While there is a difference between flavors of this ioctl (`TCSETS`,
`TCSETSF`, `TCSETSW`), in practice it seems not to matter. We should let
users call `TCSETSF` and can implement those differences if necessary.
These inodes can never be part of a filesystem tree. They are nameless and
never have a parent.
This allows us to avoid taking a lock in kernfs.InotifyWithParent for such
anonymous inodes.
PiperOrigin-RevId: 538823227
This catches up the interface to the `EmitUnimplementedEvent` method signature
on `kernel.Kernel`.
Also add build-time test to verify that `kernel.Kernel` implements this
interface, in order to catch such breakages at build time in the future.
PiperOrigin-RevId: 519000411
We no longer store the foreground process directly in the terminal. Instead, we
get it from the terminal TTY's ThreadGroup. Added a new method:
tty.SignalForegroundProcessGroup to simplify this.
Cleaned up some things along the way:
* Terminal had a bunch of methods to get/set foreground process group and
controlling TTY, but those methods were only usable by Ioctl, since they
read/wrote to syscall arguments. I moved that logic to Ioctl, and deleted the
methods from Terminal, which is now a very simple type.
* Fixed a bug in ThreadGroud.SetForegroundProcessGroup where we were
overwriting the ID of an existing process group, rather than setting a new
process group on the session.
* Simplified the construction of lineDiscipline type.
Reported-by: [email protected]
PiperOrigin-RevId: 512330758
Some implementations handle more flags than others, so it doesn't
make sense to have one set of rules for all.
This change should functionally be a no-op.
PiperOrigin-RevId: 502712415
This is consistent with Linux. Some applications recursively add
files to inotify FD. They fail if they run into kernfs files
because inotify_add_watch(2) returns EPERM in that case.
PiperOrigin-RevId: 462642204
Since refsvfs2 are used in netstack, we should use atomicbitops to avoid
breaking 32-bit builds.
On 64-bit builds there is no performance difference.
PiperOrigin-RevId: 439687980
Linux behaves differently for regular files and dirs for poll(2)/select(2)
compared to epoll_ctl(2). The latter returns EPERM for file and dirs.
I've also changed host FDs to behave like the underlying FD in regards
to epoll to keep it compatible with docker.
Fixes#7134
PiperOrigin-RevId: 429412692
Docker maps stdin to `/dev/null` which doesn't support epoll. Host FD
was ignoring the error and suceeding the epoll_ctl call from the
container, giving false impressing that epoll would be notified.
This required plumbing failure to all waiter.Waitable.EventRegister
callers and implementers.
Closes#6795
PiperOrigin-RevId: 414797621
Instead of passing the event mask at registratrion time, pass the mask as part
of the waiter. This makes the mask immutable and simplifies the architecture of
waiters. This is also necessary for a future fix that will allow the fdnotifier
to keep persistent entries, as opposed to requiring constant updates.
This change is intended to be a no-op in terms of function. The only exception
is signalfd, where this mask was abused. To handle this case, the operation of
signalfd changed to allow one layer of indirection.
PiperOrigin-RevId: 409702998
Removes package syserror and moves still relevant code to either linuxerr
or to syserr (to be later removed).
Internal errors are converted from random types to *errors.Error types used
in linuxerr. Internal errors are in linuxerr/internal.go.
PiperOrigin-RevId: 390724202
Remove three syserror entries duplicated in linuxerr. Because of the
linuxerr.Equals method, this is a mere change of return values from
syserror to linuxerr definitions.
Done with only these three errnos as CLs removing all grow to a significantly
large size.
PiperOrigin-RevId: 382173835
On Linux these are meant to be equivalent to POLLIN/POLLOUT. Rather
than hack these on in sys_poll etc it felt cleaner to just cleanup
the call sites to notify for both events. This is what linux does
as well.
Fixes#5544
PiperOrigin-RevId: 364859977
This lets us avoid treating a value of 0 as one reference. All references
using the refsvfs2 template must call InitRefs() before the reference is
incremented/decremented, or else a panic will occur. Therefore, it should be
pretty easy to identify missing InitRef calls during testing.
Updates #1486.
PiperOrigin-RevId: 341411151
Inode number consistency checks are now skipped in save/restore tests for
reasons described in greatest detail in StatTest.StateDoesntChangeAfterRename.
They pass in VFS1 due to the bug described in new test case
SimpleStatTest.DifferentFilesHaveDifferentDeviceInodeNumberPairs.
Fixes#1663
PiperOrigin-RevId: 338776148
Added the following fields in kernfs.InodeAttr:
- blockSize
- atime
- mtime
- ctime
Also resolved all TODOs for #1193.
Fixes#1193
PiperOrigin-RevId: 338714527
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
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
This change aims to fix the memory leak issue reported in #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
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
As noticed by @ayushr2, the "implements" comments are not
consistent, e.g.
// IterDirents implements kernfs.inodeDynamicLookup.
// Generate implements vfs.DynamicBytesSource.Generate.
This patch improves this by making the comments like this
consistently include the package name (when the interface
and struct are not in the same package) and method name.
Signed-off-by: Tiwei Bie <[email protected]>
This uses the refs_vfs2 template in vfs2 as well as objects common to vfs1 and
vfs2. Note that vfs1-only refcounts are not replaced, since vfs1 will be deleted
soon anyway.
The following structs now use the new tool, with leak check enabled:
devpts:rootInode
fuse:inode
kernfs:Dentry
kernfs:dir
kernfs:readonlyDir
kernfs:StaticDirectory
proc:fdDirInode
proc:fdInfoDirInode
proc:subtasksInode
proc:taskInode
proc:tasksInode
vfs:FileDescription
vfs:MountNamespace
vfs:Filesystem
sys:dir
kernel:FSContext
kernel:ProcessGroup
kernel:Session
shm:Shm
mm:aioMappable
mm:SpecialMappable
transport:queue
And the following use the template, but because they currently are not leak
checked, a TODO is left instead of enabling leak check in this patch:
kernel:FDTable
tun:tunEndpoint
Updates #1486.
PiperOrigin-RevId: 328460377
- Remove comment about GenericDirectoryFD not being compatible with
dynamic directories. It is currently being used to implement dynamic
directories.
- Try to handle SEEK_END better than setting the offset to
infinity. SEEK_END is poorly defined for dynamic directories
anyways, so at least try make it work correctly for the static
entries.
Updates #1193.
PiperOrigin-RevId: 327890128
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