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Kernel: Deemphasize inode identifiers

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These APIs were clearly modeled after Ext2FS internals, and make perfect sense
in Ext2FS context. The new APIs are more generic, and map better to the
semantics exported to the userspace, where inode identifiers only appear in
stat() and readdir() output, but never in any input.

This will also hopefully reduce the potential for races (see commit c44b4d61f3).

Lastly, this makes it way more viable to implement a filesystem that only
synthesizes its inodes lazily when queried, and destroys them when they are no
longer in use. With inode identifiers being used to reference inodes, the only
choice for such a filesystem is to persist any inode it has given out the
identifier for, because it might be queried at any later time. With direct
references to inodes, the filesystem will know when the last reference is
dropped and the inode can be safely destroyed.
This commit is contained in:
Sergey Bugaev 2020-06-24 23:35:56 +03:00 • committed by Andreas Kling
parent c689be0dbc
commit df66c28479
12 changed files with 133 additions and 160 deletions
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38
Kernel/FileSystem/ProcFS.cpp
View file

@ -1075,19 +1075,9 @@ const char* ProcFS::class_name() const
return "ProcFS";
}
KResultOr<NonnullRefPtr<Inode>> ProcFS::create_inode(InodeIdentifier, const String&, mode_t, off_t, dev_t, uid_t, gid_t)
NonnullRefPtr<Inode> ProcFS::root_inode() const
{
return KResult(-EROFS);
}
KResult ProcFS::create_directory(InodeIdentifier, const String&, mode_t, uid_t, gid_t)
{
return KResult(-EROFS);
}
InodeIdentifier ProcFS::root_inode() const
{
return { fsid(), FI_Root };
return *m_root_inode;
}
RefPtr<Inode> ProcFS::get_inode(InodeIdentifier inode_id) const
@ -1095,7 +1085,7 @@ RefPtr<Inode> ProcFS::get_inode(InodeIdentifier inode_id) const
#ifdef PROCFS_DEBUG
dbg() << "ProcFS::get_inode(" << inode_id.index() << ")";
#endif
if (inode_id == root_inode())
if (inode_id == root_inode()->identifier())
return m_root_inode;
LOCKER(m_inodes_lock);
@ -1340,7 +1330,7 @@ RefPtr<Inode> ProcFSInode::lookup(StringView name)
{
ASSERT(is_directory());
if (name == ".")
return fs().get_inode(identifier());
return this;
if (name == "..")
return fs().get_inode(to_parent_id(identifier()));
@ -1555,11 +1545,18 @@ InodeMetadata ProcFSProxyInode::metadata() const
return metadata;
}
KResult ProcFSProxyInode::add_child(InodeIdentifier child_id, const StringView& name, mode_t mode)
KResultOr<NonnullRefPtr<Inode>> ProcFSProxyInode::create_child(const String& name, mode_t mode, dev_t dev, uid_t uid, gid_t gid)
{
if (!m_fd->inode())
return KResult(-EINVAL);
return m_fd->inode()->add_child(child_id, name, mode);
return m_fd->inode()->create_child(name, mode, dev, uid, gid);
}
KResult ProcFSProxyInode::add_child(Inode& child, const StringView& name, mode_t mode)
{
if (!m_fd->inode())
return KResult(-EINVAL);
return m_fd->inode()->add_child(child, name, mode);
}
KResult ProcFSProxyInode::remove_child(const StringView& name)
@ -1583,10 +1580,13 @@ size_t ProcFSProxyInode::directory_entry_count() const
return m_fd->inode()->directory_entry_count();
}
KResult ProcFSInode::add_child(InodeIdentifier child_id, const StringView& name, mode_t)
KResultOr<NonnullRefPtr<Inode>> ProcFSInode::create_child(const String&, mode_t, dev_t, uid_t, gid_t)
{
return KResult(-EPERM);
}
KResult ProcFSInode::add_child(Inode&, const StringView&, mode_t)
{
(void)child_id;
(void)name;
return KResult(-EPERM);
}