| Message ID | 20240415081054.1782715-1-mcgrof@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [RFC] fstests: add mmap page boundary tests | expand |
On Mon, Apr 15, 2024 at 01:10:54AM -0700, Luis Chamberlain wrote: > mmap() POSIX compliance says we should zero fill data beyond a file > size up to page boundary, and issue a SIGBUS if we go beyond. While fsx > helps us test zero-fill sometimes, fsstress also let's us sometimes test > for SIGBUS however that is based on a random value and its not likley we > always test it. Dedicate a specic test for this to make testing for > this specific situation and to easily expand on other corner cases. > > Suggested-by: Matthew Wilcox <willy@infradead.org> > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > > Does enough to get us to use to test this, however I'm aware of a bit > more polishing up to do: > > * maybe moving mread to common as generic/574 did it first > * sharing round_up_to_page_boundary() as well > > generic/574 is special, it was just testing for correctness of > integrity if we muck with mmap() however if you don't have verity > stuff available obviously you won't end up testing it. > > This generalizes mmap() zero-fill and SIGBUS corner case tests. > > I've tested so far only 4k and it works well there. For 16k bs on LBS > just the SIGBUS issue exists, I'll test smaller block sizes later like > 512, 1k, 2k as well. We'll fix triggering the SIBGUS when LBS is used, > we'll address that in the next iteration. > > Is this a worthy test as a generic test? > > common/filter | 6 ++ > tests/generic/740 | 231 ++++++++++++++++++++++++++++++++++++++++++ > tests/generic/740.out | 2 + > 3 files changed, 239 insertions(+) > create mode 100755 tests/generic/740 > create mode 100644 tests/generic/740.out > > diff --git a/common/filter b/common/filter > index 36d51bd957dd..d7add06f3be7 100644 > --- a/common/filter > +++ b/common/filter > @@ -194,6 +194,12 @@ _filter_xfs_io_unique() > common_line_filter | _filter_xfs_io > } > > +_filter_xfs_io_data_unique() > +{ > + _filter_xfs_io_offset | sed -e 's| |\n|g' | egrep -v "\.|XX|\*" | \ > + sort | uniq | tr -d '\n' > +} > + > _filter_xfs_io_units_modified() > { > UNIT=$1 > diff --git a/tests/generic/740 b/tests/generic/740 > new file mode 100755 > index 000000000000..cbb823014600 > --- /dev/null > +++ b/tests/generic/740 > @@ -0,0 +1,231 @@ > +#! /bin/bash > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (c) Luis Chamberlain. All Rights Reserved. > +# > +# FS QA Test 740 > +# > +# As per POSIX NOTES mmap(2) maps multiples of the system page size, but if the > +# data mapped is not multiples of the page size the remaining bytes are zeroed > +# out when mapped and modifications to that region are not written to the file. > +# On Linux when you write data to such partial page after the end of the > +# object, the data stays in the page cache even after the file is closed and > +# unmapped and even though the data is never written to the file itself, > +# subsequent mappings may see the modified content. If you go *beyond* this > +# page, you should get a SIGBUS. This test verifies we zero-fill to page > +# boundary and ensures we get a SIGBUS if we write to data beyond the system > +# page size even if the block size is greater than the system page size. > +. ./common/preamble > +. ./common/rc > +_begin_fstest auto quick > + > +# Override the default cleanup function. > +_cleanup() > +{ > + cd / > + rm -r -f $tmp.* > +} > + > +# Import common functions. > +. ./common/filter > + > +# real QA test starts here > +_supported_fs generic > +_require_scratch_nocheck > +_require_test > + > +setup_zeroed_file() > +{ > + local file_len=$1 > + local sparse=$2 > + > + if $sparse; then > + $XFS_IO_PROG -f -c "truncate $file_len" $test_file > + else > + $XFS_IO_PROG -f -c "falloc 0 $file_len" $test_file > + fi > +} > + > +round_up_to_page_boundary() > +{ > + local n=$1 > + local page_size=$(_get_page_size) > + > + echo $(( (n + page_size - 1) & ~(page_size - 1) )) Does iomap put a large folio into the pagecache that crosses EOF, or does it back down to base page size? > +} > + > +mread() > +{ > + local file=$1 > + local map_len=$2 > + local offset=$3 > + local length=$4 > + > + # Some callers expect xfs_io to crash with SIGBUS due to the mread, > + # causing the shell to print "Bus error" to stderr. To allow this > + # message to be redirected, execute xfs_io in a new shell instance. > + # However, for