This lets us create "synthetic" mountpoint directories in ReadOnly mounts
during VFS setup.
Also add context.WithMountNamespace, as some filesystems (like overlay) require
a MountNamespace on ctx to handle vfs.Filesystem Operations.
PiperOrigin-RevId: 327874971
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
- Make FilesystemImpl methods that operate on parent directories require
!rp.Done() (i.e. there is at least one path component to resolve) as
precondition and postcondition (in cases where they do not finish path
resolution due to mount boundary / absolute symlink), and require that they
do not need to follow the last path component (the file being created /
deleted) as a symlink. Check for these in VFS.
- Add FilesystemImpl.GetParentDentryAt(), which is required to obtain the old
parent directory for VFS.RenameAt(). (Passing the Dentry to be renamed
instead has the wrong semantics if the file named by the old path is a mount
point since the Dentry will be on the wrong Mount.)
- Update memfs to implement these methods correctly (?), including RenameAt.
- Change fspath.Parse() to allow empty paths (to simplify implementation of
AT_EMPTY_PATH).
- Change vfs.PathOperation to take a fspath.Path instead of a raw pathname;
non-test callers will need to fspath.Parse() pathnames themselves anyway in
order to detect absolute paths and select PathOperation.Start accordingly.
PiperOrigin-RevId: 286934941
- Remove the Filesystem argument from DentryImpl.*Ref(); in general DentryImpls
that need the Filesystem for reference counting will probably also need it
for other interface methods that don't plumb Filesystem, so it's easier to
just store a pointer to the filesystem in the DentryImpl.
- Add a pointer to the VirtualFilesystem to Filesystem, which is needed by the
gofer client to disown dentries for cache eviction triggered by dentry
reference count changes.
- Rename FilesystemType.NewFilesystem to GetFilesystem; in some cases (e.g.
sysfs, cgroupfs) it's much cleaner for there to be only one Filesystem that
is used by all mounts, and in at least one case (devtmpfs) it's visibly
incorrect not to do so, so NewFilesystem doesn't always actually create and
return a *new* Filesystem.
- Require callers of FileDescription.Init() to increment Mount/Dentry
references. This is because the gofer client may, in the OpenAt() path, take
a reference on a dentry with 0 references, which is safe due to
synchronization that is outside the scope of this CL, and it would be safer
to still have its implementation of DentryImpl.IncRef() check for an
increment for 0 references in other cases.
- Add FileDescription.TryIncRef. This is used by the gofer client to take
references on "special file descriptions" (FDs for files such as pipes,
sockets, and devices), which use per-FD handles (fids) instead of
dentry-shared handles, for sync() and syncfs().
PiperOrigin-RevId: 282473364
Dean Deng
Fabricio Voznika
Nicolas Lacasse
Nayana Bidari
gVisor bot
Adin Scannell
Jamie Liu
Ayush Ranjan