Merge pull request #25 from plieven/master

Fix Compiler warnings + add setters for TCP keepalive values

include/iscsi-private.h

@@ -86,6 +86,10 @@ struct iscsi_context {
 	int is_connected;
 	
 	int tcp_user_timeout;
+	int tcp_keepcnt;
+	int tcp_keepintvl;
+	int tcp_keepidle;
+	int tcp_syncnt;
 
 	int current_phase;
 	int next_phase;

include/iscsi.h

@@ -974,6 +974,28 @@ iscsi_set_debug(struct iscsi_context *iscsi, int level);
 EXTERN void 
 iscsi_set_tcp_user_timeout(struct iscsi_context *iscsi, int timeout_ms);
 
+/*
+ * This function is to set the TCP_KEEPIDLE option. It has to be called after iscsi
+ * context creation. 
+ */
+EXTERN void 
+iscsi_set_tcp_keepidle(struct iscsi_context *iscsi, int value);
+
+/*
+ * This function is to set the TCP_KEEPCNT option. It has to be called after iscsi
+ * context creation. 
+ */
+EXTERN void 
+iscsi_set_tcp_keepcnt(struct iscsi_context *iscsi, int value);
+
+/*
+ * This function is to set the TCP_KEEPINTVL option. It has to be called after iscsi
+ * context creation. 
+ */
+EXTERN void 
+iscsi_set_tcp_keepintvl(struct iscsi_context *iscsi, int value);
+
+
 #ifdef __cplusplus
 }
 #endif

lib/connect.c

@@ -24,6 +24,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>
+#include <time.h>
 #include "slist.h"
 #include "iscsi.h"
 #include "iscsi-private.h"
@@ -234,6 +235,10 @@ try_again:
 	iscsi->debug = old_iscsi->debug;
 	
 	iscsi->tcp_user_timeout = old_iscsi->tcp_user_timeout;
+	iscsi->tcp_keepidle = old_iscsi->tcp_keepidle;
+	iscsi->tcp_keepcnt = old_iscsi->tcp_keepcnt;
+	iscsi->tcp_keepintvl = old_iscsi->tcp_keepintvl;
+	iscsi->tcp_syncnt = old_iscsi->tcp_syncnt;
 
 	if (iscsi_full_connect_sync(iscsi, iscsi->portal, iscsi->lun) != 0) {
 		iscsi_destroy_context(iscsi);

lib/init.c

@@ -71,6 +71,34 @@ iscsi_create_context(const char *initiator_name)
 	iscsi->use_immediate_data                     = ISCSI_IMMEDIATE_DATA_YES;
 	iscsi->want_header_digest                     = ISCSI_HEADER_DIGEST_NONE_CRC32C;
 
+	iscsi->tcp_keepcnt=3;
+	iscsi->tcp_keepintvl=30;
+	iscsi->tcp_keepidle=30;
+
+	if (getenv("LIBISCSI_DEBUG") != NULL) {
+		iscsi_set_debug(iscsi,atoi(getenv("LIBISCSI_DEBUG")));
+	}
+	
+	if (getenv("LIBISCSI_TCP_USER_TIMEOUT") != NULL) {
+		iscsi_set_tcp_user_timeout(iscsi,atoi(getenv("LIBISCSI_TCP_USER_TIMEOUT")));
+	}
+
+	if (getenv("LIBISCSI_TCP_KEEPCNT") != NULL) {
+		iscsi_set_tcp_keepcnt(iscsi,atoi(getenv("LIBISCSI_TCP_KEEPCNT")));
+	}
+
+	if (getenv("LIBISCSI_TCP_KEEPINTVL") != NULL) {
+		iscsi_set_tcp_keepintvl(iscsi,atoi(getenv("LIBISCSI_TCP_KEEPINTVL")));
+	}
+
+	if (getenv("LIBISCSI_TCP_KEEPIDLE") != NULL) {
+		iscsi_set_tcp_keepidle(iscsi,atoi(getenv("LIBISCSI_TCP_KEEPIDLE")));
+	}
+
+	if (getenv("LIBISCSI_TCP_SYNCNT") != NULL) {
+		iscsi_set_tcp_syncnt(iscsi,atoi(getenv("LIBISCSI_TCP_SYNCNT")));
+	}
+
 	return iscsi;
 }
 
