refactor: Apply code review suggestions

Changes:
- rename old write algorithm to inode based write algorithm and new
write algorithm to chunk based write algorithm.
- update help message of sfsuseinodebasedwritealgorithm option. It was
made also to be explicitly 0|1. Update doc entry accordignly.
- change safs_* functions occurrences for the safs::* equivalent ones.
- rename gWaveTimeout to gWriteWaveTimeout.
- change the throws in write_data_truncate for regular returns. Old
code was using POSIX error codes sometimes and other times SaunaFS
ancestors error codes: the POSIX errors were normally returned and the
other ones were "thrown" up. Current codebase uses for this specific
case only SaunaFS error codes.
- Log the truncateend failures.

doc/sfsmount.1.adoc

@@ -216,13 +216,14 @@ Equivalent to *--nostdopts* (*-n*) option for use in fstab.
 *-o nonempty*::
 Equivalent to *--nonempty* option for use in fstab.
 
-*-o sfsuseoldwritealgorithm*::
-Use legacy write algorithm. Though new algorithm is faster in most cases, old
-algorithm may prove useful in some scenarios.
-
-*-o sfsignoreflush*'0|1'::
-Advanced: use with caution. Ignore flush usual behavior by replying SUCCESS to it
-immediately. Targets fast creation of small files, but may cause data loss
+*-o sfsuseinodebasedwritealgorithm=*'0|1'::
+Use inode based write algorithm when set to 1. Use chunk based write algorithm
+when set to 0. Though chunk based algorithm is faster in most cases, inode
+based algorithm may prove useful in some scenarios (default: 0).
+
+*-o sfsignoreflush=*'0|1'::
+Advanced: use with caution. Ignore flush usual behavior by replying SUCCESS to
+it immediately. Targets fast creation of small files, but may cause data loss
 during crashes when allegedly flushed data is still being processed (default: 0).
 
 *-o sfsdirectio=*'0|1'::

src/mount/fuse/main.cc

@@ -253,7 +253,8 @@ static int mainloop(struct fuse_args *args, struct fuse_cmdline_opts *fuse_opts,
 	params.acl_cache_size = gMountOptions.aclcachesize;
 	params.debug_mode = gMountOptions.debug;
 	params.direct_io = gMountOptions.directio;
-	params.use_old_write_algorithm = gMountOptions.useoldwritealgorithm;
+	params.use_inode_based_write_algorithm =
+	    gMountOptions.useinodebasedwritealgorithm;
 	params.ignore_flush = gMountOptions.ignoreflush;
 
 	if (!gMountOptions.meta) {

src/mount/fuse/mount_config.cc

@@ -93,7 +93,7 @@ struct fuse_opt gSfsOptsStage2[] = {
 	SFS_OPT("bandwidthoveruse=%lf", bandwidthoveruse, 1),
 	SFS_OPT("sfsdirentrycachesize=%u", direntrycachesize, 0),
 	SFS_OPT("nostdmountoptions", nostdmountoptions, 1),
-	SFS_OPT("sfsuseoldwritealgorithm", useoldwritealgorithm, 1),
+	SFS_OPT("sfsuseinodebasedwritealgorithm=%d", useinodebasedwritealgorithm, 0),
 	SFS_OPT("sfsignoreflush=%d", ignoreflush, 0),
 
 	SFS_OPT("enablefilelocks=%u", filelocks, 0),
@@ -172,7 +172,9 @@ void usage(const char *progname) {
 "    -o sfswriteworkers=N        define number of write workers (default: %u)\n"
 "    -o sfswritewindowsize=N     define write window size (in blocks) for "
 				"each chunk (default: %u)\n"
-"    -o sfsuseoldwritealgorithm  use legacy write algorithm.\n"
+"    -o sfsuseinodebasedwritealgorithm=0|1  use inode based write algorithm when "
+				"set to 1. Use chunk based write algorithm when set to 0 "
+				"(default: %d)\n"
 "    -o sfsignoreflush=0|1       Advanced: use with caution. Ignore flush usual "
 				"behavior by replying SUCCESS to it immediately. Targets fast "
 				"creation of small files, but may cause data loss during crashes "
@@ -255,6 +257,7 @@ void usage(const char *progname) {
 		SaunaClient::FsInitParams::kDefaultCachePerInodePercentage,
 		SaunaClient::FsInitParams::kDefaultWriteWorkers,
 		SaunaClient::FsInitParams::kDefaultWriteWindowSize,
+		SaunaClient::FsInitParams::kDefaultUseInodeBasedWriteAlgorithm,
 		SaunaClient::FsInitParams::kDefaultIgnoreFlush,
 		SaunaClient::FsInitParams::kDefaultUseRwLock,
 		SaunaClient::FsInitParams::kDefaultMkdirCopySgid,

