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+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2022 BingJing Chang.
+#
+# FS QA Test No. btrfs/278
+#
+# Regression test for btrfs incremental send issue when processing inodes
+# with no links
+#
+# This issue is fixed by the following linux kernel btrfs patch:
+#
+# commit 9ed0a72e5b355d ("btrfs: send: fix failures when processing
+# inodes with no links")
+#
+. ./common/preamble
+_begin_fstest auto quick send
+
+# real QA test starts here
+_supported_fs btrfs
+_fixed_by_kernel_commit 9ed0a72e5b355d \
+ "btrfs: send: fix failures when processing inodes with no links"
+_require_test
+_require_scratch
+_require_btrfs_command "property"
+_require_fssum
+
+send_files_dir=$TEST_DIR/btrfs-test-$seq
+
+rm -fr $send_files_dir
+mkdir $send_files_dir
+
+_scratch_mkfs >>$seqres.full 2>&1
+_scratch_mount
+_run_btrfs_util_prog subvolume create $SCRATCH_MNT/vol
+
+# Creating the first snapshot looks like:
+#
+# . (ino 256)
+# |--- deleted.file (ino 257)
+# |--- deleted.dir/ (ino 258)
+# |--- changed_subcase1.file (ino 259)
+# |--- changed_subcase2.file (ino 260)
+# |--- changed_subcase1.dir/ (ino 261)
+# | |---- foo (ino 262)
+# |--- changed_subcase2.dir/ (ino 263)
+# | |---- foo (ino 264)
+#
+touch $SCRATCH_MNT/vol/deleted.file
+mkdir $SCRATCH_MNT/vol/deleted.dir
+touch $SCRATCH_MNT/vol/changed_subcase1.file
+touch $SCRATCH_MNT/vol/changed_subcase2.file
+mkdir $SCRATCH_MNT/vol/changed_subcase1.dir
+touch $SCRATCH_MNT/vol/changed_subcase1.dir/foo
+mkdir $SCRATCH_MNT/vol/changed_subcase2.dir
+touch $SCRATCH_MNT/vol/changed_subcase2.dir/foo
+_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT/vol $SCRATCH_MNT/snap1
+
+# Delete the deleted.*, create a new file and a new directory, and then
+# take the second snapshot looks like:
+#
+# . (ino 256)
+# |--- changed_subcase1.file (ino 259)
+# |--- changed_subcase2.file (ino 260)
+# |--- changed_subcase1.dir/ (ino 261)
+# | |---- foo (ino 262)
+# |--- changed_subcase2.dir/ (ino 263)
+# | |---- foo (ino 264)
+# |--- new.file (ino 265)
+# |--- new.dir/ (ino 266)
+#
+unlink $SCRATCH_MNT/vol/deleted.file
+rmdir $SCRATCH_MNT/vol/deleted.dir
+touch $SCRATCH_MNT/vol/new.file
+mkdir $SCRATCH_MNT/vol/new.dir
+_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT/vol $SCRATCH_MNT/snap2
+
+# Set the snapshot "snap1" to read-write mode and turn several inodes to
+# orphans, so that the snapshot will look like this:
+#
+# . (ino 256)
+# |--- (orphan) deleted.file (ino 257)
+# |--- (orphan) deleted.dir/ (ino 258)
+# |--- (orphan) changed_subcase1.file (ino 259)
+# |--- changed_subcase2.file (ino 260)
+# |--- (orphan) changed_subcase1.dir/ (ino 261)
+# |--- changed_subcase2.dir/ (ino 263)
+# | |---- foo (ino 264)
+#
+# Note: To make an easy illustration, I just put a tag "(orphan)" in front of
+# their original names to indicate that they're deleted, but their inodes can
+# not be removed because of open file descriptors on them. Mention that orphan
+# inodes don't have names(paths).
+#
+$BTRFS_UTIL_PROG property set $SCRATCH_MNT/snap1 ro false
+exec 71<$SCRATCH_MNT/snap1/deleted.file
+exec 72<$SCRATCH_MNT/snap1/deleted.dir
+exec 73<$SCRATCH_MNT/snap1/changed_subcase1.file
+exec 74<$SCRATCH_MNT/snap1/changed_subcase1.dir
+unlink $SCRATCH_MNT/snap1/deleted.file
+rmdir $SCRATCH_MNT/snap1/deleted.dir
+unlink $SCRATCH_MNT/snap1/changed_subcase1.file
+unlink $SCRATCH_MNT/snap1/changed_subcase1.dir/foo
+rmdir $SCRATCH_MNT/snap1/changed_subcase1.dir
+
+# Turn the snapshot "snap1" back to read-only mode.
+$BTRFS_UTIL_PROG property set $SCRATCH_MNT/snap1 ro true
+
+# Set the snapshot "snap2" to read-write mode and turn several inodes to
+# orphans, so that the snapshot will look like this:
+#
+# . (ino 256)
+# |--- (orphan) changed_subcase1.file (ino 259)
+# |--- (orphan) changed_subcase2.file (ino 260)
+# |--- (orphan) changed_subcase1.dir/ (ino 261)
+# |--- (orphan) changed_subcase2.dir/ (ino 263)
+# |--- (orphan) new.file (ino 265)
+# |--- (orphan) new.dir/ (ino 266)
+#
+# Note: Same notice as above. Mention that orphan inodes don't have
+# names(paths).