@@ -276,7 +304,7 @@ iscsi_set_error(struct iscsi_context *iscsi, const char *error_string, ...)
 	
 	va_end(ap);
 	
-	DPRINTF(iscsi,1,str);
+	DPRINTF(iscsi,1,"%s",str);
 }
 
 void
@@ -559,8 +587,7 @@ iscsi_destroy_url(struct iscsi_url *iscsi_url)
 
 int
 iscsi_set_initiator_username_pwd(struct iscsi_context *iscsi,
-    					    const char *user,
+						    const char *user, const char *passwd)
-					    const char *passwd)
 {
 	free(discard_const(iscsi->user));
 	iscsi->user = strdup(user);

lib/libiscsi.def

@@ -73,6 +73,10 @@ iscsi_set_session_type
 iscsi_set_targetname
 iscsi_set_tcp_keepalive
 iscsi_set_tcp_user_timeout
+iscsi_set_tcp_keepidle
+iscsi_set_tcp_keepcnt
+iscsi_set_tcp_keepintvl
+iscsi_set_tcp_syncnt
 iscsi_startstopunit_sync
 iscsi_startstopunit_task
 iscsi_synchronizecache10_sync

lib/libiscsi.syms

@@ -71,6 +71,10 @@ iscsi_set_session_type
 iscsi_set_targetname
 iscsi_set_tcp_keepalive
 iscsi_set_tcp_user_timeout
+iscsi_set_tcp_keepidle
+iscsi_set_tcp_keepcnt
+iscsi_set_tcp_keepintvl
+iscsi_set_tcp_syncnt
 iscsi_startstopunit_sync
 iscsi_startstopunit_task
 iscsi_synchronizecache10_sync

lib/socket.c

@@ -58,6 +58,52 @@ static void set_nonblocking(int fd)
 #endif
 }
 
+int set_tcp_sockopt(int sockfd, int optname, int value)
+{
+	int level;
+	
+	#if defined(__FreeBSD__) || defined(__sun)
+	struct protoent *buf;
+
+	if ((buf = getprotobyname("tcp")) != NULL)
+		level = buf->p_proto;
+	else
+		return -1;
+	#else
+		level = SOL_TCP;
+	#endif	
+	
+	return setsockopt(sockfd, level, optname, &value, sizeof(value));
+}
+
+#ifndef TCP_USER_TIMEOUT
+#define TCP_USER_TIMEOUT        18
+#endif
+
+int set_tcp_user_timeout(struct iscsi_context *iscsi)
+{
+	if (set_tcp_sockopt(iscsi->fd, TCP_USER_TIMEOUT, iscsi->tcp_user_timeout) != 0) {
+		iscsi_set_error(iscsi, "TCP: Failed to set tcp user timeout. Error %s(%d)", strerror(errno), errno);
+		return -1;
+	}
+	DPRINTF(iscsi,3,"TCP_USER_TIMEOUT set to %d",iscsi->tcp_user_timeout);
+	return 0;
+}
+
+#ifndef TCP_SYNCNT
+#define TCP_SYNCNT        7
+#endif
+
+int set_tcp_syncnt(struct iscsi_context *iscsi)
+{
+	if (set_tcp_sockopt(iscsi->fd, TCP_SYNCNT, iscsi->tcp_syncnt) != 0) {
+		iscsi_set_error(iscsi, "TCP: Failed to set tcp syn retries. Error %s(%d)", strerror(errno), errno);
+		return -1;
+	}
+	DPRINTF(iscsi,3,"TCP_SYNCNT set to %d",iscsi->tcp_syncnt);
+	return 0;
+}
+
 int
 iscsi_connect_async(struct iscsi_context *iscsi, const char *portal,
 		    iscsi_command_cb cb, void *private_data)
@@ -160,12 +206,16 @@ iscsi_connect_async(struct iscsi_context *iscsi, const char *portal,
 
 	set_nonblocking(iscsi->fd);
 	
