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* Linux 4.9 compat: group_info changesChunwei Chen2016-10-202-2/+13
| | | | | | | | | In Linux 4.9, torvalds/linux@81243ea, group_info changed from 2d array via ->blocks to 1d array via ->gid. We change the spl cred functions accordingly. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Closes #581
* Fix splat-cred.c cred usageChunwei Chen2016-10-201-12/+12
| | | | | | | | No need to crhold current_cred(), fix possible leak in splat_cred_test2 Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Closes #556
* Fix crgetgroups out-of-bound and misc cred fixChunwei Chen2016-10-201-15/+16
| | | | | | | | | | | | | | | | | init_groups has 0 nblocks, therefore calling the current crgetgroups with init_groups would result in out-of-bound access. We fix this by returning NULL when nblocks is 0. Cap crgetngroups to NGROUPS_PER_BLOCK, since crgetgroups will only return blocks[0]. Also, remove all get_group_info. The cred already holds reference on the group_info, and cred is not mutable. So there's no reason to hold extra reference, if we hold cred. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Closes #556
* Fix out-of-bound in per_cpu in spl_random_inittuxoko2016-10-071-1/+1
| | | | | | | | | When iterating per_cpu values, we need to use for_each_possible_cpu. While NR_CPUS indicates the number of CPU supported by the kernel, it might not initialize all of them if the kernel decides it's not possible to use them. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Closes #578
* Fix p0 initializerBrian Behlendorf2016-10-041-1/+2
| | | | | | | | | | | | Due to changes in the task_struct the following warning is occurs when initializing the global p0. Since this structure only exists for it's address to be taken initialize it in a manor which isn't sensitive to internal changes to the structure. module/spl/spl-generic.c:58:1: error: missing braces around initializer [-Werror=missing-braces] Signed-off-by: Brian Behlendorf <[email protected]> Closes #576
* Fix aarch64 type warningBrian Behlendorf2016-10-011-8/+8
| | | | | | | | | | Explicitly cast type in splat-rwlock.c test case to silence the following warning. warning: format ‘%ld’ expects argument of type ‘long int’, but argument N has type ‘int’ Signed-off-by: Brian Behlendorf <[email protected]> Closes #574
* Increase spl_kmem_alloc_warn limitBrian Behlendorf2016-09-161-2/+2
| | | | | | | | | | | | | | | | | | In order to support ABD with large blocks the spl_kmem_alloc_warn limit needs to be increased to 64K. A 16M block requires that pointers be stored for 4096 4K-pages on an x86_64 system. Each of these pointers is 8 bytes requiring an allocation of 8*4096=32,768 bytes. The addition of a small header to this structure pushes the allocation over the default 32K warning threshold. In addition, fix a small bug where MAX was used instead of MIN when setting the default. This ensures a reasonable limit is still set on systems with page sizes larger then 4K. Reviewed-by: David Quigley <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #571
* Fix: handle NULL case in spl_kmem_free_track()GeLiXin2016-08-191-0/+4
| | | | | | | | | | | | When DEBUG_KMEM_TRACKING is enabled in SPL, we keep tracking all the buffers alloced by kmem_alloc() and kmem_zalloc(). If a NULL pointer which indicates no track info in SPL is passed to spl_kmem_free_track, we just ignore it. Signed-off-by: GeLiXin <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue zfsonlinux/zfs#4967 Closes #567
* Linux 4.8 compat: rw_semaphore atomic_long_t countBrian Behlendorf2016-07-291-1/+10
| | | | | | | | | | | | | | For non-rwsem-spinlocks the "count" member was changed from a "long" to "atomic_long_t" type. A configure check has been added to detect this change along with new versions of the _rwsem_tryupgrade() function and RWSEM_COUNT() macro. See https://github.com/torvalds/linux/commit/8ee62b18 for complete details. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #563
* Improve spl slab cache allocJinshan Xiong2016-06-011-8/+35
| | | | | | | | | | | | | The policy is to try to allocate with KM_NOSLEEP, which will lead to memory allocation with GFP_ATOMIC, and if it fails, it will launch an taskq to expand slab space. This way it should be able to get better NUMA memory locality and reduce the overhead of context switch. Signed-off-by: Jinshan Xiong <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #551
* Fix use-after-free in splat_taskq_test7Chunwei Chen2016-05-311-2/+3
