[PATCH 1/2] SCSI tape: fix buffer position in partial write

[PATCH 1/2] SCSI tape: fix buffer position in partial write

[Kai Makisara]

Move buffer pointer back when data could not be written. Bug found by Mike Christie.

Signed-off-by: Kai Makisara <kai.makisara@kolumbus.fi>
---
The patch is against 2.6.26-rc1.

 drivers/scsi/st.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-2.6.26-rc1-q/drivers/scsi/st.c
===================================================================
--- linux-2.6.26-rc1-q.orig/drivers/scsi/st.c
+++ linux-2.6.26-rc1-q/drivers/scsi/st.c
@@ -17,7 +17,7 @@
    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
  */
 
-static const char *verstr = "20080224";
+static const char *verstr = "20080504";
 
 #include <linux/module.h>
 
@@ -1663,6 +1663,7 @@ st_write(struct file *filp, const char _
 				if (undone <= do_count) {
 					/* Only data from this write is not written */
 					count += undone;
+					b_point -= undone;
 					do_count -= undone;
 					if (STp->block_size)
 						blks = (transfer - undone) / STp->block_size;

Re: [PATCH 1/2] SCSI tape: fix buffer position in partial write

[Kai Makisara]

Mike Christie noticed a bogus memset. It can be removed as dead code since the
number of bytes in the driver buffer in fixed block mode is always a multiple
of the tape block size.

Signed-off-by: Kai Makisara <kai.makisara@kolumbus.fi>
---
The patch is against 2.6.26-rc1.

 drivers/scsi/st.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

Index: linux-2.6.26-rc1-q/drivers/scsi/st.c
===================================================================
--- linux-2.6.26-rc1-q.orig/drivers/scsi/st.c
+++ linux-2.6.26-rc1-q/drivers/scsi/st.c
@@ -630,7 +630,7 @@ static int cross_eof(struct scsi_tape * 
 /* Flush the write buffer (never need to write if variable blocksize). */
 static int st_flush_write_buffer(struct scsi_tape * STp)
 {
-	int offset, transfer, blks;
+	int transfer, blks;
 	int result;
 	unsigned char cmd[MAX_COMMAND_SIZE];
 	struct st_request *SRpnt;
@@ -643,14 +643,10 @@ static int st_flush_write_buffer(struct 
 	result = 0;
 	if (STp->dirty == 1) {
 
-		offset = (STp->buffer)->buffer_bytes;
-		transfer = ((offset + STp->block_size - 1) /
-			    STp->block_size) * STp->block_size;
+		transfer = STp->buffer->buffer_bytes;
                 DEBC(printk(ST_DEB_MSG "%s: Flushing %d bytes.\n",
                                tape_name(STp), transfer));
 
-		memset((STp->buffer)->b_data + offset, 0, transfer - offset);
-
 		memset(cmd, 0, MAX_COMMAND_SIZE);
 		cmd[0] = WRITE_6;
 		cmd[1] = 1;