-	iscsi_set_tcp_keepalive(iscsi, 30, 3, 30);
+	iscsi_set_tcp_keepalive(iscsi, iscsi->tcp_keepidle, iscsi->tcp_keepcnt, iscsi->tcp_keepintvl);
 	
 	if (iscsi->tcp_user_timeout > 0) {
 		set_tcp_user_timeout(iscsi);
 	}
 
+	if (iscsi->tcp_syncnt > 0) {
+		set_tcp_syncnt(iscsi);
+	}
+
 	if (connect(iscsi->fd, ai->ai_addr, socksize) != 0
 	    && errno != EINPROGRESS) {
 		iscsi_set_error(iscsi, "Connect failed with errno : "
@@ -178,7 +228,7 @@ iscsi_connect_async(struct iscsi_context *iscsi, const char *portal,
 
 	freeaddrinfo(ai);
 	
-	if (iscsi->connected_portal) free(iscsi->connected_portal);
+	if (iscsi->connected_portal) free(discard_const(iscsi->connected_portal));
 	iscsi->connected_portal=strdup(portal);
 	
 	return 0;
@@ -389,6 +439,17 @@ iscsi_write_to_socket(struct iscsi_context *iscsi)
 	return 0;
 }
 
+int inline
+iscsi_service_reconnect_if_loggedin(struct iscsi_context *iscsi)
+{
+	if (iscsi->is_loggedin) {
+		if (iscsi_reconnect(iscsi) == 0) {
+			return 0;
+		}
+	}
+	return -1;
+}
+
 int
 iscsi_service(struct iscsi_context *iscsi, int revents)
 {
@@ -410,30 +471,19 @@ iscsi_service(struct iscsi_context *iscsi, int revents)
 		}
 		iscsi->socket_status_cb(iscsi, SCSI_STATUS_ERROR, NULL,
 					iscsi->connect_data);
-		if (iscsi->is_loggedin) {
+		return iscsi_service_reconnect_if_loggedin(iscsi);
-			if (iscsi_reconnect(iscsi) == 0) {
-				return 0;
-			}
-		}
-		return -1;
 	}
 	if (revents & POLLHUP) {
 		iscsi_set_error(iscsi, "iscsi_service: POLLHUP, "
 				"socket error.");
 		iscsi->socket_status_cb(iscsi, SCSI_STATUS_ERROR, NULL,
 					iscsi->connect_data);
-		if (iscsi->is_loggedin) {
+		return iscsi_service_reconnect_if_loggedin(iscsi);
-			if (iscsi_reconnect(iscsi) == 0) {
-				return 0;
-			}
-		}
-		return -1;
 	}
 
 	if (iscsi->is_connected == 0 && iscsi->fd != -1 && revents&POLLOUT) {
 		int err = 0;
 		socklen_t err_size = sizeof(err);
-
 		if (getsockopt(iscsi->fd, SOL_SOCKET, SO_ERROR,
 			       &err, &err_size) != 0 || err != 0) {
 			if (err == 0) {
@@ -444,14 +494,11 @@ iscsi_service(struct iscsi_context *iscsi, int revents)
 					strerror(err), err);
 			iscsi->socket_status_cb(iscsi, SCSI_STATUS_ERROR,
 						NULL, iscsi->connect_data);
-			if (iscsi->is_loggedin) {
+			return iscsi_service_reconnect_if_loggedin(iscsi);
-				if (iscsi_reconnect(iscsi) == 0) {
-					return 0;
-				}
-			}
-			return -1;
 		}
 
+		DPRINTF(iscsi,2,"connection to %s established",iscsi->connected_portal);
+
 		iscsi->is_connected = 1;
 		iscsi->socket_status_cb(iscsi, SCSI_STATUS_GOOD, NULL,
 					iscsi->connect_data);
@@ -460,22 +507,12 @@ iscsi_service(struct iscsi_context *iscsi, int revents)
 
 	if (revents & POLLOUT && iscsi->outqueue != NULL) {
 		if (iscsi_write_to_socket(iscsi) != 0) {
-			if (iscsi->is_loggedin) {
+			return iscsi_service_reconnect_if_loggedin(iscsi);
-				if (iscsi_reconnect(iscsi) == 0) {
-					return 0;
-				}
-			}
-			return -1;
 		}
 	}
 	if (revents & POLLIN) {
 		if (iscsi_read_from_socket(iscsi) != 0) {
-			if (iscsi->is_loggedin) {
+			return iscsi_service_reconnect_if_loggedin(iscsi);
-				if (iscsi_reconnect(iscsi) == 0) {
-					return 0;
-				}
-			}
-			return -1;
 		}
 	}
 
