From 0e2f1b7abd219f39d67cc2cecd00c441a13eeb29 Mon Sep 17 00:00:00 2001 From: Adin Scannell Date: Mon, 27 Jan 2020 15:17:58 -0800 Subject: Update package locations. Because the abi will depend on the core types for marshalling (usermem, context, safemem, safecopy), these need to be flattened from the sentry directory. These packages contain no sentry-specific details. PiperOrigin-RevId: 291811289 --- pkg/sentry/vfs/file_description.go | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'pkg/sentry/vfs/file_description.go') diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go index 51c95c2d9..225024463 100644 --- a/pkg/sentry/vfs/file_description.go +++ b/pkg/sentry/vfs/file_description.go @@ -18,12 +18,12 @@ import ( "sync/atomic" "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" - "gvisor.dev/gvisor/pkg/sentry/context" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/memmap" - "gvisor.dev/gvisor/pkg/sentry/usermem" "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" "gvisor.dev/gvisor/pkg/waiter" ) -- cgit v1.2.3 From 34fbd8446c386fb0136dad31ab6b173f17049a58 Mon Sep 17 00:00:00 2001 From: Jamie Liu Date: Tue, 28 Jan 2020 13:10:41 -0800 Subject: Add VFS2 support for epoll. PiperOrigin-RevId: 291997879 --- pkg/abi/linux/epoll.go | 10 +- pkg/sentry/vfs/BUILD | 15 ++ pkg/sentry/vfs/epoll.go | 377 +++++++++++++++++++++++++++++++++++++ pkg/sentry/vfs/file_description.go | 38 ++++ pkg/sentry/vfs/vfs.go | 16 +- 5 files changed, 448 insertions(+), 8 deletions(-) create mode 100644 pkg/sentry/vfs/epoll.go (limited to 'pkg/sentry/vfs/file_description.go') diff --git a/pkg/abi/linux/epoll.go b/pkg/abi/linux/epoll.go index 72083b604..0e881aa3c 100644 --- a/pkg/abi/linux/epoll.go +++ b/pkg/abi/linux/epoll.go @@ -38,8 +38,14 @@ const ( // Per-file descriptor flags. const ( - EPOLLET = 0x80000000 - EPOLLONESHOT = 0x40000000 + EPOLLEXCLUSIVE = 1 << 28 + EPOLLWAKEUP = 1 << 29 + EPOLLONESHOT = 1 << 30 + EPOLLET = 1 << 31 + + // EP_PRIVATE_BITS is fs/eventpoll.c:EP_PRIVATE_BITS, the set of all bits + // in an epoll event mask that correspond to flags rather than I/O events. + EP_PRIVATE_BITS = EPOLLEXCLUSIVE | EPOLLWAKEUP | EPOLLONESHOT | EPOLLET ) // Operation flags. diff --git a/pkg/sentry/vfs/BUILD b/pkg/sentry/vfs/BUILD index 33516e6f7..ced9d07b1 100644 --- a/pkg/sentry/vfs/BUILD +++ b/pkg/sentry/vfs/BUILD @@ -1,7 +1,20 @@ load("//tools:defs.bzl", "go_library", "go_test") +load("//tools/go_generics:defs.bzl", "go_template_instance") licenses(["notice"]) +go_template_instance( + name = "epoll_interest_list", + out = "epoll_interest_list.go", + package = "vfs", + prefix = "epollInterest", + template = "//pkg/ilist:generic_list", + types = { + "Element": "*epollInterest", + "Linker": "*epollInterest", + }, +) + go_library( name = "vfs", srcs = [ @@ -10,6 +23,8 @@ go_library( "debug.go", "dentry.go", "device.go", + "epoll.go", + "epoll_interest_list.go", "file_description.go", "file_description_impl_util.go", "filesystem.go", diff --git a/pkg/sentry/vfs/epoll.go b/pkg/sentry/vfs/epoll.go new file mode 100644 index 000000000..7c83f9a5a --- /dev/null +++ b/pkg/sentry/vfs/epoll.go @@ -0,0 +1,377 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package vfs + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/waiter" +) + +// epollCycleMu serializes attempts to register EpollInstances with other +// EpollInstances in order to check for cycles. +var epollCycleMu sync.Mutex + +// EpollInstance represents an epoll instance, as described by epoll(7). +type EpollInstance struct { + vfsfd FileDescription + FileDescriptionDefaultImpl + DentryMetadataFileDescriptionImpl + + // q holds waiters on this EpollInstance. + q waiter.Queue + + // interest is the set of file descriptors that are registered with the + // EpollInstance for monitoring. interest is protected by interestMu. + interestMu sync.Mutex + interest map[epollInterestKey]*epollInterest + + // mu protects fields in registered epollInterests. + mu sync.Mutex + + // ready is the set of file descriptors that may be "ready" for I/O. Note + // that this must be an ordered list, not a map: "If more than maxevents + // file descriptors are ready when epoll_wait() is called, then successive + // epoll_wait() calls will round robin through the set of ready file + // descriptors. This behavior helps avoid starvation scenarios, where a + // process fails to notice that additional file descriptors are ready + // because it focuses on a set of file descriptors that are already known + // to be ready." - epoll_wait(2) + ready epollInterestList +} + +type epollInterestKey struct { + // file is the registered FileDescription. No reference is held on file; + // instead, when the last reference is dropped, FileDescription.DecRef() + // removes the FileDescription from all EpollInstances. file is immutable. + file *FileDescription + + // num is the file descriptor number with which this entry was registered. + // num is immutable. + num int32 +} + +// epollInterest represents an EpollInstance's interest in a file descriptor. +type epollInterest struct { + // epoll is the owning EpollInstance. epoll is immutable. + epoll *EpollInstance + + // key is the file to which this epollInterest applies. key is immutable. + key epollInterestKey + + // waiter is registered with key.file. entry is protected by epoll.mu. + waiter waiter.Entry + + // mask is the event mask associated with this registration, including + // flags EPOLLET and EPOLLONESHOT. mask is protected by epoll.mu. + mask uint32 + + // ready is true if epollInterestEntry is linked into epoll.ready. ready + // and epollInterestEntry are protected by epoll.mu. + ready bool + epollInterestEntry + + // userData is the epoll_data_t associated with this epollInterest. + // userData is protected by epoll.mu. + userData [2]int32 +} + +// NewEpollInstanceFD returns a FileDescription representing a new epoll +// instance. A reference is taken on the returned FileDescription. +func (vfs *VirtualFilesystem) NewEpollInstanceFD() (*FileDescription, error) { + vd := vfs.NewAnonVirtualDentry("[eventpoll]") + defer vd.DecRef() + ep := &EpollInstance{ + interest: make(map[epollInterestKey]*epollInterest), + } + if err := ep.vfsfd.Init(ep, linux.O_RDWR, vd.Mount(), vd.Dentry(), &FileDescriptionOptions{ + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return &ep.vfsfd, nil +} + +// Release implements FileDescriptionImpl.Release. +func (ep *EpollInstance) Release() { + // Unregister all polled fds. + ep.interestMu.Lock() + defer ep.interestMu.Unlock() + for key, epi := range ep.interest { + file := key.file + file.epollMu.Lock() + delete(file.epolls, epi) + file.epollMu.Unlock() + file.EventUnregister(&epi.waiter) + } + ep.interest = nil +} + +// Readiness implements waiter.Waitable.Readiness. +func (ep *EpollInstance) Readiness(mask waiter.EventMask) waiter.EventMask { + if mask&waiter.EventIn == 0 { + return 0 + } + ep.mu.Lock() + for epi := ep.ready.Front(); epi != nil; epi = epi.Next() { + wmask := waiter.EventMaskFromLinux(epi.mask) + if epi.key.file.Readiness(wmask)&wmask != 0 { + ep.mu.Unlock() + return waiter.EventIn + } + } + ep.mu.Unlock() + return 0 +} + +// EventRegister implements waiter.Waitable.EventRegister. +func (ep *EpollInstance) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + ep.q.EventRegister(e, mask) +} + +// EventUnregister implements waiter.Waitable.EventUnregister. +func (ep *EpollInstance) EventUnregister(e *waiter.Entry) { + ep.q.EventUnregister(e) +} + +// Seek implements FileDescriptionImpl.Seek. +func (ep *EpollInstance) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + // Linux: fs/eventpoll.c:eventpoll_fops.llseek == noop_llseek + return 0, nil +} + +// AddInterest implements the semantics of EPOLL_CTL_ADD. +// +// Preconditions: A reference must be held on file. +func (ep *EpollInstance) AddInterest(file *FileDescription, num int32, mask uint32, userData [2]int32) error { + // Check for cyclic polling if necessary. + subep, _ := file.impl.