From: John McKell <mckellj@iomega.com>
This 2.6.1 patch works by setting gendisk->policy to the correct value
during initialization as the various drivers decide whether or not the disk
is writeable. This patch persuades "blockdev --getro ..." to correctly
report the read-only state of a newly inserted disk. This patch applies to
sr.c, sd.c and ide-floppy.c. ide-cd.c already has this functionality built
into it.
Using an Iomega Zip drive as the test case...
Without the patch, I always see:
$ sudo blockdev --getro /dev/sda
0
$
That's only correct for writeable disks though. Only when the patch
is applied do I see a write-protected disk described correctly:
$ sudo blockdev --getro /dev/sda
1
$
---
drivers/ide/ide-floppy.c | 1 +
drivers/scsi/sd.c | 2 ++
drivers/scsi/sr.c | 8 +++++++-
3 files changed, 10 insertions(+), 1 deletion(-)
diff -puN drivers/ide/ide-floppy.c~fix-blockdev-getro drivers/ide/ide-floppy.c
--- 25/drivers/ide/ide-floppy.c~fix-blockdev-getro 2004-01-22 00:48:39.000000000 -0800
+++ 25-akpm/drivers/ide/ide-floppy.c 2004-01-22 00:48:39.000000000 -0800
@@ -1317,6 +1317,7 @@ static int idefloppy_get_flexible_disk_p
}
header = (idefloppy_mode_parameter_header_t *) pc.buffer;
floppy->wp = header->wp;
+ set_disk_ro(drive->disk, floppy->wp);
page = (idefloppy_flexible_disk_page_t *) (header + 1);
page->transfer_rate = ntohs(page->transfer_rate);
diff -puN drivers/scsi/sd.c~fix-blockdev-getro drivers/scsi/sd.c
--- 25/drivers/scsi/sd.c~fix-blockdev-getro 2004-01-22 00:48:39.000000000 -0800
+++ 25-akpm/drivers/scsi/sd.c 2004-01-22 00:48:39.000000000 -0800
@@ -1093,6 +1093,7 @@ sd_read_write_protect_flag(struct scsi_d
int res;
struct scsi_mode_data data;
+ set_disk_ro(sdkp->disk, 0);
if (sdkp->device->skip_ms_page_3f) {
printk(KERN_NOTICE "%s: assuming Write Enabled\n", diskname);
return;
@@ -1124,6 +1125,7 @@ sd_read_write_protect_flag(struct scsi_d
"%s: test WP failed, assume Write Enabled\n", diskname);
} else {
sdkp->write_prot = ((data.device_specific & 0x80) != 0);
+ set_disk_ro(sdkp->disk, sdkp->write_prot);
printk(KERN_NOTICE "%s: Write Protect is %s\n", diskname,
sdkp->write_prot ? "on" : "off");
printk(KERN_DEBUG "%s: Mode Sense: %02x %02x %02x %02x\n",
diff -puN drivers/scsi/sr.c~fix-blockdev-getro drivers/scsi/sr.c
--- 25/drivers/scsi/sr.c~fix-blockdev-getro 2004-01-22 00:48:39.000000000 -0800
+++ 25-akpm/drivers/scsi/sr.c 2004-01-22 00:49:29.000000000 -0800
@@ -712,6 +712,9 @@ static void get_capabilities(struct scsi
""
};
+ /* Set read only initially */
+ set_disk_ro(cd->disk, 1);
+
/* allocate a request for the TEST_UNIT_READY */
SRpnt = scsi_allocate_request(cd->device, GFP_KERNEL);
if (!SRpnt) {
@@ -825,8 +828,11 @@ static void get_capabilities(struct scsi
/*
* if DVD-RAM of MRW-W, we are randomly writeable
*/
- if ((cd->cdi.mask & (CDC_DVD_RAM | CDC_MRW_W)) != (CDC_DVD_RAM | CDC_MRW_W))
+ if ((cd->cdi.mask & (CDC_DVD_RAM | CDC_MRW_W)) !=
+ (CDC_DVD_RAM | CDC_MRW_W)) {
cd->device->writeable = 1;
+ set_disk_ro(cd->disk, 0);
+ }
scsi_release_request(SRpnt);
kfree(buffer);
_