| | | | | | | | This splat_vprint is using tq_arg->name after tq_arg is freed. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #557
* Implement a proper rw_tryupgradeChunwei Chen2016-05-312-6/+101
| | | | | | | | | | | | | | | | | | Current rw_tryupgrade does rw_exit and then rw_tryenter(RW_RWITER), and then does rw_enter(RW_READER) if it fails. This violate the assumption that rw_tryupgrade should be atomic and could cause extra contention or even lock inversion. This patch we implement a proper rw_tryupgrade. For rwsem-spinlock, we take the spinlock to check rwsem->count and rwsem->wait_list. For normal rwsem, we use cmpxchg on rwsem->count to change the value from single reader to single writer. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Closes zfsonlinux/zfs#4692 Closes #554
* Fix taskq_wait_outstanding re-evaluate tq_next_idChunwei Chen2016-05-241-2/+2
| | | | | | | | | | | wait_event is a macro, so the current implementation will cause re- evaluation of tq_next_id every time it wakes up. This would cause taskq_wait_outstanding(tq, 0) to be equivalent to taskq_wait(tq) Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Issue #553
* Fix race between taskq_destroy and dynamic spawning threadChunwei Chen2016-05-241-5/+25
| | | | | | | | | | | | | | | | While taskq_destroy would wait for dynamic_taskq to finish its tasks, but it does not implies the thread being spawned is up and running. This will cause taskq to be freed before the thread can exit. We fix this by using tq_nspawn to indicate how many threads are being spawned before they are inserted to the thread list. And have taskq_destroy to wait for it to drop to zero. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Issue #553 Closes #550
* Restore CALLOUT_FLAG_ABSOLUTE in cv_timedwait_hiresChunwei Chen2016-05-241-3/+2
| | | | | | | | | | In 39cd90e, I mistakenly disabled the ability of using absolute expire time in cv_timedwait_hires. I don't quite sure why I did that, so let's restore it. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Issue #553
* Linux 4.7 compat: inode_lock() and friendsChunwei Chen2016-05-201-1/+2
| | | | | | | | | | | | | | | | Linux 4.7 changes i_mutex to i_rwsem, and we should used inode_lock and inode_lock_shared to do exclusive and shared lock respectively. We use spl_inode_lock{,_shared}() to hide the difference. Note that on older kernel you'll always take an exclusive lock. We also add all other inode_lock friends. And nested users now should explicitly call spl_inode_lock_nested with correct subclass. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue zfsonlinux/zfs#4665 Closes #549
* Add cv_timedwait_sig_hires to allow interruptible sleepChunwei Chen2016-05-121-10/+30
| | | | | | Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #548
* Clear PF_FSTRANS over spl_filp_fallocate()Tim Chase2016-04-261-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The problem described in 2a5d574 also applies to XFS's file or inode fallocate method. Both paths may trigger writeback and expose this issue, see the full stack below. When layered on XFS a warning will be emitted under CentOS7 when entering either the file or inode fallocate method with PF_FSTRANS already set. To avoid triggering this error PF_FSTRANS is cleared and then reset in vn_space(). WARNING: at fs/xfs/xfs_aops.c:982 xfs_vm_writepage+0x58b/0x5d0 Call Trace: [<ffffffff810a1ed5>] warn_slowpath_common+0x95/0xe0 [<ffffffff810a1f3a>] warn_slowpath_null+0x1a/0x20 [<ffffffffa0231fdb>] xfs_vm_writepage+0x58b/0x5d0 [xfs] [<ffffffff81173ed7>] __writepage+0x17/0x40 [<ffffffff81176f81>] write_cache_pages+0x251/0x530 [<ffffffff811772b1>] generic_writepages+0x51/0x80 [<ffffffffa0230cb0>] xfs_vm_writepages+0x60/0x80 [xfs] [<ffffffff81177300>] do_writepages+0x20/0x30 [<ffffffff8116a5f5>] __filemap_fdatawrite_range+0xb5/0x100 [<ffffffff8116a6cb>] filemap_write_and_wait_range+0x8b/0xd0 [<ffffffffa0235bb4>] xfs_free_file_space+0xf4/0x520 [xfs] [<ffffffffa023cbce>] xfs_file_fallocate+0x19e/0x2c0 [xfs] [<ffffffffa036c6fc>] vn_space+0x3c/0x40 [spl] [<ffffffffa0434817>] vdev_file_io_start+0x207/0x260 [zfs] [<ffffffffa047170d>] zio_vdev_io_start+0xad/0x2d0 [zfs] [<ffffffffa0474942>] zio_execute+0x82/0xe0 [zfs] [<ffffffffa036ba7d>] taskq_thread+0x28d/0x5a0 [spl] [<ffffffff810c1777>] kthread+0xd7/0xf0 [<ffffffff8167de2f>] ret_from_fork+0x3f/0x70 Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Nikolay Borisov <[email protected]> Closes zfsonlinux/zfs#4529
* Allow spawning a new thread for TQ_NOQUEUE dispatch with dynamic taskqTim Chase2016-03-171-4/+18
