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2020-10-26Merge release-20201019.0-63-g652f11380 (automated)gVisor bot
2020-10-26[vfs] kernfs: Implement LRU cache for kernfs dentries.Ayush Ranjan
Much like the VFS2 gofer client, kernfs too now caches dentries. The size of the LRU cache is configurable via mount options. Have adopted the same reference semantics from gofer client dentry. Only sysfs and procfs use this LRU cache. The rest of the kernfs users (devpts, fusefs, host, pipefs, sockfs) still use the no cache approach. PiperOrigin-RevId: 339139835
2020-10-24Merge release-20201019.0-51-g9f87400f0 (automated)gVisor bot
2020-10-23Merge release-20201019.0-45-g61b379ee1 (automated)gVisor bot
2020-10-23[vfs] kernfs: cleanup/refactor.Ayush Ranjan
PiperOrigin-RevId: 338728070
2020-10-23Merge release-20201019.0-41-g6ee3520b6 (automated)gVisor bot
2020-10-23[vfs] kernfs: Implement remaining InodeAttr fields.Ayush Ranjan
Added the following fields in kernfs.InodeAttr: - blockSize - atime - mtime - ctime Also resolved all TODOs for #1193. Fixes #1193 PiperOrigin-RevId: 338714527
2020-10-23Merge release-20201019.0-34-g9ca66ec59 (automated)gVisor bot
2020-10-23Rewrite reference leak checker without finalizers.Dean Deng
Our current reference leak checker uses finalizers to verify whether an object has reached zero references before it is garbage collected. There are multiple problems with this mechanism, so a rewrite is in order. With finalizers, there is no way to guarantee that a finalizer will run before the program exits. When an unreachable object with a finalizer is garbage collected, its finalizer will be added to a queue and run asynchronously. The best we can do is run garbage collection upon sandbox exit to make sure that all finalizers are enqueued. Furthermore, if there is a chain of finalized objects, e.g. A points to B points to C, garbage collection needs to run multiple times before all of the finalizers are enqueued. The first GC run will register the finalizer for A but not free it. It takes another GC run to free A, at which point B's finalizer can be registered. As a result, we need to run GC as many times as the length of the longest such chain to have a somewhat reliable leak checker. Finally, a cyclical chain of structs pointing to one another will never be garbage collected if a finalizer is set. This is a well-known issue with Go finalizers (https://github.com/golang/go/issues/7358). Using leak checking on filesystem objects that produce cycles will not work and even result in memory leaks. The new leak checker stores reference counted objects in a global map when leak check is enabled and removes them once they are destroyed. At sandbox exit, any remaining objects in the map are considered as leaked. This provides a deterministic way of detecting leaks without relying on the complexities of finalizers and garbage collection. This approach has several benefits over the former, including: - Always detects leaks of objects that should be destroyed very close to sandbox exit. The old checker very rarely detected these leaks, because it relied on garbage collection to be run in a short window of time. - Panics if we forgot to enable leak check on a ref-counted object (we will try to remove it from the map when it is destroyed, but it will never have been added). - Can store extra logging information in the map values without adding to the size of the ref count struct itself. With the size of just an int64, the ref count object remains compact, meaning frequent operations like IncRef/DecRef are more cache-efficient. - Can aggregate leak results in a single report after the sandbox exits. Instead of having warnings littered in the log, which were non-deterministically triggered by garbage collection, we can print all warning messages at once. Note that this could also be a limitation--the sandbox must exit properly for leaks to be detected. Some basic benchmarking indicates that this change does not significantly affect performance when leak checking is enabled, which is understandable since registering/unregistering is only done once for each filesystem object. Updates #1486. PiperOrigin-RevId: 338685972
2020-10-13[vfs2] Add FilesystemType.Release to avoid reference leaks.Dean Deng
Singleton filesystem like devpts and devtmpfs have a single filesystem shared among all mounts, so they acquire a "self-reference" when initialized that must be released when the entire virtual filesystem is released at sandbox exit. PiperOrigin-RevId: 336828852
2020-10-12Merge release-20200928.0-94-ge7bbe70f7 (automated)gVisor bot
2020-10-12[vfs] kernfs: Fix inode memory leak issue.Ayush Ranjan
