[PATCH V2] xfs: Check if a direct write can result in a false ENOSPC error

[Chandan Babu R <chandan.babu@oracle.com>]

This commit adds a test to check if a direct write on a delalloc extent
present in CoW fork can result in a false ENOSPC error. The bug has been fixed
by upstream commit d62113303d691 ("xfs: Fix false ENOSPC when performing
direct write on a delalloc extent in cow fork").

Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
---
Changelog:
V1 -> V2:
  1. Use file blocks as units instead of bytes to specify file offsets.

 tests/xfs/553     | 65 +++++++++++++++++++++++++++++++++++++++++++++++
 tests/xfs/553.out |  9 +++++++
 2 files changed, 74 insertions(+)
 create mode 100755 tests/xfs/553
 create mode 100644 tests/xfs/553.out

diff --git a/tests/xfs/553 b/tests/xfs/553
new file mode 100755
index 00000000..ae52e9fc
--- /dev/null
+++ b/tests/xfs/553
@@ -0,0 +1,65 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2022 Oracle.  All Rights Reserved.
+#
+# FS QA Test 553
+#
+# Test to check if a direct write on a delalloc extent present in CoW fork can
+# result in an ENOSPC error.
+#
+. ./common/preamble
+_begin_fstest auto quick clone
+
+# Import common functions.
+. ./common/reflink
+. ./common/inject
+
+# real QA test starts here
+_supported_fs xfs
+_fixed_by_kernel_commit d62113303d691 \
+	"xfs: Fix false ENOSPC when performing direct write on a delalloc extent in cow fork"
+_require_scratch_reflink
+_require_xfs_debug
+_require_test_program "punch-alternating"
+_require_xfs_io_error_injection "bmap_alloc_minlen_extent"
+_require_xfs_io_command "reflink"
+_require_xfs_io_command "cowextsize"
+
+source=${SCRATCH_MNT}/source
+destination=${SCRATCH_MNT}/destination
+fragmented_file=${SCRATCH_MNT}/fragmented_file
+
+echo "Format and mount fs"
+_scratch_mkfs >> $seqres.full
+_scratch_mount >> $seqres.full
+
+blksz=$(_get_block_size $SCRATCH_MNT)
+
+echo "Create source file"
+$XFS_IO_PROG -f -c "pwrite 0 $((blksz * 8192))" $source >> $seqres.full
+
+echo "Reflink destination file with source file"
+$XFS_IO_PROG -f -c "reflink $source" $destination >> $seqres.full
+
+echo "Set destination file's cowextsize to 4096 blocks"
+$XFS_IO_PROG -c "cowextsize $((blksz * 4096))" $destination >> $seqres.full
+
+echo "Fragment FS"
+$XFS_IO_PROG -f -c "pwrite 0 $((blksz * 16384))" $fragmented_file >> $seqres.full
+sync
+$here/src/punch-alternating $fragmented_file >> $seqres.full
+
+echo "Inject bmap_alloc_minlen_extent error tag"
+_scratch_inject_error bmap_alloc_minlen_extent 1
+
+echo "Create delalloc extent of length 4096 blocks in destination file's CoW fork"
+$XFS_IO_PROG -c "pwrite 0 $blksz" $destination >> $seqres.full
+
+sync
+
+echo "Direct I/O write at 3rd block in destination file"
+$XFS_IO_PROG -d -c "pwrite $((blksz * 3)) $((blksz * 2))" $destination >> $seqres.full
+
+# success, all done
+status=0
+exit
diff --git a/tests/xfs/553.out b/tests/xfs/553.out
new file mode 100644
index 00000000..9f5679de
--- /dev/null
+++ b/tests/xfs/553.out
@@ -0,0 +1,9 @@
+QA output created by 553
+Format and mount fs
+Create source file
+Reflink destination file with source file
+Set destination file's cowextsize to 4096 blocks
+Fragment FS
+Inject bmap_alloc_minlen_extent error tag
+Create delalloc extent of length 4096 blocks in destination file's CoW fork
+Direct I/O write at 3rd block in destination file
-- 
2.35.1