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2020-06-23io_uring: fix io_sq_thread no schedule when busyXuan Zhuo1-2/+2
When the user consumes and generates sqe at a fast rate, io_sqring_entries can always get sqe, and ret will not be equal to -EBUSY, so that io_sq_thread will never call cond_resched or schedule, and then we will get the following system error prompt: rcu: INFO: rcu_sched self-detected stall on CPU or watchdog: BUG: soft lockup-CPU#23 stuck for 112s! [io_uring-sq:1863] This patch checks whether need to call cond_resched() by checking the need_resched() function every cycle. Suggested-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-23cifs: Fix double add page to memcg when cifs_readpagesZhang Xiaoxu1-4/+7
When xfstests generic/451, there is an BUG at mm/memcontrol.c: page:ffffea000560f2c0 refcount:2 mapcount:0 mapping:000000008544e0ea index:0xf mapping->aops:cifs_addr_ops dentry name:"tst-aio-dio-cycle-write.451" flags: 0x2fffff80000001(locked) raw: 002fffff80000001 ffffc90002023c50 ffffea0005280088 ffff88815cda0210 raw: 000000000000000f 0000000000000000 00000002ffffffff ffff88817287d000 page dumped because: VM_BUG_ON_PAGE(page->mem_cgroup) page->mem_cgroup:ffff88817287d000 ------------[ cut here ]------------ kernel BUG at mm/memcontrol.c:2659! invalid opcode: 0000 [#1] SMP CPU: 2 PID: 2038 Comm: xfs_io Not tainted 5.8.0-rc1 #44 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_ 073836-buildvm-ppc64le-16.ppc.4 RIP: 0010:commit_charge+0x35/0x50 Code: 0d 48 83 05 54 b2 02 05 01 48 89 77 38 c3 48 c7 c6 78 4a ea ba 48 83 05 38 b2 02 05 01 e8 63 0d9 RSP: 0018:ffffc90002023a50 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff88817287d000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff88817ac97ea0 RDI: ffff88817ac97ea0 RBP: ffffea000560f2c0 R08: 0000000000000203 R09: 0000000000000005 R10: 0000000000000030 R11: ffffc900020237a8 R12: 0000000000000000 R13: 0000000000000001 R14: 0000000000000001 R15: ffff88815a1272c0 FS: 00007f5071ab0800(0000) GS:ffff88817ac80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055efcd5ca000 CR3: 000000015d312000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: mem_cgroup_charge+0x166/0x4f0 __add_to_page_cache_locked+0x4a9/0x710 add_to_page_cache_locked+0x15/0x20 cifs_readpages+0x217/0x1270 read_pages+0x29a/0x670 page_cache_readahead_unbounded+0x24f/0x390 __do_page_cache_readahead+0x3f/0x60 ondemand_readahead+0x1f1/0x470 page_cache_async_readahead+0x14c/0x170 generic_file_buffered_read+0x5df/0x1100 generic_file_read_iter+0x10c/0x1d0 cifs_strict_readv+0x139/0x170 new_sync_read+0x164/0x250 __vfs_read+0x39/0x60 vfs_read+0xb5/0x1e0 ksys_pread64+0x85/0xf0 __x64_sys_pread64+0x22/0x30 do_syscall_64+0x69/0x150 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f5071fcb1af Code: Bad RIP value. RSP: 002b:00007ffde2cdb8e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000011 RAX: ffffffffffffffda RBX: 00007ffde2cdb990 RCX: 00007f5071fcb1af RDX: 0000000000001000 RSI: 000055efcd5ca000 RDI: 0000000000000003 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000001000 R11: 0000000000000293 R12: 0000000000000001 R13: 000000000009f000 R14: 0000000000000000 R15: 0000000000001000 Modules linked in: ---[ end trace 725fa14a3e1af65c ]--- Since commit 3fea5a499d57 ("mm: memcontrol: convert page cache to a new mem_cgroup_charge() API") not cancel the page charge, the pages maybe double add to pagecache: thread1 | thread2 cifs_readpages readpages_get_pages add_to_page_cache_locked(head,index=n)=0 | readpages_get_pages | add_to_page_cache_locked(head,index=n+1)=0 add_to_page_cache_locked(head, index=n+1)=-EEXIST then, will next loop with list head page's index=n+1 and the page->mapping not NULL readpages_get_pages add_to_page_cache_locked(head, index=n+1) commit_charge VM_BUG_ON_PAGE So, we should not do the next loop when any page add to page cache failed. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Steve French <stfrench@microsoft.com> Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
2020-06-23Merge tag 'for-5.8-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linuxLinus Torvalds6-36/+102
Pull btrfs fixes from David Sterba: "A number of fixes, located in two areas, one performance fix and one fixup for better integration with another patchset. - bug fixes in nowait aio: - fix snapshot creation hang after nowait-aio was used - fix failure to write to prealloc extent past EOF - don't block when extent range is locked - block group fixes: - relocation failure when scrub runs in parallel - refcount fix when removing fails - fix race between removal and creation - space accounting fixes - reinstante fast path check for log tree at unlink time, fixes performance drop up to 30% in REAIM - kzfree/kfree fixup to ease treewide patchset renaming kzfree" * tag 'for-5.8-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: use kfree() in btrfs_ioctl_get_subvol_info() btrfs: fix RWF_NOWAIT writes blocking on extent locks and waiting for IO btrfs: fix RWF_NOWAIT write not failling when we need to cow btrfs: fix failure of RWF_NOWAIT write into prealloc extent beyond eof btrfs: fix hang on snapshot creation after RWF_NOWAIT write btrfs: check if a log root exists before locking the log_mutex on unlink btrfs: fix bytes_may_use underflow when running balance and scrub in parallel btrfs: fix data block group relocation failure due to concurrent scrub btrfs: fix race between block group removal and block group creation btrfs: fix a block group ref counter leak after failure to remove block group
2020-06-22xfs: fix use-after-free on CIL context on shutdownDave Chinner2-6/+6
