Fixes to iSCSI DNBD3 proxy uplink handling.

2 files changed, 67 insertions, 87 deletions

diff --git a/src/server/iscsi.c b/src/server/iscsi.c
index afb1e6c..e9b0fc1 100644
--- a/src/server/iscsi.c
+++ b/src/server/iscsi.c
@@ -2871,20 +2871,6 @@ iscsi_task *iscsi_task_create(iscsi_connection *conn, iscsi_task *parent, iscsi_
 
 	iscsi_scsi_task_create( &task->scsi_task, callback, iscsi_task_destroy_callback );
 
-	if ( pthread_mutex_init( &task->scsi_task.uplink_mutex, NULL ) != 0 ) {
-		logadd( LOG_ERROR, "iscsi_task_create: Error while initializing DNBD3 uplink mutex for iSCSI SCSI task" );
-
-		return NULL;
-	}
-
-	if ( pthread_cond_init( &task->scsi_task.uplink_cond, NULL ) != 0 ) {
-		logadd( LOG_ERROR, "iscsi_task_create: Error while initializing DNBD3 uplink condition for iSCSI SCSI task" );
-
-		pthread_mutex_destroy( &task->scsi_task.uplink_mutex );
-
-		return NULL;
-	}
-
 	if ( parent != NULL ) {
 		parent->scsi_task.ref++;
 
@@ -2931,9 +2917,6 @@ void iscsi_task_destroy_callback(iscsi_scsi_task *scsi_task)
 			task->parent = NULL;
 		}
 
-		pthread_cond_destroy( &task->scsi_task.uplink_cond );
-		pthread_mutex_destroy( &task->scsi_task.uplink_mutex );
-
 		if ( task->pdu != NULL ) {
 			iscsi_connection_pdu_destroy( task->pdu );
 
@@ -5259,6 +5242,32 @@ static int iscsi_scsi_emu_queue_io_wait(iscsi_scsi_task *scsi_task, iscsi_scsi_e
 }
 
 /**
+ * @brief Called when data requested via an uplink server has arrived.
+ *
+ * This function is used to retrieve
+ * block data which is NOT locally
+ * available.
+ *
+ * @param[in] data Pointer to related scsi_task. May NOT
+ * be NULL, so be careful.
+ * @param[in] handle Uplink handle.
+ * @param[in] start Start of range in bytes.
+ * @param[in] length Length of range in bytes, as passed to
+ * uplink_request().
+ * @param[in] buffer Data for requested range.
+ */
+static void iscsi_uplink_callback(void *data, uint64_t handle UNUSED, uint64_t start UNUSED, uint32_t length, const char *buffer)
+{
+	iscsi_scsi_task *scsi_task = (iscsi_scsi_task *) data;
+
+	memcpy( scsi_task->buf, buffer, length );
+
+	pthread_mutex_lock( &scsi_task->uplink_mutex );
+	pthread_cond_signal( &scsi_task->uplink_cond );
+	pthread_mutex_unlock( &scsi_task->uplink_mutex );
+}
+
+/**
  * @brief Converts offset and length specified by a block size to offset and length in bytes.
  *
  * This function uses bit shifting if
@@ -5288,33 +5297,6 @@ static uint64_t iscsi_scsi_emu_blocks_to_bytes(uint64_t *offset_bytes, const uin
 }
 
