[PATCH] CDC_MMC_WR

[Pat LaVarre <p.lavarre@ieee.org>]

Jens A:

> > > Please add ...
> > > to cdrom.c instead ... GPCMD_GET_CONFIGURATION
> > 
> > Happily will do.  I'll continue to reply
> > as I progress or not.
>
> Great, thanks.

Please tell me what we think of this new patch?

You can see I've guessed I now should launch a new thread. The
linux-scsi thread "writable mmc profiles actually are writable" walked
us thru every painful step of me learning to write this patch.

So far I see Three design goals:

a) Add CDC_MMC_WR, masked by default, to: include/cdrom.h, to
drivers/ide/ide-cd.c, and to drivers/scsi/sr.c.

b) Correct device->writeable in sr.c sometime after
drivers/cdrom/cdrom.c discovers it was wrong.

c) Teach cdrom.c to discover CDC_MMC_WR.

That last goal I see divide into Eight changes to cdrom.c:

c1) Refuse to pass thru writes only if CDC_MMC_WR, no matter
CDC_DVD_RAM.

c2) Define cdrom_get_cdc and call cdrom_get_cdc only if register_cdrom
succeeds, just before register_cdrom does succeed.

c3) In cdrom_get_cdc, say &= ~CDC_MMC_WR if ide-cd or sr said &=
~CDC_DVD_RAM.

c4) In cdrom_get_cdc, also say &= ~CDC_MMC_WR if cdrom_get_capabilities
ok and cdrom_get_configuration ok and the profile fetched is any one of
the seven standard "random writable" profiles of mmc except not the
x001A dvd+rw profile that maybe can't be overwritten more than 1000
times in place, per Andy Polyakov's:
http://fy.chalmers.se/~appro/linux/DVD+RW/#udf

c5) Define cdrom_get_capabilities in terms of cdrom_mode_sense by
block-copy-edit of other cdrom.c source.

c6) Define cdrom_get_configuration in terms of cdo->generic_packet by
block-copy-edit of other cdrom.c source

c7) Add a line of text to /proc/sys/dev/cdrom/info to reveal CDC_MMC_WR.

c8) Update change history, REVISION, VERSION.

Please tell me what we think of this new patch?

Pat LaVarre

diff -Nur linux-2.6.0-test7/drivers/cdrom/cdrom.c linux/drivers/cdrom/cdrom.c
--- linux-2.6.0-test7/drivers/cdrom/cdrom.c	2003-10-08 13:24:02.000000000 -0600
+++ linux/drivers/cdrom/cdrom.c	2003-10-10 18:05:25.343260848 -0600
@@ -228,10 +228,13 @@
    3.12 Oct 18, 2000 - Jens Axboe <axboe@suse.de>
   -- Use quiet bit on packet commands not known to work
 
+   3.13 Oct 10, 2003 - Jens Axboe <axboe@suse.de>
+  -- Pass writes thru to all CDC_MMC_WR profiles, not just CDC_DVD_RAM.
+
 -------------------------------------------------------------------------*/
 
-#define REVISION "Revision: 3.12"
-#define VERSION "Id: cdrom.c 3.12 2000/10/18"
+#define REVISION "Revision: 3.13"
+#define VERSION "Id: cdrom.c 3.13 2003/10/10"
 
 /* I use an error-log mask to give fine grain control over the type of
    messages dumped to the system logs.  The available masks include: */
@@ -313,6 +316,7 @@
 #define CHECKAUDIO if ((ret=check_for_audio_disc(cdi, cdo))) return ret
 
 /* Not-exported routines. */
+static void cdrom_get_cdc(struct cdrom_device_info *cdi);
 static int open_for_data(struct cdrom_device_info * cdi);
 static int check_for_audio_disc(struct cdrom_device_info * cdi,
 			 struct cdrom_device_ops * cdo);
@@ -381,6 +385,8 @@
 	cdinfo(CD_REG_UNREG, "drive \"/dev/%s\" registered\n", cdi->name);
 	cdi->next = topCdromPtr; 	
 	topCdromPtr = cdi;
+
+	cdrom_get_cdc(cdi);
 	return 0;
 }
 #undef ENSURE
@@ -408,6 +414,71 @@
 	return 0;
 }
 
