[SCSI] st: add option to use SILI in variable block reads

Add new option MT_ST_SILI to enable setting the SILI bit in reads in variable block mode. If SILI is set, reading a block shorter than the byte count does not result in CHECK CONDITION. The length of the block is determined using the residual count from the HBA. Avoiding the REQUEST SENSE command for every block speeds up some real applications considerably. Signed-off-by: Kai Makisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

[SCSI] st: add option to use SILI in variable block reads
Add new option MT_ST_SILI to enable setting the SILI bit in reads in variable block mode. If SILI is set, reading a block shorter than the byte count does not result in CHECK CONDITION. The length of the block is determined using the residual count from the HBA. Avoiding the REQUEST SENSE command for every block speeds up some real applications considerably. Signed-off-by: Kai Makisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Kai Makisara · James Bottomley
1 parent d35055a0f2
Showing 5 changed files with 51 additions and 6 deletions Side-by-side Diff
Documentation/scsi/st.txt
drivers/scsi/st.c
drivers/scsi/st.h
drivers/scsi/st_options.h
include/linux/mtio.h
@@ -2,7 +2,7 @@
 The driver is currently maintained by Kai Mäkisara (email
 Kai.Makisara@kolumbus.fi)
  
-Last modified: Mon Mar  7 21:14:44 2005 by kai.makisara
+Last modified: Thu Feb 21 21:54:16 2008 by kai.makisara
  
  
 BASICS
@@ -372,6 +372,11 @@
 	     MT_ST_SYSV sets the SYSV semantics (mode)
 	     MT_ST_NOWAIT enables immediate mode (i.e., don't wait for
 	        the command to finish) for some commands (e.g., rewind)
+	     MT_ST_SILI enables setting the SILI bit in SCSI commands when
+		reading in variable block mode to enhance performance when
+		reading blocks shorter than the byte count; set this only
+		if you are sure that the drive supports SILI and the HBA
+		correctly returns transfer residuals
 	     MT_ST_DEBUGGING debugging (global; debugging must be
 		compiled into the driver)
 	MT_ST_SETBOOLEANS
@@ -17,7 +17,7 @@
    Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
  */
  
-static const char *verstr = "20080221";
+static const char *verstr = "20080224";
  
 #include <linux/module.h>
  
@@ -183,6 +183,7 @@
  
 static struct st_buffer *new_tape_buffer(int, int, int);
 static int enlarge_buffer(struct st_buffer *, int, int);
+static void clear_buffer(struct st_buffer *);
 static void normalize_buffer(struct st_buffer *);
 static int append_to_buffer(const char __user *, struct st_buffer *, int);
 static int from_buffer(struct st_buffer *, char __user *, int);
@@ -442,6 +443,7 @@
  
 	memcpy(SRpnt->sense, sense, SCSI_SENSE_BUFFERSIZE);
 	(STp->buffer)->cmdstat.midlevel_result = SRpnt->result = result;
+	(STp->buffer)->cmdstat.residual = resid;
 	DEB( STp->write_pending = 0; )
  
 	if (SRpnt->waiting)
@@ -1159,6 +1161,7 @@
 		goto err_out;
 	}
  
+	(STp->buffer)->cleared = 0;
 	(STp->buffer)->writing = 0;
 	(STp->buffer)->syscall_result = 0;
  
  
@@ -1432,8 +1435,14 @@
 		if (STp->block_size)
 			bufsize = STp->block_size > st_fixed_buffer_size ?
 				STp->block_size : st_fixed_buffer_size;
-		else
+		else {
 			bufsize = count;
+			/* Make sure that data from previous user is not leaked even if
+			   HBA does not return correct residual */
+			if (is_read && STp->sili && !STbp->cleared)
+				clear_buffer(STbp);
+		}
+
 		if (bufsize > STbp->buffer_size &&
 		    !enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
 			printk(KERN_WARNING "%s: Can't allocate %d byte tape buffer.\n",
@@ -1783,6 +1792,8 @@
 	memset(cmd, 0, MAX_COMMAND_SIZE);
 	cmd[0] = READ_6;
 	cmd[1] = (STp->block_size != 0);
+	if (!cmd[1] && STp->sili)
+		cmd[1] |= 2;
 	cmd[2] = blks >> 16;
 	cmd[3] = blks >> 8;
 	cmd[4] = blks;
  
