--- /dev/null
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) Luis Chamberlain. All Rights Reserved.
+#
+# FS QA Test 749
+#
+# 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 prealloc
+
+# Import common functions.
+. ./common/filter
+
+# real QA test starts here
+_supported_fs generic
+_require_scratch_nocheck
+_require_test
+_require_xfs_io_command "truncate"
+_require_xfs_io_command "falloc"
+
+# _fixed_by_git_commit kernel <pending-upstream> \
+# "filemap: cap PTE range to be created to allowed zero fill in folio_map_range()"
+
+filter_xfs_io_data_unique()
+{
+ _filter_xfs_io_offset | sed -e 's| |\n|g' | grep -E -v "\.|XX|\*" | \
+ sort -u | tr -d '\n'
+}
+
+
+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
+}
+
+mwrite()
+{
+ local file=$1
+ local offset=$2
+ local length=$3
+ local map_len=${4:-$(_round_up_to_page_boundary $(_get_filesize $file)) }
+
+ # 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; ulimit -c 0; \
+ $XFS_IO_PROG $file \
+ -c 'mmap -w 0 $map_len' \
+ -c 'mwrite $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_file_block_size $SCRATCH_MNT)
+ local failed=0
+
+ 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" >> $seqres.full
+
+ if ((fs_block_size != block_size)); then
+ _fail "Block size created ($block_size) doesn't match _get_file_block_size on mount ($fs_block_size)"
+ fi
+
+ rm -f $SCRATCH_MNT/file
+
+ # 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. As per mmap(2) subsequent mappings *may* see the modified
+ # content. This means that it also can get other data and we have
+ # no rules about what this data should be. Since the data read after
+ # the actual object data can vary this test just verifies that the
+ # filesize does not change.
+ 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" != "$expected_zero_data" ]]; then
+ let failed=$failed+1
+ echo "Expected data: $expected_zero_data"
+ echo " Actual data: $zero_filled_data"
+ echo "Zero-fill expectations with mmap() not respected"
+ fi
+
+ _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" != "$csum_post" ]]; then
+ let failed=$failed+1
+ echo "Expected csum: $csum_orig"
+ echo " Actual csum: $csum_post"
+ echo "mmap() write up to page boundary should not change actual file contents"
+ fi
+
+ local filelen_test=$(_get_filesize $test_file)
+ if [[ "$filelen_test" != "$new_filelen" ]]; then
+ let failed=$failed+1
+ echo "Expected file length: $new_filelen"
+ echo " Actual file length: $filelen_test"
+ echo "mmap() write up to page boundary should not change actual file size"
+ fi
+ fi
+
+ # Now lets ensure we get SIGBUS when we go beyond the page boundary
+ _scratch_cycle_mount
+ new_filelen=$(_get_filesize $test_file)
+ map_len=$(_round_up_to_page_boundary $new_filelen)
+ csum_orig="$(_md5_checksum $test_file)"
+ _mread $test_file 0 $map_len >> $seqres.full 2>$tmp.err
+ if grep -q 'Bus error' $tmp.err; then
+ failed=1
+ cat $tmp.err
+ echo "Not expecting SIGBUS when reading up to page boundary"
+ fi
+
+ # This should just work
+ _mread $test_file 0 $map_len >> $seqres.full 2>$tmp.err
+ if [[ $? -ne 0 ]]; then
+ let failed=$failed+1
+ echo "mmap() read up to page boundary should work"
+ fi
+
+ # This should just work
+ mwrite $map_len 0 $map_len >> $seqres.full 2>$tmp.err
+ if [[ $? -ne 0 ]]; then
+ let failed=$failed+1
+ echo "mmap() write up to page boundary should work"
+ 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 [[ $mread_err -eq 0 ]]; then
+ let failed=$failed+1
+ echo "mmap() to page boundary works as expected but reading beyond should fail: $mread_err"
+ 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 [[ $mwrite_err -eq 0 ]]; then
+ let failed=$failed+1
+ echo "mmap() to page boundary works as expected but writing beyond should fail: $mwrite_err"
+ fi
+
+ # Now let's go beyond the allowed mmap() page boundary
+ _mread $test_file 0 $((map_len + 10)) $((map_len + 10)) >> $seqres.full 2>$tmp.err
+ if ! grep -q 'Bus error' $tmp.err; then
+ let failed=$failed+1
+ echo "Expected SIGBUS when mmap() reading beyond page boundary"
+ fi
+
+ mwrite $test_file 0 $((map_len + 10)) $((map_len + 10)) >> $seqres.full 2>$tmp.err
+ if ! grep -q 'Bus error' $tmp.err; then
+ let failed=$failed+1
+ echo "Expected SIGBUS when mmap() writing beyond page boundary"
+ fi
+
+ local filelen_test=$(_get_filesize $test_file)
+ if [[ "$filelen_test" != "$new_filelen" ]]; then
+ let failed=$failed+1
+ echo "Expected file length: $new_filelen"
+ echo " Actual file length: $filelen_test"
+ echo "reading or writing beyond file size up to mmap() page boundary should not change file size"
+ fi
+
+ if [[ $failed -eq 1 ]]; then
+ _fail "Test had $failed failures..."
+ fi
+}
+
+test_block_size()
+{
+ local block_size=$1
+
+ do_mmap_tests $block_size 512 3 5
+ do_mmap_tests $block_size 11k 0 $((4096 * 3 + 3))
+ 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=$(_get_file_block_size "$SCRATCH_MNT")
+test_block_size $block_size
+
+echo "Silence is golden"
+status=0
+exit
projects / xfstests-dev.git / commitdiff