Move fd managment into open_file_map (965369af) · Commits · David Auer / gekkofs

ifs/include/preload/open_file_map.hpp

+15 −0

Original line number	Diff line number	Diff line
		@@ -5,6 +5,7 @@
		#include <map>
		#include <mutex>
		#include <memory>
		#include <atomic>

		/* Forward declaration */
		class OpenDir;
		@@ -65,6 +66,18 @@ private:

		int safe_generate_fd_idx_();

		/*
		* TODO: Setting our file descriptor index to a specific value is dangerous because we might clash with the kernel.
		* E.g., if we would passthrough and not intercept and the kernel assigns a file descriptor but we will later use
		* the same fd value, we will intercept calls that were supposed to be going to the kernel. This works the other way around too.
		* To mitigate this issue, we set the initial fd number to a high value. We "hope" that we do not clash but this is no permanent solution.
		* Note: This solution will probably work well already for many cases because kernel fd values are reused, unlike to ours.
		* The only case where we will clash with the kernel is, if one process has more than 100000 files open at the same time.
		*/
		int fd_idx;
		std::mutex fd_idx_mutex;
		std::atomic<bool> fd_validation_needed;

		public:
		OpenFileMap();

		@@ -82,6 +95,8 @@ public:

		int dup2(int oldfd, int newfd);

		int generate_fd_idx();
		int get_fd_idx();
		};

ifs/include/preload/preload_util.hpp

+0 −6

Original line number	Diff line number	Diff line
		@@ -76,15 +76,9 @@ extern hg_id_t rpc_trunc_data_id;
		extern hg_id_t rpc_get_dirents_id;
		// rpc addresses. Populated when environment is initialized. After that it is read-only accessed
		extern std::map<uint64_t, hg_addr_t> rpc_addresses;
		// file descriptor index validation flag
		extern std::atomic<bool> fd_validation_needed;

		// function definitions

		int generate_fd_idx();

		int get_fd_idx();

		bool is_fs_path(const char* path);

		int db_val_to_stat(const std::string& path, std::string db_val, struct stat& attr);

ifs/src/preload/open_file_map.cpp

+34 −2

Original line number	Diff line number	Diff line
		#include <fcntl.h>

		#include <global/global_defs.hpp>
		#include <preload/open_file_map.hpp>
		#include <preload/open_dir.hpp>
		#include <preload/preload.hpp>
		#include <preload/preload_util.hpp>

		using namespace std;

		@@ -24,7 +25,10 @@ OpenFile::OpenFile(const string& path, const int flags) : path_(path) {
		pos_ = 0; // If O_APPEND flag is used, it will be used before each write.
		}

		OpenFileMap::OpenFileMap() {}
		OpenFileMap::OpenFileMap():
		fd_idx(10000),
		fd_validation_needed(false)
		{}

		OpenFile::~OpenFile() {

		@@ -157,3 +161,31 @@ int OpenFileMap::dup2(const int oldfd, const int newfd) {
		files_.insert(make_pair(newfd, open_file));
		return newfd;
		}

		/**
		* Generate new file descriptor index to be used as an fd within one process in ADA-FS
		* @return fd_idx
		*/
		int OpenFileMap::generate_fd_idx() {
		// We need a mutex here for thread safety
		std::lock_guard<std::mutex> inode_lock(fd_idx_mutex);
		if (fd_idx == std::numeric_limits<int>::max()) {
		CTX->log()->info("{}() File descriptor index exceeded ints max value. Setting it back to 100000", __func__);
		/*
		* Setting fd_idx back to 3 could have the effect that fd are given twice for different path.
		* This must not happen. Instead a flag is set which tells can tell the OpenFileMap that it should check
		* if this fd is really safe to use.
		*/
		fd_idx = 100000;
		fd_validation_needed = true;
		}
		return fd_idx++;
		}

		int OpenFileMap::get_fd_idx() {
		std::lock_guard<std::mutex> inode_lock(fd_idx_mutex);
		return fd_idx;
		}

ifs/src/preload/preload_util.cpp

+0 −37

Original line number	Diff line number	Diff line
		@@ -15,43 +15,6 @@ using namespace std;

		static const std::string dentry_val_delim = ","s;

		/*
		* TODO: Setting our file descriptor index to a specific value is dangerous because we might clash with the kernel.
		* E.g., if we would passthrough and not intercept and the kernel assigns a file descriptor but we will later use
		* the same fd value, we will intercept calls that were supposed to be going to the kernel. This works the other way around too.
		* To mitigate this issue, we set the initial fd number to a high value. We "hope" that we do not clash but this is no permanent solution.
		* Note: This solution will probably work well already for many cases because kernel fd values are reused, unlike to ours.
		* The only case where we will clash with the kernel is, if one process has more than 100000 files open at the same time.
		*/
		static int fd_idx = 100000;
		static mutex fd_idx_mutex;
		std::atomic<bool> fd_validation_needed(false);

		/**
		* Generate new file descriptor index to be used as an fd within one process in ADA-FS
		* @return fd_idx
		*/
		int generate_fd_idx() {
		// We need a mutex here for thread safety
		std::lock_guard<std::mutex> inode_lock(fd_idx_mutex);
		if (fd_idx == std::numeric_limits<int>::max()) {
		CTX->log()->info("{}() File descriptor index exceeded ints max value. Setting it back to 100000", __func__);
		/*
		* Setting fd_idx back to 3 could have the effect that fd are given twice for different path.
		* This must not happen. Instead a flag is set which tells can tell the OpenFileMap that it should check
		* if this fd is really safe to use.
		*/
		fd_idx = 100000;
		fd_validation_needed = true;
		}
		return fd_idx++;
		}

		int get_fd_idx() {
		std::lock_guard<std::mutex> inode_lock(fd_idx_mutex);
		return fd_idx;
		}

		bool is_fs_path(const char* path) {
		return strstr(path, CTX->mountdir().c_str()) == path;
		}