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  1. 21 Dec, 2010 4 commits
    • Luben Tuikov's avatar
      [SCSI] Retrieve the Caching mode page · 24d720b7
      Luben Tuikov authored 
      Some kernel transport drivers unconditionally disable
retrieval of the Caching mode page. One such for example is
the BBB/CBI transport over USB.  Such a restraint is too
harsh as some devices do support the Caching mode
page. Unconditionally enabling the retrieval of this mode
page over those transports at their transport code level may
result in some devices failing and becoming unusable.

This patch implements a method of retrieving the Caching
mode page without unconditionally enabling it in the
transports which unconditionally disable it. The idea is to
ask for all supported pages, page code 0x3F, and then search
for the Caching mode page in the mode parameter data
returned. The sd driver already asks for all the mode pages
supported by the attached device by setting the page code to
0x3F in order to find out if the media is write protected by
reading the WP bit in the Device Specific Parameter
field. It then attempts to retrieve only the Caching mode
page by setting the page code to 8 and actually attempting
to retrieve it if and only if the transport allows it.

The method implemented here is that if the transport doesn't
allow retrieval of the Caching mode page and the device is
not RBC, then we ask for all pages supported by setting the
page code to 0x3F (similarly to how the WP bit is retrieved
above), and then we search for the Caching mode page in the
mode parameter data returned.

With this patch, devices over SATA, report this (no change):

Oct 22 18:45:58 localhost kernel: sd 0:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/465 GiB)
Oct 22 18:45:58 localhost kernel: sd 0:0:0:0: Attached scsi generic sg0 type 0
Oct 22 18:45:58 localhost kernel: sd 0:0:0:0: [sda] Write Protect is off
Oct 22 18:45:58 localhost kernel: sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
Oct 22 18:45:58 localhost kernel: sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA

Smart devices report their Caching mode page. This is a
change where we'd previously see the kernel making
assumption about the device's cache being write-through:

Oct 22 18:45:58 localhost kernel: sd 6:0:0:0: Attached scsi generic sg2 type 0
Oct 22 18:45:58 localhost kernel: sd 6:0:0:0: [sdb] 610472646 4096-byte logical blocks: (2.50 TB/2.27 TiB)
Oct 22 18:45:58 localhost kernel: sd 6:0:0:0: [sdb] Write Protect is off
Oct 22 18:45:58 localhost kernel: sd 6:0:0:0: [sdb] Mode Sense: 47 00 10 08
Oct 22 18:45:58 localhost kernel: sd 6:0:0:0: [sdb] Write cache: enabled, read cache: enabled, supports DPO and FUA

And "dumb" devices over BBB, are correctly shown not to
support reporting the Caching mode page:

Oct 22 18:49:06 localhost kernel: sd 7:0:0:0: [sdc] 15663104 512-byte logical blocks: (8.01 GB/7.46 GiB)
Oct 22 18:49:06 localhost kernel: sd 7:0:0:0: [sdc] Write Protect is off
Oct 22 18:49:06 localhost kernel: sd 7:0:0:0: [sdc] Mode Sense: 23 00 00 00
Oct 22 18:49:06 localhost kernel: sd 7:0:0:0: [sdc] No Caching mode page present
Oct 22 18:49:06 localhost kernel: sd 7:0:0:0: [sdc] Assuming drive cache: write through
Signed-off-by: default avatarLuben Tuikov <ltuikov@yahoo.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
      24d720b7
    • Dan Williams's avatar
      [SCSI] libsas: fix definition of wideport, include local sas address · 00f0254e
      Dan Williams authored 
      To date libsas has only looked at the attached sas address when
determining the formation of wide ports.  The specification and some
hardware expects that phys with different addresses will not form a wide
port unless the local peer phys also match each other.  Introduce a flag
to select stricter behavior at sas_register_ha() time.  The flag can be
dropped once it is known that all libsas users expect the same behavior.

Current drivers just initialize this field to zero and get the
traditional behavior.
Reported-by: default avatarPatrick Thomson <patrick.s.thomson@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
      00f0254e
    • Alan Stern's avatar
      [SCSI] sd: improve logic and efficiecy of media-change detection · 3ff5588d
      Alan Stern authored 
      This patch (as1415) improves the formerly incomprehensible logic in
sd_media_changed() (the current code refers to "changed" as a state,
whereas in fact it is a relation between two states).  It also adds a
big comment so that everyone can understand what is really going on.

The patch also improves efficiency by not reporting a media change
when no medium was ever present.  If no medium was present the last
time we checked and there's still no medium, it's not necessary to
tell the caller that a change occurred.  Doing so merely causes the
caller to attempt to revalidate a non-existent disk, which is a waste
of time.
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
      3ff5588d
    • James Bottomley's avatar
      [SCSI] fix up documentation for change in ->queuecommand to lockless calling · 29687512
      James Bottomley authored 
      The current doc still says we call it with the host lock held, which is
going to cause confusion.
Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
      29687512
  3. 20 Dec, 2010 1 commit
  5. 16 Dec, 2010 2 commits
  7. 15 Dec, 2010 16 commits
  9. 14 Dec, 2010 17 commits
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