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Kernel: Use KBuffers for ProcFS and SynthFS

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Instead of generating ByteBuffers and keeping those lying around, have
these filesystems generate KBuffers instead. These are way less spooky
to leave around for a while.

Since FileDescription will keep a generated file buffer around until
userspace has read the whole thing, this prevents trivially exhausting
the kmalloc heap by opening many files in /proc for example.

The code responsible for generating each /proc file is not perfectly
efficient and many of them still use ByteBuffers internally but they
at least go away when we return now. :^)
This commit is contained in:
Andreas Kling 2019-08-05 11:35:49 +02:00
parent 6b6b86fbf3
commit 79e22acb22
7 changed files with 58 additions and 43 deletions
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5
Kernel/FileSystem/ProcFS.h
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@ -3,6 +3,7 @@
#include <AK/Types.h>
#include <Kernel/FileSystem/FileSystem.h>
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/KBuffer.h>
#include <Kernel/Lock.h>
class Process;
@ -36,7 +37,7 @@ private:
struct ProcFSDirectoryEntry {
ProcFSDirectoryEntry() {}
ProcFSDirectoryEntry(const char* a_name, unsigned a_proc_file_type, Function<ByteBuffer(InodeIdentifier)>&& a_read_callback = nullptr, Function<ssize_t(InodeIdentifier, const ByteBuffer&)>&& a_write_callback = nullptr, RefPtr<ProcFSInode>&& a_inode = nullptr)
ProcFSDirectoryEntry(const char* a_name, unsigned a_proc_file_type, Function<Optional<KBuffer>(InodeIdentifier)>&& a_read_callback = nullptr, Function<ssize_t(InodeIdentifier, const ByteBuffer&)>&& a_write_callback = nullptr, RefPtr<ProcFSInode>&& a_inode = nullptr)
: name(a_name)
, proc_file_type(a_proc_file_type)
, read_callback(move(a_read_callback))
@ -47,7 +48,7 @@ private:
const char* name { nullptr };
unsigned proc_file_type { 0 };
Function<ByteBuffer(InodeIdentifier)> read_callback;
Function<Optional<KBuffer>(InodeIdentifier)> read_callback;
Function<ssize_t(InodeIdentifier, const ByteBuffer&)> write_callback;
RefPtr<ProcFSInode> inode;
InodeIdentifier identifier(unsigned fsid) const;