btrfs-progs: add test for offline filesystem resize

Add comprehensive test coverage for the new --offline resize feature.

The test suite covers:
- Valid resize operations: incremental (+1G, 1:+1G) and absolute (2G)
- Invalid operations that should fail: shrinking, multi-device, cancel
- Error conditions: invalid device IDs, malformed size arguments
- Option compatibility: --offline with --enqueue should be rejected
- Mount state validation: offline resize should fail on mounted filesystems

Each test creates temporary filesystem images, performs resize operations,
and verifies the resulting filesystem size matches expectations. Error
cases use run_mustfail to ensure proper failure handling.

Signed-off-by: Leo Martins <[email protected]>

Author: loemraw

tests/misc-tests/070-offline-resize/test.sh

@@ -0,0 +1,167 @@
+#!/bin/bash
+#
+# Test btrfs filesystem resize --offline functionality
+# Tests various resize operations on offline filesystems including:
+# - Incremental resize (+1G, 1:+1G)
+# - Absolute resize (2G)
+# - Invalid operations (multi-device, invalid syntax, shrinking)
+#
+
+source "$TEST_TOP/common" || exit
+
+check_prereq mkfs.btrfs
+check_prereq btrfs
+
+setup_root_helper
+
+_get_filesystem_size()
+{
+	local mount_point="$1"
+
+	size=$(run_check_stdout $SUDO_HELPER "$TOP/btrfs" filesystem usage -m "$mount_point" | \
+		grep "Device size:" | awk '{print $3}' | sed 's/\..*//')
+	echo "$size"
+}
+
+_create_backing_file()
+{
+	local path="$1"
+	local size_mb="$2"
+
+	run_check truncate -s "${size_mb}M" "$path"
+}
+
+# Test offline resize with incremental size (+1G)
+_log "Testing offline resize +1G"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_check "$TOP/btrfs" filesystem resize --offline "+1G" "$backing_file"
+
+TEST_DEV="$backing_file"
+run_check_mount_test_dev
+actual_size=$(_get_filesystem_size "$TEST_MNT")
+if [ "$actual_size" != "2048" ]; then
+	_fail "Size mismatch: expected 2048MiB, got ${actual_size}MiB"
+fi
+run_check_umount_test_dev
+rm -f "$backing_file"
+
+# Test offline resize with device-specific incremental size (1:+1G)
+_log "Testing offline resize 1:+1G"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_check "$TOP/btrfs" filesystem resize --offline "1:+1G" "$backing_file"
+
+TEST_DEV="$backing_file"
+run_check_mount_test_dev
+actual_size=$(_get_filesystem_size "$TEST_MNT")
+if [ "$actual_size" != "2048" ]; then
+	_fail "Size mismatch: expected 2048MiB, got ${actual_size}MiB"
+fi
+run_check_umount_test_dev
+rm -f "$backing_file"
+
+# Test offline resize with absolute size (2G)
+_log "Testing offline resize 2G"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_check "$TOP/btrfs" filesystem resize --offline "2G" "$backing_file"
+
+TEST_DEV="$backing_file"
+run_check_mount_test_dev
+actual_size=$(_get_filesystem_size "$TEST_MNT")
+if [ "$actual_size" != "2048" ]; then
+	_fail "Size mismatch: expected 2048MiB, got ${actual_size}MiB"
+fi
+run_check_umount_test_dev
+rm -f "$backing_file"
+
+# Test offline resize with invalid device id (2:+1G)
+_log "Testing offline resize with invalid device id 2:+1G"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_mustfail "offline resize should fail with invalid device id" \
+	"$TOP/btrfs" filesystem resize --offline "2:+1G" "$backing_file"
+rm -f "$backing_file"
+
+# Test offline resize with shrinking (not supported)
+_log "Testing offline resize with shrinking -10M"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_mustfail "offline resize should not support shrinking" \
+	"$TOP/btrfs" filesystem resize --offline "-10M" "$backing_file"
+rm -f "$backing_file"
+
+# Test offline resize with cancel (not supported)
+_log "Testing offline resize with cancel"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_mustfail "offline resize should not support cancel" \
+	"$TOP/btrfs" filesystem resize --offline "cancel" "$backing_file"
+rm -f "$backing_file"
+
+# Test offline resize with invalid size format
+_log "Testing offline resize with invalid size format 1:+1a"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_mustfail "offline resize should fail with invalid size format" \
+	"$TOP/btrfs" filesystem resize --offline "1:+1a" "$backing_file"
+rm -f "$backing_file"
+
+# Test offline resize on multi-device filesystem (should fail)
+_log "Testing offline resize on multi-device filesystem"
+backing_file1="$(_mktemp backing1)"
+backing_file2="$(_mktemp backing2)"
+
+_create_backing_file "$backing_file1" 1024
+_create_backing_file "$backing_file2" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file1" "$backing_file2"
+run_mustfail "offline resize should fail on multi-device filesystem" \
+	"$TOP/btrfs" filesystem resize --offline "+1G" "$backing_file1"
+
+rm -f "$backing_file1" "$backing_file2"
+
+# Test that --offline and --enqueue are incompatible
+_log "Testing that --offline and --enqueue are incompatible"
+backing_file="$(_mktemp backing)"
+_create_backing_file "$backing_file" 1024
+
+run_check "$TOP/mkfs.btrfs" -f "$backing_file"
+run_mustfail "--offline and --enqueue should be incompatible" \
+	"$TOP/btrfs" filesystem resize --offline --enqueue "+1G" "$backing_file"
+
+rm -f "$backing_file"
+
+# Test offline resize on mounted filesystem (should fail)
+_log "Testing offline resize on mounted filesystem"
+setup_loopdevs 1
+prepare_loopdevs
+
+dev="${loopdevs[1]}"
+run_check "$TOP/mkfs.btrfs" -f "$dev"
+
+TEST_DEV="$dev"
+run_check_mount_test_dev
+
+# Get the backing file path from the loop device
+backing_file=$(losetup -l "$dev" | tail -n1 | awk '{print $6}')
+run_mustfail "offline resize should fail on mounted filesystem" \
+	"$TOP/btrfs" filesystem resize --offline "+1G" "$backing_file"
+
+run_check_umount_test_dev
+cleanup_loopdevs