xlog_wait() on the CIL context can reference a freed context if the waiter doesn't get scheduled before the CIL context is freed. This can happen when a task is on the hard throttle and the CIL push aborts due to a shutdown. This was detected by generic/019: thread 1 thread 2 __xfs_trans_commit xfs_log_commit_cil <CIL size over hard throttle limit> xlog_wait schedule xlog_cil_push_work wake_up_all <shutdown aborts commit> xlog_cil_committed kmem_free remove_wait_queue spin_lock_irqsave --> UAF Fix it by moving the wait queue to the CIL rather than keeping it in in the CIL context that gets freed on push completion. Because the wait queue is now independent of the CIL context and we might have multiple contexts in flight at once, only wake the waiters on the push throttle when the context we are pushing is over the hard throttle size threshold. Fixes: 0e7ab7efe7745 ("xfs: Throttle commits on delayed background CIL push") Reported-by: Yu Kuai <yukuai3@huawei.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2020-06-21cifs: Fix cached_fid refcnt leak in open_shrootXiyu Yang1-0/+1
open_shroot() invokes kref_get(), which increases the refcount of the "tcon->crfid" object. When open_shroot() returns not zero, it means the open operation failed and close_shroot() will not be called to decrement the refcount of the "tcon->crfid". The reference counting issue happens in one normal path of open_shroot(). When the cached root have been opened successfully in a concurrent process, the function increases the refcount and jump to "oshr_free" to return. However the current return value "rc" may not equal to 0, thus the increased refcount will not be balanced outside the function, causing a refcnt leak. Fix this issue by setting the value of "rc" to 0 before jumping to "oshr_free" label. Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn> Signed-off-by: Xin Tan <tanxin.ctf@gmail.com> Signed-off-by: Steve French <stfrench@microsoft.com> CC: Stable <stable@vger.kernel.org>
2020-06-21io_uring: kill NULL checks for submit statePavel Begunkov1-5/+1
After recent changes, io_submit_sqes() always passes valid submit state, so kill leftovers checking it for NULL. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: set @poll->file after @poll initPavel Begunkov1-1/+1
It's a good practice to modify fields of a struct after but not before it was initialised. Even though io_init_poll_iocb() doesn't touch poll->file, call it first. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: remove REQ_F_MUST_PUNTPavel Begunkov1-15/+7
REQ_F_MUST_PUNT may seem looking good and clear, but it's the same as not having REQ_F_NOWAIT set. That rather creates more confusion. Moreover, it doesn't even affect any behaviour (e.g. see the patch removing it from io_{read,write}). Kill theg flag and update already outdated comments. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: remove setting REQ_F_MUST_PUNT in rwPavel Begunkov1-8/+0
io_{read,write}() { ... copy_iov: // prep async if (!(flags & REQ_F_NOWAIT) && !file_can_poll(file)) flags |= REQ_F_MUST_PUNT; } REQ_F_MUST_PUNT there is pointless, because if it happens then REQ_F_NOWAIT is known to be _not_ set, and the request will go async path in __io_queue_sqe() anyway. file_can_poll() check is also repeated in arm_poll*(), so don't need it. Remove the mentioned assignment REQ_F_MUST_PUNT in preparation for killing the flag. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: support true async buffered reads, if file provides itJens Axboe1-4/+135
If the file is flagged with FMODE_BUF_RASYNC, then we don't have to punt the buffered read to an io-wq worker. Instead we can rely on page unlocking callbacks to support retry based async IO. This is a lot more efficient than doing async thread offload. The retry is done similarly to how we handle poll based retry. From the unlock callback, we simply queue the retry to a task_work based handler. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21btrfs: flag files as supporting buffered async readsJens Axboe1-1/+1
btrfs uses generic_file_read_iter(), which already supports this. Acked-by: Chris Mason <clm@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21xfs: flag files as supporting buffered async readsJens Axboe1-1/+1
XFS uses generic_file_read_iter(), which already supports this. Acked-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21block: flag block devices as supporting IOCB_WAITQJens Axboe1-1/+1
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: re-issue block requests that failed because of resourcesJens Axboe1-24/+124
Mark the plug with nowait == true, which will cause requests to avoid blocking on request allocation. If they do, we catch them and reissue them from a task_work based handler. Normally we can catch -EAGAIN directly, but the hard case is for split requests. As an example, the application issues a 512KB request. The block core will split this into 128KB if that's the max size for the device. The first request issues just fine, but we run into -EAGAIN for some latter splits for the same request. As the bio is split, we don't get to see the -EAGAIN until one of the actual reads complete, and hence we cannot handle it inline as part of submission. This does potentially cause re-reads of parts of the range, as the whole request is reissued. There's currently no better way to handle this. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: catch -EIO from buffered issue request failureJens Axboe1-5/+23
-EIO bubbles up like -EAGAIN if we fail to allocate a request at the lower level. Play it safe and treat it like -EAGAIN in terms of sync retry, to avoid passing back an errant -EIO. Catch some of these early for block based file, as non-mq devices generally do not support NOWAIT. That saves us some overhead by not first trying, then retrying from async context. We can go straight to async punt instead. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: always plug for any number of IOsJens Axboe1-10/+5
Currently we only plug if we're doing more than two request. We're going to be relying on always having the plug there to pass down information, so plug unconditionally. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: separate reporting of ring pages from registered pagesBijan Mottahedeh1-13/+30
Ring pages are not pinned so it is more appropriate to report them as locked. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: report pinned memory usageBijan Mottahedeh1-4/+18
Report pinned memory usage always, regardless of whether locked memory limit is enforced. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: rename ctx->account_mem fieldBijan Mottahedeh1-8/+8