this to work reliably, we also need to prevent the new > + # shell instance from optimizing out the fork and directly exec'ing > + # xfs_io. The easiest way to do that is to append 'true' to the > + # commands, so that xfs_io is no longer the last command the shell sees. > + bash -c "trap '' SIGBUS; $XFS_IO_PROG -r $file \ > + -c 'mmap -r 0 $map_len' \ > + -c 'mread $offset $length'; true" Please hoist the mread() function with generic/574 to common; your copy is out of date with the original. > +} > + > +do_mmap_tests() > +{ > + local block_size=$1 > + local file_len=$2 > + local offset=$3 > + local len=$4 > + local use_sparse_file=${5:-false} > + local new_filelen=0 > + local map_len=0 > + local csum=0 > + local fs_block_size=$(_get_block_size $SCRATCH_MNT) > + > + echo -en "\n\n==> Testing blocksize $block_size " >> $seqres.full > + echo -en "file_len: $file_len offset: $offset " >> $seqres.full > + echo -e "len: $len sparse: $use_sparse_file" >> $seqres.full > + > + if ((fs_block_size != block_size)); then > + echo "Block size created ($block_size) doesn't match _get_block_size on mount ($fs_block_size)" > + _fail _fail "Block size created..." > + fi > + > + rm -rf "${SCRATCH_MNT:?}"/* > + > + # This let's us also test against sparse files > + setup_zeroed_file $file_len $use_sparse_file > + > + # This will overwrite the old data, the file size is the > + # delta between offset and len now. > + $XFS_IO_PROG -f -c "pwrite -S 0xaa -b 512 $offset $len" \ > + $test_file >> $seqres.full > + > + sync > + new_filelen=$(_get_filesize $test_file) > + map_len=$(round_up_to_page_boundary $new_filelen) > + csum_orig="$(_md5_checksum $test_file)" > + > + # A couple of mmap() tests: > + # > + # We are allowed to mmap() up to the boundary of the page size of a > + # data object, but there a few rules to follow we must check for: > + # > + # a) zero-fill test for the data: POSIX says we should zero fill any > + # partial page after the end of the object. Verify zero-fill. > + # b) do not write this bogus data to disk: on Linux, if we write data > + # to a partially filled page, it will stay in the page cache even > + # after the file is closed and unmapped even if it never reaches the > + # file. Subsequent mappings *may* see the modified content, but it > + # also can get other data. Since the data read after the actual What does "other data" mean? > + # object data can vary we just verify the filesize does not change. > + # This is not true for tmpfs. Er... is this file size change a bug? > + if [[ $map_len -gt $new_filelen ]]; then > + zero_filled_data_len=$((map_len - new_filelen)) > + _scratch_cycle_mount > + expected_zero_data="00" > + zero_filled_data=$($XFS_IO_PROG -r $test_file \ > + -c "mmap -r 0 $map_len" \ > + -c "mread -v $new_filelen $zero_filled_data_len" \ > + -c "munmap" | \ > + _filter_xfs_io_data_unique) > + if [[ "$zero_filled_data" != "$expected_zero_data" ]]; then > + echo "Expected data: $expected_zero_data" > + echo " Actual data: $zero_filled_data" > + echo "Zero-fill broken see mmap() requirements" > + _fail > + fi > + > + if [[ "$FSTYP" != "tmpfs" ]]; then > + _scratch_cycle_mount > + $XFS_IO_PROG $test_file \ > + -c "mmap -w 0 $map_len" \ > + -c "mwrite $new_filelen $zero_filled_data_len" \ > + -c "munmap" > + sync > + csum_post="$(_md5_checksum $test_file)" > + if [[ "$csum_orig" != "$csum_post" ]]; then > + echo "Expected csum: $csum_orig" > + echo " Actual csum: $csum_post" > + _fail > + fi > + > + local filelen_test=$(_get_filesize $test_file) > + if [[ "$filelen_test" != "$new_filelen" ]]; then > + echo "Expected file length: $new_filelen" > + echo " Actual file length: $filelen_test" > + _fail > + fi > + fi > + fi > + > + # Now lets ensure we get SIGBUS when we go beyond the page boundary > + if [[ "$FSTYP" != "tmpfs" ]]; then > + _scratch_cycle_mount > + new_filelen=$(_get_filesize $test_file) > + map_len=$(round_up_to_page_boundary $new_filelen) > + csum_orig="$(_md5_checksum $test_file)" > + mread $test_file $map_len 0 $map_len >> $seqres.full 2>$tmp.err > + if grep -q 'Bus error' $tmp.err; then > + echo "Not expecting SIGBUS when reading up to page boundary" > + cat $tmp.err > + _fail > + fi > + > + # This should just work > + mread $test_file $map_len 0 $map_len >> $seqres.full 2>$tmp.err > + if [[ $? -ne 0 ]]; then > + _fail > + fi > + > + # If we mmap() on the boundary but try to read beyond it just > + # fails, we don't get a SIGBUS > + $XFS_IO_PROG -r $test_file \ > + -c "mmap -r 0 $map_len" \ > + -c "mread 0 $((map_len + 10))" >> $seqres.full 2>$tmp.err > + local mread_err=$? > + if [[ $mread_err -eq 0 ]]; then > + echo "mmap() to page boundary works as expected but reading beyond should fail" > + echo "err: $?" > + _fail > + fi > + > + # Now let's go beyond the allowed mmap() page boundary > + mread $test_file $((map_len + 10)) 0 $((map_len + 10)) >> $seqres.full 2>$tmp.err > + if ! grep -q 'Bus error' $tmp.err; then > + echo "Expected SIGBUS when mmap() reading beyond page boundary" > + _fail > + fi > + local filelen_test=$(_get_filesize $test_file) > + if [[ "$filelen_test" != "$new_filelen" ]]; then > + echo "Expected file length: $new_filelen" > + echo " Actual file length: $filelen_test" > + _fail > + fi > + fi > +} > + > +test_block_size() > +{ > + local block_size=$1 > + > + do_mmap_tests $block_size 512 3 5 > + do_mmap_tests $block_size 16k 0 $((16384+3)) > + do_mmap_tests $block_size 16k $((16384-10)) $((16384+20)) > + do_mmap_tests $block_size 64k 0 $((65536+3)) > + do_mmap_tests $block_size 4k 4090 30 true > +} > + > +_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed" > +_scratch_mount > +test_file=$SCRATCH_MNT/file > +block_size=$(_get_block_size "$SCRATCH_MNT") _get_file_block_size ? > +test_block_size $block_size > +_scratch_unmount > +_check_scratch_fs This work is done for you automatically if you simply exit the test with the scratch fs still mounted. --D > + > +echo "Silence is golden" > +status=0 > +exit > diff --git a/tests/generic/740.out b/tests/generic/740.out > new file mode 100644 > index 000000000000..3f841e600ed3 > --- /dev/null > +++ b/tests/generic/740.out > @@ -0,0 +1,2 @@ > +QA output created by 740 > +Silence is golden > -- > 2.43.0 > >
On Mon, Apr 15, 2024 at 01:10:54AM -0700, Luis Chamberlain wrote: > mmap() POSIX compliance says we should zero fill data beyond a file > size up to page boundary, and issue a SIGBUS if we go beyond. While fsx > helps us test zero-fill sometimes, fsstress also let's us sometimes test > for SIGBUS however that is based on a random value and its not likley we > always test it. Dedicate a specic test for this to make testing for > this specific situation and to easily expand on other corner cases. > > Suggested-by: Matthew Wilcox <willy@infradead.org> > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > > Does enough to get us to use to test this, however I'm aware of a bit > more polishing up to do: > > * maybe moving mread to common as generic/574 did it first > * sharing round_up_to_page_boundary() as well > > generic/574 is special, it was just testing for correctness of > integrity if we muck with mmap() however if you don't have verity > stuff available obviously you won't end up testing it. > > This generalizes mmap() zero-fill and SIGBUS corner case tests. > > I've tested so far only 4k and it works well there. For 16k bs on LBS > just the SIGBUS issue exists, I'll test smaller block sizes later like > 512, 1k, 2k as well. We'll fix triggering the SIBGUS when LBS is used, > we'll address that in the next iteration. > > Is this a worthy test as a generic test? > > common/filter | 6 ++ > tests/generic/740 | 231 ++++++++++++++++++++++++++++++++++++++++++ > tests/generic/740.out | 2 + > 3 files changed, 239 insertions(+) > create mode 100755 tests/generic/740 > create mode 100644 tests/generic/740.out > > diff --git a/common/filter b/common/filter > index 36d51bd957dd..d7add06f3be7 100644 > --- a/common/filter > +++ b/common/filter > @@ -194,6 +194,12 @@ _filter_xfs_io_unique() > common_line_filter | _filter_xfs_io > } > > +_filter_xfs_io_data_unique() > +{ > + _filter_xfs_io_offset | sed -e 's| |\n|g' | egrep -v "\.|XX|\*" | \ The egrep is deprecated, please use 'grep -E'. > + sort | uniq | tr -d '\n' Isn't "sort | uniq" equal to "sort -u" ? > +} Do we need this filter to be a common helper? Will it be used widely? If not, this can be a local function of below single test case. > + > _filter_xfs_io_units_modified() > { > UNIT=$1 > diff --git a/tests/generic/740 b/tests/generic/740 > new file mode 100755 > index 000000000000..cbb823014600 > --- /dev/null > +++ b/tests/generic/740 > @@ -0,0 +1,231 @@ > +#! /bin/bash > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (c) Luis Chamberlain. All Rights Reserved. > +# > +# FS QA Test 740 > +# > +# As per POSIX NOTES mmap(2) maps multiples of the system page size, but if the > +# data mapped is not