From 1e773aeb99484a11d0b8537946fb723360dccf39 Mon Sep 17 00:00:00 2001 From: "Kenneth D. Merry" Date: Fri, 5 May 2017 21:29:28 +0000 Subject: [PATCH] When editing a mode page on a tape drive, do not clear the device specific parameter. Tape drives include write protect (WP), Buffered Mode and Speed settings in the device-specific parameter. Clearing this parameter on a mode select can have the effect of turning off write protect or buffered mode, or changing the speed setting of the tape drive. Disks report DPO/FUA support via the device specific parameter for MODE SENSE, but the bit is reserved for MODE SELECT. So we clear this for disks (and other non-tape devices) to avoid potential errors from the target device. sbin/camcontrol/modeedit.c: Clear the device-specific parameter in the mode page header if we're not operating on a tape drive. MFC after: 3 days Sponsored by: Spectra Logic --- sbin/camcontrol/modeedit.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/sbin/camcontrol/modeedit.c b/sbin/camcontrol/modeedit.c index b6365158b7cd..e7b877d7be85 100644 --- a/sbin/camcontrol/modeedit.c +++ b/sbin/camcontrol/modeedit.c @@ -629,8 +629,21 @@ editlist_save(struct cam_device *device, int dbd, int pc, int page, /* Recalculate headers & offsets. */ mh->data_length = 0; /* Reserved for MODE SELECT command. */ - mh->dev_spec = 0; /* Clear device-specific parameters. */ mh->blk_desc_len = 0; /* No block descriptors. */ + /* + * Tape drives include write protect (WP), Buffered Mode and Speed + * settings in the device-specific parameter. Clearing this + * parameter on a mode select can have the effect of turning off + * write protect or buffered mode, or changing the speed setting of + * the tape drive. + * + * Disks report DPO/FUA support via the device specific parameter + * for MODE SENSE, but the bit is reserved for MODE SELECT. So we + * clear this for disks (and other non-tape devices) to avoid + * potential errors from the target device. + */ + if (device->pd_type != T_SEQUENTIAL) + mh->dev_spec = 0; mph = MODE_PAGE_HEADER(mh); mph->page_code &= ~SMPH_PS; /* Reserved for MODE SELECT command. */