Rename account_mem to limit_name to clarify its purpose. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: add wrappers for memory accountingBijan Mottahedeh1-20/+28
Facilitate separation of locked memory usage reporting vs. limiting for upcoming patches. No functional changes. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> [axboe: kill unnecessary () around return in io_account_mem()] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: use EPOLLEXCLUSIVE flag to aoid thundering herd type behaviorJiufei Xue1-2/+7
Applications can pass this flag in to avoid accept thundering herd. Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: change the poll type to be 32-bitsJiufei Xue1-4/+9
poll events should be 32-bits to cover EPOLLEXCLUSIVE. Explicit word-swap the poll32_events for big endian to make sure the ABI is not changed. We call this feature IORING_FEAT_POLL_32BITS, applications who want to use EPOLLEXCLUSIVE should check the feature bit first. Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-20Merge tag 'trace-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-traceLinus Torvalds1-5/+10
Pull tracing fixes from Steven Rostedt: - Have recordmcount work with > 64K sections (to support LTO) - kprobe RCU fixes - Correct a kprobe critical section with missing mutex - Remove redundant arch_disarm_kprobe() call - Fix lockup when kretprobe triggers within kprobe_flush_task() - Fix memory leak in fetch_op_data operations - Fix sleep in atomic in ftrace trace array sample code - Free up memory on failure in sample trace array code - Fix incorrect reporting of function_graph fields in format file - Fix quote within quote parsing in bootconfig - Fix return value of bootconfig tool - Add testcases for bootconfig tool - Fix maybe uninitialized warning in ftrace pid file code - Remove unused variable in tracing_iter_reset() - Fix some typos * tag 'trace-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace: Fix maybe-uninitialized compiler warning tools/bootconfig: Add testcase for show-command and quotes test tools/bootconfig: Fix to return 0 if succeeded to show the bootconfig tools/bootconfig: Fix to use correct quotes for value proc/bootconfig: Fix to use correct quotes for value tracing: Remove unused event variable in tracing_iter_reset tracing/probe: Fix memleak in fetch_op_data operations trace: Fix typo in allocate_ftrace_ops()'s comment tracing: Make ftrace packed events have align of 1 sample-trace-array: Remove trace_array 'sample-instance' sample-trace-array: Fix sleeping function called from invalid context kretprobe: Prevent triggering kretprobe from within kprobe_flush_task kprobes: Remove redundant arch_disarm_kprobe() call kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex kprobes: Use non RCU traversal APIs on kprobe_tables if possible kprobes: Suppress the suspicious RCU warning on kprobes recordmcount: support >64k sections
2020-06-20afs: Fix hang on rmmod due to outstanding timerDavid Howells4-2/+16
The fileserver probe timer, net->fs_probe_timer, isn't cancelled when the kafs module is being removed and so the count it holds on net->servers_outstanding doesn't get dropped.. This causes rmmod to wait forever. The hung process shows a stack like: afs_purge_servers+0x1b5/0x23c [kafs] afs_net_exit+0x44/0x6e [kafs] ops_exit_list+0x72/0x93 unregister_pernet_operations+0x14c/0x1ba unregister_pernet_subsys+0x1d/0x2a afs_exit+0x29/0x6f [kafs] __do_sys_delete_module.isra.0+0x1a2/0x24b do_syscall_64+0x51/0x95 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by: (1) Attempting to cancel the probe timer and, if successful, drop the count that the timer was holding. (2) Make the timer function just drop the count and not schedule the prober if the afs portion of net namespace is being destroyed. Also, whilst we're at it, make the following changes: (3) Initialise net->servers_outstanding to 1 and decrement it before waiting on it so that it doesn't generate wake up events by being decremented to 0 until we're cleaning up. (4) Switch the atomic_dec() on ->servers_outstanding for ->fs_timer in afs_purge_servers() to use the helper function for that. Fixes: f6cbb368bcb0 ("afs: Actively poll fileservers to maintain NAT or firewall openings") Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-20afs: Fix afs_do_lookup() to call correct fetch-status op variantDavid Howells1-1/+1
Fix afs_do_lookup()'s fallback case for when FS.InlineBulkStatus isn't supported by the server. In the fallback, it calls FS.FetchStatus for the specific vnode it's meant to be looking up. Commit b6489a49f7b7 broke this by renaming one of the two identically-named afs_fetch_status_operation descriptors to something else so that one of them could be made non-static. The site that used the renamed one, however, wasn't renamed and didn't produce any warning because the other was declared in a header. Fix this by making afs_do_lookup() use the renamed variant. Note that there are two variants of the success method because one is called from ->lookup() where we may or may not have an inode, but can't call iget until after we've talked to the server - whereas the other is called from within iget where we have an inode, but it may or may not be initialised. The latter variant expects there to be an inode, but because it's being called from there former case, there might not be - resulting in an oops like the following: BUG: kernel NULL pointer dereference, address: 00000000000000b0 ... RIP: 0010:afs_fetch_status_success+0x27/0x7e ... Call Trace: afs_wait_for_operation+0xda/0x234 afs_do_lookup+0x2fe/0x3c1 afs_lookup+0x3c5/0x4bd __lookup_slow+0xcd/0x10f walk_component+0xa2/0x10c path_lookupat.isra.0+0x80/0x110 filename_lookup+0x81/0x104 vfs_statx+0x76/0x109 __do_sys_newlstat+0x39/0x6b do_syscall_64+0x4c/0x78 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: b6489a49f7b7 ("afs: Fix silly rename") Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-19Merge tag 'io_uring-5.8-2020-06-19' of git://git.kernel.dk/linux-blockLinus Torvalds3-112/+177
