2 files changed, 15 insertions, 11 deletions

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index e016e0906e1a..fba8b204e310 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 - 2006 Kai Makisara
+   Copyright 1992 - 2007 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 = "20061107";
+static const char *verstr = "20070203";
 
 #include <linux/module.h>
 
@@ -1168,6 +1168,7 @@ static int st_open(struct inode *inode, struct file *filp)
                 STps = &(STp->ps[i]);
                 STps->rw = ST_IDLE;
         }
+        STp->try_dio_now = STp->try_dio;
         STp->recover_count = 0;
         DEB( STp->nbr_waits = STp->nbr_finished = 0;
              STp->nbr_requests = STp->nbr_dio = STp->nbr_pages = STp->nbr_combinable = 0; )
@@ -1400,9 +1401,9 @@ static int setup_buffering(struct scsi_tape *STp, const char __user *buf,
         struct st_buffer *STbp = STp->buffer;
 
         if (is_read)
-                i = STp->try_dio && try_rdio;
+                i = STp->try_dio_now && try_rdio;
         else
-                i = STp->try_dio && try_wdio;
+                i = STp->try_dio_now && try_wdio;
 
         if (i && ((unsigned long)buf & queue_dma_alignment(
                                         STp->device->request_queue)) == 0) {
@@ -1599,7 +1600,7 @@ st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
                         STm->do_async_writes && STps->eof < ST_EOM_OK;
 
                 if (STp->block_size != 0 && STm->do_buffer_writes &&
-                    !(STp->try_dio && try_wdio) && STps->eof < ST_EOM_OK &&
+                    !(STp->try_dio_now && try_wdio) && STps->eof < ST_EOM_OK &&
                     STbp->buffer_bytes < STbp->buffer_size) {
                         STp->dirty = 1;
                         /* Don't write a buffer that is not full enough. */
@@ -1769,7 +1770,7 @@ static long read_tape(struct scsi_tape *STp, long count,
         if (STp->block_size == 0)
                 blks = bytes = count;
         else {
-                if (!(STp->try_dio && try_rdio) && STm->do_read_ahead) {
+                if (!(STp->try_dio_now && try_rdio) && STm->do_read_ahead) {
                         blks = (STp->buffer)->buffer_blocks;
                         bytes = blks * STp->block_size;
                 } else {
@@ -1948,10 +1949,12 @@ st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
                 goto out;
 
         STm = &(STp->modes[STp->current_mode]);
-        if (!(STm->do_read_ahead) && STp->block_size != 0 &&
-            (count % STp->block_size) != 0) {
-                retval = (-EINVAL);     /* Read must be integral number of blocks */
-                goto out;
+        if (STp->block_size != 0 && (count % STp->block_size) != 0) {
+                if (!STm->do_read_ahead) {
+                        retval = (-EINVAL);     /* Read must be integral number of blocks */
+                        goto out;
+                }
+                STp->try_dio_now = 0;  /* Direct i/o can't handle split blocks */
         }
 
         STps = &(STp->ps[STp->partition]);
diff --git a/drivers/scsi/st.h b/drivers/scsi/st.h
index 05a5cae126ec..50f3deb1f9ed 100644
--- a/drivers/scsi/st.h
+++ b/drivers/scsi/st.h
@@ -117,7 +117,8 @@ struct scsi_tape {
         unsigned char cln_sense_value;
         unsigned char cln_sense_mask;
         unsigned char use_pf;                   /* Set Page Format bit in all mode selects? */
-        unsigned char try_dio;                  /* try direct i/o? */
+        unsigned char try_dio;                  /* try direct i/o in general? */
+        unsigned char try_dio_now;              /* try direct i/o before next close? */
         unsigned char c_algo;                   /* compression algorithm */
         unsigned char pos_unknown;                      /* after reset position unknown */
         int tape_type;