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

[Catherine Hoang <catherine.hoang@oracle.com>]

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