@@ -1911,8 +1922,11 @@
  
 	}
 	/* End of error handling */ 
-	else			/* Read successful */
+	else {			/* Read successful */
 		STbp->buffer_bytes = bytes;
+		if (STp->sili) /* In fixed block mode residual is always zero here */
+			STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
+	}
  
 	if (STps->drv_block >= 0) {
 		if (STp->block_size == 0)
@@ -2090,7 +2104,8 @@
 		       name, STm->defaults_for_writes, STp->omit_blklims, STp->can_partitions,
 		       STp->scsi2_logical);
 		printk(KERN_INFO
-		       "%s:    sysv: %d nowait: %d\n", name, STm->sysv, STp->immediate);
+		       "%s:    sysv: %d nowait: %d sili: %d\n", name, STm->sysv, STp->immediate,
+			STp->sili);
 		printk(KERN_INFO "%s:    debugging: %d\n",
 		       name, debugging);
 	}
@@ -2133,6 +2148,7 @@
 		STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
 		STp->immediate = (options & MT_ST_NOWAIT) != 0;
 		STm->sysv = (options & MT_ST_SYSV) != 0;
+		STp->sili = (options & MT_ST_SILI) != 0;
 		DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
 		     st_log_options(STp, STm, name); )
 	} else if (code == MT_ST_SETBOOLEANS || code == MT_ST_CLEARBOOLEANS) {
@@ -2164,6 +2180,8 @@
 			STp->immediate = value;
 		if ((options & MT_ST_SYSV) != 0)
 			STm->sysv = value;
+		if ((options & MT_ST_SILI) != 0)
+			STp->sili = value;
                 DEB(
 		if ((options & MT_ST_DEBUGGING) != 0)
 			debugging = value;
@@ -3655,6 +3673,8 @@
 		STbuffer->frp_segs += 1;
 		got += b_size;
 		STbuffer->buffer_size = got;
+		if (STbuffer->cleared)
+			memset(page_address(STbuffer->frp[segs].page), 0, b_size);
 		segs++;
 	}
 	STbuffer->b_data = page_address(STbuffer->frp[0].page);
@@ -3663,6 +3683,17 @@
 }
  
  
+/* Make sure that no data from previous user is in the internal buffer */
+static void clear_buffer(struct st_buffer * st_bp)
+{
+	int i;
+
+	for (i=0; i < st_bp->frp_segs; i++)
+		memset(page_address(st_bp->frp[i].page), 0, st_bp->frp[i].length);
+	st_bp->cleared = 1;
+}
+
+
 /* Release the extra buffer */
 static void normalize_buffer(struct st_buffer * STbuffer)
 {
@@ -3987,6 +4018,7 @@
 	tpnt->two_fm = ST_TWO_FM;
 	tpnt->fast_mteom = ST_FAST_MTEOM;
 	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
+	tpnt->sili = ST_SILI;
 	tpnt->immediate = ST_NOWAIT;
 	tpnt->default_drvbuffer = 0xff;		/* No forced buffering */
 	tpnt->partition = 0;
@@ -12,6 +12,7 @@
 	int midlevel_result;
 	struct scsi_sense_hdr sense_hdr;
 	int have_sense;
+	int residual;
 	u64 uremainder64;
 	u8 flags;
 	u8 remainder_valid;
@@ -34,6 +35,7 @@
 struct st_buffer {
 	unsigned char dma;	/* DMA-able buffer */
 	unsigned char do_dio;   /* direct i/o set up? */
+	unsigned char cleared;  /* internal buffer cleared after open? */
 	int buffer_size;
 	int buffer_blocks;
 	int buffer_bytes;
@@ -122,6 +124,7 @@
 	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 */
+	unsigned char sili;			/* use SILI when reading in variable b mode */
 	int tape_type;
 	int long_timeout;	/* timeout for commands known to take long time */
  
@@ -3,7 +3,7 @@
  
    Copyright 1995-2003 Kai Makisara.
  