Pull io_uring fixes from Jens Axboe: - Catch a case where io_sq_thread() didn't do proper mm acquire - Ensure poll completions are reaped on shutdown - Async cancelation and run fixes (Pavel) - io-poll race fixes (Xiaoguang) - Request cleanup race fix (Xiaoguang) * tag 'io_uring-5.8-2020-06-19' of git://git.kernel.dk/linux-block: io_uring: fix possible race condition against REQ_F_NEED_CLEANUP io_uring: reap poll completions while waiting for refs to drop on exit io_uring: acquire 'mm' for task_work for SQPOLL io_uring: add memory barrier to synchronize io_kiocb's result and iopoll_completed io_uring: don't fail links for EAGAIN error in IOPOLL mode io_uring: cancel by ->task not pid io_uring: lazy get task io_uring: batch cancel in io_uring_cancel_files() io_uring: cancel all task's requests on exit io-wq: add an option to cancel all matched reqs io-wq: reorder cancellation pending -> running io_uring: fix lazy work init
2020-06-19Merge tag 'block-5.8-2020-06-19' of git://git.kernel.dk/linux-blockLinus Torvalds1-8/+9
Pull block fixes from Jens Axboe: - Use import_uuid() where appropriate (Andy) - bcache fixes (Coly, Mauricio, Zhiqiang) - blktrace sparse warnings fix (Jan) - blktrace concurrent setup fix (Luis) - blkdev_get use-after-free fix (Jason) - Ensure all blk-mq maps are updated (Weiping) - Loop invalidate bdev fix (Zheng) * tag 'block-5.8-2020-06-19' of git://git.kernel.dk/linux-block: block: make function 'kill_bdev' static loop: replace kill_bdev with invalidate_bdev partitions/ldm: Replace uuid_copy() with import_uuid() where it makes sense block: update hctx map when use multiple maps blktrace: Avoid sparse warnings when assigning q->blk_trace blktrace: break out of blktrace setup on concurrent calls block: Fix use-after-free in blkdev_get() trace/events/block.h: drop kernel-doc for dropped function parameter blk-mq: Remove redundant 'return' statement bcache: pr_info() format clean up in bcache_device_init() bcache: use delayed kworker fo asynchronous devices registration bcache: check and adjust logical block size for backing devices bcache: fix potential deadlock problem in btree_gc_coalesce
2020-06-18f2fs: use kfree() to free variables allocated by match_strdup()Wang Xiaojun1-18/+18
Use kfree() instead of kvfree() to free variables allocated by match_strdup(). Because the memory is allocated with kmalloc inside match_strdup(). Signed-off-by: Wang Xiaojun <wangxiaojun11@huawei.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2020-06-18Merge branch 'hch' (maccess patches from Christoph Hellwig)Linus Torvalds1-1/+2
Merge non-faulting memory access cleanups from Christoph Hellwig: "Andrew and I decided to drop the patches implementing your suggested rename of the probe_kernel_* and probe_user_* helpers from -mm as there were way to many conflicts. After -rc1 might be a good time for this as all the conflicts are resolved now" This also adds a type safety checking patch on top of the renaming series to make the subtle behavioral difference between 'get_user()' and 'get_kernel_nofault()' less potentially dangerous and surprising. * emailed patches from Christoph Hellwig <hch@lst.de>: maccess: make get_kernel_nofault() check for minimal type compatibility maccess: rename probe_kernel_address to get_kernel_nofault maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault
2020-06-18f2fs: get the right gc victim section when section has several segmentsJack Qiu3-20/+88
Assume each section has 4 segment: .___________________________. |_Segment0_|_..._|_Segment3_| . . . . .__________. |_section0_| Segment 0~2 has 0 valid block, segment 3 has 512 valid blocks. It will fail if we want to gc section0 in this scenes, because all 4 segments in section0 is not dirty. So we should use dirty section bitmap instead of dirty segment bitmap to get right victim section. Signed-off-by: Jack Qiu <jack.qiu@huawei.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2020-06-18f2fs: fix a race condition between f2fs_write_end_io and f2fs_del_fsync_node_entryWuyun Zhao1-0/+1
Under some condition, the __write_node_page will submit a page which is not f2fs_in_warm_node_list and will not call f2fs_add_fsync_node_entry. f2fs_gc continue to run to invoke f2fs_iget -> do_read_inode to read the same node page and set code node, which make f2fs_in_warm_node_list become true, that will cause f2fs_bug_on in f2fs_del_fsync_node_entry when f2fs_write_end_io called. - f2fs_write_end_io - f2fs_iget - do_read_inode - set_cold_node recover cold node flag - f2fs_in_warm_node_list - is_cold_node if node is cold, assume we have added node to fsync_node_list during writepages() - f2fs_del_fsync_node_entry - f2fs_bug_on() due to node page is not in fsync_node_list [ 34.966133] Call trace: [ 34.969902] f2fs_del_fsync_node_entry+0x100/0x108 [ 34.976071] f2fs_write_end_io+0x1e0/0x288 [ 34.981539] bio_endio+0x248/0x270 [ 34.986289] blk_update_request+0x2b0/0x4d8 [ 34.991841] scsi_end_request+0x40/0x440 [ 34.997126] scsi_io_completion+0xa4/0x748 [ 35.002593] scsi_finish_command+0xdc/0x110 [ 35.008143] scsi_softirq_done+0x118/0x150 [ 35.013610] blk_done_softirq+0x8c/0xe8 [ 35.018811] __do_softirq+0x2e8/0x578 [ 35.023828] irq_exit+0xfc/0x120 [ 35.028398] handle_IPI+0x1d8/0x330 [ 35.033233] gic_handle_irq+0x110/0x1d4 [ 35.038433] el1_irq+0xb4/0x130 [ 35.042917] kmem_cache_alloc+0x3f0/0x418 [ 35.048288] radix_tree_node_alloc+0x50/0xf8 [ 35.053933] __radix_tree_create+0xf8/0x188 [ 35.059484] __radix_tree_insert+0x3c/0x128 [ 35.065035] add_gc_inode+0x90/0x118 [ 35.069967] f2fs_gc+0x1b80/0x2d70 [ 35.074718] f2fs_disable_checkpoint+0x94/0x1d0 [ 35.080621] f2fs_fill_super+0x10c4/0x1b88 [ 35.086088] mount_bdev+0x194/0x1e0 [ 35.090923] f2fs_mount+0x40/0x50 [ 35.095589] mount_fs+0xb4/0x190 [ 35.100159] vfs_kern_mount+0x80/0x1d8 [ 35.105260] do_mount+0x478/0xf18 [ 35.109926] ksys_mount+0x90/0xd0 [ 35.114592] __arm64_sys_mount+0x24/0x38 Signed-off-by: Wuyun Zhao <zhaowuyun@wingtech.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2020-06-18f2fs: remove useless truncate in f2fs_collapse_range()Wei Fang1-2/+0
Since offset < new_size, no need to do truncate_pagecache() again with new_size. Signed-off-by: Wei Fang <fangwei1@huawei.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2020-06-18f2fs: use kfree() instead of kvfree() to free superblock dataDenis Efremov1-5/+5