multiples of the page size the remaining bytes are zeroed > +# out when mapped and modifications to that region are not written to the file. > +# On Linux when you write data to such partial page after the end of the > +# object, the data stays in the page cache even after the file is closed and > +# unmapped and even though the data is never written to the file itself, > +# subsequent mappings may see the modified content. If you go *beyond* this > +# page, you should get a SIGBUS. This test verifies we zero-fill to page > +# boundary and ensures we get a SIGBUS if we write to data beyond the system > +# page size even if the block size is greater than the system page size. > +. ./common/preamble > +. ./common/rc > +_begin_fstest auto quick > + > +# Override the default cleanup function. > +_cleanup() > +{ > + cd / > + rm -r -f $tmp.* > +} This _cleanup is same with the default one, don't need this override. > + > +# Import common functions. > +. ./common/filter > + > +# real QA test starts here > +_supported_fs generic > +_require_scratch_nocheck > +_require_test > + > +setup_zeroed_file() > +{ > + local file_len=$1 > + local sparse=$2 > + > + if $sparse; then > + $XFS_IO_PROG -f -c "truncate $file_len" $test_file _require_xfs_io_command "truncate" > + else > + $XFS_IO_PROG -f -c "falloc 0 $file_len" $test_file _require_xfs_io_command "falloc" And with this, better to add this case into "prealloc" group > + fi > +} > + > +round_up_to_page_boundary() > +{ > + local n=$1 > + local page_size=$(_get_page_size) > + > + echo $(( (n + page_size - 1) & ~(page_size - 1) )) > +} > + > +mread() > +{ > + local file=$1 > + local map_len=$2 > + local offset=$3 > + local length=$4 > + > + # Some callers expect xfs_io to crash with SIGBUS due to the mread, > + # causing the shell to print "Bus error" to stderr. To allow this > + # message to be redirected, execute xfs_io in a new shell instance. > + # However, for this to work reliably, we also need to prevent the new > + # shell instance from optimizing out the fork and directly exec'ing > + # xfs_io. The easiest way to do that is to append 'true' to the > + # commands, so that xfs_io is no longer the last command the shell sees. > + bash -c "trap '' SIGBUS; $XFS_IO_PROG -r $file \ > + -c 'mmap -r 0 $map_len' \ > + -c 'mread $offset $length'; true" > +} > + > +do_mmap_tests() > +{ > + local block_size=$1 > + local file_len=$2 > + local offset=$3 > + local len=$4 > + local use_sparse_file=${5:-false} > + local new_filelen=0 > + local map_len=0 > + local csum=0 > + local fs_block_size=$(_get_block_size $SCRATCH_MNT) Generally the _get_file_block_size is recommended, rather than _get_block_size. > + > + echo -en "\n\n==> Testing blocksize $block_size " >> $seqres.full > + echo -en "file_len: $file_len offset: $offset " >> $seqres.full > + echo -e "len: $len sparse: $use_sparse_file" >> $seqres.full > + > + if ((fs_block_size != block_size)); then > + echo "Block size created ($block_size) doesn't match _get_block_size on mount ($fs_block_size)" > + _fail _fail "Block size created ($block_size) doesn't match _get_block_size on mount ($fs_block_size)" ? Generally we don't use an empty _fail, same as all "_fail" call in this patch. > + fi > + > + rm -rf "${SCRATCH_MNT:?}"/* > + > + # This let's us also test against sparse files > + setup_zeroed_file $file_len $use_sparse_file > + > + # This will overwrite the old data, the file size is the > + # delta between offset and len now. > + $XFS_IO_PROG -f -c "pwrite -S 0xaa -b 512 $offset $len" \ > + $test_file >> $seqres.full > + > + sync > + new_filelen=$(_get_filesize $test_file) > + map_len=$(round_up_to_page_boundary $new_filelen) > + csum_orig="$(_md5_checksum $test_file)" > + > + # A couple of mmap() tests: > + # > + # We are allowed to mmap() up to the boundary of the page size of a > + # data object, but there a few rules to follow we must check for: > + # > + # a) zero-fill test for the data: POSIX says we should zero fill any > + # partial page after the end of the object. Verify zero-fill. > + # b) do not write this bogus data to disk: on Linux, if we write data > + # to a partially filled page, it will stay in the page cache even > + # after the file is closed and unmapped even if it never reaches the > + # file. Subsequent mappings *may* see the modified content, but it > + # also can get other data. Since the data read after the actual > + # object data can vary we just verify the filesize