user/sven/linux.git/fs, branch v5.0.16

NFSv4.1 fix incorrect return value in copy_file_range

2019-05-10T16:36:11Z

[ Upstream commit 0769663b4f580566ef6cdf366f3073dbe8022c39 ] According to the NFSv4.2 spec if the input and output file is the same file, operation should fail with EINVAL. However, linux copy_file_range() system call has no such restrictions. Therefore, in such case let's return EOPNOTSUPP and allow VFS to fallback to doing do_splice_direct(). Also when copy_file_range is called on an NFSv4.0 or 4.1 mount (ie., a server that doesn't support COPY functionality), we also need to return EOPNOTSUPP and fallback to a regular copy. Fixes xfstest generic/075, generic/091, generic/112, generic/263 for all NFSv4.x versions. Signed-off-by: Olga Kornievskaia Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock

2019-05-08T05:22:55Z

[ Upstream commit 10dce8af34226d90fa56746a934f8da5dcdba3df ] Commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per POSIX") added locking for file.f_pos access and in particular made concurrent read and write not possible - now both those functions take f_pos lock for the whole run, and so if e.g. a read is blocked waiting for data, write will deadlock waiting for that read to complete. This caused regression for stream-like files where previously read and write could run simultaneously, but after that patch could not do so anymore. See e.g. commit 581d21a2d02a ("xenbus: fix deadlock on writes to /proc/xen/xenbus") which fixes such regression for particular case of /proc/xen/xenbus. The patch that added f_pos lock in 2014 did so to guarantee POSIX thread safety for read/write/lseek and added the locking to file descriptors of all regular files. In 2014 that thread-safety problem was not new as it was already discussed earlier in 2006. However even though 2006'th version of Linus's patch was adding f_pos locking "only for files that are marked seekable with FMODE_LSEEK (thus avoiding the stream-like objects like pipes and sockets)", the 2014 version - the one that actually made it into the tree as 9c225f2655e3 - is doing so irregardless of whether a file is seekable or not. See https://lore.kernel.org/lkml/53022DB1.4070805@gmail.com/ https://lwn.net/Articles/180387 https://lwn.net/Articles/180396 for historic context. The reason that it did so is, probably, that there are many files that are marked non-seekable, but e.g. their read implementation actually depends on knowing current position to correctly handle the read. Some examples: kernel/power/user.c snapshot_read fs/debugfs/file.c u32_array_read fs/fuse/control.c fuse_conn_waiting_read + ... drivers/hwmon/asus_atk0110.c atk_debugfs_ggrp_read arch/s390/hypfs/inode.c hypfs_read_iter ... Despite that, many nonseekable_open users implement read and write with pure stream semantics - they don't depend on passed ppos at all. And for those cases where read could wait for something inside, it creates a situation similar to xenbus - the write could be never made to go until read is done, and read is waiting for some, potentially external, event, for potentially unbounded time -> deadlock. Besides xenbus, there are 14 such places in the kernel that I've found with semantic patch (see below): drivers/xen/evtchn.c:667:8-24: ERROR: evtchn_fops: .read() can deadlock .write() drivers/isdn/capi/capi.c:963:8-24: ERROR: capi_fops: .read() can deadlock .write() drivers/input/evdev.c:527:1-17: ERROR: evdev_fops: .read() can deadlock .write() drivers/char/pcmcia/cm4000_cs.c:1685:7-23: ERROR: cm4000_fops: .read() can deadlock .write() net/rfkill/core.c:1146:8-24: ERROR: rfkill_fops: .read() can deadlock .write() drivers/s390/char/fs3270.c:488:1-17: ERROR: fs3270_fops: .read() can deadlock .write() drivers/usb/misc/ldusb.c:310:1-17: ERROR: ld_usb_fops: .read() can deadlock .write() drivers/hid/uhid.c:635:1-17: ERROR: uhid_fops: .read() can deadlock .write() net/batman-adv/icmp_socket.c:80:1-17: ERROR: batadv_fops: .read() can deadlock .write() drivers/media/rc/lirc_dev.c:198:1-17: ERROR: lirc_fops: .read() can deadlock .write() drivers/leds/uleds.c:77:1-17: ERROR: uleds_fops: .read() can deadlock .write() drivers/input/misc/uinput.c:400:1-17: ERROR: uinput_fops: .read() can deadlock .write() drivers/infiniband/core/user_mad.c:985:7-23: ERROR: umad_fops: .read() can deadlock .write() drivers/gnss/core.c:45:1-17: ERROR: gnss_fops: .read() can deadlock .write() In addition to the cases above another regression caused by f_pos locking is that now FUSE filesystems that implement open with FOPEN_NONSEEKABLE flag, can no longer implement bidirectional stream-like files - for the same reason as above e.g. read can deadlock write locking on file.f_pos in the kernel. FUSE's