@@ -529,85 +566,66 @@ iscsi_free_iscsi_inqueue(struct iscsi_in_pdu *inqueue)
 	}
 }
 
-#ifndef TCP_USER_TIMEOUT
+void iscsi_set_tcp_syncnt(struct iscsi_context *iscsi, int value)
-#define TCP_USER_TIMEOUT        18
-#endif
-
-int set_tcp_user_timeout(struct iscsi_context *iscsi)
 {
-    int level, value;
+	iscsi->tcp_syncnt=value;
-	
+	DPRINTF(iscsi,2,"TCP_SYNCNT will be set to %d on next socket creation",value);    
-	#if defined(__FreeBSD__) || defined(__sun)
-	struct protoent *buf;
-
-	if ((buf = getprotobyname("tcp")) != NULL)
-		level = buf->p_proto;
-	else
-		return -1;
-	#else
-		level = SOL_TCP;
-	#endif
-	
-	value = iscsi->tcp_user_timeout;
-	if (setsockopt(iscsi->fd, level, TCP_USER_TIMEOUT, &value, sizeof(value)) != 0) {
-		iscsi_set_error(iscsi, "TCP: Failed to set tcp user timeout. Error %s(%d)", strerror(errno), errno);
-		return -1;
-	}
-	DPRINTF(iscsi,3,"TCP_USER_TIMEOUT set to %d",value);
-	return 0;
 }
 
-void iscsi_set_tcp_user_timeout(struct iscsi_context *iscsi, int timeout_ms)
+void iscsi_set_tcp_user_timeout(struct iscsi_context *iscsi, int value)
 {
-    iscsi->tcp_user_timeout=timeout_ms;
+	iscsi->tcp_user_timeout=value;
-    DPRINTF(iscsi,2,"TCP_USER_TIMEOUT will be set to %dms on next socket creation",timeout_ms);    
+	DPRINTF(iscsi,2,"TCP_USER_TIMEOUT will be set to %dms on next socket creation",value);    
+}
+
+void iscsi_set_tcp_keepidle(struct iscsi_context *iscsi, int value)
+{
+	iscsi->tcp_keepidle=value;
+	DPRINTF(iscsi,2,"TCP_KEEPIDLE will be set to %d on next socket creation",value);    
+}
+
+void iscsi_set_tcp_keepcnt(struct iscsi_context *iscsi, int value)
+{
+	iscsi->tcp_keepcnt=value;
+	DPRINTF(iscsi,2,"TCP_KEEPCNT will be set to %d on next socket creation",value);    
+}
+
+void iscsi_set_tcp_keepintvl(struct iscsi_context *iscsi, int value)
+{
+	iscsi->tcp_keepintvl=value;
+	DPRINTF(iscsi,2,"TCP_KEEPINTVL will be set to %d on next socket creation",value);    
 }
 