 /**
- * @brief Called when data requested via an uplink server has arrived.
- *
- * This function is used to retrieve
- * block data which is NOT locally
- * available.
- *
- * @param[in] data Pointer to related scsi_task. May NOT
- * be NULL, so be careful.
- * @param[in] handle Pointer to destination buffer, as passed to
- * iscsi_scsi_emu_io_block_read().
- * @param[in] start Start of range in bytes.
- * @param[in] length Length of range in bytes, as passed to
- * uplink_request().
- * @param[in] buffer Data for requested range.
- */
-static void iscsi_uplink_callback(void *data, uint64_t handle, uint64_t start UNUSED, uint32_t length, const char *buffer)
-{
-	iscsi_scsi_task *scsi_task = (iscsi_scsi_task *) data;
-
-	memcpy( (uint8_t *) handle, buffer, length );
-
-	pthread_mutex_lock( &scsi_task->uplink_mutex );
-	pthread_cond_signal( &scsi_task->uplink_cond );
-	pthread_mutex_unlock( &scsi_task->uplink_mutex );
-}
-
-/**
  * @brief Reads a number of blocks from a block offset of a DNBD3 image to a specified buffer.
  *
  * This function enqueues the I/O read
@@ -5325,9 +5307,6 @@ static void iscsi_uplink_callback(void *data, uint64_t handle, uint64_t start UN
  * @param[in] scsi_task Pointer to iSCSI SCSI task which
  * executes the I/O read operation, may
  * NOT be NULL, so be careful.
- * @param[in] buf Pointer to buffer where to store
- * the read data. NULL is NOT allowed
- * here, take caution.
  * @param[in] image Pointer to DNBD3 image to read
  * data from and may NOT be NULL, so
  * be careful.
@@ -5343,20 +5322,13 @@ static void iscsi_uplink_callback(void *data, uint64_t handle, uint64_t start UN
  * @return 0 on successful operation, a negative
  * error code otherwise.
  */
-int iscsi_scsi_emu_io_block_read(iscsi_scsi_task *scsi_task, uint8_t *buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data)
+int iscsi_scsi_emu_io_block_read(iscsi_scsi_task *scsi_task, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data)
 {
 	uint64_t offset_bytes;
-	const uint64_t num_bytes                = iscsi_scsi_emu_blocks_to_bytes( &offset_bytes, offset_blocks, num_blocks, block_size );
-	iscsi_connection_exec_queue *exec_queue = (iscsi_connection_exec_queue *) malloc( sizeof(struct iscsi_connection_exec_queue) );
-
-	if ( exec_queue == NULL ) {
-		logadd( LOG_ERROR, "iscsi_scsi_emu_io_block_read: Out of memory while allocating execution queue for I/O read" );
-
-		return -ENOMEM;
-	}
-
+	const uint64_t num_bytes = iscsi_scsi_emu_blocks_to_bytes( &offset_bytes, offset_blocks, num_blocks, block_size );
 	dnbd3_cache_map_t *cache = ref_get_cachemap( image );
 	bool readFromFile;
+	bool success;
 
 	if ( cache == NULL ) {
 		readFromFile = true;
@@ -5370,30 +5342,44 @@ int iscsi_scsi_emu_io_block_read(iscsi_scsi_task *scsi_task, uint8_t *buf, dnbd3
 
 		if ( !readFromFile ) {
 			// Not cached, request via uplink
-			pthread_mutex_lock( &scsi_task->uplink_mutex );
 
-			if ( !uplink_request( image, scsi_task, iscsi_uplink_callback, (uint64_t) buf, offset_bytes, num_bytes ) ) {
-				pthread_mutex_unlock( &scsi_task->uplink_mutex );
+			if ( pthread_mutex_init( &scsi_task->uplink_mutex, NULL ) != 0 ) {
+				logadd( LOG_ERROR, "iscsi_scsi_emu_io_block_read: Error while initializing DNBD3 uplink mutex for iSCSI SCSI task" );
+
+				return -ENOMEM;
+			}
+
+			if ( pthread_cond_init( &scsi_task->uplink_cond, NULL ) != 0 ) {
+				logadd( LOG_ERROR, "iscsi_scsi_emu_io_block_read: Error while initializing DNBD3 uplink condition for iSCSI SCSI task" );
 
-				logadd( LOG_DEBUG1, "Could not relay uncached request to upstream proxy for image %s:%d",
-						image->name, image->rid );
+				pthread_mutex_destroy( &scsi_task->uplink_mutex );
 
-				return -EIO;
+				return -ENOMEM;
 			}
 
-			// Wait sync (Maybe use pthread_cond_timedwait to detect unavailable uplink instead of hanging...)
-			pthread_cond_wait( &scsi_task->uplink_cond, &scsi_task->uplink_mutex );
+			pthread_mutex_lock( &scsi_task->uplink_mutex );
+			success = uplink_request( image, (void *) scsi_task, iscsi_uplink_callback, 0ULL, offset_bytes, (uint32_t) num_bytes );
+
+			if ( success )
+				pthread_cond_wait( &scsi_task->uplink_cond, &scsi_task->uplink_mutex );
+
 			pthread_mutex_unlock( &scsi_task->uplink_mutex );
+			pthread_cond_destroy( &scsi_task->uplink_cond );
+			pthread_mutex_destroy( &scsi_task->uplink_mutex );
 		}
 	}
 
