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Kernel: Protect Inode flock list with spinlock instead of mutex

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This commit is contained in:
Andreas Kling 2022-02-03 17:28:45 +01:00
parent a81aebfd6e
commit e7dc9f71b8
2 changed files with 45 additions and 48 deletions
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91
Kernel/FileSystem/Inode.cpp
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@ -289,27 +289,26 @@ ErrorOr<void> Inode::can_apply_flock(OpenFileDescription const& description, flo
{
VERIFY(new_lock.l_whence == SEEK_SET);
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
if (new_lock.l_type == F_UNLCK) {
for (auto const& lock : m_flocks) {
if (&description == lock.owner && lock.start == new_lock.l_start && lock.len == new_lock.l_len)
return {};
return m_flocks.with([&](auto& flocks) -> ErrorOr<void> {
if (new_lock.l_type == F_UNLCK) {
for (auto const& lock : flocks) {
if (&description == lock.owner && lock.start == new_lock.l_start && lock.len == new_lock.l_len)
return {};
}
return EINVAL;
}
return EINVAL;
}
for (auto const& lock : flocks) {
if (!range_overlap(lock.start, lock.len, new_lock.l_start, new_lock.l_len))
continue;
for (auto const& lock : m_flocks) {
if (!range_overlap(lock.start, lock.len, new_lock.l_start, new_lock.l_len))
continue;
if (new_lock.l_type == F_RDLCK && lock.type == F_WRLCK)
return EAGAIN;
if (new_lock.l_type == F_RDLCK && lock.type == F_WRLCK)
return EAGAIN;
if (new_lock.l_type == F_WRLCK)
return EAGAIN;
}
return {};
if (new_lock.l_type == F_WRLCK)
return EAGAIN;
}
return {};
});
}
ErrorOr<void> Inode::apply_flock(Process const& process, OpenFileDescription const& description, Userspace<flock const*> input_lock)
@ -317,22 +316,22 @@ ErrorOr<void> Inode::apply_flock(Process const& process, OpenFileDescription con
auto new_lock = TRY(copy_typed_from_user(input_lock));
TRY(normalize_flock(description, new_lock));
MutexLocker locker(m_inode_lock);
return m_flocks.with([&](auto& flocks) -> ErrorOr<void> {
TRY(can_apply_flock(description, new_lock));
TRY(can_apply_flock(description, new_lock));
if (new_lock.l_type == F_UNLCK) {
for (size_t i = 0; i < m_flocks.size(); ++i) {
if (&description == m_flocks[i].owner && m_flocks[i].start == new_lock.l_start && m_flocks[i].len == new_lock.l_len) {
m_flocks.remove(i);
return {};
if (new_lock.l_type == F_UNLCK) {
for (size_t i = 0; i < flocks.size(); ++i) {
if (&description == flocks[i].owner && flocks[i].start == new_lock.l_start && flocks[i].len == new_lock.l_len) {
flocks.remove(i);
return {};
}
}
return EINVAL;
}
return EINVAL;
}
TRY(m_flocks.try_append(Flock { new_lock.l_start, new_lock.l_len, &description, process.pid().value(), new_lock.l_type }));
return {};
TRY(flocks.try_append(Flock { new_lock.l_start, new_lock.l_len, &description, process.pid().value(), new_lock.l_type }));
return {};
});
}
ErrorOr<void> Inode::get_flock(OpenFileDescription const& description, Userspace<flock*> reference_lock) const
@ -341,31 +340,29 @@ ErrorOr<void> Inode::get_flock(OpenFileDescription const& description, Userspace
TRY(copy_from_user(&lookup, reference_lock));
TRY(normalize_flock(description, lookup));
MutexLocker locker(m_inode_lock, Mutex::Mode::Shared);
return m_flocks.with([&](auto& flocks) {
for (auto const& lock : flocks) {
if (!range_overlap(lock.start, lock.len, lookup.l_start, lookup.l_len))
continue;
for (auto const& lock : m_flocks) {
if (!range_overlap(lock.start, lock.len, lookup.l_start, lookup.l_len))
continue;
if ((lookup.l_type == F_RDLCK && lock.type == F_WRLCK) || lookup.l_type == F_WRLCK) {
lookup = { lock.type, SEEK_SET, lock.start, lock.len, lock.pid };
return copy_to_user(reference_lock, &lookup);
if ((lookup.l_type == F_RDLCK && lock.type == F_WRLCK) || lookup.l_type == F_WRLCK) {
lookup = { lock.type, SEEK_SET, lock.start, lock.len, lock.pid };
return copy_to_user(reference_lock, &lookup);
}
}
}
lookup.l_type = F_UNLCK;
return copy_to_user(reference_lock, &lookup);
lookup.l_type = F_UNLCK;
return copy_to_user(reference_lock, &lookup);
});
}
void Inode::remove_flocks_for_description(OpenFileDescription const& description)
{
MutexLocker locker(m_inode_lock);
for (size_t i = 0; i < m_flocks.size(); ++i) {
if (&description == m_flocks[i].owner)
m_flocks.remove(i--);
}
m_flocks.with([&](auto& flocks) {
flocks.remove_all_matching([&](auto& entry) { return entry.owner == &description; });
});
}
bool Inode::has_watchers() const
{
return !m_watchers.with([&](auto& watchers) { return watchers.is_empty(); });