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+#! /bin/bash
+# FSQA Test No. 113
+#
+# Test that truncating a file that consists of a compressed and inlined extent
+# to a smaller size and then cloning it into another file is not possible and
+# does not result in leaking stale data (data past the truncation offset) nor
+# losing data in the clone operation's destination file.
+#
+#-----------------------------------------------------------------------
+#
+# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
+# Author: Filipe Manana <fdmanana@suse.com>
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+tmp=/tmp/$$
+status=1 # failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+ cd /
+ rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_need_to_be_root
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+_require_cloner
+
+rm -f $seqres.full
+
+_scratch_mkfs >>$seqres.full 2>&1
+_scratch_mount "-o compress"
+
+# Create our test files. File foo is going to be the source of a clone operation
+# and consists of a single inline extent with an uncompressed size of 512 bytes,
+# while file bar consists of a single inline extent with an uncompressed size of
+# 256 bytes. For our test's purpose, it's important that file bar has an inline
+# extent with a size smaller than foo's inline extent.
+$XFS_IO_PROG -f -c "pwrite -S 0xa1 0 128" \
+ -c "pwrite -S 0x2a 128 384" \
+ $SCRATCH_MNT/foo | _filter_xfs_io
+$XFS_IO_PROG -f -c "pwrite -S 0xbb 0 256" $SCRATCH_MNT/bar | _filter_xfs_io
+
+# Now durably persist all metadata and data. We do this to make sure that we get
+# on disk an inline extent with a size of 512 bytes for file foo.
+sync
+
+# Now truncate our file foo to a smaller size. Because it consists of a
+# compressed and inline extent, btrfs did not shrink the inline extent to the
+# new size (if the extent was not compressed, btrfs would shrink it to 128
+# bytes), it only updates the inode's i_size to 128 bytes.
+$XFS_IO_PROG -c "truncate 128" $SCRATCH_MNT/foo
+
+# Now clone foo's inline extent into bar.
+# This clone operation should fail with errno EOPNOTSUPP because the source
+# file consists only of an inline extent and the file's size is smaller than
+# the inline extent of the destination (128 bytes < 256 bytes). However the
+# clone ioctl was not prepared to deal with a file that has a size smaller
+# than the size of its inline extent (something that happens only for compressed
+# inline extents), resulting in copying the full inline extent from the source
+# file into the destination file.
+#
+# Note that btrfs' clone operation for inline extents consists of removing the
+# inline extent from the destination inode and copy the inline extent from the
+# source inode into the destination inode, meaning that if the destination
+# inode's inline extent is larger (N bytes) than the source inode's inline
+# extent (M bytes), some bytes (N - M bytes) will be lost from the destination
+# file. Btrfs could copy the source inline extent's data into the destination's
+# inline extent so that we would not lose any data, but that's currently not
+# done due to the complexity that would be needed to deal with such cases
+# (specially when one or both extents are compressed), returning EOPNOTSUPP, as
+# it's normally not a very common case to clone very small files (only case
+# where we get inline extents) and copying inline extents does not save any
+# space (unlike for normal, non-inlined extents).
+$CLONER_PROG -s 0 -d 0 -l 0 $SCRATCH_MNT/foo $SCRATCH_MNT/bar
+
+# Now because the above clone operation used to succeed, and due to foo's inline
+# extent not being shinked by the truncate operation, our file bar got the whole
+# inline extent copied from foo, making us lose the last 128 bytes from bar
+# which got replaced by the bytes in range [128, 256[ from foo before foo was
+# truncated - in other words, data loss from bar and being able to read old and
+# stale data from foo that should not be possible to read anymore through normal
+# filesystem operations. Contrast with the case where we truncate a file from a
+# size N to a smaller size M, truncate it back to size N and then read the range
+# [M, N[, we should always get the value 0x00 for all the bytes in that range.
+
+# We expected the clone operation to fail with errno EOPNOTSUPP and therefore
+# not modify our file's bar data/metadata. So its content should be 256 bytes
+# long with all bytes having the value 0xbb.
+#
+# Without the btrfs bug fix, the clone operation succeeded and resulted in
+# leaking truncated data from foo, the bytes that belonged to its range
+# [128, 256[, and losing data from bar in that same range. So reading the
+# file gave us the following content:
+#
+# 0000000 a1 a1 a1 a1 a1 a1 a1 a1 a1 a1 a1 a1 a1 a1 a1 a1
+# *
+# 0000200 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a
+# *
+# 0000400
+echo "File bar's content after the clone operation:"
+od -t x1 $SCRATCH_MNT/bar
+
+# Also because the foo's inline extent was not shrunk by the truncate
+# operation, btrfs' fsck, which is run by the fstests framework everytime a
+# test completes, failed reporting the following error:
+#
+# root 5 inode 257 errors 400, nbytes wrong
+
+status=0
+exit
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@@ -0,0 +1,12 @@
+QA output created by 113
+wrote 128/128 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 384/384 bytes at offset 128
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 256/256 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+clone failed: Operation not supported
+File bar's content after the clone operation:
+0000000 bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
+*
+0000400
@@ -115,3 +115,4 @@
110 auto quick send
111 auto quick send
112 auto quick clone
+113 auto quick compress clone