From: Filipe Manana <fdmanana@xxxxxxxx> Test that overwriting a file with mmap when the filesystem has no more space available for data allocation works. The motivation here is to check that NOCOW mode of a COW filesystem (such as btrfs) works as expected. This currently fails with btrfs but it's fixed by a kernel patch that has the subject: btrfs: fix -ENOSPC mmap write failure on NOCOW files/extents Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx> --- tests/generic/211 | 58 +++++++++++++++++++++++++++++++++++++++++++ tests/generic/211.out | 6 +++++ 2 files changed, 64 insertions(+) create mode 100755 tests/generic/211 create mode 100644 tests/generic/211.out diff --git a/tests/generic/211 b/tests/generic/211 new file mode 100755 index 00000000..c77508fe --- /dev/null +++ b/tests/generic/211 @@ -0,0 +1,58 @@ +#! /bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (c) 2025 SUSE Linux Products GmbH. All Rights Reserved. +# +# FS QA Test 211 +# +# Test that overwriting a file with mmap when the filesystem has no more space +# available for data allocation works. The motivation here is to check that +# NOCOW mode of a COW filesystem (such as btrfs) works as expected. +# +. ./common/preamble +_begin_fstest auto quick rw mmap + +. ./common/filter + +_require_scratch + +[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \ + "btrfs: fix -ENOSPC mmap write failure on NOCOW files/extents" + +# Use a 512M fs so that it's fast to fill it with data but not too small such +# that on btrfs it results in a fs with mixed block groups - we want to have +# dedicated block groups for data and metadata, so that after filling all the +# data block groups we can do a NOCOW write with mmap (if we have enough free +# metadata space available). +fs_size=$(_small_fs_size_mb 512) +_scratch_mkfs_sized $((fs_size * 1024 * 1024)) >>$seqres.full 2>&1 || \ + _fail "mkfs failed" +_scratch_mount + +touch $SCRATCH_MNT/foobar + +# Set the file to NOCOW mode on btrfs, which must be done while the file is +# empty, otherwise it fails. +if [ $FSTYP == "btrfs" ]; then + _require_chattr C + $CHATTR_PROG +C $SCRATCH_MNT/foobar +fi + +# Add initial data to the file we will later overwrite with mmap. +$XFS_IO_PROG -c "pwrite -S 0xab 0 1M" $SCRATCH_MNT/foobar | _filter_xfs_io + +# Now fill all the remaining space with data. +blksz=$(_get_block_size $SCRATCH_MNT) +dd if=/dev/zero of=$SCRATCH_MNT/filler bs=$blksz >>$seqres.full 2>&1 + +# Overwrite the file with a mmap write. Should succeed. +$XFS_IO_PROG -c "mmap -w 0 1M" \ + -c "mwrite -S 0xcd 0 1M" \ + -c "munmap" \ + $SCRATCH_MNT/foobar + +# Cycle mount and dump the file's content. We expect to see the new data. +_scratch_cycle_mount +_hexdump $SCRATCH_MNT/foobar + +# success, all done +_exit 0 diff --git a/tests/generic/211.out b/tests/generic/211.out new file mode 100644 index 00000000..71cdf0f8 --- /dev/null +++ b/tests/generic/211.out @@ -0,0 +1,6 @@ +QA output created by 211 +wrote 1048576/1048576 bytes at offset 0 +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +000000 cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd >................< +* +100000 -- 2.47.2