+static int cdrom_get_capabilities(struct cdrom_device_info *cdi)
+{
+	struct cdrom_generic_command cgc0;
+	struct cdrom_generic_command * cgc = &cgc0;
+	u_char buf[0x18]; /* ide-cd length = x18, sr length = x80 */
+	int ret;
+	memset(cgc, 0, sizeof *cgc);
+	memset(&buf[0], 0, sizeof(buf));
+	cgc->buffer = buf;
+	cgc->buflen = sizeof buf;
+	ret = cdrom_mode_sense(cdi, cgc, GPMODE_CAPABILITIES_PAGE, 0);
+	return ret;
+}
+
+static int cdrom_get_configuration(struct cdrom_device_info *cdi)
+{
+	struct cdrom_generic_command cgc0;
+	struct cdrom_generic_command * cgc = &cgc0;
+	struct cdrom_device_ops *cdo = cdi->ops;
+	u_char buf[8];
+	int ret;
+	int profile;
+	memset(cgc, 0, sizeof *cgc);
+	memset(&buf[0], 0, sizeof(buf));
+	cgc->buffer = buf;
+	cgc->buflen = sizeof buf;
+	cgc->cmd[0] = GPCMD_GET_CONFIGURATION;
+	cgc->cmd[7] = cgc->buflen >> 8;
+	cgc->cmd[8] = cgc->buflen & 0xff;
+	cgc->data_direction = CGC_DATA_READ;
+	ret = cdo->generic_packet(cdi, cgc);
+	if (ret) return ret;
+	profile = buf[6] << 8 | buf[7];
+	cdinfo(CD_REG_UNREG, "profile x%04X\n", profile);
+	switch (profile) {
+		case 0x0001: /* Non-Removable Disk */
+		case 0x0002: /* Removable Disk */
+		case 0x0003: /* Magneto-Optical Erasable */
+		case 0x0005: /* AS-MO */
+		case 0x0012: /* DVD-RAM */
+		case 0x0022: /* DDCD-RW */
+			cdi->mask &= ~CDC_MMC_WR;
+			break;
+		case 0x001A: /* DVD+RW = not very rewritable in place */
+			break;
+		default:
+			break;
+	}
+	return ret;
+}
+
+static void cdrom_get_cdc(struct cdrom_device_info *cdi)
+{
+	cdinfo(CD_REG_UNREG, "cdrom_get_cdc\n");
+	if (CDROM_CAN(CDC_DVD_RAM)) {
+		cdi->mask &= ~CDC_MMC_WR;
+	} else if (cdrom_get_capabilities(cdi)) {
+		cdinfo(CD_WARNING,  "GET_CAPABILITIES not\n");
+	} else {
+		if (cdrom_get_configuration(cdi)) {
+			cdinfo(CD_WARNING,  "GET_CONFIGURATION not\n");
+		}
+	}
+}
+
 /* We use the open-option O_NONBLOCK to indicate that the
  * purpose of opening is only for subsequent ioctl() calls; no device
  * integrity checks are performed.
@@ -426,8 +497,9 @@
 	if ((fp->f_flags & O_NONBLOCK) && (cdi->options & CDO_USE_FFLAGS))
 		ret = cdi->ops->open(cdi, 1);
 	else {
-		if ((fp->f_mode & FMODE_WRITE) && !CDROM_CAN(CDC_DVD_RAM))
+		if ((fp->f_mode & FMODE_WRITE) && !CDROM_CAN(CDC_MMC_WR)) {
 			return -EROFS;
+		}
 
 		ret = open_for_data(cdi);
 	}
@@ -2406,6 +2478,10 @@
 	for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
 	    pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_DVD_RAM) != 0);
 
+	pos += sprintf(info+pos, "\nTolerates random write:");
+	for (cdi=topCdromPtr;cdi!=NULL;cdi=cdi->next)
+	    pos += sprintf(info+pos, "\t%d", CDROM_CAN(CDC_MMC_WR) != 0);
+
 	strcpy(info+pos,"\n\n");
 		
         return proc_dostring(ctl, write, filp, buffer, lenp);
diff -Nur linux-2.6.0-test7/include/linux/cdrom.h linux/include/linux/cdrom.h
--- linux-2.6.0-test7/include/linux/cdrom.h	2003-10-08 13:24:00.000000000 -0600
+++ linux/include/linux/cdrom.h	2003-10-10 15:37:16.000000000 -0600
@@ -388,6 +388,7 @@
 #define CDC_DVD_R		0x10000	/* drive can write DVD-R */
 #define CDC_DVD_RAM		0x20000	/* drive can write DVD-RAM */
 #define CDC_MO_DRIVE		0x40000 /* drive is an MO device */
+#define CDC_MMC_WR		0x80000	/* profile includes random write */
 
