For some context, write_bytes_locked used to simply bail out before
writing any data if there weren't enough blocks to cover the entire size
of an inode before 1bf7f99a.
We're not actually restoring that behavior here, since computing the
amount of blocks to be allocated would get exceedingly complex,
considering that there could always be holes in between already
allocated blocks.
Instead, this simply makes allocate_blocks() bail out properly if there
aren't any free blocks left.
Fixes#24980
This commit reorganizes the BootInfo struct definition so it can be
shared for all architectures.
The existing free extern "C" boot info variables have been removed and
replaced with a global BootInfo struct, 'g_boot_info'.
On x86-64, the BootInfo is directly copied from the Prekernel-provided
struct.
On AArch64 and RISC-V, BootInfo is populated during pre_init.
This change has many improvements:
- We don't use `LockRefPtr` to hold instances of many base devices as
with the DeviceManagement class. Instead, we have a saner pattern of
holding them in a `NonnullRefPtr<T> const`, in a small-text footprint
class definition in the `Device.cpp` file.
- The awkwardness of using `::the()` each time we need to get references
to mostly-static objects (like the Event queue) in runtime is now gone
in the migration to using the `Device` class.
- Acquiring a device feel more obvious because we use now the Device
class for this method. The method name is improved as well.
Commit ad73adef5d needlessly introduced an IPv4 directory.
If we were to keep it, sharing common headers between IPv4 and IPv6
would be much messier, and may potentially increase code duplication.
This change renames the IPv4 directory to IP to aid with later IPv6
porting efforts.
In Ext2FSInode::compute_block_list_impl(), each call to
process_block_array() creates a new ByteBuffer, which leads to a
kmalloc() call. The ByteBuffer is then discarded when
process_block_array() exits, leading to a kfree() call.
This leads to repeated kmalloc() and kfree() calls as ByteBuffers are
created and destroyed each time process_block_array() is called.
This commit makes it so that only 1 ByteBuffer is created for each level
of inode indirect block (so only 3 ByteBuffers are created at most).
These ByteBuffers are re-used on each call to process_block_array().
This reduces the number of kmalloc() and kfree() calls during
compute_block_list_impl(), especially for larger files.
Instead of using a raw `KBuffer` and letting each implementation to
populating the specific flags on its own, we change things so we only
let each FileSystem implementation to validate the flag and its value
but then store it in a HashMap which its key is the flag name and
the value is a special new class called `FileSystemSpecificOption`
which wraps around `AK::Variant<...>`.
This approach has multiple advantages over the previous:
- It allows runtime inspection of what the user has set on a `MountFile`
description for a specific filesystem.
- It ensures accidental overriding of filesystem specific option that
was already set is not possible
- It removes ugly casting of a `KBuffer` contents to a strongly-typed
values. Instead, a strongly-typed `AK::Variant` is used which ensures
we always get a value without doing any casting.
Please note that we have removed support for ASCII string-oriented flags
as there were no actual use cases, and supporting such type would make
`FileSystemSpecificOption` more complicated unnecessarily for now.
The superblock of an ext2 filesystem is always found on the storage
device at offset 1024. This 1024 number was hardcoded in the Ext2FS
code.
This commit:
* adds a constexpr to replace the hardcoded 1024 values
* removes a comment about one of the the hardcoded 1024 values which is
now umnecessary
There's no point in constructing an object just for the sake of keeping
a state that can be touched by anything in the kernel code.
Let's reduce everything to be in a C++ namespace called with the
previous name "VirtualFileSystem" and keep a smaller textual-footprint
struct called "VirtualFileSystemDetails".
This change also cleans up old "friend class" statements that were no
longer needed, and move methods from the VirtualFileSystem code to more
appropriate places as well.
Please note that the method of locking all filesystems during shutdown
is removed, as in that place there's no meaning to actually locking all
filesystems because of running in kernel mode entirely.
This new syscall will be used by the upcoming runc (run-container)
utility.
In addition to that, this syscall allows userspace to neatly copy RAMFS
instances to other places, which was not possible in the past.
The whole concept of Jails was far more complicated than I actually want
it to be, so let's reduce the complexity of how it works from now on.
Please note that we always leaked the attach count of a Jail object in
the fork syscall if it failed midway.
Instead, we should have attach to the jail just before registering the
new Process, so we don't need to worry about unsuccessful Process
creation.
The reduction of complexity in regard to jails means that instead of
relying on jails to provide PID isolation, we could simplify the whole
idea of them to be a simple SetOnce, and let the ProcessList (now called
ScopedProcessList) to be responsible for this type of isolation.