This change aims to fix the memory leak issue reported inĀ #3933. Background: VFS2 kernfs kept accumulating invalid dentries if those dentries were not walked on. After substantial consideration of the problem by our team, we decided to have an LRU cache solution. This change is the first part to that solution, where we don't cache anything. The LRU cache can be added on top of this. What has changed: - Introduced the concept of an inode tree in kernfs.OrderedChildren. This is helpful is cases where the lifecycle of an inode is different from that of a dentry. - OrderedChildren now deals with initialized inodes instead of initialized dentries. It now implements Lookup() where it constructs a new dentry using the inode. - OrderedChildren holds a ref on all its children inodes. With this change, now an inode can "outlive" a dentry pointing to it. See comments in kernfs.OrderedChildren. - The kernfs dentry tree is solely maintained by kernfs only. Inode implementations can not modify the dentry tree. - Dentries that reach ref count 0 are removed from the dentry tree. - revalidateChildLocked now defer-DecRefs the newly created dentry from Inode.Lookup(), limiting its life to the current filesystem operation. If refs are picked on the dentry during the FS op (via an FD or something), then it will stick around and will be removed when the FD is closed. So there is essentially _no caching_ for Look()ed up dentries. - kernfs.DecRef does not have the precondition that fs.mu must be locked. Fixes #3933 PiperOrigin-RevId: 336768576
2020-10-09Merge release-20200928.0-78-g743327817 (automated)gVisor bot
2020-10-08Merge release-20200928.0-66-ga55bd73d4 (automated)gVisor bot
2020-09-27Merge release-20200921.0-54-gfa995da84 (automated)gVisor bot
2020-09-27Fix kernfs race condition.Dean Deng
Do not release dirMu between checking whether to create a child and actually inserting it. Also fixes a bug in fusefs which was causing it to deadlock under the new lock ordering. We do not need to call kernfs.Dentry.InsertChild from newEntry because it will always be called at the kernfs filesystem layer. Updates #1193. PiperOrigin-RevId: 334049264
2020-09-24Merge release-20200914.0-158-g832d91b80 (automated)gVisor bot
2020-09-24[vfs] kernfs: Do not hold reference on the inode when opening FD.Ayush Ranjan
The FD should hold a reference on the dentry they were opened on which in turn holds a reference on the inode it points to. PiperOrigin-RevId: 333589223
2020-09-24Merge release-20200914.0-154-g2a10bc1e4 (automated)gVisor bot
2020-09-24[vfs] [2/2] kernfs: kernfs: Internally use kernfs.Dentry instead of vfs.Dentry.Ayush Ranjan
Update signatures for: - All methods in inodeDirectory - deferDecRef() and Filesystem.droppedDentries - newSyntheticDirectory() - `slot`s used in OrderedChildren and subsequent methods like replaceChildLocked() and checkExistingLocked() - stepExistingLocked(), walkParentDirLocked(), checkCreateLocked() Updates #1193 PiperOrigin-RevId: 333558866
2020-09-24Merge release-20200914.0-152-g0a7075f38 (automated)gVisor bot
2020-09-24Add basic stateify annotations.Adin Scannell
Updates #1663 PiperOrigin-RevId: 333539293
2020-09-24Merge release-20200914.0-144-g08bbad690 (automated)gVisor bot
2020-09-23[vfs] kernfs: Enable leak checking consistently.Ayush Ranjan
There were some instances where we were not enabling leak checking. PiperOrigin-RevId: 333418571
2020-09-23Merge release-20200914.0-137-g99decaadd (automated)gVisor bot
2020-09-23Merge release-20200914.0-136-gb54dbdfdc (automated)gVisor bot
2020-09-23Merge release-20200914.0-135-gc0f21bb19 (automated)gVisor bot
2020-09-22Merge release-20200914.0-134-gcf3cef117 (automated)gVisor bot
2020-09-22Merge release-20200914.0-133-g20dc83c9e (automated)gVisor bot
2020-09-22[vfs] [1/2] kernfs: Internally use kernfs.Dentry instead of vfs.Dentry.Ayush Ranjan
Update signatures for: - walkExistingLocked - checkDeleteLocked - Inode.Open Updates #1193 PiperOrigin-RevId: 333163381
2020-09-22Merge release-20200914.0-132-g778c36717 (automated)gVisor bot
2020-09-22Merge release-20200914.0-130-g13a9a622e (automated)gVisor bot
2020-09-22Merge release-20200914.0-129-gf134f873f (automated)gVisor bot
2020-09-21Merge release-20200914.0-127-g059d90b9f (automated)gVisor bot
2020-09-21Merge release-20200914.0-125-g06dbd5b7b (automated)gVisor bot
2020-09-21Merge release-20200914.0-124-g10dcefbc7 (automated)gVisor bot
2020-09-21Use kernfs.Dentry for kernfs.Lookup.Dean Deng
Updates #1193. PiperOrigin-RevId: 332939026
2020-09-21Merge release-20200914.0-123-ga129204cf (automated)gVisor bot
2020-09-21Merge release-20200914.0-122-gd72022373 (automated)gVisor bot
2020-09-18Merge release-20200907.0-153-g4ba86e625 (automated)gVisor bot
2020-09-18Merge release-20200907.0-151-g6c9989cb8 (automated)gVisor bot
2020-09-18Merge release-20200907.0-150-gc23e39f41 (automated)gVisor bot
2020-09-18Merge release-20200907.0-149-gb8ba0893e (automated)gVisor bot
2020-09-18Merge release-20200907.0-148-gca4ecf481 (automated)gVisor bot
2020-09-18Merge release-20200907.0-147-gf911b43f0 (automated)gVisor bot
2020-09-18Merge release-20200907.0-146-gddf37cb19 (automated)gVisor bot
2020-09-18Merge release-20200907.0-144-gdedef4392 (automated)gVisor bot
2020-09-18Merge pull request #3972 from btw616:fix/commentsgVisor bot
PiperOrigin-RevId: 332486111
2020-09-18Merge release-20200907.0-142-gfcf8d7c6d (automated)gVisor bot
2020-09-18Merge release-20200907.0-140-gef7d9a6fc (automated)gVisor bot