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;
 };