-   Last modified: Mon Apr  7 22:49:18 2003 by makisara
+   Last modified: Thu Feb 21 21:47:07 2008 by kai.makisara
 */
  
 #ifndef _ST_OPTIONS_H
@@ -93,6 +93,10 @@
 /* If ST_SYSV is non-zero, the tape behaves according to the SYS V semantics.
    The default is BSD semantics. */
 #define ST_SYSV 0
+
+/* If ST_SILI is non-zero, the SILI bit is set when reading in variable block
+   mode and the block size is determined using the residual returned by the HBA. */
+#define ST_SILI 0
  
 /* Time to wait for the drive to become ready if blocking open */
 #define ST_BLOCK_SECONDS     120
@@ -192,6 +192,7 @@
 #define MT_ST_SCSI2LOGICAL      0x800
 #define MT_ST_SYSV              0x1000
 #define MT_ST_NOWAIT            0x2000
+#define MT_ST_SILI		0x4000
  
 /* The mode parameters to be controlled. Parameter chosen with bits 20-28 */
 #define MT_ST_CLEAR_DEFAULT	0xfffff
...	...	@@ -2,7 +2,7 @@
2	2	The driver is currently maintained by Kai Mäkisara (email
3	3	Kai.Makisara@kolumbus.fi)
4	4
5		-Last modified: Mon Mar 7 21:14:44 2005 by kai.makisara
	5	+Last modified: Thu Feb 21 21:54:16 2008 by kai.makisara
6	6
7	7
8	8	BASICS
...	...	@@ -372,6 +372,11 @@
372	372	MT_ST_SYSV sets the SYSV semantics (mode)
373	373	MT_ST_NOWAIT enables immediate mode (i.e., don't wait for
374	374	the command to finish) for some commands (e.g., rewind)
	375	+ MT_ST_SILI enables setting the SILI bit in SCSI commands when
	376	+ reading in variable block mode to enhance performance when
	377	+ reading blocks shorter than the byte count; set this only
	378	+ if you are sure that the drive supports SILI and the HBA
	379	+ correctly returns transfer residuals
375	380	MT_ST_DEBUGGING debugging (global; debugging must be
376	381	compiled into the driver)
377	382	MT_ST_SETBOOLEANS
...	...	@@ -17,7 +17,7 @@
17	17	Last modified: 18-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Devfs support
18	18	*/
19	19
20		-static const char *verstr = "20080221";
	20	+static const char *verstr = "20080224";
21	21
22	22	#include <linux/module.h>
23	23
...	...	@@ -183,6 +183,7 @@
183	183
184	184	static struct st_buffer *new_tape_buffer(int, int, int);
185	185	static int enlarge_buffer(struct st_buffer *, int, int);
	186	+static void clear_buffer(struct st_buffer *);
186	187	static void normalize_buffer(struct st_buffer *);
187	188	static int append_to_buffer(const char __user , struct st_buffer , int);
188	189	static int from_buffer(struct st_buffer , char __user , int);
...	...	@@ -442,6 +443,7 @@
442	443
443	444	memcpy(SRpnt->sense, sense, SCSI_SENSE_BUFFERSIZE);
444	445	(STp->buffer)->cmdstat.midlevel_result = SRpnt->result = result;
	446	+ (STp->buffer)->cmdstat.residual = resid;
445	447	DEB( STp->write_pending = 0; )
446	448
447	449	if (SRpnt->waiting)
...	...	@@ -1159,6 +1161,7 @@
1159	1161	goto err_out;
1160	1162	}
1161	1163
	1164	+ (STp->buffer)->cleared = 0;
