linux/drivers/scsi/device_handler, branch v3.6

[SCSI] scsi_dh: add scsi_dh_attached_handler_name

2012-07-20T07:58:42Z

Introduce scsi_dh_attached_handler_name() to retrieve the name of the scsi_dh that is attached to the scsi_device associated with the provided request queue. Returns NULL if a scsi_dh is not attached. Also, fix scsi_dh_{attach,detach} function header comments to document @q rather than @sdev. Signed-off-by: Mike Snitzer Tested-by: Babu Moger Reviewed-by: Chandra Seetharaman Acked-by: Hannes Reinecke Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: Re-enable STPG for unavailable ports

2012-07-20T07:58:36Z

A quote from SPC-4: "While in the unavailable primary target port asymmetric access state, the device server shall support those of the following commands that it supports while in the active/optimized state: [ ... ] d) SET TARGET PORT GROUPS; [ ... ]". Hence re-enable sending STPG to a target port group that is in the unavailable state. Signed-off-by: Bart Van Assche Reviewed-by: Babu Moger Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: backoff alua rtpg retry linearly vs. geometrically

2012-07-20T07:58:33Z

Currently the backoff algorithm for when to retry alua rtpg requests progresses geometrically as so: 2, 4, 8, 16, 32, 64... seconds. This progression can lead to un-needed delay in retrying alua rtpg requests when the rtpgs are delayed. A less aggressive backoff algorithm that is additive would not lead to such large jumps when delays start getting long, but would backoff linearly: 2, 4, 6, 8, 10... seconds. Signed-off-by: Martin George Signed-off-by: Rob Evers Reviewed-by: Babu Moger Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: retry alua rtpg extended header for illegal request response

2012-07-20T07:58:33Z

Some storage arrays are known to return 'illegal request' when an rtpg extended header request is made. T10 says the array should ignore the bit, and return the non-extended rtpg as the array doesn't support the request. Working around this by retrying the rtpg request without the extended header bit set when the extended rtpg request results in illegal request. Signed-off-by: Rob Evers Reviewed-by: Babu Moger Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: implement 'implied transition timeout'

2012-07-20T07:58:32Z

During alua transitions, an array can return transitioning status in response to rtpg requests. These requests get retried for a maximum of 60 seconds by default before timing out. Sometimes this timeout isn't sufficient to allow the array to complete the transition. T10-spc4 addresses this under 'Report Target Port Groups' command. This update retrieves the timeout value from the storage array if available and retries the transitioning rtpgs for up to the 'implied transitioning timeout' value Signed-off-by: Rob Evers Reviewed-by: Babu Moger Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: Optimize the STPG command

2012-04-23T18:28:18Z

This patch optimizes the set target port group(STPG) command. During our testing, we found that it is not optimal to send stpg command every time the path group switch happens. This patch uses PREF (preferred target port) bit with combination of flags passed by multipath user level tool to optimize this behaviour. If PREF bit is set then it issues a STPG command, otherwise it will let implicit transfer take place. By default there is no change in the behaviour. User tool needs to pass the parameter to make this change take effect. Patch has been tested on NetApp E series storage. Signed-off-by: Babu Moger Reviewed-by: Hannes Reinecke Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: Store the PREF bit from RTPG

2012-04-23T18:28:13Z

PREF bit indicates preferred target port group for accessing a logical unit. This bit is used to optimize the STPG command handling. Signed-off-by: Babu Moger Reviewed-by: Hannes Reinecke Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: Inroduce the set_params interface scsi_dh_alua handler

2012-04-23T18:28:07Z

Handler expects only one parameter to set the flag ALUA_OPTIMIZE_STPG. This flag is used to optimize the STPG behaviour. There is no change in behaviour by default. For example, to set the flag pass the following parameters from multipath.conf hardware_handler "2 alua 1" Signed-off-by: Babu Moger Reviewed-by: Hannes Reinecke Signed-off-by: James Bottomley