+#
+$BTRFS_UTIL_PROG property set $SCRATCH_MNT/snap2 ro false
+exec 81<$SCRATCH_MNT/snap2/changed_subcase1.file
+exec 82<$SCRATCH_MNT/snap2/changed_subcase1.dir
+exec 83<$SCRATCH_MNT/snap2/changed_subcase2.file
+exec 84<$SCRATCH_MNT/snap2/changed_subcase2.dir
+exec 85<$SCRATCH_MNT/snap2/new.file
+exec 86<$SCRATCH_MNT/snap2/new.dir
+unlink $SCRATCH_MNT/snap2/changed_subcase1.file
+unlink $SCRATCH_MNT/snap2/changed_subcase1.dir/foo
+rmdir $SCRATCH_MNT/snap2/changed_subcase1.dir
+unlink $SCRATCH_MNT/snap2/changed_subcase2.file
+unlink $SCRATCH_MNT/snap2/changed_subcase2.dir/foo
+rmdir $SCRATCH_MNT/snap2/changed_subcase2.dir
+unlink $SCRATCH_MNT/snap2/new.file
+rmdir $SCRATCH_MNT/snap2/new.dir
+
+# Turn the snapshot "snap2" back to read-only mode.
+$BTRFS_UTIL_PROG property set $SCRATCH_MNT/snap2 ro true
+
+# Test that a full send operation can handle orphans with no paths
+_run_btrfs_util_prog send -f $send_files_dir/1.snap $SCRATCH_MNT/snap1
+
+# Test that an incremental send operation can handle orphans.
+#
+# Here're descriptions for the details:
+#
+# Case 1: new.file and new.dir (BTRFS_COMPARE_TREE_NEW)
+# | send snapshot | action
+# --------------------------------
+# nlink | 0 | ignore
+#
+# They are new inodes in the send snapshot ("snap2"), but they don't have
+# paths because they have no links. Test that the send operation can ignore
+# them in order not to generate the creation commands for them. Or it will
+# fail, with -ENOENT, when trying to generate paths for them.
+#
+#
+# Case 2: deleted.file and deleted.dir (BTRFS_COMPARE_TREE_DELETED)
+# | parent snapshot | action
+# ----------------------------------
+# nlink | 0 | as usual
+#
+# They're deleted in the parent snapshot ("snap1") but become orphans which
+# have no paths. Test that no deletion commands will be generated as usual.
+# This case didn't fail before.
+#
+#
+# Case 3: changed_*.file and changed_*.dir (BTRFS_COMPARE_TREE_CHANGED)
+# | | parent snapshot | send snapshot | action
+# -----------------------------------------------------------------------
+# subcase 1 | nlink | 0 | 0 | ignore
+# subcase 2 | nlink | >0 | 0 | new_gen(deletion)
+#
+# In subcase 1, test that the send operation can ignore them without trying
+# to generate any commands.
+#
+# In subcase 2, test that the send operation can generate an unlink command
+# for that file and test that it can generate a rename command for the
+# non-empty directory first and a rmdir command to remove it finally. Or
+# the receive operation will fail with a wrong unlink on a non-empty
+# directory.
+#
+_run_btrfs_util_prog send -p $SCRATCH_MNT/snap1 -f $send_files_dir/2.snap \
+ $SCRATCH_MNT/snap2
+
+$FSSUM_PROG -A -f -w $send_files_dir/1.fssum $SCRATCH_MNT/snap1
+$FSSUM_PROG -A -f -w $send_files_dir/2.fssum \
+ -x $SCRATCH_MNT/snap2/snap1 $SCRATCH_MNT/snap2
+
+# Recreate the filesystem by receiving both send streams and verify we get
+# the same content that the original filesystem had.
+exec 71>&-
+exec 72>&-
+exec 73>&-
+exec 74>&-
+exec 81>&-
+exec 82>&-
+exec 83>&-
+exec 84>&-
+exec 85>&-
+exec 86>&-
+_scratch_unmount
+_scratch_mkfs >>$seqres.full 2>&1
+_scratch_mount
+
+# Add the first snapshot to the new filesystem by applying the first send
+# stream.
+_run_btrfs_util_prog receive -f $send_files_dir/1.snap $SCRATCH_MNT
+
+# Test the incremental send stream
+_run_btrfs_util_prog receive -f $send_files_dir/2.snap $SCRATCH_MNT
+
+$FSSUM_PROG -r $send_files_dir/1.fssum $SCRATCH_MNT/snap1
+$FSSUM_PROG -r $send_files_dir/2.fssum $SCRATCH_MNT/snap2
+
+status=0
+exit
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+QA output created by 278
+OK
+OK