Bug 237588
| Summary: | [fusefs] data corruption when mixing normal writes and mmap writes with Write-through cache mode | ||
|---|---|---|---|
| Product: | Base System | Reporter: | Alan Somers <asomers> |
| Component: | kern | Assignee: | Alan Somers <asomers> |
| Status: | Closed FIXED | ||
| Severity: | Affects Many People | CC: | cem |
| Priority: | --- | Flags: | asomers:
mfc-stable12+
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| Version: | CURRENT | ||
| Hardware: | Any | ||
| OS: | Any | ||
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Description
Alan Somers
2019-04-26 20:47:59 UTC
The best solution would probably be to implement true write-through caching. Here's cem's notes on the subject: For WT, you'd want to go back to the biobackend for writes, but be sure they are flushed synchronously with the VOP_WRITE, and probably in-order. A simple way to do that would be to bwrite() each buf as we go. That makes for a lot of serialized IPC latency, though. With our fairly large buf block size (and we pick the maximum — 64kB by default on amd64 GENERIC), it may not be awful. But it probably isn't great, either. It might be worthwhile to use bawrite() / bufwrite + O_ASYNC (immediate, but async completion writes) to at least pipeline multiple bufs at a time. We would want to hook b_iodone to override the default bufdone() handling of async buf writes. We would also want to wait for all async writes we issued to complete before returning. I'm not sure how we would handle signals. If /any/ buf write fails, we would return failure (or short write) depending on if it was the first buf or not. We probably want to evict cache contents of any buf write that fails, and probably also any after it (userspace can't know those were written, and will likely try to rewrite them anyway). The next step performance wise beyond bawrite pipelining is attempting to do delayed (bdwrite) / clustered (vfs_bio_awrite) writes, but I don't think the locking works there such that we can reliably do that without allowing dirty data caching, so maybe that's pending 7.23. A commit references this bug: Author: asomers Date: Fri Jun 14 19:47:49 UTC 2019 New revision: 349038 URL: https://svnweb.freebsd.org/changeset/base/349038 Log: fusefs: fix the "write-through" of write-through cacheing Our fusefs(5) module supports three cache modes: uncached, write-through, and write-back. However, the write-through mode (which is the default) has never actually worked as its name suggests. Rather, it's always been more like "write-around". It wrote directly, bypassing the cache. The cache would only be populated by a subsequent read of the same data. This commit fixes that problem. Now the write-through mode works as one would expect: write(2) immediately adds data to the cache and then blocks while the daemon processes the write operation. A side effect of this change is that non-cache-block-aligned writes will now incur a read-modify-write cycle of the cache block. The old behavior (bypassing write cache entirely) can still be achieved by opening a file with O_DIRECT. PR: 237588 Sponsored by: The FreeBSD Foundation Changes: projects/fuse2/sys/fs/fuse/fuse_io.c projects/fuse2/tests/sys/fs/fusefs/write.cc A commit references this bug: Author: asomers Date: Wed Aug 7 00:38:31 UTC 2019 New revision: 350665 URL: https://svnweb.freebsd.org/changeset/base/350665 Log: fusefs: merge from projects/fuse2 This commit imports the new fusefs driver. It raises the protocol level from 7.8 to 7.23, fixes many bugs, adds a test suite for the driver, and adds many new features. New features include: * Optional kernel-side permissions checks (-o default_permissions) * Implement VOP_MKNOD, VOP_BMAP, and VOP_ADVLOCK * Allow interrupting FUSE operations * Support named pipes and unix-domain sockets in fusefs file systems * Forward UTIME_NOW during utimensat(2) to the daemon * kqueue support for /dev/fuse * Allow updating mounts with "mount -u" * Allow exporting fusefs file systems over NFS * Server-initiated invalidation of the name cache or data cache * Respect RLIMIT_FSIZE * Try to