does not change. > + # This is not true for tmpfs. > + if [[ $map_len -gt $new_filelen ]]; then > + zero_filled_data_len=$((map_len - new_filelen)) > + _scratch_cycle_mount > + expected_zero_data="00" > + zero_filled_data=$($XFS_IO_PROG -r $test_file \ > + -c "mmap -r 0 $map_len" \ > + -c "mread -v $new_filelen $zero_filled_data_len" \ > + -c "munmap" | \ > + _filter_xfs_io_data_unique) > + if [[ "$zero_filled_data" != "$expected_zero_data" ]]; then > + echo "Expected data: $expected_zero_data" > + echo " Actual data: $zero_filled_data" > + echo "Zero-fill broken see mmap() requirements" > + _fail > + fi > + > + if [[ "$FSTYP" != "tmpfs" ]]; then > + _scratch_cycle_mount > + $XFS_IO_PROG $test_file \ > + -c "mmap -w 0 $map_len" \ > + -c "mwrite $new_filelen $zero_filled_data_len" \ > + -c "munmap" > + sync > + csum_post="$(_md5_checksum $test_file)" > + if [[ "$csum_orig" != "$csum_post" ]]; then > + echo "Expected csum: $csum_orig" > + echo " Actual csum: $csum_post" > + _fail > + fi > + > + local filelen_test=$(_get_filesize $test_file) > + if [[ "$filelen_test" != "$new_filelen" ]]; then > + echo "Expected file length: $new_filelen" > + echo " Actual file length: $filelen_test" > + _fail > + fi > + fi > + fi > + > + # Now lets ensure we get SIGBUS when we go beyond the page boundary > + if [[ "$FSTYP" != "tmpfs" ]]; then > + _scratch_cycle_mount > + new_filelen=$(_get_filesize $test_file) > + map_len=$(round_up_to_page_boundary $new_filelen) > + csum_orig="$(_md5_checksum $test_file)" > + mread $test_file $map_len 0 $map_len >> $seqres.full 2>$tmp.err > + if grep -q 'Bus error' $tmp.err; then > + echo "Not expecting SIGBUS when reading up to page boundary" > + cat $tmp.err > + _fail > + fi > + > + # This should just work > + mread $test_file $map_len 0 $map_len >> $seqres.full 2>$tmp.err > + if [[ $? -ne 0 ]]; then > + _fail > + fi > + > + # If we mmap() on the boundary but try to read beyond it just > + # fails, we don't get a SIGBUS > + $XFS_IO_PROG -r $test_file \ > + -c "mmap -r 0 $map_len" \ > + -c "mread 0 $((map_len + 10))" >> $seqres.full 2>$tmp.err > + local mread_err=$? > + if [[ $mread_err -eq 0 ]]; then > + echo "mmap() to page boundary works as expected but reading beyond should fail" > + echo "err: $?" > + _fail > + fi > + > + # Now let's go beyond the allowed mmap() page boundary > + mread $test_file $((map_len + 10)) 0 $((map_len + 10)) >> $seqres.full 2>$tmp.err > + if ! grep -q 'Bus error' $tmp.err; then > + echo "Expected SIGBUS when mmap() reading beyond page boundary" > + _fail > + fi > + local filelen_test=$(_get_filesize $test_file) > + if [[ "$filelen_test" != "$new_filelen" ]]; then > + echo "Expected file length: $new_filelen" > + echo " Actual file length: $filelen_test" > + _fail > + fi > + fi > +} > + > +test_block_size() > +{ > + local block_size=$1 > + > + do_mmap_tests $block_size 512 3 5 > + do_mmap_tests $block_size 16k 0 $((16384+3)) > + do_mmap_tests $block_size 16k $((16384-10)) $((16384+20)) > + do_mmap_tests $block_size 64k 0 $((65536+3)) > + do_mmap_tests $block_size 4k 4090 30 true > +} > + > +_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed" > +_scratch_mount > +test_file=$SCRATCH_MNT/file > +block_size=$(_get_block_size "$SCRATCH_MNT") > +test_block_size $block_size > +_scratch_unmount > +_check_scratch_fs The _scratch_unmount && _check_scratch_fs aren't needed, they'll be done after this test done. > + > +echo "Silence is golden" > +status=0 > +exit > diff --git a/tests/generic/740.out b/tests/generic/740.out > new file mode 100644 > index 000000000000..3f841e600ed3 > --- /dev/null > +++ b/tests/generic/740.out > @@ -0,0 +1,2 @@ > +QA output created by 740 > +Silence is golden > -- > 2.43.0 > >
> > +setup_zeroed_file() > > +{ > > + local file_len=$1 > > + local sparse=$2 > > + > > + if $sparse; then > > + $XFS_IO_PROG -f -c "truncate $file_len" $test_file > > + else > > + $XFS_IO_PROG -f -c "falloc 0 $file_len" $test_file > > + fi > > +} > > + > > +round_up_to_page_boundary() > > +{ > > + local n=$1 > > + local page_size=$(_get_page_size) > > + > > + echo $(( (n + page_size - 1) & ~(page_size - 1) )) > > Does iomap put a large folio into the pagecache that crosses EOF, or > does it back down to base page size? No, we back it down to the base page size if the higher order folio crosses EOF. But this changes when we have the LBS support as we need to guarantee the base folio order that will be based on the filesystem BS.
