On 3/20/24 20:06, Josef Bacik wrote:
Btrfs had a deadlock that you could trigger by mmap'ing a large file and
using that as the buffer for fiemap. This test adds a c program to do
this, and the fstest creates a large enough file and then runs the
reproducer on the file. Without the fix btrfs deadlocks, with the fix
we pass fine.
Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
---
v2->v3:
- Add fiemap-fault to .gitignore
- Added a _cleanup() helper
- Just let the output of fiemap-fault go instead of using || _fail
- Added the munmap
- Moved $dst to $TEST_DIR/$seq
looks good.
Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
A minor whitespace error below, maybe Zorro can handle it when applied.
<snap>
diff --git a/tests/generic/808 b/tests/generic/808
new file mode 100755
index 00000000..36015f35
--- /dev/null
+++ b/tests/generic/808
@@ -0,0 +1,48 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2024 Meta Platforms, Inc. All Rights Reserved.
+#
+# FS QA Test 808
+#
+# Test fiemap into an mmaped buffer of the same file
+#
+# Create a reasonably large file, then run a program which mmaps it and uses
+# that as a buffer for an fiemap call. This is a regression test for btrfs
+# where we used to hold a lock for the duration of the fiemap call which would
+# result in a deadlock if we page faulted.
+#
+. ./common/preamble
+_begin_fstest quick auto fiemap
+[ $FSTYP == "btrfs" ] && \
+ _fixed_by_kernel_commit b0ad381fa769 \
+ "btrfs: fix deadlock with fiemap and extent locking"
+
+_cleanup()
+{
+ rm -f $dst
+ cd /
+ rm -r -f $tmp.*
+}
+
+# real QA test starts here
+_supported_fs generic
+_require_test
+_require_odirect
+_require_test_program fiemap-fault
+dst=$TEST_DIR/$seq/fiemap-fault
+
+mkdir -p $TEST_DIR/$seq
+
+echo "Silence is golden"
+
+for i in $(seq 0 2 1000)
+do
+ $XFS_IO_PROG -d -f -c "pwrite -q $((i * 4096)) 4096" $dst
+done
+
+$here/src/fiemap-fault $dst
+
+# success, all done
+status=$?
+exit
+
Applying: generic/808: add a regression test for fiemap into an mmap range
.git/rebase-apply/patch:177: new blank line at EOF.
+
warning: 1 line adds whitespace errors.
Thanks.
