kernel/linux.git, branch v4.4.195

Linux 4.4.195

2019-10-05T10:27:56+00:00

Btrfs: fix race setting up and completing qgroup rescan workers

2019-10-05T10:27:56+00:00

[ Upstream commit 13fc1d271a2e3ab8a02071e711add01fab9271f6 ] There is a race between setting up a qgroup rescan worker and completing a qgroup rescan worker that can lead to callers of the qgroup rescan wait ioctl to either not wait for the rescan worker to complete or to hang forever due to missing wake ups. The following diagram shows a sequence of steps that illustrates the race. CPU 1 CPU 2 CPU 3 btrfs_ioctl_quota_rescan() btrfs_qgroup_rescan() qgroup_rescan_init() mutex_lock(&fs_info->qgroup_rescan_lock) spin_lock(&fs_info->qgroup_lock) fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN init_completion( &fs_info->qgroup_rescan_completion) fs_info->qgroup_rescan_running = true mutex_unlock(&fs_info->qgroup_rescan_lock) spin_unlock(&fs_info->qgroup_lock) btrfs_init_work() --> starts the worker btrfs_qgroup_rescan_worker() mutex_lock(&fs_info->qgroup_rescan_lock) fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN mutex_unlock(&fs_info->qgroup_rescan_lock) starts transaction, updates qgroup status item, etc btrfs_ioctl_quota_rescan() btrfs_qgroup_rescan() qgroup_rescan_init() mutex_lock(&fs_info->qgroup_rescan_lock) spin_lock(&fs_info->qgroup_lock) fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN init_completion( &fs_info->qgroup_rescan_completion) fs_info->qgroup_rescan_running = true mutex_unlock(&fs_info->qgroup_rescan_lock) spin_unlock(&fs_info->qgroup_lock) btrfs_init_work() --> starts another worker mutex_lock(&fs_info->qgroup_rescan_lock) fs_info->qgroup_rescan_running = false mutex_unlock(&fs_info->qgroup_rescan_lock) complete_all(&fs_info->qgroup_rescan_completion) Before the rescan worker started by the task at CPU 3 completes, if another task calls btrfs_ioctl_quota_rescan(), it will get -EINPROGRESS because the flag BTRFS_QGROUP_STATUS_FLAG_RESCAN is set at fs_info->qgroup_flags, which is expected and correct behaviour. However if other task calls btrfs_ioctl_quota_rescan_wait() before the rescan worker started by the task at CPU 3 completes, it will return immediately without waiting for the new rescan worker to complete, because fs_info->qgroup_rescan_running is set to false by CPU 2. This race is making test case btrfs/171 (from fstests) to fail often: btrfs/171 9s ... - output mismatch (see /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad) # --- tests/btrfs/171.out 2018-09-16 21:30:48.505104287 +0100 # +++ /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad 2019-09-19 02:01:36.938486039 +0100 # @@ -1,2 +1,3 @@ # QA output created by 171 # +ERROR: quota rescan failed: Operation now in progress # Silence is golden # ... # (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/btrfs/171.out /home/fdmanana/git/hub/xfstests/results//btrfs/171.out.bad' to see the entire diff) That is because the test calls the btrfs-progs commands "qgroup quota rescan -w", "qgroup assign" and "qgroup remove" in a sequence that makes calls to the rescan start ioctl fail with -EINPROGRESS (note the "btrfs" commands 'qgroup assign' and 'qgroup remove' often call the rescan start ioctl after calling the qgroup assign ioctl, btrfs_ioctl_qgroup_assign()), since previous waits didn't actually wait for a rescan worker to complete. Another problem the race can cause is missing wake ups for waiters, since the call to complete_all() happens outside a critical section and after clearing the flag BTRFS_QGROUP_STATUS_FLAG_RESCAN. In the sequence diagram above, if we have a waiter for the first rescan task (executed by CPU 2), then fs_info->qgroup_rescan_completion.wait is not empty, and if after the rescan worker clears BTRFS_QGROUP_STATUS_FLAG_RESCAN and before it calls complete_all() against fs_info->qgroup_rescan_completion, the task at CPU 3 calls init_completion() against fs_info->qgroup_rescan_completion which re-initilizes its wait queue to an empty queue, therefore causing the rescan worker at CPU 2 to call complete_all() against an empty queue, never waking up the task waiting for that rescan worker. Fix this by clearing BTRFS_QGROUP_STATUS_FLAG_RESCAN and setting fs_info->qgroup_rescan_running to false in the same critical section, delimited by the mutex fs_info->qgroup_rescan_lock, as well as doing the call to complete_all() in that same critical section. This gives the protection needed to avoid rescan wait ioctl callers not waiting for a running rescan worker and the lost wake ups problem, since setting that rescan flag and boolean as well as initializing the wait queue is done already in a critical section delimited by that mutex (at qgroup_rescan_init()). Fixes: 57254b6ebce4ce ("Btrfs: add ioctl to wait for qgroup rescan completion") Fixes: d2c609b834d62f ("btrfs: properly track when rescan worker is running") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Sasha Levin