-	bool success;
-
 	if ( readFromFile ) {
-		const int64_t len = pread( image->readFd, buf, (size_t) num_bytes, offset_bytes );
+		const int64_t len = pread( image->readFd, scsi_task->buf, (size_t) num_bytes, offset_bytes );
 		success           = ((uint64_t) len == num_bytes);
-	} else {
-		success = true;
+	}
+
+	iscsi_connection_exec_queue *exec_queue = (iscsi_connection_exec_queue *) malloc( sizeof(struct iscsi_connection_exec_queue) );
+
+	if ( exec_queue == NULL ) {
+		logadd( LOG_ERROR, "iscsi_scsi_emu_io_block_read: Out of memory while allocating execution queue for I/O read" );
+
+		return -ENOMEM;
 	}
 
 	exec_queue->data.io.callback  = callback;
@@ -5452,9 +5438,6 @@ uint8_t *iscsi_scsi_emu_block_read_complete_callback(dnbd3_image_t *image, uint8
  * executes the I/O compare and write
  * operation, may NOT be NULL, so be
  * careful.
- * @param[in] buf Pointer to buffer which contains
- * the data to be written. NULL is NOT
- * allowed here, take caution.
  * @param[in] cmp_buf Pointer to buffer which contains
  * the data to be compared and may NOT
  * be NULL, so be careful.
@@ -5473,7 +5456,7 @@ uint8_t *iscsi_scsi_emu_block_read_complete_callback(dnbd3_image_t *image, uint8
  * @return 0 on successful operation, a negative
  * error code otherwise.
  */
-int iscsi_scsi_emu_io_block_cmp_write(iscsi_scsi_task *scsi_task, uint8_t *buf, uint8_t *cmp_buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data)
+int iscsi_scsi_emu_io_block_cmp_write(iscsi_scsi_task *scsi_task, uint8_t *cmp_buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data)
 {
 	// TODO: Implement compare and write I/O.
 
@@ -5525,9 +5508,6 @@ uint8_t *iscsi_scsi_emu_block_write_complete_callback(dnbd3_image_t *image, uint
  * @param[in] scsi_task Pointer to iSCSI SCSI task which
  * executes the I/O write operation, may
  * NOT be NULL, so be careful.
- * @param[in] buf Pointer to buffer which contains
- * the data to be written. NULL is NOT
- * allowed here, take caution.
  * @param[in] image Pointer to DNBD3 image to write
  * data to and may NOT be NULL, so
  * be careful.
@@ -5543,11 +5523,11 @@ uint8_t *iscsi_scsi_emu_block_write_complete_callback(dnbd3_image_t *image, uint
  * @return 0 on successful operation, a negative
  * error code otherwise.
  */
-int iscsi_scsi_emu_io_block_write(iscsi_scsi_task *scsi_task, uint8_t *buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data)
+int iscsi_scsi_emu_io_block_write(iscsi_scsi_task *scsi_task, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data)
 {
 	uint64_t offset_bytes;
 	const uint64_t num_bytes                = iscsi_scsi_emu_blocks_to_bytes( &offset_bytes, offset_blocks, num_blocks, block_size );
-	const int64_t len                       = pwrite( image->readFd, buf, (size_t) num_bytes, offset_bytes );
+	const int64_t len                       = pwrite( image->readFd, scsi_task->buf, (size_t) num_bytes, offset_bytes );
 	const bool success                      = ((uint64_t) len == num_bytes);
 	iscsi_connection_exec_queue *exec_queue = (iscsi_connection_exec_queue *) malloc( sizeof(struct iscsi_connection_exec_queue) );
 
@@ -5660,7 +5640,7 @@ static int iscsi_scsi_emu_block_read_write(dnbd3_image_t *image, iscsi_scsi_task
 			return ISCSI_SCSI_TASK_RUN_PENDING;
 		}
 
-		rc = iscsi_scsi_emu_io_block_read( scsi_task, scsi_task->buf, image, offset_blocks, num_blocks, block_size, iscsi_scsi_emu_block_read_complete_callback, (uint8_t *) scsi_task );
+		rc = iscsi_scsi_emu_io_block_read( scsi_task, image, offset_blocks, num_blocks, block_size, iscsi_scsi_emu_block_read_complete_callback, (uint8_t *) scsi_task );
 	} else if ( iscsi_scsi_emu_io_type_is_supported( image, ISCSI_SCSI_EMU_IO_TYPE_PHYSICAL_READ_ONLY ) || iscsi_scsi_emu_io_type_is_supported( image, ISCSI_SCSI_EMU_IO_TYPE_WRITE_PROTECT ) ) {
 		iscsi_scsi_task_status_set( scsi_task, ISCSI_SCSI_STATUS_CHECK_COND, ISCSI_SCSI_SENSE_KEY_DATA_PROTECT, ISCSI_SCSI_ASC_WRITE_PROTECTED, ISCSI_SCSI_ASCQ_CAUSE_NOT_REPORTABLE );
 
@@ -5674,9 +5654,9 @@ static int iscsi_scsi_emu_block_read_write(dnbd3_image_t *image, iscsi_scsi_task
 
 		uint8_t *cmp_buf = (scsi_task->buf + block_size);
 