src/mount/fuse/mount_config.h

@@ -115,7 +115,7 @@ struct sfsopts_ {
 	double bandwidthoveruse;
 	int nonemptymount;
 	bool directio;
-    int useoldwritealgorithm;
+    int useinodebasedwritealgorithm;
 	int ignoreflush;
 
 	sfsopts_()
@@ -174,7 +174,7 @@ struct sfsopts_ {
 		bandwidthoveruse(SaunaClient::FsInitParams::kDefaultBandwidthOveruse),
 		nonemptymount(SaunaClient::FsInitParams::kDefaultNonEmptyMounts),
 		directio(SaunaClient::FsInitParams::kDirectIO),
-        useoldwritealgorithm(SaunaClient::FsInitParams::kDefaultUseOldWriteAlgorithm),
+        useinodebasedwritealgorithm(SaunaClient::FsInitParams::kDefaultUseInodeBasedWriteAlgorithm),
 		ignoreflush(SaunaClient::FsInitParams::kDefaultIgnoreFlush)
 	{ }
 };

src/mount/sauna_client.cc

@@ -3497,7 +3497,7 @@ void fs_init(FsInitParams &params) {
 			params.prefetch_xor_stripes,
 			std::max(params.bandwidth_overuse, 1.));
 
-	gUseOldWriteAlgorithm = params.use_old_write_algorithm;
+	gUseInodeBasedWriteAlgorithm = params.use_inode_based_write_algorithm;
 	write_data_init(
 	    params.write_cache_size, params.io_retries, params.write_workers,
 	    params.write_window_size, params.chunkserver_write_timeout_ms,

src/mount/sauna_client.h

@@ -81,7 +81,7 @@ struct FsInitParams {
 	static constexpr float    kDefaultBandwidthOveruse = 1.0;
 	static constexpr unsigned kDefaultChunkserverWriteTo = 5000;
 	static constexpr bool     kDefaultIgnoreFlush = false;
-	static constexpr bool     kDefaultUseOldWriteAlgorithm = false;
+	static constexpr bool     kDefaultUseInodeBasedWriteAlgorithm = false;
 	static constexpr unsigned kDefaultWriteCacheSize = 128;
 #ifdef _WIN32
 	static constexpr unsigned kDefaultWriteWaveTo = 10;
@@ -152,7 +152,7 @@ struct FsInitParams {
 #ifdef _WIN32
 	             mounting_uid(USE_LOCAL_ID), mounting_gid(USE_LOCAL_ID),
 #endif
-	             use_old_write_algorithm(kDefaultUseOldWriteAlgorithm),
+	             use_inode_based_write_algorithm(kDefaultUseInodeBasedWriteAlgorithm),
 	             ignore_flush(kDefaultIgnoreFlush), verbose(kDefaultVerbose), direct_io(kDirectIO) {
 	}
 
@@ -187,7 +187,7 @@ struct FsInitParams {
 #ifdef _WIN32
 	             mounting_uid(USE_LOCAL_ID), mounting_gid(USE_LOCAL_ID),
 #endif
-	             use_old_write_algorithm(kDefaultUseOldWriteAlgorithm),
+	             use_inode_based_write_algorithm(kDefaultUseInodeBasedWriteAlgorithm),
 	             ignore_flush(kDefaultIgnoreFlush), verbose(kDefaultVerbose), direct_io(kDirectIO) {
 	}
 
@@ -241,7 +241,7 @@ struct FsInitParams {
 	std::unordered_set<uint32_t> allowed_users;
 #endif
 
-	bool use_old_write_algorithm;
+	bool use_inode_based_write_algorithm;
 	bool ignore_flush;
 	bool verbose;
 	bool direct_io;