btrfs: Relinquish CPUs in btrfs_compare_trees

2019-10-05T10:27:56+00:00

commit 6af112b11a4bc1b560f60a618ac9c1dcefe9836e upstream. When doing any form of incremental send the parent and the child trees need to be compared via btrfs_compare_trees. This can result in long loop chains without ever relinquishing the CPU. This causes softlockup detector to trigger when comparing trees with a lot of items. Example report: watchdog: BUG: soft lockup - CPU#0 stuck for 24s! [snapperd:16153] CPU: 0 PID: 16153 Comm: snapperd Not tainted 5.2.9-1-default #1 openSUSE Tumbleweed (unreleased) Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 pstate: 40000005 (nZcv daif -PAN -UAO) pc : __ll_sc_arch_atomic_sub_return+0x14/0x20 lr : btrfs_release_extent_buffer_pages+0xe0/0x1e8 [btrfs] sp : ffff00001273b7e0 Call trace: __ll_sc_arch_atomic_sub_return+0x14/0x20 release_extent_buffer+0xdc/0x120 [btrfs] free_extent_buffer.part.0+0xb0/0x118 [btrfs] free_extent_buffer+0x24/0x30 [btrfs] btrfs_release_path+0x4c/0xa0 [btrfs] btrfs_free_path.part.0+0x20/0x40 [btrfs] btrfs_free_path+0x24/0x30 [btrfs] get_inode_info+0xa8/0xf8 [btrfs] finish_inode_if_needed+0xe0/0x6d8 [btrfs] changed_cb+0x9c/0x410 [btrfs] btrfs_compare_trees+0x284/0x648 [btrfs] send_subvol+0x33c/0x520 [btrfs] btrfs_ioctl_send+0x8a0/0xaf0 [btrfs] btrfs_ioctl+0x199c/0x2288 [btrfs] do_vfs_ioctl+0x4b0/0x820 ksys_ioctl+0x84/0xb8 __arm64_sys_ioctl+0x28/0x38 el0_svc_common.constprop.0+0x7c/0x188 el0_svc_handler+0x34/0x90 el0_svc+0x8/0xc Fix this by adding a call to cond_resched at the beginning of the main loop in btrfs_compare_trees. Fixes: 7069830a9e38 ("Btrfs: add btrfs_compare_trees function") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Johannes Thumshirn Signed-off-by: Nikolay Borisov Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