 /* drive status possibilities returned by CDROM_DRIVE_STATUS ioctl */
 #define CDS_NO_INFO		0	/* if not implemented */
diff -Nur linux-2.6.0-test7/drivers/ide/ide-cd.c linux/drivers/ide/ide-cd.c
--- linux-2.6.0-test7/drivers/ide/ide-cd.c	2003-10-08 13:24:04.000000000 -0600
+++ linux/drivers/ide/ide-cd.c	2003-10-10 15:36:33.000000000 -0600
@@ -2822,7 +2822,7 @@
 				CDC_MEDIA_CHANGED | CDC_PLAY_AUDIO | CDC_RESET |
 				CDC_IOCTLS | CDC_DRIVE_STATUS | CDC_CD_R |
 				CDC_CD_RW | CDC_DVD | CDC_DVD_R| CDC_DVD_RAM |
-				CDC_GENERIC_PACKET | CDC_MO_DRIVE,
+				CDC_GENERIC_PACKET | CDC_MO_DRIVE | CDC_MMC_WR,
 	.generic_packet		= ide_cdrom_packet,
 };
 
@@ -2832,7 +2832,7 @@
 	struct cdrom_device_info *devinfo = &info->devinfo;
 
 	devinfo->ops = &ide_cdrom_dops;
-	devinfo->mask = 0;
+	devinfo->mask = CDC_MMC_WR;
 	devinfo->speed = CDROM_STATE_FLAGS(drive)->current_speed;
 	devinfo->capacity = nslots;
 	devinfo->handle = (void *) drive;
diff -Nur linux-2.6.0-test7/drivers/scsi/sr.c linux/drivers/scsi/sr.c
--- linux-2.6.0-test7/drivers/scsi/sr.c	2003-10-08 13:24:03.000000000 -0600
+++ linux/drivers/scsi/sr.c	2003-10-10 15:48:12.000000000 -0600
@@ -67,7 +67,8 @@
 	(CDC_CLOSE_TRAY|CDC_OPEN_TRAY|CDC_LOCK|CDC_SELECT_SPEED| \
 	 CDC_SELECT_DISC|CDC_MULTI_SESSION|CDC_MCN|CDC_MEDIA_CHANGED| \
 	 CDC_PLAY_AUDIO|CDC_RESET|CDC_IOCTLS|CDC_DRIVE_STATUS| \
-	 CDC_CD_R|CDC_CD_RW|CDC_DVD|CDC_DVD_R|CDC_DVD_RAM|CDC_GENERIC_PACKET)
+	 CDC_CD_R|CDC_CD_RW|CDC_DVD|CDC_DVD_R|CDC_DVD_RAM|CDC_GENERIC_PACKET| \
+	 CDC_MMC_WR)
 
 static int sr_probe(struct device *);
 static int sr_remove(struct device *);
@@ -327,8 +328,12 @@
 	}
 
 	if (rq_data_dir(SCpnt->request) == WRITE) {
-		if (!cd->device->writeable)
-			return 0;
+		if (!cd->device->writeable) {
+			if ((cd->cdi.mask & CDC_MMC_WR) != 0) {
+				return 0;
+			}
+			cd->device->writeable = 1;
+		}
 		SCpnt->cmnd[0] = WRITE_10;
 		SCpnt->sc_data_direction = SCSI_DATA_WRITE;
 	} else if (rq_data_dir(SCpnt->request) == READ) {
@@ -550,7 +555,7 @@
 
 	cd->cdi.ops = &sr_dops;
 	cd->cdi.handle = cd;
-	cd->cdi.mask = 0;
+	cd->cdi.mask = CDC_MMC_WR;
 	cd->cdi.capacity = 1;
 	sprintf(cd->cdi.name, "sr%d", minor);