1162	1165	(STp->buffer)->writing = 0;
1163	1166	(STp->buffer)->syscall_result = 0;
1164	1167
1165	1168
...	...	@@ -1432,8 +1435,14 @@
1432	1435	if (STp->block_size)
1433	1436	bufsize = STp->block_size > st_fixed_buffer_size ?
1434	1437	STp->block_size : st_fixed_buffer_size;
1435		- else
	1438	+ else {
1436	1439	bufsize = count;
	1440	+ /* Make sure that data from previous user is not leaked even if
	1441	+ HBA does not return correct residual */
	1442	+ if (is_read && STp->sili && !STbp->cleared)
	1443	+ clear_buffer(STbp);
	1444	+ }
	1445	+
1437	1446	if (bufsize > STbp->buffer_size &&
1438	1447	!enlarge_buffer(STbp, bufsize, STp->restr_dma)) {
1439	1448	printk(KERN_WARNING "%s: Can't allocate %d byte tape buffer.\n",
...	...	@@ -1783,6 +1792,8 @@
1783	1792	memset(cmd, 0, MAX_COMMAND_SIZE);
1784	1793	cmd[0] = READ_6;
1785	1794	cmd[1] = (STp->block_size != 0);
	1795	+ if (!cmd[1] && STp->sili)
	1796	+ cmd[1] \|= 2;
1786	1797	cmd[2] = blks >> 16;
1787	1798	cmd[3] = blks >> 8;
1788	1799	cmd[4] = blks;
1789	1800
...	...	@@ -1911,8 +1922,11 @@
1911	1922
1912	1923	}
1913	1924	/* End of error handling */
1914		- else /* Read successful */
	1925	+ else { /* Read successful */
1915	1926	STbp->buffer_bytes = bytes;
	1927	+ if (STp->sili) /* In fixed block mode residual is always zero here */
	1928	+ STbp->buffer_bytes -= STp->buffer->cmdstat.residual;
	1929	+ }
1916	1930
1917	1931	if (STps->drv_block >= 0) {
1918	1932	if (STp->block_size == 0)
...	...	@@ -2090,7 +2104,8 @@
2090	2104	name, STm->defaults_for_writes, STp->omit_blklims, STp->can_partitions,
2091	2105	STp->scsi2_logical);
2092	2106	printk(KERN_INFO
2093		- "%s: sysv: %d nowait: %d\n", name, STm->sysv, STp->immediate);
	2107	+ "%s: sysv: %d nowait: %d sili: %d\n", name, STm->sysv, STp->immediate,
	2108	+ STp->sili);
2094	2109	printk(KERN_INFO "%s: debugging: %d\n",
2095	2110	name, debugging);
2096	2111	}
...	...	@@ -2133,6 +2148,7 @@
2133	2148	STp->scsi2_logical = (options & MT_ST_SCSI2LOGICAL) != 0;
2134	2149	STp->immediate = (options & MT_ST_NOWAIT) != 0;
2135	2150	STm->sysv = (options & MT_ST_SYSV) != 0;
	2151	+ STp->sili = (options & MT_ST_SILI) != 0;
2136	2152	DEB( debugging = (options & MT_ST_DEBUGGING) != 0;
2137	2153	st_log_options(STp, STm, name); )
2138	2154	} else if (code == MT_ST_SETBOOLEANS \|\| code == MT_ST_CLEARBOOLEANS) {
...	...	@@ -2164,6 +2180,8 @@
2164	2180	STp->immediate = value;
2165	2181	if ((options & MT_ST_SYSV) != 0)
2166	2182	STm->sysv = value;
	2183	+ if ((options & MT_ST_SILI) != 0)
	2184	+ STp->sili = value;
2167	2185	DEB(
2168	2186	if ((options & MT_ST_DEBUGGING) != 0)
2169	2187	debugging = value;
...	...	@@ -3655,6 +3673,8 @@
3655	3673	STbuffer->frp_segs += 1;
3656	3674	got += b_size;
3657	3675	STbuffer->buffer_size = got;
	3676	+ if (STbuffer->cleared)
	3677	+ memset(page_address(STbuffer->frp[segs].page), 0, b_size);
3658	3678	segs++;