| | | | | | | | | | | | When a TQ_NOQUEUE dispatch is done on a dynamic taskq, allow another thread to be spawned. This will cause TQ_NOQUEUE to behave similarly as it does with non-dynamic taskqs. Add support for TQ_NOQUEUE to taskq_dispatch_ent(). Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #530
* Add rw_tryupgrade()Brian Behlendorf2016-03-102-66/+0
| | | | | | | | | | | | | | | | | | | | This implementation of rw_tryupgrade() behaves slightly differently from its counterparts on other platforms. It drops the RW_READER lock and then acquires the RW_WRITER lock leaving a small window where no lock is held. On other platforms the lock is never released during the upgrade process. This is necessary under Linux because the kernel does not provide an upgrade function. There are currently no callers in the ZFS code where this change in behavior is a problem. In fact, in most cases the code is already written such that if the upgrade fails the RW_READER lock is dropped and the caller blocks waiting to acquire the lock as RW_WRITER. Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Matthew Thode <[email protected]> Closes zfsonlinux/zfs#4388 Closes #534
* random_get_pseudo_bytes() need not provide cryptographic strength entropyRichard Yao2016-02-171-0/+148
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Perf profiling of dd on a zvol revealed that my system spent 3.16% of its time in random_get_pseudo_bytes(). No SPL consumers need cryptographic strength entropy, so we can reduce our overhead by changing the implementation to utilize a fast PRNG. The Linux kernel did not export a suitable PRNG function until it exported get_random_int() in Linux 3.10. While we could implement an autotools check so that we use it when it is available or even try to access the symbol on older kernels where it is not exported using the fact that it is exported on newer ones as justification, we can instead implement our own pseudo-random data generator. For this purpose, I have written one based on a 128-bit pseudo-random number generator proposed in a paper by Sebastiano Vigna that itself was based on work by the late George Marsaglia. http://vigna.di.unimi.it/ftp/papers/xorshiftplus.pdf Profiling the same benchmark with an earlier variant of this patch that used a slightly different generator (roughly same number of instructions) by the same author showed that time spent in random_get_pseudo_bytes() dropped to 0.06%. That is a factor of 50 improvement. This particular generator algorithm is also well known to be fast: http://xorshift.di.unimi.it/#speed The benchmark numbers there state that it runs at 1.12ns/64-bits or 7.14 GBps of throughput on an Intel Core i7-4770 in what is presumably a single-threaded context. Using it in `random_get_pseudo_bytes()` in the manner I have will probably not reach that level of performance, but it should be fairly high and many times higher than the Linux `get_random_bytes()` function that we use now, which runs at 16.3 MB/s on my Intel Xeon E3-1276v3 processor when measured by using dd on /dev/urandom. Also, putting this generator's seed into per-CPU variables allows us to eliminate overhead from both spin locks and CPU memory barriers, which is NUMA friendly. We could have alternatively modified consumers to use something like `gethrtime() % 3` as suggested by both Matthew Ahrens and Tim Chase, but that has a few potential problems that this approach avoids: 1. Switching to `gethrtime() % 3` in hot code paths today requires diverging from illumos-gate and does nothing about potential future patches from illumos-gate that call our slow `random_get_pseudo_bytes()` in different hot code paths. Reimplementing `random_get_pseudo_bytes()` with a per-CPU PRNG avoids both of those things entirely, which means less work for us in the future. 2. Looking at the code that implements `gethrtime()`, I think it is unlikely to be faster than this per-CPU PRNG implementation of `random_get_pseudo_bytes()`. It would be best to go with something fast now so that there is no point in revisiting this from a performance perspective. 3. `gethrtime() % 3` can vary in behavior from system to system based on kernel version, architecture and clock source. In comparison, this per-CPU PRNG is about ~40 lines of code in `random_get_pseudo_bytes()` that should behave consistently across all systems regardless of kernel version, system architecture or machine clock source. It is unlikely that we would ever need to revisit this per-CPU PRNG while the same cannot be said for `gethrtime() % 3`. 