From 9b74284e35aa73d24439350ad95647ee1e6490ea Mon Sep 17 00:00:00 2001
From: Andrea Mazzoleni <amadvance@gmail.com>
Date: Mon, 10 Mar 2014 21:17:10 +0100
Subject: [PATCH] Avoids to access parity disks when not needed.

---
 HISTORY    |  2 ++
 snapraid.c | 19 +++++++++++++++++++
 state.c    | 36 +++++++++++++++++++++---------------
 state.h    |  1 +
 4 files changed, 43 insertions(+), 15 deletions(-)

diff --git a/HISTORY b/HISTORY
index a2de1bc9..db168569 100644
--- a/HISTORY
+++ b/HISTORY
@@ -25,6 +25,8 @@ SnapRAID HISTORY
    default value even if the other one is specified.
  * Moved the .lock file in the same dir of the first specified content
    file. This avoid to spin the parity disks in all commands.
+ * The "diff", "list", "dup", "status" and "pool" commands don't access
+   anymore the parity disks that can stay powered down.
  * New source code organization. The RAID engine is now
    an external component usable also in other projects.
 
diff --git a/snapraid.c b/snapraid.c
index acfe51f6..0faa6afa 100644
--- a/snapraid.c
+++ b/snapraid.c
@@ -211,6 +211,7 @@ void log_close(const char* log)
 #define OPT_TEST_FORCE_CONTENT_WRITE 273
 #define OPT_TEST_FORCE_CONTENT_TEXT 274
 #define OPT_TEST_SKIP_CONTENT_CHECK 275
+#define OPT_TEST_SKIP_PARITY_ACCESS 276
 
 #if HAVE_GETOPT_LONG
 struct option long_options[] = {
@@ -296,6 +297,9 @@ struct option long_options[] = {
 	/* Relax the checks done at the content file */
 	{ "test-skip-content-check", 0, 0, OPT_TEST_SKIP_CONTENT_CHECK },
 
+	/* Skip the parity access */
+	{ "test-skip-parity-access", 0, 0, OPT_TEST_SKIP_PARITY_ACCESS },
+
 	{ 0, 0, 0, 0 }
 };
 #endif
@@ -535,6 +539,9 @@ int main(int argc, char* argv[])
 		case OPT_TEST_SKIP_CONTENT_CHECK :
 			opt.skip_content_check = 1;
 			break;
+		case OPT_TEST_SKIP_PARITY_ACCESS :
+			opt.skip_parity_access = 1;
+			break;
 		case OPT_TEST_FORCE_MURMUR3 :
 			opt.force_murmur3 = 1;
 			break;
@@ -696,6 +703,18 @@ int main(int argc, char* argv[])
 		}
 	}
 
+	switch (operation) {
+	case OPERATION_DIFF :
+	case OPERATION_LIST :
+	case OPERATION_DUP :
+	case OPERATION_POOL :
+	case OPERATION_STATUS :
+	case OPERATION_REWRITE :
+		/* avoid to check and access parity disks if not needed */
+		opt.skip_parity_access = 1;
+		break;
+	}
+
 	/* open the log file */
 	log_open(log);
 
diff --git a/state.c b/state.c
index 3309b8e5..8b8e3368 100644
--- a/state.c
+++ b/state.c
@@ -452,7 +452,6 @@ void state_config(struct snapraid_state* state, const char* path, const char* co
 		) {
 			char device[PATH_MAX];
 			char* slash;
-			struct stat st;
 			unsigned l;
 
 			switch (tag[0]) {
@@ -500,21 +499,28 @@ void state_config(struct snapraid_state* state, const char* path, const char* co
 
 			pathimport(state->parity_path[l], sizeof(state->parity_path[l]), buffer);
 
-			/* get the device of the directory containing the parity file */
-			pathimport(device, sizeof(device), buffer);
-			slash = strrchr(device, '/');
-			if (slash)
-				*slash = 0;
-			else
-				pathcpy(device, sizeof(device), ".");
-			if (stat(device, &st) != 0) {
-				/* LCOV_EXCL_START */
-				fprintf(stderr, "Error accessing 'parity' dir '%s' specification in '%s' at line %u\n", device, path, line);
-				exit(EXIT_FAILURE);
-				/* LCOV_EXCL_STOP */
-			}
+			if (state->opt.skip_parity_access) {
+				struct stat st;
 
-			state->parity_device[l] = st.st_dev;
+				/* get the device of the directory containing the parity file */
+				pathimport(device, sizeof(device), buffer);
+				slash = strrchr(device, '/');
+				if (slash)
+					*slash = 0;
+				else
+					pathcpy(device, sizeof(device), ".");
+				if (stat(device, &st) != 0) {
+					/* LCOV_EXCL_START */
+					fprintf(stderr, "Error accessing 'parity' dir '%s' specification in '%s' at line %u\n", device, path, line);
+					exit(EXIT_FAILURE);
+					/* LCOV_EXCL_STOP */
+				}
+
+				state->parity_device[l] = st.st_dev;
+			} else {
+				/* if parity is skipped, uses a fake device */
+				state->parity_device[l] = -1LL - l;
+			}
 
 			/* adjust the level */
 			if (state->level < l + 1)
diff --git a/state.h b/state.h
index 82c4e3aa..8117a9ab 100644
--- a/state.h
+++ b/state.h
@@ -74,6 +74,7 @@ struct snapraid_option {
 	int skip_lock; /**< Skip the lock file protection. */
 	int skip_self; /**< Skip the self-test. */
 	int skip_content_check; /**< Relax some content file checks. */
+	int skip_parity_access; /**< Skip the parity access for commands that don't need it. */
 	int kill_after_sync; /**< Kill the process after sync without saving the final state. */
 	int force_murmur3; /**< Force Murmur3 choice. */
 	int force_spooky2; /**< Force Spooky2 choice. */