Use kfree() instead of kvfree() to free super in read_raw_super_block() because the memory is allocated with kzalloc() in the function. Use kfree() instead of kvfree() to free sbi, raw_super in f2fs_fill_super() and f2fs_put_super() because the memory is allocated with kzalloc(). Signed-off-by: Denis Efremov <efremov@linux.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2020-06-18f2fs: avoid checkpatch errorJaegeuk Kim1-1/+1
ERROR:INITIALISED_STATIC: do not initialise statics to NULL Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
2020-06-18block: make function 'kill_bdev' staticZheng Bin1-3/+2
kill_bdev does not have any external user, so make it static. Signed-off-by: Zheng Bin <zhengbin13@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-18io_uring: fix possible race condition against REQ_F_NEED_CLEANUPXiaoguang Wang1-4/+4
In io_read() or io_write(), when io request is submitted successfully, it'll go through the below sequence: kfree(iovec); req->flags &= ~REQ_F_NEED_CLEANUP; return ret; But clearing REQ_F_NEED_CLEANUP might be unsafe. The io request may already have been completed, and then io_complete_rw_iopoll() and io_complete_rw() will be called, both of which will also modify req->flags if needed. This causes a race condition, with concurrent non-atomic modification of req->flags. To eliminate this race, in io_read() or io_write(), if io request is submitted successfully, we don't remove REQ_F_NEED_CLEANUP flag. If REQ_F_NEED_CLEANUP is set, we'll leave __io_req_aux_free() to the iovec cleanup work correspondingly. Cc: stable@vger.kernel.org Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-17io_uring: reap poll completions while waiting for refs to drop on exitJens Axboe1-1/+11
If we're doing polled IO and end up having requests being submitted async, then completions can come in while we're waiting for refs to drop. We need to reap these manually, as nobody else will be looking for them. Break the wait into 1/20th of a second time waits, and check for done poll completions if we time out. Otherwise we can have done poll completions sitting in ctx->poll_list, which needs us to reap them but we're just waiting for them. Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-17io_uring: acquire 'mm' for task_work for SQPOLLJens Axboe1-15/+29
If we're unlucky with timing, we could be running task_work after having dropped the memory context in the sq thread. Since dropping the context requires a runnable task state, we cannot reliably drop it as part of our check-for-work loop in io_sq_thread(). Instead, abstract out the mm acquire for the sq thread into a helper, and call it from the async task work handler. Cc: stable@vger.kernel.org # v5.7 Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-17io_uring: add memory barrier to synchronize io_kiocb's result and iopoll_completedXiaoguang Wang1-24/+29
In io_complete_rw_iopoll(), stores to io_kiocb's result and iopoll completed are two independent store operations, to ensure that once iopoll_completed is ture and then req->result must been perceived by the cpu executing io_do_iopoll(), proper memory barrier should be used. And in io_do_iopoll(), we check whether req->result is EAGAIN, if it is, we'll need to issue this io request using io-wq again. In order to just issue a single smp_rmb() on the completion side, move the re-submit work to io_iopoll_complete(). Cc: stable@vger.kernel.org Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> [axboe: don't set ->iopoll_completed for -EAGAIN retry] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-17io_uring: don't fail links for EAGAIN error in IOPOLL modeXiaoguang Wang1-1/+1
In IOPOLL mode, for EAGAIN error, we'll try to submit io request again using io-wq, so don't fail rest of links if this io request has links. Cc: stable@vger.kernel.org Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-17maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofaultChristoph Hellwig1-1/+2
Better describe what these functions do. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-17nfsd: apply umask on fs without ACL supportJ. Bruce Fields1-0/+6
The server is failing to apply the umask when creating new objects on filesystems without ACL support. To reproduce this, you need to use NFSv4.2 and a client and server recent enough to support umask, and you need to export a filesystem that lacks ACL support (for example, ext4 with the "noacl" mount option). Filesystems with ACL support are expected to take care of the umask themselves (usually by calling posix_acl_create). For filesystems without ACL support, this is up to the caller of vfs_create(), vfs_mknod(), or vfs_mkdir(). Reported-by: Elliott Mitchell <ehem+debian@m5p.com> Reported-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Fixes: 47057abde515 ("nfsd: add support for the umask attribute") Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2020-06-16proc/bootconfig: Fix to use correct quotes for valueMasami Hiramatsu1-5/+10
Fix /proc/bootconfig to select double or single quotes corrctly according to the value. If a bootconfig value includes a double quote character, we must use single-quotes to quote that value. This modifies if() condition and blocks for avoiding double-quote in value check in 2 places. Anyway, since xbc_array_for_each_value() can handle the array which has a single node correctly. Thus, if (vnode && xbc_node_is_array(vnode)) { xbc_array_for_each_value(vnode) /* vnode->next != NULL */ ... } else { snprintf(val); /* val is an empty string if !vnode */ } is equivalent to if (vnode) { xbc_array_for_each_value(vnode) /* vnode->next can be NULL */ ... } else { snprintf(""); /* value is always empty */ } Link: http://lkml.kernel.org/r/159230244786.65555.3763894451251622488.stgit@devnote2 Cc: stable@vger.kernel.org Fixes: c1a3c36017d4 ("proc: bootconfig: Add /proc/bootconfig to show boot config list") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-06-16Merge tag 'afs-fixes-20200616' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fsLinus Torvalds10-124/+225
