From 779f8e1fd431f3b3438109fccee8374c19f39b80 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Fri, 11 Jan 2013 20:16:40 +0000
Subject: [PATCH] Introduce a mode enum to block_io<>

---
 persistent-data/block.h       |  9 +++++++--
 persistent-data/block.tcc     | 26 +++++++++++++++++++++-----
 thin-provisioning/metadata.cc |  6 +++++-
 3 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/persistent-data/block.h b/persistent-data/block.h
index 3236d17..d463083 100644
--- a/persistent-data/block.h
+++ b/persistent-data/block.h
@@ -82,8 +82,12 @@ namespace persistent_data {
 	class block_io : private boost::noncopyable {
 	public:
 		typedef boost::shared_ptr<block_io> ptr;
+		enum mode {
+			READ_ONLY,
+			READ_WRITE,
+		};
 
-		block_io(std::string const &path, block_address nr_blocks, bool writeable = false);
+		block_io(std::string const &path, block_address nr_blocks, mode m);
 		~block_io();
 
 		block_address get_nr_blocks() const {
@@ -96,6 +100,7 @@ namespace persistent_data {
 	private:
 		int fd_;
 		block_address nr_blocks_;
+		mode mode_;
 		bool writeable_;
 	};
 
@@ -107,7 +112,7 @@ namespace persistent_data {
 		block_manager(std::string const &path,
 			      block_address nr_blocks,
 			      unsigned max_concurrent_locks,
-			      bool writeable = false);
+			      typename block_io<BlockSize>::mode m);
 
 		class validator {
 		public:
diff --git a/persistent-data/block.tcc b/persistent-data/block.tcc
index 8f2594d..a7faae3 100644
--- a/persistent-data/block.tcc
+++ b/persistent-data/block.tcc
@@ -36,12 +36,28 @@ using namespace std;
 //----------------------------------------------------------------
 
 template <uint32_t BlockSize>
-block_io<BlockSize>::block_io(std::string const &path, block_address nr_blocks, bool writeable)
+block_io<BlockSize>::block_io(std::string const &path, block_address nr_blocks, mode m)
 	: nr_blocks_(nr_blocks),
-	  writeable_(writeable)
+	  mode_(m)
 {
+	int fd_mode = O_DIRECT | O_SYNC;
+
+	switch (m) {
+	case READ_ONLY:
+		fd_mode |= O_RDONLY;
+		break;
+
+	case READ_WRITE:
+		fd_mode |= O_RDWR;
+		break;
+
+	default:
+		throw runtime_error("unsupported mode");
+		break;
+	}
+
 	// fd_ = ::open(path.c_str(), writeable ? (O_RDWR | O_CREAT) : O_RDONLY, 0666);
-	fd_ = ::open(path.c_str(), O_DIRECT | O_SYNC | (writeable ? O_RDWR : O_RDONLY), 0666);
+	fd_ = ::open(path.c_str(), fd_mode, 0666);
 	if (fd_ < 0)
 		throw std::runtime_error("couldn't open file");
 }
@@ -237,8 +253,8 @@ template <uint32_t BlockSize>
 block_manager<BlockSize>::block_manager(std::string const &path,
 					block_address nr_blocks,
 					unsigned max_concurrent_blocks,
-					bool writeable)
-	: io_(new block_io<BlockSize>(path, nr_blocks, writeable)),
+					typename block_io<BlockSize>::mode mode)
+	: io_(new block_io<BlockSize>(path, nr_blocks, mode)),
 	  cache_(max(64u, max_concurrent_blocks)),
 	  tracker_(0, nr_blocks)
 {
diff --git a/thin-provisioning/metadata.cc b/thin-provisioning/metadata.cc
index 276a7f3..ccb6eba 100644
--- a/thin-provisioning/metadata.cc
+++ b/thin-provisioning/metadata.cc
@@ -91,7 +91,11 @@ namespace {
 	transaction_manager::ptr
 	open_tm(string const &dev_path, bool writeable) {
 		block_address nr_blocks = get_nr_blocks(dev_path);
-		block_manager<>::ptr bm(new block_manager<>(dev_path, nr_blocks, 1, writeable));
+		typename block_io<>::mode m = writeable ?
+			block_io<>::READ_WRITE :
+			block_io<>::READ_ONLY;
+
+		block_manager<>::ptr bm(new block_manager<>(dev_path, nr_blocks, 1, m));
 		space_map::ptr sm(new core_map(nr_blocks));
 		sm->inc(SUPERBLOCK_LOCATION);
 		transaction_manager::ptr tm(new transaction_manager(bm, sm));