FOPEN_NONSEEKABLE was added in 2008 in a7c1b990f715 ("fuse: implement nonseekable open") to support OSSPD. OSSPD implements /dev/dsp in userspace with FOPEN_NONSEEKABLE flag, with corresponding read and write routines not depending on current position at all, and with both read and write being potentially blocking operations: See https://github.com/libfuse/osspd https://lwn.net/Articles/308445 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1406 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1438-L1477 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1479-L1510 Corresponding libfuse example/test also describes FOPEN_NONSEEKABLE as "somewhat pipe-like files ..." with read handler not using offset. However that test implements only read without write and cannot exercise the deadlock scenario: https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L124-L131 https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L146-L163 https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L209-L216 I've actually hit the read vs write deadlock for real while implementing my FUSE filesystem where there is /head/watch file, for which open creates separate bidirectional socket-like stream in between filesystem and its user with both read and write being later performed simultaneously. And there it is semantically not easy to split the stream into two separate read-only and write-only channels: https://lab.nexedi.com/kirr/wendelin.core/blob/f13aa600/wcfs/wcfs.go#L88-169 Let's fix this regression. The plan is: 1. We can't change nonseekable_open to include &~FMODE_ATOMIC_POS - doing so would break many in-kernel nonseekable_open users which actually use ppos in read/write handlers. 2. Add stream_open() to kernel to open stream-like non-seekable file descriptors. Read and write on such file descriptors would never use nor change ppos. And with that property on stream-like files read and write will be running without taking f_pos lock - i.e. read and write could be running simultaneously. 3. With semantic patch search and convert to stream_open all in-kernel nonseekable_open users for which read and write actually do not depend on ppos and where there is no other methods in file_operations which assume @offset access. 4. Add FOPEN_STREAM to fs/fuse/ and open in-kernel file-descriptors via steam_open if that bit is present in filesystem open reply. It was tempting to change fs/fuse/ open handler to use stream_open instead of nonseekable_open on just FOPEN_NONSEEKABLE flags, but grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE, and in particular GVFS which actually uses offset in its read and write handlers https://codesearch.debian.net/search?q=-%3Enonseekable+%3D https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481 so if we would do such a change it will break a real user. 5. Add stream_open and FOPEN_STREAM handling to stable kernels starting from v3.14+ (the kernel where 9c225f2655 first appeared). This will allow to patch OSSPD and other FUSE filesystems that provide stream-like files to return FOPEN_STREAM | FOPEN_NONSEEKABLE in their open handler and this way avoid the deadlock on all kernel versions. This should work because fs/fuse/ ignores unknown open flags returned from a filesystem and so passing FOPEN_STREAM to a kernel that is not aware of this flag cannot hurt. In turn the kernel that is not aware of FOPEN_STREAM will be < v3.14 where just FOPEN_NONSEEKABLE is sufficient to implement streams without read vs write deadlock. This patch adds stream_open, converts /proc/xen/xenbus to it and adds semantic patch to automatically locate in-kernel places that are either required to be converted due to read vs write deadlock, or that are just safe to be converted because read and write do not use ppos and there are no other funky methods in file_operations. Regarding semantic patch I've verified each generated change manually - that it is correct to convert - and each other nonseekable_open instance left - that it is either not correct to convert there, or that it is not converted due to current stream_open.cocci limitations. The script also does not convert files that should be valid to convert, but that currently have .llseek = noop_llseek or generic_file_llseek for unknown reason despite file being opened with nonseekable_open (e.g. drivers/input/mousedev.c) Cc: Michael Kerrisk Cc: Yongzhi Pan Cc: Jonathan Corbet Cc: David Vrabel Cc: Juergen Gross Cc: Miklos Szeredi Cc: Tejun Heo Cc: Kirill Tkhai Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Greg Kroah-Hartman Cc: Julia Lawall Cc: Nikolaus Rath Cc: Han-Wen Nienhuys Signed-off-by: Kirill Smelkov Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin (Microsoft)