3659	3679	}
3660	3680	STbuffer->b_data = page_address(STbuffer->frp[0].page);
...	...	@@ -3663,6 +3683,17 @@
3663	3683	}
3664	3684
3665	3685
	3686	+/* Make sure that no data from previous user is in the internal buffer */
	3687	+static void clear_buffer(struct st_buffer * st_bp)
	3688	+{
	3689	+ int i;
	3690	+
	3691	+ for (i=0; i < st_bp->frp_segs; i++)
	3692	+ memset(page_address(st_bp->frp[i].page), 0, st_bp->frp[i].length);
	3693	+ st_bp->cleared = 1;
	3694	+}
	3695	+
	3696	+
3666	3697	/* Release the extra buffer */
3667	3698	static void normalize_buffer(struct st_buffer * STbuffer)
3668	3699	{
...	...	@@ -3987,6 +4018,7 @@
3987	4018	tpnt->two_fm = ST_TWO_FM;
3988	4019	tpnt->fast_mteom = ST_FAST_MTEOM;
3989	4020	tpnt->scsi2_logical = ST_SCSI2LOGICAL;
	4021	+ tpnt->sili = ST_SILI;
3990	4022	tpnt->immediate = ST_NOWAIT;
3991	4023	tpnt->default_drvbuffer = 0xff; /* No forced buffering */
3992	4024	tpnt->partition = 0;
...	...	@@ -12,6 +12,7 @@
12	12	int midlevel_result;
13	13	struct scsi_sense_hdr sense_hdr;
14	14	int have_sense;
	15	+ int residual;
15	16	u64 uremainder64;
16	17	u8 flags;
17	18	u8 remainder_valid;
...	...	@@ -34,6 +35,7 @@
34	35	struct st_buffer {
35	36	unsigned char dma; /* DMA-able buffer */
36	37	unsigned char do_dio; /* direct i/o set up? */
	38	+ unsigned char cleared; /* internal buffer cleared after open? */
37	39	int buffer_size;
38	40	int buffer_blocks;
39	41	int buffer_bytes;
...	...	@@ -122,6 +124,7 @@
122	124	unsigned char try_dio_now; /* try direct i/o before next close? */
123	125	unsigned char c_algo; /* compression algorithm */
124	126	unsigned char pos_unknown; /* after reset position unknown */
	127	+ unsigned char sili; /* use SILI when reading in variable b mode */
125	128	int tape_type;
126	129	int long_timeout; /* timeout for commands known to take long time */
127	130
...	...	@@ -3,7 +3,7 @@
3	3
4	4	Copyright 1995-2003 Kai Makisara.
5	5
6		- Last modified: Mon Apr 7 22:49:18 2003 by makisara
	6	+ Last modified: Thu Feb 21 21:47:07 2008 by kai.makisara
7	7	*/
8	8
9	9	#ifndef _ST_OPTIONS_H
...	...	@@ -93,6 +93,10 @@
93	93	/* If ST_SYSV is non-zero, the tape behaves according to the SYS V semantics.
94	94	The default is BSD semantics. */
95	95	#define ST_SYSV 0
	96	+
	97	+/* If ST_SILI is non-zero, the SILI bit is set when reading in variable block
	98	+ mode and the block size is determined using the residual returned by the HBA. */
	99	+#define ST_SILI 0
96	100
97	101	/* Time to wait for the drive to become ready if blocking open */
98	102	#define ST_BLOCK_SECONDS 120
...	...	@@ -192,6 +192,7 @@
192	192	#define MT_ST_SCSI2LOGICAL 0x800
193	193	#define MT_ST_SYSV 0x1000
194	194	#define MT_ST_NOWAIT 0x2000
	195	+#define MT_ST_SILI 0x4000
195	196
196	197	/* The mode parameters to be controlled. Parameter chosen with bits 20-28 */
197	198	#define MT_ST_CLEAR_DEFAULT 0xfffff