Allow SCSI hosts to request avoiding trailing allocation length with VPD inquiries, and use the mechanism to work around an issue with at least some BusLogic MultiMaster host bus adapters and observed with the BT-958 model specifically where issuing commands that return less data than provided for causes fatal failures:
scsi host0: BusLogic BT-958 scsi 0:0:0:0: Direct-Access IBM DDYS-T18350M SA5A PQ: 0 ANSI: 3 scsi 0:0:1:0: Direct-Access SEAGATE ST336607LW 0006 PQ: 0 ANSI: 3 scsi 0:0:5:0: Direct-Access IOMEGA ZIP 100 E.08 PQ: 0 ANSI: 2 sd 0:0:1:0: [sdb] 71687372 512-byte logical blocks: (36.7 GB/34.2 GiB) sd 0:0:0:0: [sda] 35843670 512-byte logical blocks: (18.4 GB/17.1 GiB) sd 0:0:1:0: [sdb] Write Protect is off sd 0:0:5:0: [sdc] Attached SCSI removable disk sd 0:0:0:0: [sda] Write Protect is off sd 0:0:1:0: [sdb] Write cache: enabled, read cache: enabled, supports DPO and FUA sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA scsi0: *** BusLogic BT-958 Initialized Successfully *** scsi0: *** BusLogic BT-958 Initialized Successfully *** scsi0: *** BusLogic BT-958 Initialized Successfully *** scsi0: *** BusLogic BT-958 Initialized Successfully *** sd 0:0:0:0: Device offlined - not ready after error recovery sd 0:0:1:0: Device offlined - not ready after error recovery sd 0:0:0:0: scsi_vpd_inquiry(0): buf[64] => -5 sd 0:0:1:0: scsi_vpd_inquiry(0): buf[64] => -5 sd 0:0:0:0: [sda] Attached SCSI disk sd 0:0:1:0: [sdb] Attached SCSI disk VFS: Cannot open root device "802" or unknown-block(8,2): error -6
(here and elsewhere reported with some instrumentation added so as to show the causing requests and with irrelevant messages filtered out).
As already observed back in 2003 and worked around in smartmontools at least some versions of BusLogic firmware such as 5.07B are unable to handle such commands, but it is possible to request enough data first for the length of the data response to be determined and then reissue the same command with the allocation length matching the response expected.
It is what this change does on a host-by-host basis, by providing a flag for individual HBA drivers to enable this workaround, currently set by the BusLogic driver, and then issuing these double calls as requested, which then produce results as expected:
sd 0:0:1:0: [sdb] Write cache: enabled, read cache: enabled, supports DPO and FUA sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA sd 0:0:1:0: scsi_vpd_inquiry(0): buf[64] => 13 sd 0:0:0:0: scsi_vpd_inquiry(0): buf[64] => 7 sdb: sdb1 sdb2 sd 0:0:1:0: scsi_vpd_inquiry(0): buf[64] => 13 sd 0:0:1:0: [sdb] Attached SCSI disk sda: sda1 sda2 sda3 sda4 < sda5 sda6 sda7 sda8 sda9 sda10 > sd 0:0:0:0: scsi_vpd_inquiry(0): buf[64] => 7 sd 0:0:0:0: [sda] Attached SCSI disk EXT4-fs (sda2): mounting ext2 file system using the ext4 subsystem EXT4-fs (sda2): mounted filesystem without journal. Opts: (null). Quota mode: disabled. VFS: Mounted root (ext2 filesystem) readonly on device 8:2.
The minimum request size of 4 for the repeated call has been chosen to match one required for a successful return from `scsi_vpd_inquiry'.
