> http://marc.theaimsgroup.com/?l=linux-scsi&m=106813641032686
> List: linux-scsi
> Subject: Re: [PATCH] CDC_MMC_WR
> Date: 2003-11-06 16:32:35
The inline text patch of this email concretely demoes why I think the sr
cd->device->writeable bit becomes vestigial - has no remaining purpose -
once we branch on CDC_MMC_WR instead of cd->device->writeable to decide
to pass thru or reject writes.
This patch differs from that simpler CDC_MMC_WR patch by updating sr
cd->device->writeable bit whenever cdrom corrects the sr guess of
CDC_MMC_WR via op x46 GPCMD_GET_CONFIGURATION.
But as far as I can tell, Linux works no better when I add this
complication. Can anyone educate me differently? I need to learn
something new before I can understand that offline suggestion of "have
the ->writeable bit actually be set if the device is writeable".
Running this code against ATAPI/USB DVD/CD of various kinds, I notice
sr_cdi_notify always clears cd->device->writeable. This consequence
arises naturally from the fact that this patch calls cdo->cdi_notify
only after cdi->mask |= CDC_MMC_WR.
Pat LaVarre x4402
diff -Nur linux-2.6.0-test9/drivers/cdrom/cdrom.c linux/drivers/cdrom/cdrom.c
--- linux-2.6.0-test9/drivers/cdrom/cdrom.c 2003-10-25 12:43:01.000000000
-0600
+++ linux/drivers/cdrom/cdrom.c 2003-11-06 16:18:55.470432000 -0700
@@ -313,6 +313,7 @@
#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);
@@ -365,6 +366,7 @@
ENSURE(audio_ioctl, CDC_PLAY_AUDIO);
ENSURE(dev_ioctl, CDC_IOCTLS);
ENSURE(generic_packet, CDC_GENERIC_PACKET);
+/* ENSURE(cdi_notify, CDC_); */
cdi->mc_flags = 0;
cdo->n_minors = 0;
cdi->options = CDO_USE_FFLAGS;
@@ -381,6 +383,8 @@
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 +412,52 @@
return 0;
}
+static int cdrom_get_configuration(struct cdrom_device_info *cdi)
+{
+ struct cdrom_generic_command cgc;
+ struct cdrom_device_ops *cdo = cdi->ops;
+ u_char buf[8];
+ int ret;
+ init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
+ 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) {
+ int profile = buf[6] << 8 | buf[7];
+ cdinfo(CD_REG_UNREG, "/dev/%s: "
+ "MMC profile x%04X\n", cdi->name, 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 */
+ return 0;
+ case 0x001A: /* DVD+RW = not much rewrite in place */
+ default:
+ break;
+ }
+ }
+ cdi->mask |= CDC_MMC_WR;
+ if (cdo->cdi_notify != NULL) cdo->cdi_notify(cdi);
+ return ret; /* ret may here be zero */
+}
+
+static void cdrom_get_cdc(struct cdrom_device_info *cdi)
+{
+ if (CDROM_CAN(CDC_MMC_WR) && !CDROM_CAN(CDC_DVD_RAM)) {
+ cdinfo(CD_REG_UNREG, "/dev/%s: "
+ "cdrom_get_configuration\n", cdi->name);
+ if (cdrom_get_configuration(cdi)) {
+ cdinfo(CD_REG_UNREG, "/dev/%s: "
+ "cdrom_get_configuration not\n", cdi->name);
+ }
+ }
+}
+
/* 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 +476,9 @@
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 +2457,10 @@
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-test9/include/linux/cdrom.h linux/include/linux/cdrom.h
--- linux-2.6.0-test9/include/linux/cdrom.h 2003-10-25 12:42:47.000000000
-0600
+++ linux/include/linux/cdrom.h 2003-11-06 14:47:52.000000000 -0700
@@ -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 */
@@ -773,6 +774,7 @@
/* handle uniform packets for scsi type devices (scsi,atapi) */
int (*generic_packet) (struct cdrom_device_info *,
struct cdrom_generic_command *);
+ void (*cdi_notify) (struct cdrom_device_info *);
};
/* the general block_device operations structure: */
diff -Nur linux-2.6.0-test9/drivers/ide/ide-cd.c linux/drivers/ide/ide-cd.c
--- linux-2.6.0-test9/drivers/ide/ide-cd.c 2003-10-25 12:43:32.000000000
-0600
+++ linux/drivers/ide/ide-cd.c 2003-11-06 14:48:18.000000000 -0700
@@ -2822,7 +2822,8 @@
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,
+ .cdi_notify = NULL,
.generic_packet = ide_cdrom_packet,
};
diff -Nur linux-2.6.0-test9/drivers/scsi/sr.c linux/drivers/scsi/sr.c
--- linux-2.6.0-test9/drivers/scsi/sr.c 2003-10-25 12:43:12.000000000 -0600
+++ linux/drivers/scsi/sr.c 2003-11-06 15:04:33.000000000 -0700
@@ -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 *);
@@ -94,6 +95,7 @@
static int sr_media_change(struct cdrom_device_info *, int);
static int sr_packet(struct cdrom_device_info *, struct cdrom_generic_command
*);
+static void sr_cdi_notify(struct cdrom_device_info *);
static struct cdrom_device_ops sr_dops = {
.open = sr_open,
@@ -110,9 +112,23 @@
.dev_ioctl = sr_dev_ioctl,
.capability = SR_CAPABILITIES,
.generic_packet = sr_packet,
+ .cdi_notify = sr_cdi_notify,
};
/*
+ * sr_cdi_notify carelessly accepts any cdi change whatsoever,
+ * and copies CDC_MMC_WR-not-masked into writeable more often than useful.
+ */
+
+static void sr_cdi_notify(struct cdrom_device_info *cdi)
+{
+ struct scsi_cd *cd = cdi->handle;
+ cd->device->writeable = ((cd->cdi.mask & CDC_MMC_WR) == 0);
+ printk("/dev/%s: sr_cdi_notify: writeable %d\n",
+ cdi->name, cd->device->writeable);
+}
+
+/*
* This function checks to see if the media has been changed in the
* CDROM drive. It is possible that we have already sensed a change,
* or the drive may have sensed one and not yet reported it. We must
@@ -327,8 +343,9 @@
}
if (rq_data_dir(SCpnt->request) == WRITE) {
- if (!cd->device->writeable)
+ if ((cd->cdi.mask & CDC_MMC_WR) != 0) {
return 0;
+ }
SCpnt->cmnd[0] = WRITE_10;
SCpnt->sc_data_direction = SCSI_DATA_WRITE;
} else if (rq_data_dir(SCpnt->request) == READ) {
@@ -557,6 +574,7 @@
sdev->sector_size = 2048; /* A guess, just in case */
/* FIXME: need to handle a get_capabilities failure properly ?? */
+ cd->device->writeable = 1; /* ((cd->cdi.mask & CDC_MMC_WR) == 0); */
get_capabilities(cd);
sr_vendor_init(cd);
@@ -788,8 +806,6 @@
if ((buffer[n + 3] & 0x20) == 0) {
/* can't write DVD-RAM media */
cd->cdi.mask |= CDC_DVD_RAM;
- } else {
- cd->device->writeable = 1;
}
if ((buffer[n + 3] & 0x10) == 0)
/* can't write DVD-R media */
-
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