2 # SPDX-License-Identifier: GPL-2.0
3 # Copyright (C) 2014 SUSE Linux Products GmbH. All Rights Reserved.
7 # Regression test for a btrfs issue where if right after the snapshot creation
8 # ioctl started, a file write followed by a file truncate happened, with both
9 # operations increasing the file's size, the created snapshot would capture an
10 # inconsistent state of the file system tree. That state reflected the file
11 # truncation but it didn't reflect the write operation, and left a gap between
12 # two file extent items (and that gap corresponded to the total or a partial
13 # area of the write operation's range).
15 # This issue was fixed by the following linux kernel patch:
17 # Btrfs: fix snapshot inconsistency after a file write followed by truncate
20 seqres=$RESULT_DIR/$seq
21 echo "QA output created by $seq"
23 status=1 # failure is the default!
24 trap "_cleanup; exit \$status" 0 1 2 3 15
28 for p in ${cpu_stress_pids[*]}; do
34 # get standard environment, filters and checks
38 # real QA test starts here
41 _require_scratch_nocheck
47 local ts=`date +'%H_%M_%S_%N'`
49 _run_btrfs_util_prog subvolume snapshot -r \
50 $SCRATCH_MNT $SCRATCH_MNT/"${ts}_snap"
57 run_check $XFS_IO_PROG -f \
58 -c "pwrite -S 0xaa -b 32K 0 32K" \
60 -c "pwrite -S 0xbb -b 32770 16K 32770" \
77 if [ $create_ret != 0 -o $snap_ret != 0 ]; then
78 _fail "Failure creating file or snapshot, check $seqres.full for details"
82 # If the installed btrfs mkfs supports the no-holes feature, make sure the
83 # created fs doesn't get that feature enabled. With it enabled, the below fsck
84 # call wouldn't fail. This feature hasn't been enabled by default since it was
85 # introduced, but be safe and explicitly disable it.
86 _scratch_mkfs -O list-all 2>&1 | grep -q '\bno\-holes\b'
88 mkfs_options="-O ^no-holes"
90 _scratch_mkfs "$mkfs_options" >>$seqres.full 2>&1
94 # Run some background load in order to make the issue easier to trigger.
95 # Specially needed when testing with non-debug kernels and there isn't
96 # any other significant load on the test machine other than this test.
97 num_cpus=`$here/src/feature -o`
98 num_procs=$(($num_cpus * 20))
99 for ((i = 0; i < $num_procs; i++)); do
103 cpu_stress_pids[$i]=$!
106 for ((i = 1; i <= 100; i++)); do
110 for ((i = 0; i < $num_procs; i++)); do
111 kill ${cpu_stress_pids[$i]} &> /dev/null
112 unset cpu_stress_pids[$i]
115 for f in $(find $SCRATCH_MNT -type f -name 'foobar_*'); do
116 digest=`md5sum $f | cut -d ' ' -f 1`
118 "d41d8cd98f00b204e9800998ecf8427e")
121 "c28418534a020122aca59fd3ff9581b5")
122 # ok, only first write captured
124 "cd0032da89254cdc498fda396e6a9b54")
125 # ok, only 2 first writes captured
127 "a1963f914baf4d2579d643425f4e54bc")
128 # ok, the 2 writes and the truncate were captured
131 # not ok, truncate captured but not one or both writes
132 _fail "Unexpected digest for file $f"
136 # Check the filesystem for inconsistencies.
137 # Before the btrfs kernel fix mentioned above, we would very often get fsck
138 # error messages like: "root 306 inode 338 errors 100, file extent discount".
140 # This was because if right after the snapshot creation ioctl started, a file
141 # write followed by a file truncate, with both operations increasing the file's
142 # size, we would get a snapshot that reflected a state where the file truncation
143 # was visible but the previous file write was not visible, breaking expected
144 # total ordering of operations and causing a gap between 2 file extents, where a
145 # file extent item representing the range [32K .. ALIGN(16K + 32770, 4096)] was
146 # missing in the snapshot's btree.
149 echo "Silence is golden"