Therefore, we apply the following changes to do so:
- We make the Jail concept no longer a class of its own. Instead, we
simplify the idea of being jailed to a simple ProtectedValues boolean
flag. This means that we no longer check of matching jail pointers
anywhere in the Kernel code.
To set a process as jailed, a new prctl option was added to set a
Kernel SetOnce boolean flag (so it cannot change ever again).
- We provide Process & Thread methods to iterate over process lists.
A process can either iterate on the global process list, or if it's
attached to a scoped process list, then only over that list.
This essentially replaces the need of checking the Jail pointer of a
process when iterating over process lists.
Expose some initial interfaces in the mount-related syscalls to select
the desired VFSRootContext, by specifying the VFSRootContext index
number.
For now there's still no way to create a different VFSRootContext, so
the only valid IDs are -1 (for currently attached VFSRootContext) or 1
for the first userspace VFSRootContext.
The VFSRootContext class, as its name suggests, holds a context for a
root directory with its mount table and the root custody/inode in the
same class.
The idea is derived from the Linux mount namespace mechanism.
It mimicks the concept of the ProcessList object, but it is adjusted for
a root directory tree context.
In contrast to the ProcessList concept, processes that share the default
VFSRootContext can't see other VFSRootContext related properties such as
as the mount table and root custody/inode.
To accommodate to this change progressively, we internally create 2 main
VFS root contexts for now - one for kernel processes (as they don't need
to care about VFS root contexts for the most part), and another for all
userspace programs.
This separation allows us to continue pretending for userspace that
everything is "normal" as it is used to be, until we introduce proper
interfaces in the mount-related syscalls as well as in the SysFS.
We make VFSRootContext objects being listed, as another preparation
before we could expose interfaces to userspace.
As a result, the PowerStateSwitchTask now iterates on all contexts
and tear them down one by one.
After the previous commit, we are able to create a comprehensive list of
all devices' major number allocations.
To help userspace to distinguish between character and block devices, we
expose 2 sysfs nodes so userspace can decide which list it needs to open
in order to iterate on it.
Instead of putting everything in one hash map, let's distinguish between
the devices based on their type.
This change makes the devices semantically separated, and is considered
a preparation before we could expose a comprehensive list of allocations
per major numbers and their purpose.
With this change, we no longer preallocate blocks when an inode's size
is updated, and instead only allocate the minimum amount of blocks when
the inode is actually written to.
This is a large commit, since this is essentially a complete rewrite of
the key low-level functions that handle reading/writing blocks. This is,
however, a necessary prerequisite of being able to write holes.
The previous version of `flush_block_list()` (along with its numerous
helper functions) was entirely reliant on all blocks being sequential.
In contrast to the previous implementation, the new version
of `flush_block_list()` simply writes out the difference between the old
block list and the new block list by calculating the correct indirect
block(s) to update based on the relevant block's logical index.
`compute_block_list()` has also been rewritten, since the estimated
amount of meta blocks was incorrectly calculated for files with holes as
a result of the estimated amount of blocks being a function of the file
size. Since it isn't possible to accurately compute the shape of the
block list without traversing it, we no longer try to perform such a
computation, and instead simply search through all of the allocated
indirect blocks.
`compute_block_list_with_meta_blocks()` has also been removed in favor
of the new `compute_meta_blocks()`, since meta blocks are fundamentally
distinct from data blocks due to there being no mapping between any
logical block index and the physical block index.
Since we now only store blocks that are actually allocated, it is
entirely valid for the block list to be empty, so this commit lifts the
restrictions on accessing inodes with an empty block list.
It can be possible for a request to be blocked on another request, so
this patch allows us to send more requests even when a request is
already pending.
To be able to do this, we add a new class called CustodyBase, which can
be resolved on-demand internally in the VirtualFileSystem resolving path
code.
When being resolved, CustodyBase will return a known custody if it was
constructed with such, if that's not the case it will provide the root
custody if the original path is absolute.
Lastly, if that's not the case as well, it will resolve the given dirfd
to provide a Custody object.
This is a large commit because it implements a lot of stuff to make
add_child simpler to get working. This allows us to create new files
on a FAT partition.
This is the first part of write support, it allows for full file
modification, but no creating or removing files yet.
Co-Authored-By: implicitfield <114500360+implicitfield@users.noreply.github.com>
Caching the cluster list allows us to fill the two fields in the
InodeMetadata. While at it, don't cache the metadata as when we
have write support having to keep both InodeMetadata and FATEntry
correct is going to get very annoying.
