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
This is needed so that connectioned endpoint in the transport package can use
this endpoint to implement host FD based binded endpoints.
I had to simplify some other dependencies to make this possible.
- Removed uniqueid's dependency on transport package completely.
- Removed SCMConnectedEndpoint and HostConnectedEndpoint's dependency on
control package so they could be moved to transport. control already depends
on transport.
- scmRights struct from fsimpl/host/control.go had to be moved into transport
so that HostConnectedEndpoint could be implemented. But scmRights.Fill()
could not be moved because it inherently depends on making
vfs.FileDescriptions which depends on vfs which in turn depends on transport.
So now that scmRights -> vfs.FD conversion happens in the syscall package.
PiperOrigin-RevId: 413839350
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
Add Equals method to compare syserror and unix.Errno errors to linuxerr errors.
This will facilitate removal of syserror definitions in a followup, and
finding needed conversions from unix.Errno to linuxerr.
PiperOrigin-RevId: 380909667
Split usermem package to help remove syserror dependency in go_marshal.
New hostarch package contains code not dependent on syserror.
PiperOrigin-RevId: 365651233
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
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
Now it calls pkt.Data.ToView() when writing the packet. This may require
copying when the packet is large, which puts the worse case in an even worse
situation.
This sent out in a separate preparation change as it requires syscall filter
changes. This change will be followed by the change for the adoption of the new
PacketHeader API.
PiperOrigin-RevId: 321447003
- Change FileDescriptionImpl Lock/UnlockPOSIX signature to
take {start,length,whence}, so the correct offset can be
calculated in the implementations.
- Create PosixLocker interface to make it possible to share
the same locking code from different implementations.
Closes#1480
PiperOrigin-RevId: 316910286
LockFD is the generic implementation that can be embedded in
FileDescriptionImpl implementations. Unique lock ID is
maintained in vfs.FileDescription and is created on demand.
Updates #1480
PiperOrigin-RevId: 315604825
In VFS1, both fs/host and fs/gofer used the same utils for host file mappings.
Refactor parts of fsimpl/gofer to create similar utils to share with
fsimpl/host (memory accounting code moved to fsutil, page rounding arithmetic
moved to usermem).
Updates #1476.
PiperOrigin-RevId: 312345090
The FileDescription implementation for hostfs sockets uses the standard Unix
socket implementation (unix.SocketVFS2), but is also tied to a hostfs dentry.
Updates #1672, #1476
PiperOrigin-RevId: 308716426
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