support servers as old as protocol 7.4 Performance enhancements include: * Implement FUSE's FOPEN_KEEP_CACHE and FUSE_ASYNC_READ flags * Cache file attributes * Cache lookup entries, both positive and negative * Server-selectable cache modes: writethrough, writeback, or uncached * Write clustering * Readahead * Use counter(9) for statistical reporting PR: 199934 216391 233783 234581 235773 235774 235775 PR: 236226 236231 236236 236291 236329 236381 236405 PR: 236327 236466 236472 236473 236474 236530 236557 PR: 236560 236844 237052 237181 237588 238565 Reviewed by: bcr (man pages) Reviewed by: cem, ngie, rpokala, glebius, kib, bde, emaste (post-commit review on project branch) MFC after: 3 weeks Relnotes: yes Sponsored by: The FreeBSD Foundation Pull Request: https://reviews.freebsd.org/D21110 Changes: _U head/ head/MAINTAINERS head/UPDATING head/etc/mtree/BSD.tests.dist head/sbin/mount_fusefs/mount_fusefs.8 head/sbin/mount_fusefs/mount_fusefs.c head/share/man/man5/fusefs.5 head/sys/fs/fuse/fuse.h head/sys/fs/fuse/fuse_device.c head/sys/fs/fuse/fuse_file.c head/sys/fs/fuse/fuse_file.h head/sys/fs/fuse/fuse_internal.c head/sys/fs/fuse/fuse_internal.h head/sys/fs/fuse/fuse_io.c head/sys/fs/fuse/fuse_io.h head/sys/fs/fuse/fuse_ipc.c head/sys/fs/fuse/fuse_ipc.h head/sys/fs/fuse/fuse_kernel.h head/sys/fs/fuse/fuse_main.c head/sys/fs/fuse/fuse_node.c head/sys/fs/fuse/fuse_node.h head/sys/fs/fuse/fuse_param.h head/sys/fs/fuse/fuse_vfsops.c head/sys/fs/fuse/fuse_vnops.c head/sys/sys/param.h head/tests/sys/fs/Makefile head/tests/sys/fs/fusefs/ A commit references this bug: Author: asomers Date: Sun Sep 15 04:14:37 UTC 2019 New revision: 352351 URL: https://svnweb.freebsd.org/changeset/base/352351 Log: MFC the new fusefs driver MFC r350665, r350990, r350992, r351039, r351042, r351061, r351066, r351113, r351560, r351961, r351963, r352021, r352025, r352230 r350665: fusefs: merge from projects/fuse2 This commit imports the new fusefs driver. It raises the protocol level from 7.8 to 7.23, fixes many bugs, adds a test suite for the driver, and adds many new features. New features include: * Optional kernel-side permissions checks (-o default_permissions) * Implement VOP_MKNOD, VOP_BMAP, and VOP_ADVLOCK * Allow interrupting FUSE operations * Support named pipes and unix-domain sockets in fusefs file systems * Forward UTIME_NOW during utimensat(2) to the daemon * kqueue support for /dev/fuse * Allow updating mounts with "mount -u" * Allow exporting fusefs file systems over NFS * Server-initiated invalidation of the name cache or data cache * Respect RLIMIT_FSIZE * Try to support servers as old as protocol 7.4 Performance enhancements include: * Implement FUSE's FOPEN_KEEP_CACHE and FUSE_ASYNC_READ flags * Cache file attributes * Cache lookup entries, both positive and negative * Server-selectable cache modes: writethrough, writeback, or uncached * Write clustering * Readahead * Use counter(9) for statistical reporting PR: 199934 216391 233783 234581 235773 235774 235775 PR: 236226 236231 236236 236291 236329 236381 236405 PR: 236327 236466 236472 236473 236474 236530 236557 PR: 236560 236844 237052 237181 237588 238565 Reviewed by: bcr (man pages) Reviewed by: cem, ngie, rpokala, glebius, kib, bde, emaste (post-commit review on project branch) Relnotes: yes Sponsored by: The FreeBSD Foundation Pull Request: https://reviews.freebsd.org/D21110 r350990: fusefs: add SVN Keywords to the test files Reported by: SVN pre-commit hooks MFC-With: r350665 Sponsored by: The FreeBSD Foundation r350992: fusefs: skip some tests when unsafe aio is disabled MFC-With: r350665 Sponsored by: The FreeBSD Foundation r351039: fusefs: fix intermittency in the default_permissions.Unlink.ok test The test needs to expect a FUSE_FORGET operation. Most of the time the test would pass anyway, because by chance FUSE_FORGET would arrive after the unmount. MFC-With: 350665 Sponsored by: The FreeBSD Foundation r351042: fusefs: Fix the size of fuse_getattr_in In FUSE protocol 7.9, the size of the FUSE_GETATTR request has increased. However, the fusefs driver is currently not sending the additional