4. `gethrtime()` uses CPU memory barriers and maybe atomic instructions depending on the clock source, so replacing `random_get_pseudo_bytes()` with `gethrtime()` in hot code paths could still require a future person working on NUMA scalability to reimplement it anyway while this per-CPU PRNG would not by virtue of using neither CPU memory barriers nor atomic instructions. Note that I did not check various clock sources for the presence of atomic instructions. There is simply too much code to read and given the drawbacks versus this per-cpu PRNG, there is no point in being certain. 5. I have heard of instances where poor quality pseudo-random numbers caused problems for HPC code in ways that took more than a year to identify and were remedied by switching to a higher quality source of pseudo-random numbers. While filesystems are different than HPC code, I do not think it is impossible for us to have instances where poor quality pseudo-random numbers can cause problems. Opting for a well studied PRNG algorithm that passes tests for statistical randomness over changing callers to use `gethrtime() % 3` bypasses the need to think about both whether poor quality pseudo-random numbers can cause problems and the statistical quality of numbers from `gethrtime() % 3`. 6. `gethrtime()` calls `getrawmonotonic()`, which uses seqlocks. This is probably not a huge issue, but anyone using kgdb would never be able to step through a seqlock critical section, which is not a problem either now or with the per-CPU PRNG: https://en.wikipedia.org/wiki/Seqlock The only downside that I can see is that this code's memory requirement is O(N) where N is NR_CPUS, versus the current code and `gethrtime() % 3`, which are O(1), but that should not be a problem. The seeds will use 64KB of memory at the high end (i.e `NR_CPU == 4096`) and 16 bytes of memory at the low end (i.e. `NR_CPU == 1`). In either case, we should only use a few hundred bytes of code for text, especially since `spl_rand_jump()` should be inlined into `spl_random_init()`, which should be removed during early boot as part of "Freeing unused kernel memory". In either case, the memory requirements are minuscule. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Closes #372
* Allow kicking a taskq to spawn more threadsChunwei Chen2016-02-051-0/+60
| | | | | | | | | | | This patch add a module parameter spl_taskq_kick. When writing non-zero value to it, it will scan all the taskq, if a taskq contains a task pending for more than 5 seconds, it will be forced to spawn a new thread. This is use as an emergency recovery from deadlock, not a general solution. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #529
* Remove RLIM64_INFINITY assert in vn_rdwr()Brian Behlendorf2016-01-231-1/+0
| | | | | | | | | Previous commit be29e6a updated kobj_read_file() so it no longer unconditionally passes RLIM64_INFINITY. The vn_rdwr() function needs to be updated accordingly. Signed-off-by: Brian Behlendorf <[email protected]> Issue #513
* kobj_read_file: Return -1 on vn_rdwr() errorRichard Yao2016-01-231-3/+8
| | | | | | | | | | | | | I noticed that the SPL implementation of kobj_read_file is not correct after comparing it with the userland implementation of kobj_read_file() in zfsonlinux/zfs#4104. Note that we no longer pass RLIM64_INFINITY with this, but our vn_rdwr implementation did not support it anyway, so there is no difference. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #513
* Use tsd to store tq for taskq_memberChunwei Chen2016-01-203-56/+61
| | | | | | | | | | | | | To prevent taskq_member holding tq_lock and doing linear search, thus causing contention. We store the taskq pointer to which the thread belongs in tsd. This way taskq_member will not need to touch tq_lock, and tsd has per slot spinlock. So the contention should be reduced greatly. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #500 Closes #504 Closes #505
* Don't hold mutex until release cv in cv_waitChunwei Chen2016-01-122-15/+70
| | | | | | | | | | | | | | | | | | | | | | | | If a thread is holding mutex when doing cv_destroy, it might end up waiting a thread in cv_wait. The waiter would wake up trying to aquire the same mutex and cause deadlock. We solve this by move the mutex_enter to the bottom of cv_wait, so that the waiter will release the cv first, allowing cv_destroy to succeed and have a chance to free the mutex. This would create race condition on the cv_mutex. We use xchg to set and check it to ensure we won't be harmed by the race. This would result in the cv_mutex debugging becomes best-effort. Also, the change reveals a race, which was unlikely before, where we call mutex_destroy while test threads are still holding the mutex. We use kthread_stop to make sure the threads are exit before mutex_destroy. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Issue zfsonlinux/zfs#4166 Issue zfsonlinux/zfs#4106