On Mon, Apr 15, 2024 at 01:10:54AM -0700, Luis Chamberlain wrote: > mmap() POSIX compliance says we should zero fill data beyond a file > size up to page boundary, and issue a SIGBUS if we go beyond. While fsx > helps us test zero-fill sometimes, fsstress also let's us sometimes test > for SIGBUS however that is based on a random value and its not likley we > always test it. Dedicate a specic test for this to make testing for > this specific situation and to easily expand on other corner cases. > > Suggested-by: Matthew Wilcox <willy@infradead.org> > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > > Does enough to get us to use to test this, however I'm aware of a bit > more polishing up to do: > > * maybe moving mread to common as generic/574 did it first > * sharing round_up_to_page_boundary() as well > > generic/574 is special, it was just testing for correctness of > integrity if we muck with mmap() however if you don't have verity > stuff available obviously you won't end up testing it. > > This generalizes mmap() zero-fill and SIGBUS corner case tests. > > I've tested so far only 4k and it works well there. For 16k bs on LBS > just the SIGBUS issue exists, I'll test smaller block sizes later like > 512, 1k, 2k as well. We'll fix triggering the SIBGUS when LBS is used, > we'll address that in the next iteration. > > Is this a worthy test as a generic test? > > common/filter | 6 ++ > tests/generic/740 | 231 ++++++++++++++++++++++++++++++++++++++++++ > tests/generic/740.out | 2 + > 3 files changed, 239 insertions(+) > create mode 100755 tests/generic/740 > create mode 100644 tests/generic/740.out > We could also extend the test to include mmap writes. I took the lazy approach here but I think we can make the code look prettier by adding some more functions that can do both mmap read and writes. diff --git a/tests/generic/740 b/tests/generic/740 index cbb82301..93663964 100755 --- a/tests/generic/740 +++ b/tests/generic/740 @@ -53,6 +53,25 @@ round_up_to_page_boundary() echo $(( (n + page_size - 1) & ~(page_size - 1) )) } +mwrite() +{ + local file=$1 + local map_len=$2 + local offset=$3 + local length=$4 + + # Some callers expect xfs_io to crash with SIGBUS due to the mread, + # causing the shell to print "Bus error" to stderr. To allow this + # message to be redirected, execute xfs_io in a new shell instance. + # However, for this to work reliably, we also need to prevent the new + # shell instance from optimizing out the fork and directly exec'ing + # xfs_io. The easiest way to do that is to append 'true' to the + # commands, so that xfs_io is no longer the last command the shell sees. + bash -c "trap '' SIGBUS; $XFS_IO_PROG $file \ + -c 'mmap -w 0 $map_len' \ + -c 'mwrite $offset $length'; true" +} + mread() { local file=$1 @@ -180,6 +199,12 @@ do_mmap_tests() _fail fi + # This should just work + mwrite $test_file $map_len 0 $map_len >> $seqres.full 2>$tmp.err + if [[ $? -ne 0 ]]; then + _fail + fi + # If we mmap() on the boundary but try to read beyond it just # fails, we don't get a SIGBUS $XFS_IO_PROG -r $test_file \ @@ -192,12 +217,29 @@ do_mmap_tests() _fail fi + $XFS_IO_PROG -w $test_file \ + -c "mmap -w 0 $map_len" \ + -c "mwrite 0 $((map_len + 10))" >> $seqres.full 2>$tmp.err + local mwrite_err=$? + if [[ $mwrite_err -eq 0 ]]; then + echo "mmap() to page boundary works as expected but writing beyond should fail" + echo "err: $?" + _fail + fi + # Now let's go beyond the allowed mmap() page boundary mread $test_file $((map_len + 10)) 0 $((map_len + 10)) >> $seqres.full 2>$tmp.err if ! grep -q 'Bus error' $tmp.err; then echo "Expected SIGBUS when mmap() reading beyond page boundary" _fail fi + + mwrite $test_file $((map_len + 10)) 0 $((map_len + 10)) >> $seqres.full 2>$tmp.err + if ! grep -q 'Bus error' $tmp.err; then + echo "Expected SIGBUS when mmap() writing beyond page boundary" + _fail + fi + local filelen_test=$(_get_filesize $test_file) if [[ "$filelen_test" != "$new_filelen" ]]; then echo "Expected file length: $new_filelen" -- Pankaj
