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OvmfPkg/VirtioFsDxe: implement EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume()

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With the help of the VirtioFsFuseOpenDir() and
VirtioFsFuseReleaseFileOrDir() functions introduced previously, we can now
open and close the root directory. So let's implement
EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume().

OpenVolume() creates a new EFI_FILE_PROTOCOL object -- a reference to the
root directory of the filesystem. Thus, we have to start tracking
references to EFI_SIMPLE_FILE_SYSTEM_PROTOCOL, lest we unbind the
virtio-fs device while files are open.

There are two methods that release an EFI_FILE_PROTOCOL object: the
Close() and the Delete() member functions. In particular, they are not
allowed to fail with regard to resource management -- they must release
resources unconditionally. Thus, for rolling back the resource accounting
that we do in EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume(), we have to
implement the first versions of EFI_FILE_PROTOCOL.Close() and
EFI_FILE_PROTOCOL.Delete() in this patch as well.

With this patch applied, the UEFI shell can enter the root directory of
the Virtio Filesystem (such as with the "FS3:" shell command), and the
"DIR" shell command exercises FUSE_OPENDIR and FUSE_RELEASEDIR, according
to the virtiofsd log. The "DIR" command reports the root directory as if
it were empty; probably because at this time, we only allow the shell to
open and to close the root directory, but not to read it.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20201216211125.19496-12-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
This commit is contained in:
Laszlo Ersek
2020-12-16 22:10:48 +01:00
committed by mergify[bot]
parent 72d4f133e9
commit 334c13e106
15 changed files with 432 additions and 1 deletions
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5
OvmfPkg/VirtioFsDxe/DriverBinding.c
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@@ -95,6 +95,7 @@ VirtioFsBindingStart (
goto UninitVirtioFs;
}
InitializeListHead (&VirtioFs->OpenFiles);
VirtioFs->SimpleFs.Revision = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_REVISION;
VirtioFs->SimpleFs.OpenVolume = VirtioFsOpenVolume;
@@ -149,6 +150,10 @@ VirtioFsBindingStop (
VirtioFs = VIRTIO_FS_FROM_SIMPLE_FS (SimpleFs);
if (!IsListEmpty (&VirtioFs->OpenFiles)) {
return EFI_ACCESS_DENIED;
}
Status = gBS->UninstallProtocolInterface (ControllerHandle,
&gEfiSimpleFileSystemProtocolGuid, SimpleFs);
if (EFI_ERROR (Status)) {