Btrfs: fix use-after-free when using the tree modification log

2019-10-05T10:27:56+00:00

commit efad8a853ad2057f96664328a0d327a05ce39c76 upstream. At ctree.c:get_old_root(), we are accessing a root's header owner field after we have freed the respective extent buffer. This results in an use-after-free that can lead to crashes, and when CONFIG_DEBUG_PAGEALLOC is set, results in a stack trace like the following: [ 3876.799331] stack segment: 0000 [#1] SMP DEBUG_PAGEALLOC PTI [ 3876.799363] CPU: 0 PID: 15436 Comm: pool Not tainted 5.3.0-rc3-btrfs-next-54 #1 [ 3876.799385] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 [ 3876.799433] RIP: 0010:btrfs_search_old_slot+0x652/0xd80 [btrfs] (...) [ 3876.799502] RSP: 0018:ffff9f08c1a2f9f0 EFLAGS: 00010286 [ 3876.799518] RAX: ffff8dd300000000 RBX: ffff8dd85a7a9348 RCX: 000000038da26000 [ 3876.799538] RDX: 0000000000000000 RSI: ffffe522ce368980 RDI: 0000000000000246 [ 3876.799559] RBP: dae1922adadad000 R08: 0000000008020000 R09: ffffe522c0000000 [ 3876.799579] R10: ffff8dd57fd788c8 R11: 000000007511b030 R12: ffff8dd781ddc000 [ 3876.799599] R13: ffff8dd9e6240578 R14: ffff8dd6896f7a88 R15: ffff8dd688cf90b8 [ 3876.799620] FS: 00007f23ddd97700(0000) GS:ffff8dda20200000(0000) knlGS:0000000000000000 [ 3876.799643] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3876.799660] CR2: 00007f23d4024000 CR3: 0000000710bb0005 CR4: 00000000003606f0 [ 3876.799682] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 3876.799703] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 3876.799723] Call Trace: [ 3876.799735] ? do_raw_spin_unlock+0x49/0xc0 [ 3876.799749] ? _raw_spin_unlock+0x24/0x30 [ 3876.799779] resolve_indirect_refs+0x1eb/0xc80 [btrfs] [ 3876.799810] find_parent_nodes+0x38d/0x1180 [btrfs] [ 3876.799841] btrfs_check_shared+0x11a/0x1d0 [btrfs] [ 3876.799870] ? extent_fiemap+0x598/0x6e0 [btrfs] [ 3876.799895] extent_fiemap+0x598/0x6e0 [btrfs] [ 3876.799913] do_vfs_ioctl+0x45a/0x700 [ 3876.799926] ksys_ioctl+0x70/0x80 [ 3876.799938] ? trace_hardirqs_off_thunk+0x1a/0x20 [ 3876.799953] __x64_sys_ioctl+0x16/0x20 [ 3876.799965] do_syscall_64+0x62/0x220 [ 3876.799977] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 3876.799993] RIP: 0033:0x7f23e0013dd7 (...) [ 3876.800056] RSP: 002b:00007f23ddd96ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 3876.800078] RAX: ffffffffffffffda RBX: 00007f23d80210f8 RCX: 00007f23e0013dd7 [ 3876.800099] RDX: 00007f23d80210f8 RSI: 00000000c020660b RDI: 0000000000000003 [ 3876.800626] RBP: 000055fa2a2a2440 R08: 0000000000000000 R09: 00007f23ddd96d7c [ 3876.801143] R10: 00007f23d8022000 R11: 0000000000000246 R12: 00007f23ddd96d80 [ 3876.801662] R13: 00007f23ddd96d78 R14: 00007f23d80210f0 R15: 00007f23ddd96d80 (...) [ 3876.805107] ---[ end trace e53161e179ef04f9 ]--- Fix that by saving the root's header owner field into a local variable before freeing the root's extent buffer, and then use that local variable when needed. Fixes: 30b0463a9394d9 ("Btrfs: fix accessing the root pointer in tree mod log functions") CC: stable@vger.kernel.org # 3.10+ Reviewed-by: Nikolay Borisov Reviewed-by: Anand Jain Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman

ovl: filter of trusted xattr results in audit

2019-10-05T10:27:56+00:00

commit 5c2e9f346b815841f9bed6029ebcb06415caf640 upstream. When filtering xattr list for reading, presence of trusted xattr results in a security audit log. However, if there is other content no errno will be set, and if there isn't, the errno will be -ENODATA and not -EPERM as is usually associated with a lack of capability. The check does not block the request to list the xattrs present. Switch to ns_capable_noaudit to reflect a more appropriate check. Signed-off-by: Mark Salyzyn Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: stable@vger.kernel.org # v3.18+ Fixes: a082c6f680da ("ovl: filter trusted xattr for non-admin") Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