-		rc = iscsi_scsi_emu_io_block_cmp_write( scsi_task, scsi_task->buf, cmp_buf, image, offset_blocks, 1ULL, block_size, iscsi_scsi_emu_block_write_complete_callback, (uint8_t *) scsi_task );
+		rc = iscsi_scsi_emu_io_block_cmp_write( scsi_task, cmp_buf, image, offset_blocks, 1ULL, block_size, iscsi_scsi_emu_block_write_complete_callback, (uint8_t *) scsi_task );
 	} else {
-		rc = iscsi_scsi_emu_io_block_write( scsi_task, scsi_task->buf, image, offset_blocks, num_blocks, block_size, iscsi_scsi_emu_block_write_complete_callback, (uint8_t *) scsi_task );
+		rc = iscsi_scsi_emu_io_block_write( scsi_task, image, offset_blocks, num_blocks, block_size, iscsi_scsi_emu_block_write_complete_callback, (uint8_t *) scsi_task );
 	}
 
 	if ( rc < 0 ) {
diff --git a/src/server/iscsi.h b/src/server/iscsi.h
index 7ce4122..ded2d1d 100644
--- a/src/server/iscsi.h
+++ b/src/server/iscsi.h
@@ -10823,10 +10823,10 @@ typedef struct iscsi_scsi_task {
     /// I/O task wait.
     iscsi_scsi_emu_io_wait io_wait;
 
-    /// Uplink read mutex for sync
+    /// Uplink read mutex for synchronization.
     pthread_mutex_t uplink_mutex;
 
-    /// Conditional to signal uplink read complete
+    /// Conditional to signal uplink read complete.
     pthread_cond_t uplink_cond;
 
     /// Output buffer.
@@ -10941,11 +10941,11 @@ int iscsi_scsi_pr_in(iscsi_scsi_task *scsi_task, iscsi_scsi_pr_reserve_in_parame
 int iscsi_scsi_pr_reserve_scsi2(iscsi_scsi_task *scsi_task, const iscsi_scsi_cdb_pr_reserve_6 *cdb_pr_reserve_6); // Reserves an iSCSI SCSI Persistent Reservation (PR) of an iSCSI SCSI task
 int iscsi_scsi_pr_release_scsi2(iscsi_scsi_task *scsi_task); // Releases an iSCSI SCSI Persistent Reservation (PR) of an iSCSI SCSI task
 
-int iscsi_scsi_emu_io_block_read(iscsi_scsi_task *scsi_task, uint8_t *buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data); // Reads a number of blocks from a block offset of a DNBD3 image to a specified buffer
+int iscsi_scsi_emu_io_block_read(iscsi_scsi_task *scsi_task, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data); // Reads a number of blocks from a block offset of a DNBD3 image to a specified buffer
 uint8_t *iscsi_scsi_emu_block_read_complete_callback(dnbd3_image_t *image, uint8_t *user_data, const bool success); // Completes an iSCSI SCSI task after a finished I/O read operation
-int iscsi_scsi_emu_io_block_cmp_write(iscsi_scsi_task *scsi_task, uint8_t *buf, uint8_t *cmp_buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data); // Compares and writes a number of blocks starting from a block offset in a DNBD3 image with specified buffers
+int iscsi_scsi_emu_io_block_cmp_write(iscsi_scsi_task *scsi_task, uint8_t *cmp_buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data); // Compares and writes a number of blocks starting from a block offset in a DNBD3 image with specified buffers
 uint8_t *iscsi_scsi_emu_block_write_complete_callback(dnbd3_image_t *image, uint8_t *user_data, const bool success); // Completes an iSCSI SCSI task after a finished I/O write operation
-int iscsi_scsi_emu_io_block_write(iscsi_scsi_task *scsi_task, uint8_t *buf, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data); // Writes a number of blocks from a block offset to a DNBD3 image of a specified buffer
+int iscsi_scsi_emu_io_block_write(iscsi_scsi_task *scsi_task, dnbd3_image_t *image, const uint64_t offset_blocks, const uint64_t num_blocks, const uint32_t block_size, iscsi_scsi_emu_io_complete_callback callback, uint8_t *user_data); // Writes a number of blocks from a block offset to a DNBD3 image of a specified buffer
 int iscsi_scsi_emu_io_queue(iscsi_scsi_emu_io_wait *io_wait); // Enqueues an I/O wait in the thread pool to execute
 uint8_t *iscsi_scsi_emu_block_resubmit_process_callback(uint8_t *user_data); // Resubmits an iSCSI SCSI task for execution