diff --git a/common/filter b/common/filter index 36d51bd957dd..d7add06f3be7 100644 --- a/common/filter +++ b/common/filter @@ -194,6 +194,12 @@ _filter_xfs_io_unique() common_line_filter | _filter_xfs_io } +_filter_xfs_io_data_unique() +{ + _filter_xfs_io_offset | sed -e 's| |\n|g' | egrep -v "\.|XX|\*" | \ + sort | uniq | tr -d '\n' +} + _filter_xfs_io_units_modified() { UNIT=$1 diff --git a/tests/generic/740 b/tests/generic/740 new file mode 100755 index 000000000000..cbb823014600 --- /dev/null +++ b/tests/generic/740 @@ -0,0 +1,231 @@ +#! /bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (c) Luis Chamberlain. All Rights Reserved. +# +# FS QA Test 740 +# +# As per POSIX NOTES mmap(2) maps multiples of the system page size, but if the +# data mapped is not multiples of the page size the remaining bytes are zeroed +# out when mapped and modifications to that region are not written to the file. +# On Linux when you write data to such partial page after the end of the +# object, the data stays in the page cache even after the file is closed and +# unmapped and even though the data is never written to the file itself, +# subsequent mappings may see the modified content. If you go *beyond* this +# page, you should get a SIGBUS. This test verifies we zero-fill to page +# boundary and ensures we get a SIGBUS if we write to data beyond the system +# page size even if the block size is greater than the system page size. +. ./common/preamble +. ./common/rc +_begin_fstest auto quick + +# Override the default cleanup function. +_cleanup() +{ + cd / + rm -r -f $tmp.* +} + +# Import common functions. +. ./common/filter + +# real QA test starts here +_supported_fs generic +_require_scratch_nocheck +_require_test + +setup_zeroed_file() +{ + local file_len=$1 + local sparse=$2 + + if $sparse; then + $XFS_IO_PROG -f -c "truncate $file_len" $test_file + else + $XFS_IO_PROG -f -c "falloc 0 $file_len" $test_file + fi +} + +round_up_to_page_boundary() +{ + local n=$1 + local page_size=$(_get_page_size) + + echo $(( (n + page_size - 1) & ~(page_size - 1) )) +} + +mread() +{ + local file=$1 + local map_len=$2 + local offset=$3 + local length=$4 + + # Some callers expect xfs_io to crash with SIGBUS due to the mread, + # causing the shell to print "Bus error" to stderr. To allow this + # message to be redirected, execute xfs_io in a new shell instance. + # However, for this to work reliably, we also need to prevent the new + # shell instance from optimizing out the fork and directly exec'ing + # xfs_io. The easiest way to do that is to append 'true' to the + # commands, so that xfs_io is no longer the last command the shell sees. + bash -c "trap '' SIGBUS; $XFS_IO_PROG -r $file \ + -c 'mmap -r 0 $map_len' \ + -c 'mread $offset $length'; true" +} + +do_mmap_tests() +{ + local block_size=$1 + local file_len=$2 + local offset=$3 + local len=$4 + local use_sparse_file=${5:-false} + local new_filelen=0 + local map_len=0 + local csum=0 + local fs_block_size=$(_get_block_size $SCRATCH_MNT) + + echo -en "\n\n==> Testing blocksize $block_size " >> $seqres.full + echo -en "file_len: $file_len offset: $offset " >> $seqres.full + echo -e "len: $len sparse: $use_sparse_file" >> $seqres.full + + if ((fs_block_size != block_size)); then + echo "Block size created ($block_size) doesn't match _get_block_size on mount ($fs_block_size)" + _fail + fi + + rm -rf "${SCRATCH_MNT:?}"/* + + # This let's us also test against sparse files + setup_zeroed_file $file_len $use_sparse_file + + # This will overwrite the old data, the file size is the + # delta between offset and len now. + $XFS_IO_PROG -f -c "pwrite -S 0xaa -b 512 $offset $len" \ + $test_file >> $seqres.full + + sync + new_filelen=$(_get_filesize $test_file) + map_len=$(round_up_to_page_boundary $new_filelen) + csum_orig="$(_md5_checksum $test_file)" + + # A couple of mmap() tests: + # + # We are allowed to mmap() up to the boundary of the page size of a + # data object, but there a few rules to follow we must check for: + # + # a) zero-fill test for the data: POSIX says we should zero fill any + # partial page after the end of the object. Verify zero-fill. + # b) do not write this bogus data to disk: on Linux, if we write data + # to a partially filled page, it will stay in the page cache even + # after the file is closed and unmapped even if it never reaches the + # file. Subsequent mappings *may* see the modified content, but it + # also can get other data. Since the data read after the actual + # object data can vary we just verify the filesize does not change. + # This is not true for tmpfs. + if [[ $map_len -gt $new_filelen ]]; then + zero_filled_data_len=$((map_len - new_filelen)) + _scratch_cycle_mount + expected_zero_data="00" + zero_filled_data=$($XFS_IO_PROG -r $test_file \ + -c "mmap -r 0 $map_len" \ + -c "mread -v $new_filelen $zero_filled_data_len" \ + -c "munmap" | \ + _filter_xfs_io_data_unique) + if [[ "$zero_filled_data" != "$expected_zero_data" ]]; then + echo "Expected data: $expected_zero_data" + echo " Actual data: $zero_filled_data" + echo "Zero-fill broken see mmap() requirements" + _fail + fi + + if [[ "$FSTYP" != "tmpfs" ]]; then + _scratch_cycle_mount + $XFS_IO_PROG $test_file \ + -c "mmap -w 0 $map_len" \ + -c "mwrite $new_filelen $zero_filled_data_len" \ + -c "munmap" + sync + csum_post="$(_md5_checksum $test_file)" + if [[ "$csum_orig" != "$csum_post" ]]; then + echo "Expected csum: $csum_orig" + echo " Actual csum: $csum_post" + _fail + fi + + local filelen_test=$(_get_filesize $test_file) + if [[ "$filelen_test" != "$new_filelen" ]]; then + echo "Expected file length: $new_filelen" + echo " Actual file length: $filelen_test" + _fail + fi + fi + fi + + # Now lets ensure we get SIGBUS when we go beyond the page boundary + if [[ "$FSTYP" != "tmpfs" ]]; then + _scratch_cycle_mount + new_filelen=$(_get_filesize $test_file) + map_len=$(round_up_to_page_boundary $new_filelen) + csum_orig="$(_md5_checksum $test_file)" + mread $test_file $map_len 0 $map_len >> $seqres.full 2>$tmp.err + if grep -q 'Bus error' $tmp.err; then + echo "Not expecting SIGBUS when reading up to page boundary" + cat $tmp.err + _fail + fi + + # This should just work + mread $test_file $map_len 0 $map_len >> $seqres.full 2>$tmp.err + if [[ $? -ne 0 ]]; then + _fail + fi + + # If we mmap() on the boundary but try to read beyond it just + # fails, we don't get a SIGBUS + $XFS_IO_PROG -r $test_file \ + -c "mmap -r 0 $map_len" \ + -c "mread 0 $((map_len + 10))" >> $seqres.full 2>$tmp.err + local mread_err=$? + if [[ $mread_err -eq 0 ]]; then + echo "mmap() to page boundary works as expected but reading beyond should fail" + echo "err: $?" + _fail + fi + + # Now let's go beyond the allowed mmap() page boundary + mread $test_file $((map_len + 10)) 0 $((map_len + 10)) >> $seqres.full 2>$tmp.err + if ! grep -q 'Bus error' $tmp.err; then + echo "Expected SIGBUS when mmap() reading beyond page boundary" + _fail + fi + local filelen_test=$(_get_filesize $test_file) + if [[ "$filelen_test" != "$new_filelen" ]]; then + echo "Expected file length: $new_filelen" + echo " Actual file length: $filelen_test" + _fail + fi + fi +} + +test_block_size() +{ + local block_size=$1 + + do_mmap_tests $block_size 512 3 5 + do_mmap_tests $block_size 16k 0 $((16384+3)) + do_mmap_tests $block_size 16k $((16384-10)) $((16384+20)) + do_mmap_tests $block_size 64k 0 $((65536+3)) + do_mmap_tests $block_size 4k 4090 30 true +} + +_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed" +_scratch_mount +test_file=$SCRATCH_MNT/file +block_size=$(_get_block_size "$SCRATCH_MNT") +test_block_size $block_size +_scratch_unmount +_check_scratch_fs + +echo "Silence is golden" +status=0 +exit diff --git a/tests/generic/740.out b/tests/generic/740.out new file mode 100644 index 000000000000..3f841e600ed3 --- /dev/null +++ b/tests/generic/740.out @@ -0,0 +1,2 @@ +QA output created by 740 +Silence is golden
mmap() POSIX compliance says we should zero fill data beyond a file size up to page boundary, and issue a SIGBUS if we go beyond. While fsx helps us test zero-fill sometimes, fsstress also let's us sometimes test for SIGBUS however that is based on a random value and its not likley we always test it. Dedicate a specic test for this to make testing for this specific situation and to easily expand on other corner cases. Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> --- Does enough to get us to use to test this, however I'm aware of a bit more polishing up to do: * maybe moving mread to common as generic/574 did it first * sharing round_up_to_page_boundary() as well generic/574 is special, it was just testing for correctness of integrity if we muck with mmap() however if you don't have verity stuff available obviously you won't end up testing it. This generalizes mmap() zero-fill and SIGBUS corner case tests. I've tested so far only 4k and it works well there. For 16k bs on LBS just the SIGBUS issue exists, I'll test smaller block sizes later like 512, 1k, 2k as well. We'll fix triggering the SIBGUS when LBS is used, we'll address that in the next iteration. Is this a worthy test as a generic test? common/filter | 6 ++ tests/generic/740 | 231 ++++++++++++++++++++++++++++++++++++++++++ tests/generic/740.out | 2 + 3 files changed, 239 insertions(+) create mode 100755 tests/generic/740 create mode 100644 tests/generic/740.out