Pull AFS fixes from David Howells: "I've managed to get xfstests kind of working with afs. Here are a set of patches that fix most of the bugs found. There are a number of primary issues: - Incorrect handling of mtime and non-handling of ctime. It might be argued, that the latter isn't a bug since the AFS protocol doesn't support ctime, but I should probably still update it locally. - Shared-write mmap, truncate and writeback bugs. This includes not changing i_size under the callback lock, overwriting local i_size with the reply from the server after a partial writeback, not limiting the writeback from an mmapped page to EOF. - Checks for an abort code indicating that the primary vnode in an operation was deleted by a third-party are done in the wrong place. - Silly rename bugs. This includes an incomplete conversion to the new operation handling, duplicate nlink handling, nlink changing not being done inside the callback lock and insufficient handling of third-party conflicting directory changes. And some secondary ones: - The UAEOVERFLOW abort code should map to EOVERFLOW not EREMOTEIO. - Remove a couple of unused or incompletely used bits. - Remove a couple of redundant success checks. These seem to fix all the data-corruption bugs found by ./check -afs -g quick along with the obvious silly rename bugs and time bugs. There are still some test failures, but they seem to fall into two classes: firstly, the authentication/security model is different to the standard UNIX model and permission is arbitrated by the server and cached locally; and secondly, there are a number of features that AFS does not support (such as mknod). But in these cases, the tests themselves need to be adapted or skipped. Using the in-kernel afs client with xfstests also found a bug in the AuriStor AFS server that has been fixed for a future release" * tag 'afs-fixes-20200616' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: afs: Fix silly rename afs: afs_vnode_commit_status() doesn't need to check the RPC error afs: Fix use of afs_check_for_remote_deletion() afs: Remove afs_operation::abort_code afs: Fix yfs_fs_fetch_status() to honour vnode selector afs: Remove yfs_fs_fetch_file_status() as it's not used afs: Fix the mapping of the UAEOVERFLOW abort code afs: Fix truncation issues and mmap writeback size afs: Concoct ctimes afs: Fix EOF corruption afs: afs_write_end() should change i_size under the right lock afs: Fix non-setting of mtime when writing into mmap
2020-06-16Merge tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linuxLinus Torvalds4-12/+12
Pull flexible-array member conversions from Gustavo A. R. Silva: "Replace zero-length arrays with flexible-array members. Notice that all of these patches have been baking in linux-next for two development cycles now. There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. C99 introduced “flexible array members”, which lacks a numeric size for the array declaration entirely: struct something { size_t count; struct foo items[]; }; This is the way the kernel expects dynamically sized trailing elements to be declared. It allows the compiler to generate errors when the flexible array does not occur last in the structure, which helps to prevent some kind of undefined behavior[3] bugs from being inadvertently introduced to the codebase. It also allows the compiler to correctly analyze array sizes (via sizeof(), CONFIG_FORTIFY_SOURCE, and CONFIG_UBSAN_BOUNDS). For instance, there is no mechanism that warns us that the following application of the sizeof() operator to a zero-length array always results in zero: struct something { size_t count; struct foo items[0]; }; struct something *instance; instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL); instance->count = count; size = sizeof(instance->items) * instance->count; memcpy(instance->items, source, size); At the last line of code above, size turns out to be zero, when one might have thought it represents the total size in bytes of the dynamic memory recently allocated for the trailing array items. Here are a couple examples of this issue[4][5]. Instead, flexible array members have incomplete type, and so the sizeof() operator may not be applied[6], so any misuse of such operators will be immediately noticed at build time. The cleanest and least error-prone way to implement this is through the use of a flexible array member: struct something { size_t count; struct foo items[]; }; struct something *instance; instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL); instance->count = count; size = sizeof(instance->items[0]) * instance->count; memcpy(instance->items, source, size); instead" [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") [4] commit f2cd32a443da ("rndis_wlan: Remove logically dead code") [5] commit ab91c2a89f86 ("tpm: eventlog: Replace zero-length array with flexible-array member") [6] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html * tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (41 commits) w1: Replace zero-length array with flexible-array tracing/probe: Replace zero-length array with flexible-array soc: ti: Replace zero-length array with flexible-array tifm: Replace zero-length array with flexible-array dmaengine: tegra-apb: Replace zero-length array with flexible-array stm class: Replace zero-length array with flexible-array Squashfs: Replace zero-length array with flexible-array ASoC: SOF: Replace zero-length array with flexible-array ima: Replace zero-length array with flexible-array sctp: Replace zero-length array with flexible-array phy: samsung: Replace zero-length array with flexible-array RxRPC: Replace zero-length array with flexible-array rapidio: Replace zero-length array with flexible-array media: pwc: Replace zero-length array with flexible-array firmware: pcdp: Replace zero-length array with flexible-array oprofile: Replace zero-length array with flexible-array block: Replace zero-length array with flexible-array tools/testing/nvdimm: Replace zero-length array with flexible-array libata: Replace zero-length array with flexible-array kprobes: Replace zero-length array with flexible-array ...
