[PATCH v5] generic: add a test for atomic writes

Catherine Hoang
2025-04-10T04:23:24Z

Add a test to validate the new atomic writes feature.

Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
Reviewed-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@gmail.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
---
common/rc | 51 ++++++++++++
tests/generic/765 | 188 ++++++++++++++++++++++++++++++++++++++++++
tests/generic/765.out | 2 +
3 files changed, 241 insertions(+)
create mode 100755 tests/generic/765
create mode 100644 tests/generic/765.out

diff --git a/common/rc b/common/rc
index 16d627e1..25e6a1f7 100644
--- a/common/rc
+++ b/common/rc
@@ -2996,6 +2996,10 @@ _require_xfs_io_command()
opts+=" -d"
pwrite_opts+="-V 1 -b 4k"
fi
+ if [ "$param" == "-A" ]; then
+ opts+=" -d"
+ pwrite_opts+="-D -V 1 -b 4k"
+ fi
testio=`$XFS_IO_PROG -f $opts -c \
"pwrite $pwrite_opts $param 0 4k" $testfile 2>&1`
param_checked="$pwrite_opts $param"
@@ -5443,6 +5447,53 @@ _require_scratch_btime()
_scratch_unmount
}

+_get_atomic_write_unit_min()
+{
+ $XFS_IO_PROG -c "statx -r -m $STATX_WRITE_ATOMIC" $1 | \
+ grep atomic_write_unit_min | grep -o '[0-9]\+'
+}
+
+_get_atomic_write_unit_max()
+{
+ $XFS_IO_PROG -c "statx -r -m $STATX_WRITE_ATOMIC" $1 | \
+ grep atomic_write_unit_max | grep -o '[0-9]\+'
+}
+
+_get_atomic_write_segments_max()
+{
+ $XFS_IO_PROG -c "statx -r -m $STATX_WRITE_ATOMIC" $1 | \
+ grep atomic_write_segments_max | grep -o '[0-9]\+'
+}
+
+_require_scratch_write_atomic()
+{
+ _require_scratch
+
+ export STATX_WRITE_ATOMIC=0x10000
+
+ awu_min_bdev=$(_get_atomic_write_unit_min $SCRATCH_DEV)
+ awu_max_bdev=$(_get_atomic_write_unit_max $SCRATCH_DEV)
+
+ if [ $awu_min_bdev -eq 0 ] && [ $awu_max_bdev -eq 0 ]; then
+ _notrun "write atomic not supported by this block device"
+ fi
+
+ _scratch_mkfs > /dev/null 2>&1
+ _scratch_mount
+
+ testfile=$SCRATCH_MNT/testfile
+ touch $testfile
+
+ awu_min_fs=$(_get_atomic_write_unit_min $testfile)
+ awu_max_fs=$(_get_atomic_write_unit_max $testfile)
+
+ _scratch_unmount
+
+ if [ $awu_min_fs -eq 0 ] && [ $awu_max_fs -eq 0 ]; then
+ _notrun "write atomic not supported by this filesystem"
+ fi
+}
+
_require_inode_limits()
{
if [ $(_get_free_inode $TEST_DIR) -eq 0 ]; then
diff --git a/tests/generic/765 b/tests/generic/765
new file mode 100755
index 00000000..9bab3b8a
--- /dev/null
+++ b/tests/generic/765
@@ -0,0 +1,188 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 Oracle. All Rights Reserved.
+#
+# FS QA Test 765
+#
+# Validate atomic write support
+#
+. ./common/preamble
+_begin_fstest auto quick rw
+
+_require_scratch_write_atomic
+_require_xfs_io_command pwrite -A
+
+get_supported_bsize()
+{
+ case "$FSTYP" in
+ "xfs")
+ min_bsize=1024
+ for ((i = 65536; i >= 1024; i /= 2)); do
+ _scratch_mkfs -b size=$i >> $seqres.full || continue
+ if _try_scratch_mount >> $seqres.full 2>&1; then
+ max_bsize=$i
+ _scratch_unmount
+ break;
+ fi
+ done
+ ;;
+ "ext4")
+ min_bsize=1024
+ max_bsize=4096
+ ;;
+ *)
+ _notrun "$FSTYP does not support atomic writes"
+ ;;
+ esac
+}
+
+get_mkfs_opts()
+{
+ local bsize=$1
+
+ case "$FSTYP" in
+ "xfs")
+ mkfs_opts="-b size=$bsize"
+ ;;
+ "ext4")
+ mkfs_opts="-b $bsize"
+ ;;
+ *)
+ _notrun "$FSTYP does not support atomic writes"
+ ;;
+ esac
+}
+
+test_atomic_writes()
+{
+ local bsize=$1
+
+ get_mkfs_opts $bsize
+ _scratch_mkfs $mkfs_opts >> $seqres.full
+ _scratch_mount
+
+ test "$FSTYP" = "xfs" && _xfs_force_bdev data $SCRATCH_MNT
+
+ testfile=$SCRATCH_MNT/testfile
+ touch $testfile
+
+ file_min_write=$(_get_atomic_write_unit_min $testfile)
+ file_max_write=$(_get_atomic_write_unit_max $testfile)
+ file_max_segments=$(_get_atomic_write_segments_max $testfile)
+
+ # Check that atomic min/max = FS block size
+ test $file_min_write -eq $bsize || \
+ echo "atomic write min $file_min_write, should be fs block size $bsize"
+ test $file_min_write -eq $bsize || \
+ echo "atomic write max $file_max_write, should be fs block size $bsize"
+ test $file_max_segments -eq 1 || \
+ echo "atomic write max segments $file_max_segments, should be 1"
+
+ # Check that we can perform an atomic write of len = FS block size
+ bytes_written=$($XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 0 $bsize" $testfile | \
+ grep wrote | awk -F'[/ ]' '{print $2}')