fields. In our implementation, the additional fields are always zero, so I there haven't been any test failures until now. But fusefs-lkl requires the request's length to be correct. Fix this bug, and also enhance the test suite to catch similar bugs. PR: 239830 MFC-With: 350665 Sponsored by: The FreeBSD Foundation r351061: fusefs: fix the 32-bit build after 351042 Reported by: jhb MFC-With: 351042 Sponsored by: The FreeBSD Foundation r351066: fusefs: fix conditional from r351061 The entirety of r351061 was a copy/paste error. I'm sorry I've been comitting so hastily. Reported by: rpokala Reviewed by: rpokala MFC-With: 351061 Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21265 r351113: fusefs: don't send the namespace during listextattr The FUSE_LISTXATTR operation always returns the full list of a file's extended attributes, in all namespaces. There's no way to filter the list server-side. However, currently FreeBSD's fusefs driver sends a namespace string with the FUSE_LISTXATTR request. That behavior was probably copied from fuse_vnop_getextattr, which has an attribute name argument. It's been there ever since extended attribute support was added in r324620. This commit removes it. Reviewed by: cem Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21280 r351560: fusefs: Fix some bugs regarding the size of the LISTXATTR list * A small error in r338152 let to the returned size always being exactly eight bytes too large. * The FUSE_LISTXATTR operation works like Linux's listxattr(2): if the caller does not provide enough space, then the server should return ERANGE rather than return a truncated list. That's true even though in FUSE's case the kernel doesn't provide space to the client at all; it simply requests a maximum size for the list. We previously weren't handling the case where the server returns ERANGE even though the kernel requested as much size as the server had told us it needs; that can happen due to a race. * We also need to ensure that a pathological server that always returns ERANGE no matter what size we request in FUSE_LISTXATTR won't cause an infinite loop in the kernel. As of this commit, it will instead cause an infinite loop that exits and enters the kernel on each iteration, allowing signals to be processed. Reviewed by: cem Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21287 r351961: Coverity fixes in fusefs(5) CID 1404532 fixes a signed vs unsigned comparison error in fuse_vnop_bmap. It could potentially have resulted in VOP_BMAP reporting too many consecutive blocks. CID 1404364 is much worse. It was an array access by an untrusted, user-provided variable. It could potentially have resulted in a malicious file system crashing the kernel or worse. Reported by: Coverity Reviewed by: emaste Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21466 r351963: fusefs: coverity cleanup in the tests Address the following defects reported by Coverity: * Structurally dead code (CID 1404366): set m_quit before FAIL, not after * Unchecked return value of sysctlbyname (CID 1404321) * Unchecked return value of stat(2) (CID 1404471) * Unchecked return value of open(2) (CID 1404402, 1404529) * Unchecked return value of dup(2) (CID 1404478) * Buffer overflows. These are all false positives caused by the fact that Coverity thinks I'm using a buffer to store strings, when in fact I'm really just using it to store a byte array that happens to be initialized with a string. I'm changing the type from char to uint8_t in the hopes that it will placate Coverity. (CID 1404338, 1404350, 1404367, 1404376, 1404379, 1404381, 1404388, 1404403, 1404425, 1404433, 1404434, 1404474, 1404480, 1404484, 1404503, 1404505) * False positive file descriptor leak. I'm going to try to fix this with Coverity modeling, but I'll also change an EXPECT to ASSERT so we don't perform meaningless assertions after the failure. (CID 1404320, 1404324, 1404440, 1404445). * Unannotated file descriptor leak. This will be followed up by a Coverity modeling change. (CID 1404326, 1404334, 1404336, 1404357, 1404361, 1404372, 1404391, 1404395, 1404409, 1404430, 