| #! /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) |
| _try_scratch_mkfs_sized $((fs_size * 1024 * 1024)) >>$seqres.full 2>&1 || \ |
| _fail "mkfs failed" |
| _scratch_mount |
| _require_inplace_writes $SCRATCH_MNT |
| |
| touch $SCRATCH_MNT/foobar |
| _force_inplace_writes $SCRATCH_MNT/foobar |
| |
| # Add initial data to the file we will later overwrite with mmap. |
| $XFS_IO_PROG -c "pwrite -S 0xab 0 1M" $SCRATCH_MNT/foobar | _filter_xfs_io |
| |
| # Now fill all the remaining space with data. We use dd because we want to fill |
| # only data space in btrfs - creating files with __populate_fill_fs() would also |
| # fill metadata space. We want to exhaust data space on btrfs but still have |
| # metadata space available, as metadata is always COWed on btrfs, so that the |
| # mmap writes below succeed (metadata space available but no more data space |
| # available). |
| blksz=$(_get_file_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 |