hugetlbfs: fix memory leak for resv_map

2019-05-08T05:22:54Z

[ Upstream commit 58b6e5e8f1addd44583d61b0a03c0f5519527e35 ] When mknod is used to create a block special file in hugetlbfs, it will allocate an inode and kmalloc a 'struct resv_map' via resv_map_alloc(). inode->i_mapping->private_data will point the newly allocated resv_map. However, when the device special file is opened bd_acquire() will set inode->i_mapping to bd_inode->i_mapping. Thus the pointer to the allocated resv_map is lost and the structure is leaked. Programs to reproduce: mount -t hugetlbfs nodev hugetlbfs mknod hugetlbfs/dev b 0 0 exec 30<> hugetlbfs/dev umount hugetlbfs/ resv_map structures are only needed for inodes which can have associated page allocations. To fix the leak, only allocate resv_map for those inodes which could possibly be associated with page allocations. Link: http://lkml.kernel.org/r/20190401213101.16476-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz Reviewed-by: Andrew Morton Reported-by: Yufen Yu Suggested-by: Yufen Yu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin (Microsoft)

debugfs: fix use-after-free on symlink traversal

2019-05-08T05:22:51Z

[ Upstream commit 93b919da64c15b90953f96a536e5e61df896ca57 ] symlink body shouldn't be freed without an RCU delay. Switch debugfs to ->destroy_inode() and use of call_rcu(); free both the inode and symlink body in the callback. Similar to solution for bpf, only here it's even more obvious that ->evict_inode() can be dropped. Signed-off-by: Al Viro Signed-off-by: Sasha Levin (Microsoft)

jffs2: fix use-after-free on symlink traversal

2019-05-08T05:22:51Z

[ Upstream commit 4fdcfab5b5537c21891e22e65996d4d0dd8ab4ca ] free the symlink body after the same RCU delay we have for freeing the struct inode itself, so that traversal during RCU pathwalk wouldn't step into freed memory. Signed-off-by: Al Viro Signed-off-by: Sasha Levin (Microsoft)

afs: Fix StoreData op marshalling

2019-05-04T07:21:20Z

[ Upstream commit 8c7ae38d1ce12a0eaeba655df8562552b3596c7f ] The marshalling of AFS.StoreData, AFS.StoreData64 and YFS.StoreData64 calls generated by ->setattr() ops for the purpose of expanding a file is incorrect due to older documentation incorrectly describing the way the RPC 'FileLength' parameter is meant to work. The older documentation says that this is the length the file is meant to end up at the end of the operation; however, it was never implemented this way in any of the servers, but rather the file is truncated down to this before the write operation is effected, and never expanded to it (and, indeed, it was renamed to 'TruncPos' in 2014). Fix this by setting the position parameter to the new file length and doing a zero-lengh write there. The bug causes Xwayland to SIGBUS due to unexpected non-expansion of a file it then mmaps. This can be tested by giving the following test program a filename in an AFS directory: #include #include #include #include #include int main(int argc, char *argv[]) { char *p; int fd; if (argc != 2) { fprintf(stderr, "Format: test-trunc-mmap \n"); exit(2); } fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC); if (fd < 0) { perror(argv[1]); exit(1); } if (ftruncate(fd, 0x140008) == -1) { perror("ftruncate"); exit(1); } p = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (p == MAP_FAILED) { perror("mmap"); exit(1); } p[0] = 'a'; if (munmap(p, 4096) < 0) { perror("munmap"); exit(1); } if (close(fd) < 0) { perror("close"); exit(1); } exit(0); } Fixes: 31143d5d515e ("AFS: implement basic file write support") Reported-by: Jonathan Billings Tested-by: Jonathan Billings Signed-off-by: David Howells Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin (Microsoft)

ceph: fix use-after-free on symlink traversal

2019-05-04T07:21:19Z

[ Upstream commit daf5cc27eed99afdea8d96e71b89ba41f5406ef6 ] free the symlink body after the same RCU delay we have for freeing the struct inode itself, so that traversal during RCU pathwalk wouldn't step into freed memory. Signed-off-by: Al Viro Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin (Microsoft)