(*EpollInstance) + if subep != nil { + epollCycleMu.Lock() + // epollCycleMu must be locked for the rest of AddInterest to ensure + // that cyclic polling is not introduced after the check. + defer epollCycleMu.Unlock() + if subep.mightPoll(ep) { + return syserror.ELOOP + } + } + + ep.interestMu.Lock() + defer ep.interestMu.Unlock() + + // Fail if the key is already registered. + key := epollInterestKey{ + file: file, + num: num, + } + if _, ok := ep.interest[key]; ok { + return syserror.EEXIST + } + + // Register interest in file. + mask |= linux.EPOLLERR | linux.EPOLLRDHUP + epi := &epollInterest{ + epoll: ep, + key: key, + mask: mask, + userData: userData, + } + ep.interest[key] = epi + wmask := waiter.EventMaskFromLinux(mask) + file.EventRegister(&epi.waiter, wmask) + + // Check if the file is already ready. + if file.Readiness(wmask)&wmask != 0 { + epi.Callback(nil) + } + + // Add epi to file.epolls so that it is removed when the last + // FileDescription reference is dropped. + file.epollMu.Lock() + file.epolls[epi] = struct{}{} + file.epollMu.Unlock() + + return nil +} + +func (ep *EpollInstance) mightPoll(ep2 *EpollInstance) bool { + return ep.mightPollRecursive(ep2, 4) // Linux: fs/eventpoll.c:EP_MAX_NESTS +} + +func (ep *EpollInstance) mightPollRecursive(ep2 *EpollInstance, remainingRecursion int) bool { + ep.interestMu.Lock() + defer ep.interestMu.Unlock() + for key := range ep.interest { + nextep, ok := key.file.impl.(*EpollInstance) + if !ok { + continue + } + if nextep == ep2 { + return true + } + if remainingRecursion == 0 { + return true + } + if nextep.mightPollRecursive(ep2, remainingRecursion-1) { + return true + } + } + return false +} + +// ModifyInterest implements the semantics of EPOLL_CTL_MOD. +// +// Preconditions: A reference must be held on file. +func (ep *EpollInstance) ModifyInterest(file *FileDescription, num int32, mask uint32, userData [2]int32) error { + ep.interestMu.Lock() + defer ep.interestMu.Unlock() + + // Fail if the key is not already registered. + epi, ok := ep.interest[epollInterestKey{ + file: file, + num: num, + }] + if !ok { + return syserror.ENOENT + } + + // Update epi for the next call to ep.ReadEvents(). + ep.mu.Lock() + epi.mask = mask + epi.userData = userData + ep.mu.Unlock() + + // Re-register with the new mask. + mask |= linux.EPOLLERR | linux.EPOLLRDHUP + file.EventUnregister(&epi.waiter) + wmask := waiter.EventMaskFromLinux(mask) + file.EventRegister(&epi.waiter, wmask) + + // Check if the file is already ready with the new mask. + if file.Readiness(wmask)&wmask != 0 { + epi.Callback(nil) + } + + return nil +} + +// DeleteInterest implements the semantics of EPOLL_CTL_DEL. +// +// Preconditions: A reference must be held on file. +func (ep *EpollInstance) DeleteInterest(file *FileDescription, num int32) error { + ep.interestMu.Lock() + defer ep.interestMu.Unlock() + + // Fail if the key is not already registered. + epi, ok := ep.interest[epollInterestKey{ + file: file, + num: num, + }] + if !ok { + return syserror.ENOENT + } + + // Unregister from the file so that epi will no longer be readied. + file.EventUnregister(&epi.waiter) + + // Forget about epi. + ep.removeLocked(epi) + + file.epollMu.Lock() + delete(file.epolls, epi) + file.epollMu.Unlock() + + return nil +} + +// Callback implements waiter.EntryCallback.Callback. +func (epi *epollInterest) Callback(*waiter.Entry) { + newReady := false + epi.epoll.mu.Lock() + if !epi.ready { + newReady = true + epi.ready = true + epi.epoll.ready.PushBack(epi) + } + epi.epoll.mu.Unlock() + if newReady { + epi.epoll.q.Notify(waiter.EventIn) + } +} + +// Preconditions: ep.interestMu must be locked. +func (ep *EpollInstance) removeLocked(epi *epollInterest) { + delete(ep.interest, epi.key) + ep.mu.Lock() + if epi.ready { + epi.ready = false + ep.ready.Remove(epi) + } + ep.mu.Unlock() +} + +// ReadEvents reads up to len(events) ready events into events and returns the +// number of events read. +// +// Preconditions: len(events) != 0. +func (ep *EpollInstance) ReadEvents(events []linux.EpollEvent) int { + i := 0 + // Hot path: avoid