* Fix do_div() types in condvar:timeoutBrian Behlendorf2015-12-221-5/+6
| | | | | | | | The do_div() macro expects unsigned types and this is detected in powerpc implementation of do_div(). Signed-off-by: Brian Behlendorf <[email protected]> Closes #516
* Use spl_fstrans_mark instead of memalloc_noio_saveChunwei Chen2015-12-184-37/+5
| | | | | | | | | | | | | | | | | | | For earlier versions of the kernel with memalloc_noio_save, it only turns off __GFP_IO but leaves __GFP_FS untouched during direct reclaim. This would cause threads to direct reclaim into ZFS and cause deadlock. Instead, we should stick to using spl_fstrans_mark. Since we would explicitly turn off both __GFP_IO and __GFP_FS before allocation, it will work on every version of the kernel. This impacts kernel versions 3.9-3.17, see upstream kernel commit torvalds/linux@934f307 for reference. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Chase <[email protected]> Closes #515 Issue zfsonlinux/zfs#4111
* Provide kstat for taskqsTim Chase2015-12-162-0/+269
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch provides 2 new kstats to display task queues: /proc/spl/taskqs-all - Display all task queues /proc/spl/taskqs - Display only "active" task queues A task queue is considered to be "active" if it currently has active (running) threads or if any of its pending, priority, delay or waitq lists are not empty. If the task queue has running threads, displays each thread function's address (symbolically, if possibly) and its argument. If the task queue has a non-empty list of pending, priority or delayed task queue entries (taskq_ent_t), displays each entry's thread function address and arguemnt. If the task queue has any waiters, displays each waiting task's pid. Note: This patch also updates some comments in taskq.h which referred to "taskq_t" when they should have referred to "taskq_ent_t". Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #491
* Fix cstyle issues in spl-taskq.c and taskq.hBrian Behlendorf2015-12-111-34/+41
| | | | | | | This patch only addresses the issues identified by the style checker. It contains no functional changes. Signed-off-by: Brian Behlendorf <[email protected]>
* Don't use tq->tq_lock_flagsChunwei Chen2015-12-111-61/+62
| | | | | | | | | | The flags argument in spin_lock_irqsave is modified out side of spin_lock context. We cannot use a shared variable like tq->tq_lock_flags for them. This patch removes it and uses local variable for the flags. Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #506
* Subclass tq_lock to eliminate a lockdep warningOlaf Faaland2015-12-111-21/+49
| | | | | | | | | | | | | | | | | | | | | | | | | | When taskq_dispatch() calls taskq_thread_spawn() to create a new thread for a taskq, linux lockdep warns of possible recursive locking. This is a false positive. One such call chain is as follows, when a taskq needs more threads: taskq_dispatch->taskq_thread_spawn->taskq_dispatch The initial taskq_dispatch() holds tq_lock on the taskq that needed more worker threads. The later call into taskq_dispatch() takes dynamic_taskq->tq_lock. Without subclassing, lockdep believes these could potentially be the same lock and complains. A similar case occurs when taskq_dispatch() then calls task_alloc(). This patch uses spin_lock_irqsave_nested() when taking tq_lock, with one of two new lock subclasses: subclass taskq TQ_LOCK_DYNAMIC dynamic_taskq TQ_LOCK_GENERAL any other Signed-off-by: Olaf Faaland <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #480
* Revert "Make taskq_member() use ->journal_info"Brian Behlendorf2015-12-081-3/+34
| | | | | | | | This reverts commit a430c11f0b1ef16ca5edf3059e4082709277376c. Using journal_info like this can cause a BUG at kernel fs/jbd2/transaction.c:425! Signed-off-by: Brian Behlendorf <[email protected]> Issue #500
* Make taskq_member() use ->journal_infoRichard Yao2015-12-081-34/+3
