mirror of
https://github.com/SerenityOS/serenity
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fea3cb5ff9
This commit reached that goal of "safely discarding" a filesystem by doing the following: 1. Stop using the s_file_system_map HashMap as it was an unsafe measure to access pointers of FileSystems. Instead, make sure to register all FileSystems at the VFS layer, with an IntrusiveList, to avoid problems related to OOM conditions. 2. Make sure to cleanly remove the DiskCache object from a BlockBased filesystem, so the destructor of such object will not need to do that in the destruction point. 3. For ext2 filesystems, don't cache the root inode at m_inode_cache HashMap. The reason for this is that when unmounting an ext2 filesystem, we lookup at the cache to see if there's a reference to a cached inode and if that's the case, we fail with EBUSY. If we keep the m_root_inode also being referenced at the m_inode_cache map, we have 2 references to that object, which will lead to fail with EBUSY. Also, it's much simpler to always ask for a root inode and get it immediately from m_root_inode, instead of looking up the cache for that inode.
116 lines
5.3 KiB
C++
116 lines
5.3 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Badge.h>
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#include <AK/Error.h>
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#include <AK/Function.h>
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#include <AK/HashMap.h>
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#include <AK/NonnullOwnPtrVector.h>
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#include <AK/OwnPtr.h>
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#include <AK/RefPtr.h>
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#include <Kernel/FileSystem/FileBackedFileSystem.h>
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#include <Kernel/FileSystem/FileSystem.h>
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#include <Kernel/FileSystem/InodeIdentifier.h>
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#include <Kernel/FileSystem/InodeMetadata.h>
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#include <Kernel/FileSystem/Mount.h>
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#include <Kernel/FileSystem/UnveilNode.h>
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#include <Kernel/Forward.h>
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#include <Kernel/Library/LockRefPtr.h>
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#include <Kernel/Locking/SpinlockProtected.h>
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namespace Kernel {
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// Kernel internal options.
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#define O_NOFOLLOW_NOERROR (1 << 29)
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#define O_UNLINK_INTERNAL (1 << 30)
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struct UidAndGid {
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UserID uid;
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GroupID gid;
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};
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class VirtualFileSystem {
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public:
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// Required to be at least 8 by POSIX
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// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html
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static constexpr int symlink_recursion_limit = 8;
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static void initialize();
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static VirtualFileSystem& the();
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VirtualFileSystem();
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~VirtualFileSystem();
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ErrorOr<void> mount_root(FileSystem&);
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ErrorOr<void> mount(FileSystem&, Custody& mount_point, int flags);
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ErrorOr<void> bind_mount(Custody& source, Custody& mount_point, int flags);
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ErrorOr<void> remount(Custody& mount_point, int new_flags);
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ErrorOr<void> unmount(Custody& mount_point);
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ErrorOr<NonnullLockRefPtr<OpenFileDescription>> open(Credentials const&, StringView path, int options, mode_t mode, Custody& base, Optional<UidAndGid> = {});
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ErrorOr<NonnullLockRefPtr<OpenFileDescription>> create(Credentials const&, StringView path, int options, mode_t mode, Custody& parent_custody, Optional<UidAndGid> = {});
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ErrorOr<void> mkdir(Credentials const&, StringView path, mode_t mode, Custody& base);
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ErrorOr<void> link(Credentials const&, StringView old_path, StringView new_path, Custody& base);
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ErrorOr<void> unlink(Credentials const&, StringView path, Custody& base);
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ErrorOr<void> symlink(Credentials const&, StringView target, StringView linkpath, Custody& base);
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ErrorOr<void> rmdir(Credentials const&, StringView path, Custody& base);
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ErrorOr<void> chmod(Credentials const&, StringView path, mode_t, Custody& base, int options = 0);
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ErrorOr<void> chmod(Credentials const&, Custody&, mode_t);
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ErrorOr<void> chown(Credentials const&, StringView path, UserID, GroupID, Custody& base, int options);
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ErrorOr<void> chown(Credentials const&, Custody&, UserID, GroupID);
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ErrorOr<void> access(Credentials const&, StringView path, int mode, Custody& base);
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ErrorOr<InodeMetadata> lookup_metadata(Credentials const&, StringView path, Custody& base, int options = 0);
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ErrorOr<void> utime(Credentials const&, StringView path, Custody& base, time_t atime, time_t mtime);
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ErrorOr<void> utimensat(Credentials const&, StringView path, Custody& base, timespec const& atime, timespec const& mtime, int options = 0);
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ErrorOr<void> rename(Credentials const&, StringView oldpath, StringView newpath, Custody& base);
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ErrorOr<void> mknod(Credentials const&, StringView path, mode_t, dev_t, Custody& base);
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ErrorOr<NonnullRefPtr<Custody>> open_directory(Credentials const&, StringView path, Custody& base);
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ErrorOr<void> for_each_mount(Function<ErrorOr<void>(Mount const&)>) const;
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ErrorOr<NonnullLockRefPtr<FileBackedFileSystem>> find_already_existing_or_create_file_backed_file_system(OpenFileDescription& description, Function<ErrorOr<NonnullLockRefPtr<FileSystem>>(OpenFileDescription&)> callback);
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InodeIdentifier root_inode_id() const;
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void sync_filesystems();
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void lock_all_filesystems();
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static void sync();
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NonnullRefPtr<Custody> root_custody();
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ErrorOr<NonnullRefPtr<Custody>> resolve_path(Credentials const&, StringView path, NonnullRefPtr<Custody> base, RefPtr<Custody>* out_parent = nullptr, int options = 0, int symlink_recursion_level = 0);
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ErrorOr<NonnullRefPtr<Custody>> resolve_path_without_veil(Credentials const&, StringView path, NonnullRefPtr<Custody> base, RefPtr<Custody>* out_parent = nullptr, int options = 0, int symlink_recursion_level = 0);
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private:
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friend class OpenFileDescription;
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UnveilNode const& find_matching_unveiled_path(StringView path);
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ErrorOr<void> validate_path_against_process_veil(Custody const& path, int options);
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ErrorOr<void> validate_path_against_process_veil(StringView path, int options);
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bool is_vfs_root(InodeIdentifier) const;
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ErrorOr<void> traverse_directory_inode(Inode&, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>);
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bool mount_point_exists_at_inode(InodeIdentifier inode);
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// FIXME: These functions are totally unsafe as someone could unmount the returned Mount underneath us.
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Mount* find_mount_for_host(InodeIdentifier);
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Mount* find_mount_for_guest(InodeIdentifier);
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LockRefPtr<Inode> m_root_inode;
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SpinlockProtected<RefPtr<Custody>> m_root_custody;
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SpinlockProtected<Vector<NonnullOwnPtr<Mount>, 16>> m_mounts { LockRank::None };
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SpinlockProtected<IntrusiveList<&FileBackedFileSystem::m_file_backed_file_system_node>> m_file_backed_file_systems_list { LockRank::None };
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SpinlockProtected<IntrusiveList<&FileSystem::m_file_system_node>> m_file_systems_list { LockRank::FileSystem };
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};
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}
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