Interestingly enough it has only started triggering with not so recent commit af73623f5f10 ("[SCSI] sd: Reduce buffer size for vpd request") that decreased the allocation length for the originating request from 512 down to 64. Previously the request was rejected outright by the respective targets as invalid and therefore did not trigger the issue with MultiMaster firmware as that would only happen for a command that succeeded but produced less data than provided for:
scsi0: CCB #36 Target 0: Result 2 Host Adapter Status 00 Target Status 02 scsi0: CDB 12 01 00 02 00 00 scsi0: Sense 70 00 05 00 00 00 00 18 00 00 00 00 24 00 00 C0 00 03 00 [...] sd 0:0:0:0: scsi_vpd_inquiry(0): buf[512] => -5 scsi0: CCB #37 Target 1: Result 2 Host Adapter Status 00 Target Status 02 scsi0: CDB 12 01 00 02 00 00 scsi0: Sense 70 00 05 00 00 00 00 0A 00 00 00 00 24 00 01 C9 00 03 00 [...] sd 0:0:1:0: scsi_vpd_inquiry(0): buf[512] => -5
(here with the buffer size set back to 512, the `BusLogic=TraceErrors' parameter and trailing sense data zeros trimmed for brevity). Note the sense key of 0x5 returned denoting an illegal request even for page 0.
Signed-off-by: Maciej W. Rozycki macro@orcam.me.uk Fixes: 881a256d84e6 ("[SCSI] Add VPD helper") Cc: stable@vger.kernel.org # v2.6.30+ --- No changes from v1. --- drivers/scsi/BusLogic.c | 1 + drivers/scsi/scsi.c | 24 +++++++++++++++++++++--- include/scsi/scsi_host.h | 3 +++ 3 files changed, 25 insertions(+), 3 deletions(-)
linux-buslogic-get-vpd-page-buffer.diff Index: linux-macro-ide/drivers/scsi/BusLogic.c =================================================================== --- linux-macro-ide.orig/drivers/scsi/BusLogic.c +++ linux-macro-ide/drivers/scsi/BusLogic.c @@ -2301,6 +2301,7 @@ static void __init blogic_inithoststruct host->sg_tablesize = adapter->drvr_sglimit; host->unchecked_isa_dma = adapter->need_bouncebuf; host->cmd_per_lun = adapter->untag_qdepth; + host->no_trailing_allocation_length = true; }
/* Index: linux-macro-ide/drivers/scsi/scsi.c =================================================================== --- linux-macro-ide.orig/drivers/scsi/scsi.c +++ linux-macro-ide/drivers/scsi/scsi.c @@ -346,8 +346,19 @@ int scsi_get_vpd_page(struct scsi_device if (sdev->skip_vpd_pages) goto fail;
- /* Ask for all the pages supported by this device */ - result = scsi_vpd_inquiry(sdev, buf, 0, buf_len); + /* + * Ask for all the pages supported by this device. Determine the + * actual data length first if so required by the host, e.g. + * BusLogic BT-958. + */ + if (sdev->host->no_trailing_allocation_length) { + result = scsi_vpd_inquiry(sdev, buf, 0, min(4, buf_len)); + if (result < 4) + goto fail; + } else { + result = buf_len; + } + result = scsi_vpd_inquiry(sdev, buf, 0, min(result, buf_len)); if (result < 4) goto fail;
@@ -366,7 +377,14 @@ int scsi_get_vpd_page(struct scsi_device goto fail;
found: - result = scsi_vpd_inquiry(sdev, buf, page, buf_len); + if (sdev->host->no_trailing_allocation_length) { + result = scsi_vpd_inquiry(sdev, buf, page, min(4, buf_len)); + if (result < 4) + goto fail; + } else { + result = buf_len; + } + result = scsi_vpd_inquiry(sdev, buf, page, min(result, buf_len)); if (result < 0) goto fail;
Index: linux-macro-ide/include/scsi/scsi_host.h =================================================================== --- linux-macro-ide.orig/include/scsi/scsi_host.h +++ linux-macro-ide/include/scsi/scsi_host.h @@ -653,6 +653,9 @@ struct Scsi_Host { /* The transport requires the LUN bits NOT to be stored in CDB[1] */ unsigned no_scsi2_lun_in_cdb:1;
+ /* Allocation length must not exceed actual data length. */ + unsigned no_trailing_allocation_length:1; + /* * Optional work queue to be utilized by the transport */