From: Menny Hamburger Date: Thu, 16 Dec 2010 19:57:07 +0000 (-0500) Subject: [SCSI] scsi_dh: propagate SCSI device deletion X-Git-Tag: v2.6.38-rc1~27^2~21 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=db422318cbca55168cf965f655471dbf8be82433;p=pandora-kernel.git [SCSI] scsi_dh: propagate SCSI device deletion Currently, when scsi_dh_activate() returns with an error (e.g. SCSI_DH_NOSYS) the activate_complete callback is not called and the error is not propagated to DM mpath. When a SCSI device attached to a device handler is deleted, userland processes currently performing I/O on the device will have their I/O hang forever. - Set SCSI_DH_NOSYS error when the handler is in the process of being deleted (e.g. the SCSI device is in a SDEV_CANCEL or SDEV_DEL state). - Set SCSI_DH_DEV_OFFLINED error when device is in SDEV_OFFLINE state. - Call the activate_complete callback function directly from scsi_dh_activate if an error has been set (when either the scsi_dh internal data has already been deleted or is in the process of being deleted). The patch was tested in an iSCSI environment, RDAC H/W handler and multipath. In the following reproduction process, dd will I/O hang forever and the only way to release it will be to reboot the machine: 1) Perform I/O on a multipath device: dd if=/dev/dm-0 of=/dev/zero bs=8k count=1000000 & 2) Delete all slave SCSI devices contained in the mpath device: I) In an iSCSI environment, the easiest way to do this is by stopping iSCSI: /etc/init.d/iscsi stop II) Another way to delete the devices is by applying the following bash scriptlet: dm_devs=$(ls /sys/block/ | grep dm- | xargs) for dm_dev in $dm_devs; do devices=$(ls /sys/block/$dm_dev/slaves) for device in $devices; do echo 1 > /sys/block/$device/device/delete done done NOTE: when DM mpath's fail_path uses blk_abort_queue this scsi_dh change isn't strictly required. However, DM mpath's call to blk_abort_queue will soon be reverted because it has proven to be unsafe due to a race (between blk_abort_queue and scsi_request_fn) that can lead to list corruption. Therefore we cannot rely on blk_abort_queue via fail_path, but even if we could this scsi_dh change is still preferrable. Signed-off-by: Menny Hamburger Signed-off-by: Mike Snitzer Reviewed-by: Babu Moger Signed-off-by: James Bottomley --- Reading git-diff-tree failed