CIFS: Fix oplock handling for SMB 2.1+ protocols

2019-10-05T10:27:55+00:00

commit a016e2794fc3a245a91946038dd8f34d65e53cc3 upstream. There may be situations when a server negotiates SMB 2.1 protocol version or higher but responds to a CREATE request with an oplock rather than a lease. Currently the client doesn't handle such a case correctly: when another CREATE comes in the server sends an oplock break to the initial CREATE and the client doesn't send an ack back due to a wrong caching level being set (READ instead of RWH). Missing an oplock break ack makes the server wait until the break times out which dramatically increases the latency of the second CREATE. Fix this by properly detecting oplocks when using SMB 2.1 protocol version and higher. Cc: Signed-off-by: Pavel Shilovsky Signed-off-by: Steve French Reviewed-by: Ronnie Sahlberg Signed-off-by: Greg Kroah-Hartman

i2c: riic: Clear NACK in tend isr

2019-10-05T10:27:55+00:00

commit a71e2ac1f32097fbb2beab098687a7a95c84543e upstream. The NACKF flag should be cleared in INTRIICNAKI interrupt processing as description in HW manual. This issue shows up quickly when PREEMPT_RT is applied and a device is probed that is not plugged in (like a touchscreen controller). The result is endless interrupts that halt system boot. Fixes: 310c18a41450 ("i2c: riic: add driver") Cc: stable@vger.kernel.org Reported-by: Chien Nguyen Signed-off-by: Chris Brandt Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman

hwrng: core - don't wait on add_early_randomness()

2019-10-05T10:27:55+00:00

commit 78887832e76541f77169a24ac238fccb51059b63 upstream. add_early_randomness() is called by hwrng_register() when the hardware is added. If this hardware and its module are present at boot, and if there is no data available the boot hangs until data are available and can't be interrupted. For instance, in the case of virtio-rng, in some cases the host can be not able to provide enough entropy for all the guests. We can have two easy ways to reproduce the problem but they rely on misconfiguration of the hypervisor or the egd daemon: - if virtio-rng device is configured to connect to the egd daemon of the host but when the virtio-rng driver asks for data the daemon is not connected, - if virtio-rng device is configured to connect to the egd daemon of the host but the egd daemon doesn't provide data. The guest kernel will hang at boot until the virtio-rng driver provides enough data. To avoid that, call rng_get_data() in non-blocking mode (wait=0) from add_early_randomness(). Signed-off-by: Laurent Vivier Fixes: d9e797261933 ("hwrng: add randomness to system from rng...") Cc: Reviewed-by: Theodore Ts'o Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

quota: fix wrong condition in is_quota_modification()

2019-10-05T10:27:55+00:00

commit 6565c182094f69e4ffdece337d395eb7ec760efc upstream. Quoted from commit 3da40c7b0898 ("ext4: only call ext4_truncate when size <= isize") " At LSF we decided that if we truncate up from isize we shouldn't trim fallocated blocks that were fallocated with KEEP_SIZE and are past the new i_size. This patch fixes ext4 to do this. " And generic/092 of fstest have covered this case for long time, however is_quota_modification() didn't adjust based on that rule, so that in below condition, we will lose to quota block change: - fallocate blocks beyond EOF - remount - truncate(file_path, file_size) Fix it. Link: https://lore.kernel.org/r/20190911093650.35329-1-yuchao0@huawei.com Fixes: 3da40c7b0898 ("ext4: only call ext4_truncate when size <= isize") CC: stable@vger.kernel.org Signed-off-by: Chao Yu Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

ext4: fix punch hole for inline_data file systems

2019-10-05T10:27:54+00:00

commit c1e8220bd316d8ae8e524df39534b8a412a45d5e upstream. If a program attempts to punch a hole on an inline data file, we need to convert it to a normal file first. This was detected using ext4/032 using the adv configuration. Simple reproducer: mke2fs -Fq -t ext4 -O inline_data /dev/vdc mount /vdc echo "" > /vdc/testfile xfs_io -c 'truncate 33554432' /vdc/testfile xfs_io -c 'fpunch 0 1048576' /vdc/testfile umount /vdc e2fsck -fy /dev/vdc Cc: stable@vger.kernel.org Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman