target/file: Update hw_max_sectors based on current block_size

This patch allows FILEIO to update hw_max_sectors based on the current
max_bytes_per_io.  This is required because vfs_[writev,readv]() can accept
a maximum of 2048 iovecs per call, so the enforced hw_max_sectors really
needs to be calculated based on block_size.

This addresses a >= v3.5 bug where block_size=512 was rejecting > 1M
sized I/O requests, because FD_MAX_SECTORS was hardcoded to 2048 for
the block_size=4096 case.

(v2: Use max_bytes_per_io instead of ->update_hw_max_sectors)
Reported-by: Henrik Goldman <hg@x-formation.com>
Cc: <stable@vger.kernel.org> #3.5+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_device.c

@@ -1106,6 +1106,11 @@ int se_dev_set_block_size(struct se_device *dev, u32 block_size)
 	dev->dev_attrib.block_size = block_size;
 	pr_debug("dev[%p]: SE Device block_size changed to %u\n",
 			dev, block_size);
+
+	if (dev->dev_attrib.max_bytes_per_io)
+		dev->dev_attrib.hw_max_sectors =
+			dev->dev_attrib.max_bytes_per_io / block_size;
+
 	return 0;
 }
 

drivers/target/target_core_file.c

@@ -66,9 +66,8 @@ static int fd_attach_hba(struct se_hba *hba, u32 host_id)
 	pr_debug("CORE_HBA[%d] - TCM FILEIO HBA Driver %s on Generic"
 		" Target Core Stack %s\n", hba->hba_id, FD_VERSION,
 		TARGET_CORE_MOD_VERSION);
-	pr_debug("CORE_HBA[%d] - Attached FILEIO HBA: %u to Generic"
-		" MaxSectors: %u\n",
-		hba->hba_id, fd_host->fd_host_id, FD_MAX_SECTORS);
+	pr_debug("CORE_HBA[%d] - Attached FILEIO HBA: %u to Generic\n",
+		hba->hba_id, fd_host->fd_host_id);
 
 	return 0;
 }
@@ -220,7 +219,8 @@ static int fd_configure_device(struct se_device *dev)
 	}
 
 	dev->dev_attrib.hw_block_size = fd_dev->fd_block_size;
-	dev->dev_attrib.hw_max_sectors = FD_MAX_SECTORS;
+	dev->dev_attrib.max_bytes_per_io = FD_MAX_BYTES;
+	dev->dev_attrib.hw_max_sectors = FD_MAX_BYTES / fd_dev->fd_block_size;
 	dev->dev_attrib.hw_queue_depth = FD_MAX_DEVICE_QUEUE_DEPTH;
 
 	if (fd_dev->fbd_flags & FDBD_HAS_BUFFERED_IO_WCE) {

drivers/target/target_core_file.h

@@ -7,7 +7,10 @@
 #define FD_DEVICE_QUEUE_DEPTH	32
 #define FD_MAX_DEVICE_QUEUE_DEPTH 128
 #define FD_BLOCKSIZE		512
-#define FD_MAX_SECTORS		2048
+/*
+ * Limited by the number of iovecs (2048) per vfs_[writev,readv] call
+ */
+#define FD_MAX_BYTES		8388608
 
 #define RRF_EMULATE_CDB		0x01
 #define RRF_GOT_LBA		0x02

include/target/target_core_base.h

@@ -620,6 +620,7 @@ struct se_dev_attrib {
 	u32		unmap_granularity;
 	u32		unmap_granularity_alignment;
 	u32		max_write_same_len;
+	u32		max_bytes_per_io;
 	struct se_device *da_dev;
 	struct config_group da_group;
 };