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Kernel/FileSystem: Fix kernel panic during FS init or mount failure

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Resolves issue where a panic would occur if the file system failed to
initialize or mount, due to how the FileSystem was already added to
VFS's list. The newly-created FileSystem destructor would fail as a
result of the object still remaining in the IntrusiveList.
This commit is contained in:
Taj Morton 2023-01-07 16:19:43 -08:00 • committed by Andrew Kaster
parent 6fcc1c7426
commit 20991a6a3c
1 changed files with 23 additions and 5 deletions
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28
Kernel/FileSystem/VirtualFileSystem.cpp
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@ -76,6 +76,23 @@ ErrorOr<void> VirtualFileSystem::mount(FileSystem& fs, Custody& mount_point, int
// Note: Actually add a mount for the filesystem and increment the filesystem mounted count // Note: Actually add a mount for the filesystem and increment the filesystem mounted count
new_mount->guest_fs().mounted_count({}).with([&](auto& mounted_count) { new_mount->guest_fs().mounted_count({}).with([&](auto& mounted_count) {
mounted_count++; mounted_count++;
// When this is the first time this FileSystem is mounted,
// begin managing the FileSystem by adding it to the list of
// managed file systems. This is symmetric with
// VirtualFileSystem::unmount()'s `remove()` calls (which remove
// the FileSystem once it is no longer mounted).
if (mounted_count == 1) {
m_file_systems_list.with([&](auto& fs_list) {
fs_list.append(fs);
});
if (fs.is_file_backed()) {
auto& file_backed_fs = static_cast<FileBackedFileSystem&>(fs);
m_file_backed_file_systems_list.with([&](auto& fs_list) {
fs_list.append(file_backed_fs);
});
}
}
}); });
// NOTE: Leak the mount pointer so it can be added to the mount list, but it won't be // NOTE: Leak the mount pointer so it can be added to the mount list, but it won't be
@ -329,11 +346,12 @@ ErrorOr<NonnullLockRefPtr<FileBackedFileSystem>> VirtualFileSystem::find_already
} }
} }
auto fs = TRY(callback(description)); auto fs = TRY(callback(description));
VERIFY(fs->is_file_backed());
list.append(static_cast<FileBackedFileSystem&>(*fs)); // The created FileSystem is only added to the file_systems_lists
m_file_systems_list.with([&](auto& fs_list) { // when the FS has been successfully initialized and mounted
fs_list.append(*fs); // (in VirtualFileSystem::mount()). This prevents file systems which
}); // fail to initialize or mount from existing in the list when the
// FileSystem is destroyed after failure.
return static_ptr_cast<FileBackedFileSystem>(fs); return static_ptr_cast<FileBackedFileSystem>(fs);
})); }));
} }