[SCSI] scsi_dh_rdac: Fix for unbalanced reference count

2012-02-22T18:15:19Z

This patch fixes an unbalanced refcount issue. Elevating the lock for both kref_put and also for controller node deletion. Previously, controller deletion was protected but the not the kref_put. This was causing the other thread to pick up the controller structure which was already kref'd zero. This was causing the following WARN_ON and also sometimes panic. WARNING: at lib/kref.c:43 kref_get+0x2d/0x30() (Not tainted) Hardware name: IBM System x3655 -[7985AC1]- Modules linked in: fuse scsi_dh_rdac autofs4 nfs lockd fscache nfs_acl auth_rpcgss sunrpc 8021q garp stp llc ipv6 ib_srp(U) scsi_transport_srp scsi_tgt ib_cm(U) ib_sa(U) ib_uverbs(U) ib_umad(U) mlx4_ib(U) mlx4_core(U) ib_mthca(U) ib_mad(U) ib_core(U) dm_mirror dm_region_hash dm_log dm_round_robin dm_multipath uinput bnx2 ses enclosure sg ibmpex ibmaem ipmi_msghandler serio_raw k8temp hwmon amd64_edac_mod edac_core edac_mce_amd shpchp i2c_piix4 ext4 mbcache jbd2 sr_mod cdrom sd_mod crc_t10dif sata_svw pata_acpi ata_generic pata_serverworks aacraid radeon ttm drm_kms_helper drm i2c_algo_bit i2c_core dm_mod [last unloaded: freq_table] Pid: 13735, comm: srp_daemon Not tainted 2.6.32-71.el6.x86_64 #1 Call Trace: [] warn_slowpath_common+0x87/0xc0 [] warn_slowpath_null+0x1a/0x20 [] kref_get+0x2d/0x30 [] rdac_bus_attach+0x459/0x580 [scsi_dh_rdac] [] scsi_dh_handler_attach+0x2a/0x80 [] scsi_dh_notifier+0x9b/0xa0 [] notifier_call_chain+0x55/0x80 [] __blocking_notifier_call_chain+0x5a/0x80 [] blocking_notifier_call_chain+0x16/0x20 [] device_add+0x515/0x640 [] ? attribute_container_device_trigger+0xc4/0xe0 [] scsi_sysfs_add_sdev+0x89/0x2c0 [] scsi_probe_and_add_lun+0xea6/0xed0 [] ? scsi_alloc_target+0x292/0x2d0 [] __scsi_scan_target+0x121/0x750 [] ? sysfs_create_file+0x26/0x30 [] ? device_create_file+0x19/0x20 [] ? attribute_container_add_attrs+0x78/0x90 [] ? klist_next+0x4c/0xf0 [] ? transport_configure+0x0/0x20 [] ? attribute_container_device_trigger+0xc4/0xe0 [] scsi_scan_target+0xd0/0xe0 [] srp_create_target+0x75a/0x890 [ib_srp] [] dev_attr_store+0x20/0x30 [] sysfs_write_file+0xe5/0x170 [] vfs_write+0xb8/0x1a0 [] ? audit_syscall_entry+0x272/0x2a0 [] sys_write+0x51/0x90 [] system_call_fastpath+0x16/0x1b Signed-off-by: Babu Moger Acked-by: Mike Snitzer Signed-off-by: James Bottomley

[SCSI] scsi_dh_alua: Retry the check-condition in case Mode Parameters Changed

2012-01-10T23:01:24Z

This patch adds a check-condition in scsi_dh_alua handler for a retry. Sometimes, I have seen attach failing due to this check-condition with following error messages on NetApp E series storage. Dec 7 15:31:01 nilgiris kernel: [102979.696673] scsi 3:0:2:9: alua: port group 00 rel port 01 Dec 7 15:31:01 nilgiris kernel: [102979.697082] scsi 3:0:2:9: alua: rtpg failed with 8000002 Dec 7 15:31:01 nilgiris kernel: [102979.697086] scsi 3:0:2:9: alua: rtpg sense code 06/2a/01 Dec 7 15:31:01 nilgiris kernel: [102979.697088] scsi 3:0:2:9: alua: not attached Signed-off-by: Babu Moger Signed-off-by: James Bottomley