 int iscsi_set_tcp_keepalive(struct iscsi_context *iscsi, int idle, int count, int interval)
 {
-	int level, value;
-#if defined(__FreeBSD__) || defined(__sun)
-	struct protoent *buf;
-
-	if ((buf = getprotobyname("tcp")) != NULL)
-		level = buf->p_proto;
-	else
-		return -1;
-#else
-	level = SOL_TCP;
-#endif
-
 #ifdef SO_KEEPALIVE
-	value =1;
+	int value = 1;
 	if (setsockopt(iscsi->fd, SOL_SOCKET, SO_KEEPALIVE, &value, sizeof(value)) != 0) {
 		iscsi_set_error(iscsi, "TCP: Failed to set socket option SO_KEEPALIVE. Error %s(%d)", strerror(errno), errno);
 		return -1;
 	}
 	DPRINTF(iscsi,3,"SO_KEEPALIVE set to %d",value);
-#endif
 #ifdef TCP_KEEPCNT
-	value = count;
+	if (set_tcp_sockopt(iscsi->fd, TCP_KEEPCNT, count) != 0) {
-	if (setsockopt(iscsi->fd, level, TCP_KEEPCNT, &value, sizeof(value)) != 0) {
 		iscsi_set_error(iscsi, "TCP: Failed to set tcp keepalive count. Error %s(%d)", strerror(errno), errno);
 		return -1;
 	}
-	DPRINTF(iscsi,3,"TCP_KEEPCNT set to %d",value);
+	DPRINTF(iscsi,3,"TCP_KEEPCNT set to %d",count);
 #endif
 #ifdef TCP_KEEPINTVL
-	value = interval;
+	if (set_tcp_sockopt(iscsi->fd, TCP_KEEPINTVL, interval) != 0) {
-	if (setsockopt(iscsi->fd, level, TCP_KEEPINTVL, &value, sizeof(value)) != 0) {
 		iscsi_set_error(iscsi, "TCP: Failed to set tcp keepalive interval. Error %s(%d)", strerror(errno), errno);
 		return -1;
 	}
-	DPRINTF(iscsi,3,"TCP_KEEPINTVL set to %d",value);
+	DPRINTF(iscsi,3,"TCP_KEEPINTVL set to %d",interval);
 #endif
 #ifdef TCP_KEEPIDLE
-	value = idle;
+	if (set_tcp_sockopt(iscsi->fd, TCP_KEEPIDLE, idle) != 0) {
-	if (setsockopt(iscsi->fd, level, TCP_KEEPIDLE, &value, sizeof(value)) != 0) {
 		iscsi_set_error(iscsi, "TCP: Failed to set tcp keepalive idle. Error %s(%d)", strerror(errno), errno);
 		return -1;
 	}
-	DPRINTF(iscsi,3,"TCP_KEEPIDLE set to %d",value);
+	DPRINTF(iscsi,3,"TCP_KEEPIDLE set to %d",idle);
+#endif
 #endif
 
 	return 0;

src/ld_iscsi.c

@@ -37,6 +37,10 @@ static const char *initiator = "iqn.2007-10.com.github:sahlberg:libiscsi:ld-iscs
 
 #define ISCSI_MAX_FD  255
 
+static int debug = 0;
+
+#define LD_ISCSI_DPRINTF(level,fmt,args...) do { if ((debug) >= level) {fprintf(stderr,"ld_iscsi: ");fprintf(stderr, (fmt), ##args); fprintf(stderr,"\n");} } while (0);
+
 struct iscsi_fd_list {
        int is_iscsi;
        int dup2fd;
@@ -46,6 +50,10 @@ struct iscsi_fd_list {
        uint32_t block_size;
        uint64_t num_blocks;
        off_t offset;
+       mode_t mode;
+       int get_lba_status;
+       struct scsi_lba_status_descriptor lbasd_cached;
+       int lbasd_cache_valid;
 };
 
 static struct iscsi_fd_list iscsi_fd_list[ISCSI_MAX_FD];
@@ -60,19 +68,24 @@ int open(const char *path, int flags, mode_t mode)
 		struct iscsi_context *iscsi;
 		struct iscsi_url *iscsi_url;
 		struct scsi_task *task;
-		struct scsi_readcapacity10 *rc10;
+		struct scsi_readcapacity16 *rc16;
+
+        if (mode & O_NONBLOCK) {
+			LD_ISCSI_DPRINTF(0,"Non-blocking I/O is currently not supported");
+			errno = EINVAL;
+			return -1;			
+		}
 
 		iscsi = iscsi_create_context(initiator);
 		if (iscsi == NULL) {
-			fprintf(stderr, "ld-iscsi: Failed to create context\n");
+			LD_ISCSI_DPRINTF(0,"Failed to create context");
 			errno = ENOMEM;
 			return -1;
 		}
 
 		iscsi_url = iscsi_parse_full_url(iscsi, path);
 		if (iscsi_url == NULL) {
-			fprintf(stderr, "ld-iscsi: Failed to parse URL: %s\n", 
+			LD_ISCSI_DPRINTF(0,"Failed to parse URL: %s\n", iscsi_get_error(iscsi));
-				iscsi_get_error(iscsi));
 			iscsi_destroy_context(iscsi);
 			errno = EINVAL;
 			return -1;
@@ -84,7 +97,7 @@ int open(const char *path, int flags, mode_t mode)
 