| | | | | | | | | | | | | | | | | | | | | | The ->journal_info pointer in the task_struct is reserved for use by filesystems and because the kernel can have multiple file systems on the same stack due to direct reclaim, each filesystem that touches ->journal_info in a callback function will save the value at the start of its frame and restore it at the end of its frame. This allows us to safely use ->journal_info to store a pointer to the taskq's struct in taskq threads so that ZFS code paths can detect the presence of a taskq. This could break if the ZFS code were to use taskq_member from the context of direct reclaim. However, there are no such uses of it in that manner, so this is safe. This eliminates an O(N) list traversal under a spinlock with an O(1) unlocked pointer comparison. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: tuxoko <[email protected]> Signed-off-by: Tim Chase <[email protected]> Closes #500
* Fix race between getf() and areleasef()Richard Yao2015-12-031-0/+13
| | | | | | | | | | | | | | | | | | If a vnode is released asynchronously through areleasef(), it is possible for the user process to reuse the file descriptor before areleasef is called. When this happens, getf() will return a stale reference, any operations in the kernel on that file descriptor will fail (as it is closed) and the operations meant for that fd will never occur from userspace's perspective. We correct this by detecting this condition in getf(), doing a putf on the old file handle, updating the file descriptor and proceeding as if everything was fine. When the areleasef() is done, it will harmlessly decrement the reference counter on the Illumos file handle. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #492
* Prevent rm modules.* when make installtuxoko2015-12-021-1/+1
| | | | | | | | | | | This was originally in e80cd06b8e0428f3ca2c62e4cb0e4ec54fda1d5c, but somehow was changed and not working anymore. And it will cause the following error: modprobe: ERROR: ../libkmod/libkmod.c:506 lookup_builtin_file() could not open builtin file '/lib/modules/4.2.0-18-generic/modules.builtin.bin' Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #501
* spl-kmem-cache: include linux/prefetch.h for prefetchw()Dimitri John Ledkov2015-12-021-0/+1
| | | | | | | | This is needed for architectures that do not have a builtin prefetchw() Signed-off-by: Dimitri John Ledkov <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #502
* Limit maximum object size in kmem testsBrian Behlendorf2015-11-161-1/+4
| | | | | | | | | | Limit the maximum object size to 1/128 of total system memory for the kmem cache tests. Large values can result in out of memory errors for systems with less the 512M of memory. Additionally, use the known number of objects per-slab for calculating the number of objects to use for a test. Signed-off-by: Brian Behlendorf <[email protected]>
* Remove superfluous `newline` characterloli10K2015-11-131-1/+1
| | | | | | | | | Remove superfluous `newline` character from spl_kmem_cache_magazine_size module parameter description. Signed-off-by: loli10K <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #499
* Fix taskq dynamic spawningtuxoko2015-11-131-14/+11
| | | | | | | | | | | | | | | | | | | | Currently taskq_dispatch() will spawn new task with a condition that the caller is also a member of the taskq. However, under this condition, it will still cause deadlock where a task on tq1 is waiting another thread, who is trying to dispatch a task on tq1. So this patch removes the check. For example when you do: zfs send pp/fs0@001 | zfs recv pp/fs0_copy This will easily deadlock before this patch. Also, move the seq_task check from taskq_thread_spawn() to taskq_thread() because it's not used by the caller from taskq_dispatch(). Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #496
* Don't call kmem_cache_shrink from shrinkerChunwei Chen2015-11-111-6/+1
| | | | | | | | | | | | | Linux slab will automatically free empty slab when number of partial slab is over min_partial, so we don't need to explicitly shrink it. In fact, calling kmem_cache_shrink from shrinker will cause heavy contention on kmem_cache_node->list_lock, to the point that it might cause __slab_free to livelock (see zfsonlinux/zfs#3936) Signed-off-by: Chunwei Chen <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes zfsonlinux/zfs#3936 Closes #487
* Fix CPU hotplugBrian Behlendorf2015-10-131-8/+7
| | | | | | | | | | | | | | | | Allocate a kmem cache magazine for every possible CPU which might be added to the system. This ensures that when one of these CPUs is enabled it can be safely used immediately. For many systems the number of online CPUs is identical to the number of present CPUs so this does imply an increased memory footprint. In fact, dynamically allocating the array of magazine pointers instead of using the worst case NR_CPUS can end up decreasing our memory footprint. Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Ned Bass <[email protected]> Closes #482