2020-06-17close_range: add CLOSE_RANGE_UNSHAREChristian Brauner2-11/+59
One of the use-cases of close_range() is to drop file descriptors just before execve(). This would usually be expressed in the sequence: unshare(CLONE_FILES); close_range(3, ~0U); as pointed out by Linus it might be desirable to have this be a part of close_range() itself under a new flag CLOSE_RANGE_UNSHARE. This expands {dup,unshare)_fd() to take a max_fds argument that indicates the maximum number of file descriptors to copy from the old struct files. When the user requests that all file descriptors are supposed to be closed via close_range(min, max) then we can cap via unshare_fd(min) and hence don't need to do any of the heavy fput() work for everything above min. The patch makes it so that if CLOSE_RANGE_UNSHARE is requested and we do in fact currently share our file descriptor table we create a new private copy. We then close all fds in the requested range and finally after we're done we install the new fd table. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2020-06-17open: add close_range()Christian Brauner2-8/+76
This adds the close_range() syscall. It allows to efficiently close a range of file descriptors up to all file descriptors of a calling task. I was contacted by FreeBSD as they wanted to have the same close_range() syscall as we proposed here. We've coordinated this and in the meantime, Kyle was fast enough to merge close_range() into FreeBSD already in April: https://reviews.freebsd.org/D21627 https://svnweb.freebsd.org/base?view=revision&revision=359836 and the current plan is to backport close_range() to FreeBSD 12.2 (cf. [2]) once its merged in Linux too. Python is in the process of switching to close_range() on FreeBSD and they are waiting on us to merge this to switch on Linux as well: https://bugs.python.org/issue38061 The syscall came up in a recent discussion around the new mount API and making new file descriptor types cloexec by default. During this discussion, Al suggested the close_range() syscall (cf. [1]). Note, a syscall in this manner has been requested by various people over time. First, it helps to close all file descriptors of an exec()ing task. This can be done safely via (quoting Al's example from [1] verbatim): /* that exec is sensitive */ unshare(CLONE_FILES); /* we don't want anything past stderr here */ close_range(3, ~0U); execve(....); The code snippet above is one way of working around the problem that file descriptors are not cloexec by default. This is aggravated by the fact that we can't just switch them over without massively regressing userspace. For a whole class of programs having an in-kernel method of closing all file descriptors is very helpful (e.g. demons, service managers, programming language standard libraries, container managers etc.). (Please note, unshare(CLONE_FILES) should only be needed if the calling task is multi-threaded and shares the file descriptor table with another thread in which case two threads could race with one thread allocating file descriptors and the other one closing them via close_range(). For the general case close_range() before the execve() is sufficient.) Second, it allows userspace to avoid implementing closing all file descriptors by parsing through /proc/<pid>/fd/* and calling close() on each file descriptor. From looking at various large(ish) userspace code bases this or similar patterns are very common in: - service managers (cf. [4]) - libcs (cf. [6]) - container runtimes (cf. [5]) - programming language runtimes/standard libraries - Python (cf. [2]) - Rust (cf. [7], [8]) As Dmitry pointed out there's even a long-standing glibc bug about missing kernel support for this task (cf. [3]). In addition, the syscall will also work for tasks that do not have procfs mounted and on kernels that do not have procfs support compiled in. In such situations the only way to make sure that all file descriptors are closed is to call close() on each file descriptor up to UINT_MAX or RLIMIT_NOFILE, OPEN_MAX trickery (cf. comment [8] on Rust). The performance is striking. For good measure, comparing the following simple close_all_fds() userspace implementation that is essentially just glibc's version in [6]: static int close_all_fds(void) { int dir_fd; DIR *dir; struct dirent *direntp; dir = opendir("/proc/self/fd"); if (!dir) return -1; dir_fd = dirfd(dir); while ((direntp = readdir(dir))) { int fd; if (strcmp(direntp->d_name, ".") == 0) continue; if (strcmp(direntp->d_name, "..") == 0) continue; fd = atoi(direntp->d_name); if (fd == dir_fd || fd == 0 || fd == 1 || fd == 2) continue; close(fd); } closedir(dir); return 0; } to close_range() yields: 1. closing 4 open files: - close_all_fds(): ~280 us - close_range(): ~24 us 2. closing 1000 open files: - close_all_fds(): ~5000 us - close_range(): ~800 us close_range() is designed to allow for some flexibility. Specifically, it does not simply always close all open file descriptors of a task. Instead, callers can specify an upper bound. This is e.g. useful for scenarios where specific file descriptors are created with well-known numbers that are supposed to be excluded from getting closed. For extra paranoia close_range() comes with a flags argument. This can e.g. be used to implement extension. Once can imagine userspace wanting to stop at the first error instead of ignoring errors under certain circumstances. There might be other valid ideas in the future. In any case, a flag argument doesn't hurt and keeps us on the safe side. From an implementation side this is kept rather dumb. It saw some input from David and Jann but all nonsense is obviously my own! - Errors to close file descriptors are currently ignored. (Could be changed by setting a flag in the future if needed.) - __close_range() is a rather simplistic wrapper around __close_fd(). My reasoning behind this is based on the nature of how __close_fd() needs to release an fd. But maybe I misunderstood specifics: We take the files_lock and rcu-dereference the fdtable of the calling task, we find the entry in the fdtable, get the file and need to release files_lock before calling filp_close(). In the meantime the fdtable might have been altered so we can't just retake the spinlock and keep the old rcu-reference of