 		if (iscsi_url->user != NULL) {
 			if (iscsi_set_initiator_username_pwd(iscsi, iscsi_url->user, iscsi_url->passwd) != 0) {
-				fprintf(stderr, "Failed to set initiator username and password\n");
+				LD_ISCSI_DPRINTF(0,"Failed to set initiator username and password");
 				iscsi_destroy_context(iscsi);
 				errno = ENOMEM;
 				return -1;
@@ -92,25 +105,25 @@ int open(const char *path, int flags, mode_t mode)
 		}
 
 		if (iscsi_full_connect_sync(iscsi, iscsi_url->portal, iscsi_url->lun) != 0) {
-			fprintf(stderr, "ld-iscsi: Login Failed. %s\n", iscsi_get_error(iscsi));
+			LD_ISCSI_DPRINTF(0,"Login Failed. %s\n", iscsi_get_error(iscsi));
 			iscsi_destroy_url(iscsi_url);
 			iscsi_destroy_context(iscsi);
 			errno = EIO;
 			return -1;
 		}
 
-		task = iscsi_readcapacity10_sync(iscsi, iscsi_url->lun, 0, 0);
+		task = iscsi_readcapacity16_sync(iscsi, iscsi_url->lun);
 		if (task == NULL || task->status != SCSI_STATUS_GOOD) {
-			fprintf(stderr, "ld-iscsi: failed to send readcapacity command\n");
+			LD_ISCSI_DPRINTF(0,"failed to send readcapacity command");
 			iscsi_destroy_url(iscsi_url);
 			iscsi_destroy_context(iscsi);
 			errno = EIO;
 			return -1;
 		}
 
-		rc10 = scsi_datain_unmarshall(task);
+		rc16 = scsi_datain_unmarshall(task);
-		if (rc10 == NULL) {
+		if (rc16 == NULL) {
-			fprintf(stderr, "ld-iscsi: failed to unmarshall readcapacity10 data\n");
+			LD_ISCSI_DPRINTF(0,"failed to unmarshall readcapacity10 data");
 			scsi_free_scsi_task(task);
 			iscsi_destroy_url(iscsi_url);
 			iscsi_destroy_context(iscsi);
@@ -118,9 +131,11 @@ int open(const char *path, int flags, mode_t mode)
 			return -1;
 		}
       
+        LD_ISCSI_DPRINTF(4,"readcapacity16_sync: block_size: %d, num_blocks: %lu",rc16->block_length,rc16->returned_lba + 1);
+
 		fd = iscsi_get_fd(iscsi);
 		if (fd >= ISCSI_MAX_FD) {
-			fprintf(stderr, "ld-iscsi: Too many files open\n");
+			LD_ISCSI_DPRINTF(0,"Too many files open");
 			iscsi_destroy_url(iscsi_url);
 			iscsi_destroy_context(iscsi);
 			errno = ENFILE;
@@ -130,10 +145,19 @@ int open(const char *path, int flags, mode_t mode)
 		iscsi_fd_list[fd].is_iscsi   = 1;
 		iscsi_fd_list[fd].dup2fd     = -1;
 		iscsi_fd_list[fd].iscsi      = iscsi;
-		iscsi_fd_list[fd].block_size = rc10->block_size;
+		iscsi_fd_list[fd].block_size = rc16->block_length;
-		iscsi_fd_list[fd].num_blocks = rc10->lba + 1;
+		iscsi_fd_list[fd].num_blocks = rc16->returned_lba + 1;
 		iscsi_fd_list[fd].offset     = 0;
 		iscsi_fd_list[fd].lun        = iscsi_url->lun;
+		iscsi_fd_list[fd].mode       = mode;
+
+		if (getenv("LD_ISCSI_GET_LBA_STATUS") != NULL) {
+			iscsi_fd_list[fd].get_lba_status = atoi(getenv("LD_ISCSI_GET_LBA_STATUS"));
+			if (rc16->lbpme == 0){
+				LD_ISCSI_DPRINTF(1,"Logical unit is fully provisioned. Will skip get_lba_status tasks");
+				iscsi_fd_list[fd].get_lba_status = 0;
+			}
+		}
 
 		scsi_free_scsi_task(task);
 		iscsi_destroy_url(iscsi_url);
@@ -257,8 +281,9 @@ ssize_t read(int fd, void *buf, size_t count)
 {
 	if ((iscsi_fd_list[fd].is_iscsi == 1) && (iscsi_fd_list[fd].in_flight == 0)) {
 		uint64_t offset;
-		uint32_t num_blocks, lba;
+		uint64_t num_blocks, lba;
 		struct scsi_task *task;
+		struct scsi_get_lba_status *lbas;
 
 		if (iscsi_fd_list[fd].dup2fd >= 0) {
 			return read(iscsi_fd_list[fd].dup2fd, buf, count);
@@ -278,10 +303,70 @@ ssize_t read(int fd, void *buf, size_t count)
 		}
 
 		iscsi_fd_list[fd].in_flight = 1;
-		task = iscsi_read10_sync(iscsi_fd_list[fd].iscsi, iscsi_fd_list[fd].lun, lba, num_blocks * iscsi_fd_list[fd].block_size, iscsi_fd_list[fd].block_size, 0, 0, 0, 0, 0);
+        if (iscsi_fd_list[fd].get_lba_status != 0) {
+			if (iscsi_fd_list[fd].lbasd_cache_valid==1) {
+				LD_ISCSI_DPRINTF(5,"cached get_lba_status_descriptor is lba %lu, num_blocks %d, provisioning %d",iscsi_fd_list[fd].lbasd_cached.lba,iscsi_fd_list[fd].lbasd_cached.num_blocks,iscsi_fd_list[fd].lbasd_cached.provisioning);
+			    if (iscsi_fd_list[fd].lbasd_cached.provisioning != 0x00 && lba >= iscsi_fd_list[fd].lbasd_cached.lba && lba+num_blocks < iscsi_fd_list[fd].lbasd_cached.lba+iscsi_fd_list[fd].lbasd_cached.num_blocks)
+			    {
+					LD_ISCSI_DPRINTF(4,"skipped read16_sync for non-allocated blocks: lun %d, lba %lu, num_blocks: %lu, block_size: %d, offset: %lu count: %lu",iscsi_fd_list[fd].lun,lba,num_blocks,iscsi_fd_list[fd].block_size,offset,count);
+					memset(buf, 0x00, count);
+					iscsi_fd_list[fd].offset += count;
+					iscsi_fd_list[fd].in_flight = 0;
+					return count;
+				}
+			}
+			LD_ISCSI_DPRINTF(4,"get_lba_status_sync: lun %d, lba %lu, num_blocks: %lu",iscsi_fd_list[fd].lun,lba,num_blocks);
+			task = iscsi_get_lba_status_sync(iscsi_fd_list[fd].iscsi, iscsi_fd_list[fd].lun, lba, 8+16);
+			if (task == NULL || task->status != SCSI_STATUS_GOOD) {
+				LD_ISCSI_DPRINTF(0,"failed to send get_lba_status command");
+				iscsi_fd_list[fd].in_flight = 0;
+				errno = EIO;
+				return -1;
+			}
+			lbas = scsi_datain_unmarshall(task);
+			if (lbas == NULL) {
+				LD_ISCSI_DPRINTF(0,"failed to unmarshall get_lba_status data");
+				scsi_free_scsi_task(task);
+				iscsi_fd_list[fd].in_flight = 0;
+				errno = EIO;
+				return -1;
+			}
+
+			u_int32_t i;
+			LD_ISCSI_DPRINTF(5,"get_lba_status: num_descriptors: %d",lbas->num_descriptors);
+			u_int32_t _num_allocated=0;
+			u_int32_t _num_blocks=0;
+			for (i=0;i<lbas->num_descriptors;i++) {
+				struct scsi_lba_status_descriptor *lbasd = &lbas->descriptors[i];
+				LD_ISCSI_DPRINTF(5,"get_lba_status_descriptor %d, lba %lu, num_blocks %d, provisioning %d",i,lbasd->lba,lbasd->num_blocks,lbasd->provisioning);
+				if (lbasd->lba != _num_blocks+lba) {
+					LD_ISCSI_DPRINTF(0,"get_lba_status response is non-continuous");
+					scsi_free_scsi_task(task);
+					iscsi_fd_list[fd].in_flight = 0;
+					errno = EIO;
+					return -1;
+			    }
+				_num_allocated+=(lbasd->provisioning==0x00)?lbasd->num_blocks:0;
+				_num_blocks+=lbasd->num_blocks;
+				iscsi_fd_list[fd].lbasd_cached=lbas->descriptors[i];
+				iscsi_fd_list[fd].lbasd_cache_valid=1;
+			}
+			scsi_free_scsi_task(task);
+            if (_num_allocated == 0 && _num_blocks >= num_blocks) {
+		        LD_ISCSI_DPRINTF(4,"skipped read16_sync for non-allocated blocks: lun %d, lba %lu, num_blocks: %lu, block_size: %d, offset: %lu count: %lu",iscsi_fd_list[fd].lun,lba,num_blocks,iscsi_fd_list[fd].block_size,offset,count);
+				memset(buf, 0x00, count);
+		        iscsi_fd_list[fd].offset += count;
+		        iscsi_fd_list[fd].in_flight = 0;
+		        return count;
+			}
+		}
+
+        LD_ISCSI_DPRINTF(4,"read16_sync: lun %d, lba %lu, num_blocks: %lu, block_size: %d, offset: %lu count: %lu",iscsi_fd_list[fd].lun,lba,num_blocks,iscsi_fd_list[fd].block_size,offset,count);
+
+		task = iscsi_read16_sync(iscsi_fd_list[fd].iscsi, iscsi_fd_list[fd].lun, lba, num_blocks * iscsi_fd_list[fd].block_size, iscsi_fd_list[fd].block_size, 0, 0, 0, 0, 0);
 		iscsi_fd_list[fd].in_flight = 0;
 		if (task == NULL || task->status != SCSI_STATUS_GOOD) {
-			fprintf(stderr, "ld-iscsi: failed to send read10 command\n");
+			LD_ISCSI_DPRINTF(0,"failed to send read16 command");
 			errno = EIO;
 			return -1;
 		}
@@ -381,59 +466,63 @@ static void __attribute__((constructor)) _init(void)
 		iscsi_fd_list[i].dup2fd = -1;
 	}
 