NFS: Fix a typo in nfs_init_timeout_values()

2019-05-04T07:21:17Z

[ Upstream commit 5a698243930c441afccec04e4d5dc8febfd2b775 ] Specifying a retrans=0 mount parameter to a NFS/TCP mount, is inadvertently causing the NFS client to rewrite any specified timeout parameter to the default of 60 seconds. Fixes: a956beda19a6 ("NFS: Allow the mount option retrans=0") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin (Microsoft)

Btrfs: fix file corruption after snapshotting due to mix of buffered/DIO writes

2019-05-04T07:21:12Z

[ Upstream commit 609e804d771f59dc5d45a93e5ee0053c74bbe2bf ] When we are mixing buffered writes with direct IO writes against the same file and snapshotting is happening concurrently, we can end up with a corrupt file content in the snapshot. Example: 1) Inode/file is empty. 2) Snapshotting starts. 2) Buffered write at offset 0 length 256Kb. This updates the i_size of the inode to 256Kb, disk_i_size remains zero. This happens after the task doing the snapshot flushes all existing delalloc. 3) DIO write at offset 256Kb length 768Kb. Once the ordered extent completes it sets the inode's disk_i_size to 1Mb (256Kb + 768Kb) and updates the inode item in the fs tree with a size of 1Mb (which is the value of disk_i_size). 4) The dealloc for the range [0, 256Kb[ did not start yet. 5) The transaction used in the DIO ordered extent completion, which updated the inode item, is committed by the snapshotting task. 6) Snapshot creation completes. 7) Dealloc for the range [0, 256Kb[ is flushed. After that when reading the file from the snapshot we always get zeroes for the range [0, 256Kb[, the file has a size of 1Mb and the data written by the direct IO write is found. From an application's point of view this is a corruption, since in the source subvolume it could never read a version of the file that included the data from the direct IO write without the data from the buffered write included as well. In the snapshot's tree, file extent items are missing for the range [0, 256Kb[. The issue, obviously, does not happen when using the -o flushoncommit mount option. Fix this by flushing delalloc for all the roots that are about to be snapshotted when committing a transaction. This guarantees total ordering when updating the disk_i_size of an inode since the flush for dealloc is done when a transaction is in the TRANS_STATE_COMMIT_START state and wait is done once no more external writers exist. This is similar to what we do when using the flushoncommit mount option, but we do it only if the transaction has snapshots to create and only for the roots of the subvolumes to be snapshotted. The bulk of the dealloc is flushed in the snapshot creation ioctl, so the flush work we do inside the transaction is minimized. This issue, involving buffered and direct IO writes with snapshotting, is often triggered by fstest btrfs/078, and got reported by fsck when not using the NO_HOLES features, for example: $ cat results/btrfs/078.full (...) _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent *** fsck.btrfs output *** [1/7] checking root items [2/7] checking extents [3/7] checking free space cache [4/7] checking fs roots root 258 inode 264 errors 100, file extent discount Found file extent holes: start: 524288, len: 65536 ERROR: errors found in fs roots Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Sasha Levin (Microsoft)

fs: prevent page refcount overflow in pipe_buf_get

2019-05-04T07:21:11Z

commit 15fab63e1e57be9fdb5eec1bbc5916e9825e9acb upstream. Change pipe_buf_get() to return a bool indicating whether it succeeded in raising the refcount of the page (if the thing in the pipe is a page). This removes another mechanism for overflowing the page refcount. All callers converted to handle a failure. Reported-by: Jann Horn Signed-off-by: Matthew Wilcox Cc: stable@kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman