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Tue, 13 Feb 2024 02:50:29 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap2.dmz-prg2.suse.org with ESMTPSA id L+sLBvXYymWSVQAAn2gu4w (envelope-from ); Tue, 13 Feb 2024 02:50:29 +0000 Date: Tue, 13 Feb 2024 13:50:19 +1100 From: David Disseldorp To: Josef Bacik Cc: fstests@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2] fstests: add a regression test for fiemap into an mmap range Message-ID: <20240213135019.24c3c595@echidna> In-Reply-To: References: Precedence: bulk X-Mailing-List: fstests@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [-2.60 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%] X-Spam-Level: X-Spam-Flag: NO X-Spam-Score: -2.60 On Mon, 12 Feb 2024 11:41:14 -0500, Josef Bacik wrote: > Btrfs had a deadlock that you could trigger by mmap'ing a large file and > using that as the buffer for fiemap. This test adds a c program to do > this, and the fstest creates a large enough file and then runs the > reproducer on the file. Without the fix btrfs deadlocks, with the fix > we pass fine. > > Signed-off-by: Josef Bacik With a .gitignore entry added for the fiemap-fault binary: Revewed-by: David Disseldorp A few other minor nits below... > --- > v1->v2: > - Add the fiemap group to the test. > - Actually include the reproducer helper program. > > src/Makefile | 2 +- > src/fiemap-fault.c | 73 +++++++++++++++++++++++++++++++++++++++++++ > tests/generic/740 | 41 ++++++++++++++++++++++++ > tests/generic/740.out | 2 ++ > 4 files changed, 117 insertions(+), 1 deletion(-) > create mode 100644 src/fiemap-fault.c > create mode 100644 tests/generic/740 > create mode 100644 tests/generic/740.out > > diff --git a/src/Makefile b/src/Makefile > index d79015ce..916f6755 100644 > --- a/src/Makefile > +++ b/src/Makefile > @@ -34,7 +34,7 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ > attr_replace_test swapon mkswap t_attr_corruption t_open_tmpfiles \ > fscrypt-crypt-util bulkstat_null_ocount splice-test chprojid_fail \ > detached_mounts_propagation ext4_resize t_readdir_3 splice2pipe \ > - uuid_ioctl > + uuid_ioctl fiemap-fault Nit: FWIW, this hunk collides with 3a0381a4 ("btrfs: test snapshotting a deleted subvolume") > EXTRA_EXECS = dmerror fill2attr fill2fs fill2fs_check scaleread.sh \ > btrfs_crc32c_forged_name.py popdir.pl popattr.py \ > diff --git a/src/fiemap-fault.c b/src/fiemap-fault.c > new file mode 100644 > index 00000000..27081188 > --- /dev/null > +++ b/src/fiemap-fault.c > @@ -0,0 +1,73 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2024 Meta Platforms, Inc. All Rights Reserved. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +int prep_mmap_buffer(int fd, void **addr) > +{ > + struct stat st; > + int ret; > + > + ret = fstat(fd, &st); > + if (ret) > + err(1, "failed to stat %d", fd); > + > + *addr = mmap(NULL, st.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); > + if (*addr == MAP_FAILED) > + err(1, "failed to mmap %d", fd); > + > + return st.st_size; > +} > + > +int main(int argc, char *argv[]) > +{ > + struct fiemap *fiemap; > + size_t sz, last = 0; > + void *buf = NULL; > + int ret, fd; > + > + if (argc != 2) > + errx(1, "no in and out file name arguments given"); > + > + fd = open(argv[1], O_RDWR, 0666); > + if (fd == -1) > + err(1, "failed to open %s", argv[1]); > + > + sz = prep_mmap_buffer(fd, &buf); > + > + fiemap = (struct fiemap *)buf; > + fiemap->fm_flags = 0; > + fiemap->fm_extent_count = (sz - sizeof(struct fiemap)) / > + sizeof(struct fiemap_extent); > + > + while (last < sz) { > + int i; > + > + fiemap->fm_start = last; > + fiemap->fm_length = sz - last; > + > + ret = ioctl(fd, FS_IOC_FIEMAP, (unsigned long)fiemap); > + if (ret < 0) > + err(1, "fiemap failed %d (%s)", errno, strerror(errno)); Nit: err() should already append the strerror() string. > + for (i = 0; i < fiemap->fm_mapped_extents; i++) > + last = fiemap->fm_extents[i].fe_logical + > + fiemap->fm_extents[i].fe_length; > + } > + > + close(fd); > + return 0; > +} > diff --git a/tests/generic/740 b/tests/generic/740 > new file mode 100644 > index 00000000..30ace1dd > --- /dev/null > +++ b/tests/generic/740 > @@ -0,0 +1,41 @@ > +#! /bin/bash > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (c) 2023 Meta Platforms, Inc. All Rights Reserved. > +# > +# FS QA Test 708 Test 740 > +# > +# Test fiemap into an mmaped buffer of the same file > +# > +# Create a reasonably large file, then run a program which mmaps it and uses > +# that as a buffer for an fiemap call. This is a regression test for btrfs > +# where we used to hold a lock for the duration of the fiemap call which would > +# result in a deadlock if we page faulted. > +# > +. ./common/preamble > +_begin_fstest quick auto fiemap > +[ $FSTYP == "btrfs" ] && \ > + _fixed_by_kernel_commit xxxxxxxxxxxx \ > + "btrfs: fix deadlock with fiemap and extent locking" > + > +# real QA test starts here > +_supported_fs generic > +_require_test > +_require_odirect > +_require_test_program fiemap-fault > +dst=$TEST_DIR/fiemap-fault-$seq > + > +echo "Silence is golden" > + > +for i in $(seq 0 2 1000) > +do > + $XFS_IO_PROG -d -f -c "pwrite -q $((i * 4096)) 4096" $dst > +done > + > +$here/src/fiemap-fault $dst > /dev/null || _fail "failed doing fiemap" Nit: the error paths print errors, so the explicit _fail should be unnecessary, or you could turn it into an echo. > + > +rm -f $dst > + > +# success, all done > +status=$? > +exit > + > diff --git a/tests/generic/740.out b/tests/generic/740.out > new file mode 100644 > index 00000000..3f841e60 > --- /dev/null > +++ b/tests/generic/740.out > @@ -0,0 +1,2 @@ > +QA output created by 740 > +Silence is golden