1404448, 1404451, 1404455, 1404457, 1404458, 1404460) * Uninitialized variables in C++ constructors (CID 1404327, 1404346). In the case of m_maxphys, this actually led to part of the FUSE_INIT's response being set to stack garbage during the WriteCluster::clustering test. * Uninitialized sun_len field in struct sockaddr_un (CID 1404330, 1404371, 1404429). Reported by: Coverity Reviewed by: emaste Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21457 r352021: fusefs: suppress some Coverity resource leak CIDs in the tests The fusefs tests deliberately leak file descriptors. To do otherwise would add extra complications to the tests' mock FUSE server. This annotation should hopefully convince Coverity to shut up about the leaks. Reviewed by: uqs Sponsored by: The FreeBSD Foundation r352025: mount_fusefs: fix a segfault on memory allocation failure Reported by: Coverity Coverity CID: 1354188 Sponsored by: The FreeBSD Foundation r352230: fusefs: Fix iosize for FUSE_WRITE in 7.8 compat mode When communicating with a FUSE server that implements version 7.8 (or older) of the FUSE protocol, the FUSE_WRITE request structure is 16 bytes shorter than normal. The protocol version check wasn't applied universally, leading to an extra 16 bytes being sent to such servers. The extra bytes were allocated and bzero()d, so there was no information disclosure. Reviewed by: emaste MFC-With: r350665 Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D21557 Changes: _U stable/12/ stable/12/MAINTAINERS stable/12/UPDATING stable/12/etc/mtree/BSD.tests.dist stable/12/sbin/mount_fusefs/mount_fusefs.8 stable/12/sbin/mount_fusefs/mount_fusefs.c stable/12/share/man/man5/fusefs.5 stable/12/sys/fs/fuse/fuse.h stable/12/sys/fs/fuse/fuse_device.c stable/12/sys/fs/fuse/fuse_file.c stable/12/sys/fs/fuse/fuse_file.h stable/12/sys/fs/fuse/fuse_internal.c stable/12/sys/fs/fuse/fuse_internal.h stable/12/sys/fs/fuse/fuse_io.c stable/12/sys/fs/fuse/fuse_io.h stable/12/sys/fs/fuse/fuse_ipc.c stable/12/sys/fs/fuse/fuse_ipc.h stable/12/sys/fs/fuse/fuse_kernel.h stable/12/sys/fs/fuse/fuse_main.c stable/12/sys/fs/fuse/fuse_node.c stable/12/sys/fs/fuse/fuse_node.h stable/12/sys/fs/fuse/fuse_param.h stable/12/sys/fs/fuse/fuse_vfsops.c stable/12/sys/fs/fuse/fuse_vnops.c stable/12/sys/sys/param.h stable/12/tests/sys/fs/Makefile stable/12/tests/sys/fs/fusefs/ stable/12/tests/sys/fs/fusefs/access.cc stable/12/tests/sys/fs/fusefs/allow_other.cc stable/12/tests/sys/fs/fusefs/bmap.cc stable/12/tests/sys/fs/fusefs/create.cc stable/12/tests/sys/fs/fusefs/default_permissions.cc stable/12/tests/sys/fs/fusefs/default_permissions_privileged.cc stable/12/tests/sys/fs/fusefs/destroy.cc stable/12/tests/sys/fs/fusefs/dev_fuse_poll.cc stable/12/tests/sys/fs/fusefs/fifo.cc stable/12/tests/sys/fs/fusefs/flush.cc stable/12/tests/sys/fs/fusefs/forget.cc stable/12/tests/sys/fs/fusefs/fsync.cc stable/12/tests/sys/fs/fusefs/fsyncdir.cc stable/12/tests/sys/fs/fusefs/getattr.cc stable/12/tests/sys/fs/fusefs/interrupt.cc stable/12/tests/sys/fs/fusefs/io.cc stable/12/tests/sys/fs/fusefs/link.cc stable/12/tests/sys/fs/fusefs/locks.cc stable/12/tests/sys/fs/fusefs/lookup.cc stable/12/tests/sys/fs/fusefs/mkdir.cc stable/12/tests/sys/fs/fusefs/mknod.cc stable/12/tests/sys/fs/fusefs/mockfs.cc stable/12/tests/sys/fs/fusefs/mockfs.hh stable/12/tests/sys/fs/fusefs/mount.cc stable/12/tests/sys/fs/fusefs/nfs.cc stable/12/tests/sys/fs/fusefs/notify.cc stable/12/tests/sys/fs/fusefs/open.cc stable/12/tests/sys/fs/fusefs/opendir.cc stable/12/tests/sys/fs/fusefs/read.cc stable/12/tests/sys/fs/fusefs/readdir.cc stable/12/tests/sys/fs/fusefs/readlink.cc stable/12/tests/sys/fs/fusefs/release.cc stable/12/tests/sys/fs/fusefs/releasedir.cc stable/12/tests/sys/fs/fusefs/rename.cc stable/12/tests/sys/fs/fusefs/rmdir.cc stable/12/tests/sys/fs/fusefs/setattr.cc stable/12/tests/sys/fs/fusefs/statfs.cc stable/12/tests/sys/fs/fusefs/symlink.cc stable/12/tests/sys/fs/fusefs/unlink.cc stable/12/tests/sys/fs/fusefs/utils.cc stable/12/tests/sys/fs/fusefs/utils.hh stable/12/tests/sys/fs/fusefs/write.cc stable/12/tests/sys/fs/fusefs/xattr.cc |