+ test $bytes_written -eq $bsize || echo "atomic write len=$bsize failed"
+
+ # Check that we can perform an atomic single-block cow write
+ if [ "$FSTYP" == "xfs" ]; then
+ testfile_cp=$SCRATCH_MNT/testfile_copy
+ if _xfs_has_feature $SCRATCH_MNT reflink; then
+ cp --reflink $testfile $testfile_cp
+ fi
+ bytes_written=$($XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 0 $bsize" $testfile_cp | \
+ grep wrote | awk -F'[/ ]' '{print $2}')
+ test $bytes_written -eq $bsize || echo "atomic write on reflinked file failed"
+ fi
+
+ # Check that we can perform an atomic write on an unwritten block
+ $XFS_IO_PROG -c "falloc $bsize $bsize" $testfile
+ bytes_written=$($XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize $bsize $bsize" $testfile | \
+ grep wrote | awk -F'[/ ]' '{print $2}')
+ test $bytes_written -eq $bsize || echo "atomic write to unwritten block failed"
+
+ # Check that we can perform an atomic write on a sparse hole
+ $XFS_IO_PROG -c "fpunch 0 $bsize" $testfile
+ bytes_written=$($XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 0 $bsize" $testfile | \
+ grep wrote | awk -F'[/ ]' '{print $2}')
+ test $bytes_written -eq $bsize || echo "atomic write to sparse hole failed"
+
+ # Check that we can perform an atomic write on a fully mapped block
+ bytes_written=$($XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 0 $bsize" $testfile | \
+ grep wrote | awk -F'[/ ]' '{print $2}')
+ test $bytes_written -eq $bsize || echo "atomic write to mapped block failed"
+
+ # Reject atomic write if len is out of bounds
+ $XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 0 $((bsize - 1))" $testfile 2>> $seqres.full && \
+ echo "atomic write len=$((bsize - 1)) should fail"
+ $XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 0 $((bsize + 1))" $testfile 2>> $seqres.full && \
+ echo "atomic write len=$((bsize + 1)) should fail"
+
+ # Reject atomic write when iovecs > 1
+ $XFS_IO_PROG -dc "pwrite -A -D -V2 -b $bsize 0 $bsize" $testfile 2>> $seqres.full && \
+ echo "atomic write only supports iovec count of 1"
+
+ # Reject atomic write when not using direct I/O
+ $XFS_IO_PROG -c "pwrite -A -V1 -b $bsize 0 $bsize" $testfile 2>> $seqres.full && \
+ echo "atomic write requires direct I/O"
+
+ # Reject atomic write when offset % bsize != 0
+ $XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 1 $bsize" $testfile 2>> $seqres.full && \
+ echo "atomic write requires offset to be aligned to bsize"
+
+ _scratch_unmount
+}
+
+test_atomic_write_bounds()
+{
+ local bsize=$1
+
+ get_mkfs_opts $bsize
+ _scratch_mkfs $mkfs_opts >> $seqres.full
+ _scratch_mount
+
+ test "$FSTYP" = "xfs" && _xfs_force_bdev data $SCRATCH_MNT
+
+ testfile=$SCRATCH_MNT/testfile
+ touch $testfile
+
+ $XFS_IO_PROG -dc "pwrite -A -D -V1 -b $bsize 0 $bsize" $testfile 2>> $seqres.full && \
+ echo "atomic write should fail when bsize is out of bounds"
+
+ _scratch_unmount
+}
+
+sys_min_write=$(cat "/sys/block/$(_short_dev $SCRATCH_DEV)/queue/atomic_write_unit_min_bytes")
+sys_max_write=$(cat "/sys/block/$(_short_dev $SCRATCH_DEV)/queue/atomic_write_unit_max_bytes")
+
+bdev_min_write=$(_get_atomic_write_unit_min $SCRATCH_DEV)
+bdev_max_write=$(_get_atomic_write_unit_max $SCRATCH_DEV)
+
+# Test that statx atomic values are the same as sysfs values
+if [ "$sys_min_write" -ne "$bdev_min_write" ]; then
+ echo "bdev min write != sys min write"
+fi
+if [ "$sys_max_write" -ne "$bdev_max_write" ]; then
+ echo "bdev max write != sys max write"
+fi
+
+get_supported_bsize
+
+# Test all supported block sizes between bdev min and max
+for ((bsize=$bdev_min_write; bsize<=bdev_max_write; bsize*=2)); do
+ if [ "$bsize" -ge "$min_bsize" ] && [ "$bsize" -le "$max_bsize" ]; then
+ test_atomic_writes $bsize
+ fi
+done;
+
+# Check that atomic write fails if bsize < bdev min or bsize > bdev max
+if [ $((bdev_min_write / 2)) -ge "$min_bsize" ]; then
+ test_atomic_write_bounds $((bdev_min_write / 2))
+fi
+if [ $((bdev_max_write * 2)) -le "$max_bsize" ]; then
+ test_atomic_write_bounds $((bdev_max_write * 2))
+fi
+
+# success, all done
+echo Silence is golden
+status=0
+exit
diff --git a/tests/generic/765.out b/tests/generic/765.out
new file mode 100644
index 00000000..39c254ae
--- /dev/null
+++ b/tests/generic/765.out
@@ -0,0 +1,2 @@
+QA output created by 765
+Silence is golden
--
2.34.1