the fdtable around. Instead we need to grab a fresh reference to the fdtable. If my reasoning is correct then there's really no point in fancyfying __close_range(): We just need to rcu-dereference the fdtable of the calling task once to cap the max_fd value correctly and then go on calling __close_fd() in a loop. /* References */ [1]: https://lore.kernel.org/lkml/20190516165021.GD17978@ZenIV.linux.org.uk/ [2]: https://github.com/python/cpython/blob/9e4f2f3a6b8ee995c365e86d976937c141d867f8/Modules/_posixsubprocess.c#L220 [3]: https://sourceware.org/bugzilla/show_bug.cgi?id=10353#c7 [4]: https://github.com/systemd/systemd/blob/5238e9575906297608ff802a27e2ff9effa3b338/src/basic/fd-util.c#L217 [5]: https://github.com/lxc/lxc/blob/ddf4b77e11a4d08f09b7b9cd13e593f8c047edc5/src/lxc/start.c#L236 [6]: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/grantpt.c;h=2030e07fa6e652aac32c775b8c6e005844c3c4eb;hb=HEAD#l17 Note that this is an internal implementation that is not exported. Currently, libc seems to not provide an exported version of this because of missing kernel support to do this. Note, in a recent patch series Florian made grantpt() a nop thereby removing the code referenced here. [7]: https://github.com/rust-lang/rust/issues/12148 [8]: https://github.com/rust-lang/rust/blob/5f47c0613ed4eb46fca3633c1297364c09e5e451/src/libstd/sys/unix/process2.rs#L303-L308 Rust's solution is slightly different but is equally unperformant. Rust calls getdtablesize() which is a glibc library function that simply returns the current RLIMIT_NOFILE or OPEN_MAX values. Rust then goes on to call close() on each fd. That's obviously overkill for most tasks. Rarely, tasks - especially non-demons - hit RLIMIT_NOFILE or OPEN_MAX. Let's be nice and assume an unprivileged user with RLIMIT_NOFILE set to 1024. Even in this case, there's a very high chance that in the common case Rust is calling the close() syscall 1021 times pointlessly if the task just has 0, 1, and 2 open. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Kyle Evans <self@kyle-evans.net> Cc: Jann Horn <jannh@google.com> Cc: David Howells <dhowells@redhat.com> Cc: Dmitry V. Levin <ldv@altlinux.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Florian Weimer <fweimer@redhat.com> Cc: linux-api@vger.kernel.org
2020-06-16afs: Fix silly renameDavid Howells4-16/+80
Fix AFS's silly rename by the following means: (1) Set the destination directory in afs_do_silly_rename() so as to avoid misbehaviour and indicate that the directory data version will increment by 1 so as to avoid warnings about unexpected changes in the DV. Also indicate that the ctime should be updated to avoid xfstest grumbling. (2) Note when the server indicates that a directory changed more than we expected (AFS_OPERATION_DIR_CONFLICT), indicating a conflict with a third party change, checking on successful completion of unlink and rename. The problem is that the FS.RemoveFile RPC op doesn't report the status of the unlinked file, though YFS.RemoveFile2 does. This can be mitigated by the assumption that if the directory DV cranked by exactly 1, we can be sure we removed one link from the file; further, ordinarily in AFS, files cannot be hardlinked across directories, so if we reduce nlink to 0, the file is deleted. However, if the directory DV jumps by more than 1, we cannot know if a third party intervened by adding or removing a link on the file we just removed a link from. The same also goes for any vnode that is at the destination of the FS.Rename RPC op. (3) Make afs_vnode_commit_status() apply the nlink drop inside the cb_lock section along with the other attribute updates if ->op_unlinked is set on the descriptor for the appropriate vnode. (4) Issue a follow up status fetch to the unlinked file in the event of a third party conflict that makes it impossible for us to know if we actually deleted the file or not. (5) Provide a flag, AFS_VNODE_SILLY_DELETED, to make afs_getattr() lie to the user about the nlink of a silly deleted file so that it appears as 0, not 1. Found with the generic/035 and generic/084 xfstests. Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept") Reported-by: Marc Dionne <marc.dionne@auristor.com> Signed-off-by: David Howells <dhowells@redhat.com>
2020-06-16btrfs: use kfree() in btrfs_ioctl_get_subvol_info()Waiman Long1-1/+1
In btrfs_ioctl_get_subvol_info(), there is a classic case where kzalloc() was incorrectly paired with kzfree(). According to David Sterba, there isn't any sensitive information in the subvol_info that needs to be cleared before freeing. So kzfree() isn't really needed, use kfree() instead. Signed-off-by: Waiman Long <longman@redhat.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2020-06-16btrfs: fix RWF_NOWAIT writes blocking on extent locks and waiting for IOFilipe Manana1-11/+26
A RWF_NOWAIT write is not supposed to wait on filesystem locks that can be held for a long time or for ongoing IO to complete. However when calling check_can_nocow(), if the inode has prealloc extents or has the NOCOW flag set, we can block on extent (file range) locks through the call to btrfs_lock_and_flush_ordered_range(). Such lock can take a significant amount of time to be available. For example, a fiemap task may be running, and iterating through the entire file range checking all extents and doing backref walking to determine if they are shared, or a readpage operation may be in progress. Also at btrfs_lock_and_flush_ordered_range(), called by check_can_nocow(), after locking the file range we wait for any existing ordered extent that is in progress to complete. Another operation that can take a significant amount of time and defeat the purpose of RWF_NOWAIT. So fix this by trying to lock the file range and if it's currently locked return -EAGAIN to user space. If we are able to lock the file range without waiting and there is an ordered extent in the range, return -EAGAIN as well, instead of waiting for it to complete. Finally, don't bother trying to lock the snapshot lock of the root when attempting a RWF_NOWAIT write, as that is only important for buffered writes. Fixes: edf064e7c6fec3 ("btrfs: nowait aio support") Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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