[SCSI] st: add MTWEOFI to write filemarks without flushing drive buffer

This patch adds a new MTIOCTOP operation MTWEOFI that writes filemarks with
immediate bit set. This means that the drive does not flush its buffer and the
next file can be started immediately. This speeds up writing in applications
that have to write multiple small files.

Signed-off-by: Kai Makisara <kai.makisara@kolumbus.fi>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 24211d0efa6d..9e2c3a72ff4d 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -9,7 +9,7 @@
    Steve Hirsch, Andreas Koppenh"ofer, Michael Leodolter, Eyal Lebedinsky,
    Michael Schaefer, J"org Weule, and Eric Youngdale.
 
-   Copyright 1992 - 2008 Kai Makisara
+   Copyright 1992 - 2010 Kai Makisara
    email Kai.Makisara@kolumbus.fi
 
    Some small formal changes - aeb, 950809
@@ -17,7 +17,7 @@
    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
  */
 
-static const char *verstr = "20081215";
+static const char *verstr = "20100829";
 
 #include <linux/module.h>
 
@@ -2696,18 +2696,21 @@ static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned lon
                 }
                 break;
         case MTWEOF:
+        case MTWEOFI:
         case MTWSM:
                 if (STp->write_prot)
                         return (-EACCES);
                 cmd[0] = WRITE_FILEMARKS;
                 if (cmd_in == MTWSM)
                         cmd[1] = 2;
+                if (cmd_in == MTWEOFI)
+                        cmd[1] |= 1;
                 cmd[2] = (arg >> 16);
                 cmd[3] = (arg >> 8);
                 cmd[4] = arg;
                 timeout = STp->device->request_queue->rq_timeout;
                 DEBC(
-                     if (cmd_in == MTWEOF)
+                     if (cmd_in != MTWSM)
                                printk(ST_DEB_MSG "%s: Writing %d filemarks.\n", name,
                                  cmd[2] * 65536 + cmd[3] * 256 + cmd[4]);
                      else
@@ -2883,8 +2886,8 @@ static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned lon
                 else if (chg_eof)
                         STps->eof = ST_NOEOF;
 
-                if (cmd_in == MTWEOF)
-                        STps->rw = ST_IDLE;
+                if (cmd_in == MTWEOF || cmd_in == MTWEOFI)
+                        STps->rw = ST_IDLE;  /* prevent automatic WEOF at close */
         } else { /* SCSI command was not completely successful. Don't return
                     from this block without releasing the SCSI command block! */
                 struct st_cmdstatus *cmdstatp = &STp->buffer->cmdstat;
@@ -2901,7 +2904,7 @@ static int st_int_ioctl(struct scsi_tape *STp, unsigned int cmd_in, unsigned lon
                 else
                         undone = 0;
 
-                if (cmd_in == MTWEOF &&
+                if ((cmd_in == MTWEOF || cmd_in == MTWEOFI) &&
                     cmdstatp->have_sense &&
                     (cmdstatp->flags & SENSE_EOM)) {
                         if (cmdstatp->sense_hdr.sense_key == NO_SENSE ||