On Thu, Feb 02, 2023 at 08:44:28PM +0000, Matthew Wilcox (Oracle) wrote: > https://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html > specifies that "If the file size is increased, the extended area shall > appear as if it were zero-filled." Many filesystems do not currently > do this for the portion of the page after EOF. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > --- > .gitignore | 1 + > src/Makefile | 2 +- > src/truncate-zero.c | 50 +++++++++++++++++++++++++++++++++++++++++++ > tests/generic/707 | 31 +++++++++++++++++++++++++++ > tests/generic/707.out | 2 ++ > 5 files changed, 85 insertions(+), 1 deletion(-) > create mode 100644 src/truncate-zero.c > create mode 100755 tests/generic/707 > create mode 100644 tests/generic/707.out > > diff --git a/.gitignore b/.gitignore > index a6f433f1..6aa5bca9 100644 > --- a/.gitignore > +++ b/.gitignore > @@ -169,6 +169,7 @@ tags > /src/test-nextquota > /src/testx > /src/trunc > +/src/truncate-zero > /src/truncfile > /src/unwritten_mmap > /src/unwritten_sync > diff --git a/src/Makefile b/src/Makefile > index afdf6b30..83ca11ac 100644 > --- a/src/Makefile > +++ b/src/Makefile > @@ -19,7 +19,7 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \ > t_ofd_locks t_mmap_collision mmap-write-concurrent \ > t_get_file_time t_create_short_dirs t_create_long_dirs t_enospc \ > t_mmap_writev_overlap checkpoint_journal mmap-rw-fault allocstale \ > - t_mmap_cow_memory_failure fake-dump-rootino > + t_mmap_cow_memory_failure fake-dump-rootino truncate-zero > > LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ > preallo_rw_pattern_writer ftrunc trunc fs_perms testx looptest \ > diff --git a/src/truncate-zero.c b/src/truncate-zero.c > new file mode 100644 > index 00000000..67f53912 > --- /dev/null > +++ b/src/truncate-zero.c > @@ -0,0 +1,50 @@ Needs to have a SPDX header and the customary Oracle copyright. > +#include <fcntl.h> > +#include <stdio.h> > +#include <string.h> > +#include <sys/mman.h> > +#include <unistd.h> > + > +int main(int argc, char **argv) > +{ > + char *buf; > + int i, fd; > + > + if (argc != 2) { > + fprintf(stderr, "Usage: %s <file>\n", argv[0]); > + return 1; > + } > + > + fd = open(argv[1], O_RDWR | O_CREAT, 0644); > + if (fd < 0) { > + perror(argv[1]); > + return 1; > + } > + > + if (ftruncate(fd, 1) < 0) { > + perror("ftruncate"); > + return 1; > + } > + > + buf = mmap(NULL, 1024, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); > + if (buf == MAP_FAILED) { > + perror("mmap"); > + return 1; > + } > + > + memset(buf, 'a', 10); > + > + if (ftruncate(fd, 5) < 0) { > + perror("ftruncate"); > + return 1; > + } > + > + if (memcmp(buf, "a\0\0\0\0", 5) == 0) > + return 0; > + > + fprintf(stderr, "Truncation did not zero new bytes:\n"); > + for (i = 0; i < 5; i++) > + fprintf(stderr, "%#x ", buf[i]); > + fputc('\n', stderr); > + > + return 2; > +} > diff --git a/tests/generic/707 b/tests/generic/707 > new file mode 100755 > index 00000000..ddc82a9a > --- /dev/null > +++ b/tests/generic/707 > @@ -0,0 +1,31 @@ > +#! /bin/bash > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (c) 2023 Matthew Wilcox for Oracle. All Rights Reserved. > +# > +# FS QA Test 707 > +# > +# Test whether we obey this part of POSIX-2017 ftruncate: > +# "If the file size is increased, the extended area shall appear as if > +# it were zero-filled" > +# > +. ./common/preamble > +_begin_fstest auto quick posix > + > +_supported_fs generic > +_require_test > +_require_test_program "truncate-zero" > + > +test_file=$TEST_DIR/test.$seq > + > +_cleanup() > +{ > + cd / > + rm -f $test_file > +} > + > +$here/src/truncate-zero $test_file > $seqres.full 2>&1 || > + _fail "truncate zero failed!" Omit the _fail here because any extra stdout/stderr output that is not in the .out file suffices to record the test as failed. _fail is only useful if you need to exit the shell script immediately. > + > +echo "Silence is golden" It's customary (though not required) to put "silence is golden" before "but my eyes still see"^W^W^W^W^Wthe test starts running programs. Other than those minor things, this looks reasonable to me. --D > +status=0 > +exit > diff --git a/tests/generic/707.out b/tests/generic/707.out > new file mode 100644 > index 00000000..8e57a1d8 > --- /dev/null > +++ b/tests/generic/707.out > @@ -0,0 +1,2 @@ > +QA output created by 707 > +Silence is golden > -- > 2.35.1 >