+	if (getenv("LD_ISCSI_DEBUG") != NULL) {
+		debug = atoi(getenv("LD_ISCSI_DEBUG"));
+	}
+
 	real_open = dlsym(RTLD_NEXT, "open");
 	if (real_open == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(open)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(open)");
 		exit(10);
 	}
 
 	real_close = dlsym(RTLD_NEXT, "close");
 	if (real_close == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(close)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(close)");
 		exit(10);
 	}
 
 	real_fxstat = dlsym(RTLD_NEXT, "__fxstat");
 	if (real_fxstat == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(__fxstat)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(__fxstat)");
 		exit(10);
 	}
 
 	real_lxstat = dlsym(RTLD_NEXT, "__lxstat");
 	if (real_lxstat == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(__lxstat)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(__lxstat)");
 		exit(10);
 	}
 	real_xstat = dlsym(RTLD_NEXT, "__xstat");
 	if (real_xstat == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(__xstat)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(__xstat)");
 		exit(10);
 	}
 
 	real_read = dlsym(RTLD_NEXT, "read");
 	if (real_read == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(read)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(read)");
 		exit(10);
 	}
 
 	real_dup2 = dlsym(RTLD_NEXT, "dup2");
 	if (real_dup2 == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(dup2)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(dup2)");
 		exit(10);
 	}
 
 	real_fxstat64 = dlsym(RTLD_NEXT, "__fxstat64");
 	if (real_fxstat64 == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(__fxstat64)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(__fxstat64)");
 	}
 
 	real_lxstat64 = dlsym(RTLD_NEXT, "__lxstat64");
 	if (real_lxstat64 == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(_lxstat64)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(_lxstat64)");
 	}
 
 	real_xstat64 = dlsym(RTLD_NEXT, "__xstat64");
 	if (real_xstat64 == NULL) {
-		fprintf(stderr, "ld_iscsi: Failed to dlsym(__xstat64)\n");
+		LD_ISCSI_DPRINTF(0,"Failed to dlsym(__xstat64)");
 	}
 }