* Fix PAX Patch/Grsec SLAB_USERCOPY panicBrian Behlendorf2015-09-281-1/+11
| | | | | | | | | | | | | | | Support grsecurity/PaX kernel configurations where CONFIG_PAX_USERCOPY_SLABS are enabled. When this kernel option is enabled slabs which are used to copy between user and kernel space must be created with SLAB_USERCOPY. Stock Linux kernels do not have a SLAB_USERCOPY definition so this causes no change in behavior for non-PAX-enabled kernels. Verified-by: Wuffleton <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #2977 Issue #3796
* Disable direct reclaim in taskq worker threads on Linux 3.9+Richard Yao2015-09-091-0/+4
| | | | | | | | | | | | | | | Illumos does not have direct reclaim and code run inside taskq worker threads is not designed to deal with it. Allowing direct reclaim inside a worker thread can therefore deadlock. We set PF_MEMALLOC_NOIO through memalloc_noio_save() to indicate to the kernel's reclaim code that we are inside a context where memory allocations cannot be allowed to block on filesystem activity. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue zfsonlinux/zfs#1274 Issue zfsonlinux/zfs#2390 Closes #474
* Linux 4.2 compat: misc_deregister()Brian Behlendorf2015-09-011-5/+1
| | | | | | | | | The misc_deregister() function was changed to a void return type. Rather than add compatibility code to detect this change simply ignore the return code on all kernels. It was only used to log an informational error message of no real value. Signed-off-by: Brian Behlendorf <[email protected]>
* Create a new thread during recursive taskq dispatch if necessaryTim Chase2015-09-011-3/+28
| | | | | | | | | | | | | When dynamic taskq is enabled and all threads for a taskq are occupied, a recursive dispatch can cause a deadlock if calling thread depends on the recursively-dispatched thread for its return condition. This patch attempts to create a new thread for recursive dispatch when none are available. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #472
* Revert "Create a new thread during recursive taskq dispatch if necessary"Brian Behlendorf2015-08-311-22/+0
| | | | | | | | | | | This reverts commit 076821e due to a locking issue uncovered in subsequent testing. An ASSERT is hit due to tq->tq_nspawn being updated outside the lock. The patch will need to be reworked. VERIFY3(0 == tq->tq_nspawn) failed (0 == -1) Signed-off-by: Brian Behlendorf <[email protected]> Issue #472
* Create a new thread during recursive taskq dispatch if necessaryTim Chase2015-08-311-0/+22
| | | | | | | | | | | | | When dynamic taskq is enabled and all threads for a taskq are occupied, a recursive dispatch can cause a deadlock if calling thread depends on the recursively-dispatched thread for its return condition. This patch attempts to create a new thread for recursive dispatch when none are available. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #472
* Linux 4.2 compat: vfs_rename()Brian Behlendorf2015-08-192-0/+7
| | | | | | | | | | | | | Attempting to perform a vfs_rename() on Linux 4.2 and newer kernels results in an EACCES error. Rather than attempting to add and maintain more ugly compatibility code it's best to just retire this interface. As a first step the SPLAT test is disabled for Linux 4.2 and newer kernels. vn_rename: Failed vn_rename /tmp/vn.tmp.1 -> /tmp/vn.tmp.2 (13) Signed-off-by: Brian Behlendorf <[email protected]> Issue zfsonlinux/zfs#3653
* Invert minclsyspri and maxclsyspriBrian Behlendorf2015-07-282-4/+3
| | | | | | | | | | | | | | | | | | | | | | | On Linux the meaning of a processes priority is inverted with respect to illumos. High values on Linux indicate a _low_ priority while high value on illumos indicate a _high_ priority. In order to preserve the logical meaning of the minclsyspri and maxclsyspri macros when they are used by the illumos wrapper functions their values have been inverted. This way when changes are merged from upstream illumos we won't need to remember to invert the macro. It could also lead to confusion. Note this change also reverts some of the priorities changes in prior commit 62aa81a. The rational is as follows: spl_kmem_cache - High priority may result in blocked memory allocs spl_system_taskq - May perform I/O for file backed VDEVs spl_dynamic_taskq - New taskq threads should be spawned promptly Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Ned Bass <[email protected]> Issue zfsonlinux/zfs#3607
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