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ladybird/Kernel/FileSystem/BlockBasedFileSystem.h

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Kernel: Split BlockBasedFileSystem off FileBackedFileSystem FileBackedFileSystem is one that's backed by (mounted from) a file, in other words one that has a "source" of the mount; that doesn't mean it deals in blocks. The hierarchy now becomes: * FS * ProcFS * DevPtsFS * TmpFS * FileBackedFS * (future) Plan9FS * BlockBasedFS * Ext2FS
2020-07-02 09:48:08 +00:00
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <Kernel/FileSystem/FileBackedFileSystem.h>
namespace Kernel {
class BlockBasedFS : public FileBackedFS {
public:
virtual ~BlockBasedFS() override;
size_t logical_block_size() const { return m_logical_block_size; };
virtual void flush_writes() override;
void flush_writes_impl();
protected:
explicit BlockBasedFS(FileDescription&);
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
int read_block(unsigned index, UserOrKernelBuffer* buffer, size_t count, size_t offset = 0, bool allow_cache = true) const;
int read_blocks(unsigned index, unsigned count, UserOrKernelBuffer& buffer, bool allow_cache = true) const;
Kernel: Split BlockBasedFileSystem off FileBackedFileSystem FileBackedFileSystem is one that's backed by (mounted from) a file, in other words one that has a "source" of the mount; that doesn't mean it deals in blocks. The hierarchy now becomes: * FS * ProcFS * DevPtsFS * TmpFS * FileBackedFS * (future) Plan9FS * BlockBasedFS * Ext2FS
2020-07-02 09:48:08 +00:00
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
bool raw_read(unsigned index, UserOrKernelBuffer& buffer);
bool raw_write(unsigned index, const UserOrKernelBuffer& buffer);
Kernel: Split BlockBasedFileSystem off FileBackedFileSystem FileBackedFileSystem is one that's backed by (mounted from) a file, in other words one that has a "source" of the mount; that doesn't mean it deals in blocks. The hierarchy now becomes: * FS * ProcFS * DevPtsFS * TmpFS * FileBackedFS * (future) Plan9FS * BlockBasedFS * Ext2FS
2020-07-02 09:48:08 +00:00
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
bool raw_read_blocks(unsigned index, size_t count, UserOrKernelBuffer& buffer);
bool raw_write_blocks(unsigned index, size_t count, const UserOrKernelBuffer& buffer);
Kernel: Split BlockBasedFileSystem off FileBackedFileSystem FileBackedFileSystem is one that's backed by (mounted from) a file, in other words one that has a "source" of the mount; that doesn't mean it deals in blocks. The hierarchy now becomes: * FS * ProcFS * DevPtsFS * TmpFS * FileBackedFS * (future) Plan9FS * BlockBasedFS * Ext2FS
2020-07-02 09:48:08 +00:00
Kernel: Make copy_to/from_user safe and remove unnecessary checks Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-09-12 03:11:07 +00:00
int write_block(unsigned index, const UserOrKernelBuffer& buffer, size_t count, size_t offset = 0, bool allow_cache = true);
int write_blocks(unsigned index, unsigned count, const UserOrKernelBuffer&, bool allow_cache = true);
Kernel: Split BlockBasedFileSystem off FileBackedFileSystem FileBackedFileSystem is one that's backed by (mounted from) a file, in other words one that has a "source" of the mount; that doesn't mean it deals in blocks. The hierarchy now becomes: * FS * ProcFS * DevPtsFS * TmpFS * FileBackedFS * (future) Plan9FS * BlockBasedFS * Ext2FS
2020-07-02 09:48:08 +00:00
size_t m_logical_block_size { 512 };
private:
DiskCache& cache() const;
void flush_specific_block_if_needed(unsigned index);
mutable OwnPtr<DiskCache> m_cache;
};
}
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