defer. + ep.mu.Lock() + var next *epollInterest + var requeue epollInterestList + for epi := ep.ready.Front(); epi != nil; epi = next { + next = epi.Next() + // Regardless of what else happens, epi is initially removed from the + // ready list. + ep.ready.Remove(epi) + wmask := waiter.EventMaskFromLinux(epi.mask) + ievents := epi.key.file.Readiness(wmask) & wmask + if ievents == 0 { + // Leave epi off the ready list. + epi.ready = false + continue + } + // Determine what we should do with epi. + switch { + case epi.mask&linux.EPOLLONESHOT != 0: + // Clear all events from the mask; they must be re-added by + // EPOLL_CTL_MOD. + epi.mask &= linux.EP_PRIVATE_BITS + fallthrough + case epi.mask&linux.EPOLLET != 0: + // Leave epi off the ready list. + epi.ready = false + default: + // Queue epi to be moved to the end of the ready list. + requeue.PushBack(epi) + } + // Report ievents. + events[i] = linux.EpollEvent{ + Events: ievents.ToLinux(), + Fd: epi.userData[0], + Data: epi.userData[1], + } + i++ + if i == len(events) { + break + } + } + ep.ready.PushBackList(&requeue) + ep.mu.Unlock() + return i +} diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go index 225024463..badacb55e 100644 --- a/pkg/sentry/vfs/file_description.go +++ b/pkg/sentry/vfs/file_description.go @@ -22,6 +22,7 @@ import ( "gvisor.dev/gvisor/pkg/sentry/arch" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/memmap" + "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/syserror" "gvisor.dev/gvisor/pkg/usermem" "gvisor.dev/gvisor/pkg/waiter" @@ -45,6 +46,11 @@ type FileDescription struct { // memory operations. statusFlags uint32 + // epolls is the set of epollInterests registered for this FileDescription. + // epolls is protected by epollMu. + epollMu sync.Mutex + epolls map[*epollInterest]struct{} + // vd is the filesystem location at which this FileDescription was opened. // A reference is held on vd. vd is immutable. vd VirtualDentry @@ -141,6 +147,23 @@ func (fd *FileDescription) TryIncRef() bool { // DecRef decrements fd's reference count. func (fd *FileDescription) DecRef() { if refs := atomic.AddInt64(&fd.refs, -1); refs == 0 { + // Unregister fd from all epoll instances. + fd.epollMu.Lock() + epolls := fd.epolls + fd.epolls = nil + fd.epollMu.Unlock() + for epi := range epolls { + ep := epi.epoll + ep.interestMu.Lock() + // Check that epi has not been concurrently unregistered by + // EpollInstance.DeleteInterest() or EpollInstance.Release(). + if _, ok := ep.interest[epi.key]; ok { + fd.EventUnregister(&epi.waiter) + ep.removeLocked(epi) + } + ep.interestMu.Unlock() + } + // Release implementation resources. fd.impl.Release() if fd.writable { fd.vd.mount.EndWrite() @@ -453,6 +476,21 @@ func (fd *FileDescription) StatFS(ctx context.Context) (linux.Statfs, error) { return fd.impl.StatFS(ctx) } +// Readiness returns fd's I/O readiness. +func (fd *FileDescription) Readiness(mask waiter.EventMask) waiter.EventMask { + return fd.impl.Readiness(mask) +} + +// EventRegister registers e for I/O readiness events in mask. +func (fd *FileDescription) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + fd.impl.EventRegister(e, mask) +} + +// EventUnregister unregisters e for I/O readiness events. +func (fd *FileDescription) EventUnregister(e *waiter.Entry) { + fd.impl.EventUnregister(e) +} + // PRead reads from the file represented by fd into dst, starting at the given // offset, and returns the number of bytes read. PRead is permitted to return // partial reads with a nil error. diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go index d730530b9..908c69f91 100644 --- a/pkg/sentry/vfs/vfs.go +++ b/pkg/sentry/vfs/vfs.go @@ -16,15 +16,19 @@ // // Lock order: // -// FilesystemImpl/FileDescriptionImpl locks -// VirtualFilesystem.mountMu -// Dentry.mu -// Locks acquired by FilesystemImpls between Prepare{Delete,Rename}Dentry and Commit{Delete,Rename*}Dentry -// VirtualFilesystem.filesystemsMu +// EpollInstance.interestMu +// FileDescription.epollMu +// FilesystemImpl/FileDescriptionImpl locks +// VirtualFilesystem.mountMu +// Dentry.mu +// Locks acquired by FilesystemImpls between Prepare{Delete,Rename}Dentry and Commit{Delete,Rename*}Dentry +// VirtualFilesystem.filesystemsMu +// EpollInstance.mu // VirtualFilesystem.fsTypesMu // // Locking Dentry.mu in multiple Dentries requires holding -// VirtualFilesystem.mountMu. +// VirtualFilesystem.mountMu. Locking EpollInstance.interestMu in multiple +// EpollInstances requires holding epollCycleMu. package vfs import ( -- cgit v1.2.3 From 148fda60e8dee29f2df85e3104e3d5de1a225bcf Mon Sep 17 00:00:00 2001 From: Dean Deng Date: Wed, 29 Jan 2020 11:15:59 -0800 Subject: Add plumbing for file locks in VFS2. Updates #1480 PiperOrigin-RevId: 292180192 --- pkg/sentry/vfs/BUILD | 1 + pkg/sentry/vfs/file_description.go | 21 ++++++++++++++++++++- pkg/sentry/vfs/file_description_impl_util.go | 21 +++++++++++++++++++++ 3 files changed, 42 insertions(+), 1 deletion(-) (limited to 'pkg/sentry/vfs/file_description.go') diff --git a/pkg/sentry/vfs/BUILD b/pkg/sentry/vfs/BUILD index ced9d07b1..14b39eb9d 100644 --- a/pkg/sentry/vfs/BUILD +++ b/pkg/sentry/vfs/BUILD @@ -44,6 +44,7 @@ go_library( "//pkg/context", "//pkg/fspath", "//pkg/sentry/arch", + "//pkg/sentry/fs/lock", "//pkg/sentry/kernel/auth", "//pkg/sentry/memmap", "//pkg/sync", diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go index badacb55e..5bac660c7 100644 --- a/pkg/sentry/vfs/file_description.go +++ b/pkg/sentry/vfs/file_description.go @@ -20,6 +20,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sync" @@ -393,7 +394,25 @@ type FileDescriptionImpl interface { // Removexattr removes the given extended attribute from the file. Removexattr(ctx context.Context, name string) error - // TODO: file locking + // LockBSD tries to acquire a BSD-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): BSD-style file locking + LockBSD(ctx context.Context, uid lock.UniqueID, t lock.LockType, block lock.Blocker) error + + // LockBSD releases a BSD-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): BSD-style file locking + UnlockBSD(ctx context.Context, uid lock.UniqueID) error + + // LockPOSIX tries to acquire a POSIX-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): POSIX-style file locking + LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, rng lock.LockRange, block lock.Blocker) error + + // UnlockPOSIX releases a POSIX-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): POSIX-style file locking + UnlockPOSIX(ctx context.Context, uid lock.UniqueID, rng lock.LockRange) error } // Dirent holds the information contained in struct linux_dirent64. diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go index a4900c170..c2a52ec1b 100644 --- a/pkg/sentry/vfs/file_description_impl_util.go +++ b/pkg/sentry/vfs/file_description_impl_util.go @@ -21,6 +21,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/syserror" @@ -152,6 +153,26 @@ func (FileDescriptionDefaultImpl) Removexattr(ctx context.Context, name string) return syserror.ENOTSUP } +// LockBSD implements FileDescriptionImpl.LockBSD. +func (FileDescriptionDefaultImpl) LockBSD(ctx context.Context, uid lock.UniqueID, t lock.LockType, block lock.Blocker) error { + return syserror.EBADF +} + +// UnlockBSD implements FileDescriptionImpl.UnlockBSD. +func (FileDescriptionDefaultImpl) UnlockBSD(ctx context.Context, uid lock.UniqueID) error { + return syserror.EBADF +} + +// LockPOSIX implements FileDescriptionImpl.LockPOSIX. +func (FileDescriptionDefaultImpl) LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, rng lock.LockRange, block lock.Blocker) error { + return syserror.EBADF +} + +// UnlockPOSIX implements FileDescriptionImpl.UnlockPOSIX. +func (FileDescriptionDefaultImpl) UnlockPOSIX(ctx context.Context, uid lock.UniqueID, rng lock.LockRange) error { + return syserror.EBADF +} + // DirectoryFileDescriptionDefaultImpl may be embedded by implementations of // FileDescriptionImpl that always represent directories to obtain // implementations of non-directory I/O methods that return EISDIR. -- cgit v1.2.3