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In the final step of the udev rules toolset, we either know that the
current event subject is the re-IPL target, a dm-multipath device with
the re-IPL target, or represents the same volume based on its WWID. As
such it is a candidate to replace the current re-IPL target.
The new helper `chreipl-fcp-mpath-try-change-ipl-path` will use the
subject itself - in case it is a single scsi disk -, or the dm-multipath
device, to test whether there is a path in a good state.
"Good state" is based on the zfcp device driver state
(<SDEV>/zfcp_failed, <SDEV>/zfcp_in_recovery), the scsi_transport_fc
port state (<SDEV>/../../fc_remote_ports/rport-*/port_state), and the
scsi device state (<SDEV>/state). A path is only considered if they all
indicate a device in good conditions.
If such a path is found, the helper will try to set it as new re-IPL
target regardless of whether the current re-IPL is still in good shape
or not. This is by design, and done to reduce complexity in further
state checking, and prevention of races with overlapping events in udev
(when executing in parallel workers).
Whenever a new re-IPL target is selected and set in
/sys/firmware/reipl/fcp/{device,wwpn,lun}, the helper will also update
the records in the ID-file - otherwise they might appear as stale, when
they aren't.
This step in the udev rule processing might also result in log messages
written to the syslog (using the utility `logger` from util-linux;
writing to /dev/log).
In case the re-IPL target is changed, a message with level notice is
logged, informing about the new target.
In case no good path is found as part of a dm-multipath device, a
message with level critical is logged, as it might result in a failed
re-IPL if no path is available.
Lastly, when changing the information in /sys/firmware/reipl/fcp/ fails
for whatever reason, a message with level alert is logged, as the
written information might be inconsistent and must be audited/corrected
manually by an operator.
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
102 lines
4.1 KiB
Plaintext
102 lines
4.1 KiB
Plaintext
# SPDX-License-Identifier: MIT
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#
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# chreipl-fcp-mpath: use multipath information to change FCP IPL target
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# (C) Copyright IBM Corp. 2021
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# Did the event affect a multipath or scsi disk device?
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ACTION=="change", KERNEL=="dm-[0-9]*", SUBSYSTEM=="block", \
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ENV{DM_UUID}=="mpath-*", ENV{DM_ACTION}=="PATH_FAILED", \
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GOTO="chreipl_fcp_mpath_path_change"
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ACTION=="change", KERNEL=="dm-[0-9]*", SUBSYSTEM=="block", \
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ENV{DM_UUID}=="mpath-*", ENV{DM_ACTION}=="PATH_REINSTATED", \
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GOTO="chreipl_fcp_mpath_path_change"
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ACTION=="add", KERNEL=="sd[a-z]*", SUBSYSTEM=="block", \
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GOTO="chreipl_fcp_mpath_path_change"
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GOTO="chreipl_fcp_mpath_end"
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LABEL="chreipl_fcp_mpath_path_change"
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# Is this system IPL'ed (IOW, are we on s390x)? And do we ReIPL via zFCP?
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#
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# udev(7): If no absolute path is given, the program is expected to live
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# in /usr/lib/udev; otherwise, the absolute path must be
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# specified.
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TEST!="/sys/firmware/ipl", GOTO="chreipl_fcp_mpath_end"
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PROGRAM!="chreipl-fcp-mpath-is-reipl-zfcp", GOTO="chreipl_fcp_mpath_end"
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# Consider the following scenarios.
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# Either:
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#
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# (A) We recognized a new SCSI Disk. This might represent:
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# (a) the path we want to ReIPL from;
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# (b) an alternative path to the volume we want to ReIPL from;
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# (c) a path to some unrelated volume.
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#
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# Or:
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#
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# (B) We recognized a PATH_ event for a multipath device. This might represent:
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# the path we want to ReIPL from:
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# (a) went away;
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# (b) came back online;
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# an alternative path to the volume we want to ReIPL from:
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# (c) went away;
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# (d) came back online;
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# (e) some unrelated multipath device saw an event.
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# Test whether the affected device is, or contains, the current IPL target.
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#
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# This covers scenarios:
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# (A) (a),
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# (B) (a)/(b)/(c)/(d)
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PROGRAM!="chreipl-fcp-mpath-is-ipl-tgt", \
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ENV{CHREIPL_FCP_MPATH_IS_TGT}="false", \
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GOTO="chreipl_fcp_mpath_not_direct_match"
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ENV{CHREIPL_FCP_MPATH_IS_TGT}="true"
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# Record the WWID, Device-Bus-ID, Remote WWPN, and LUN of the ReIPL target
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# (see `chreipl-fcp-mpath-is-ipl-vol` for usecases). This information
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# might change, depending on whether the machine operator changes the ReIPL
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# target to a different volume.
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#
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# XXX: Because the kernel doesn't generate any events upon changing of
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# the ReIPL target, the chreipl-fcp-mpath toolset can't take any
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# actions until the next path event for the new target is
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# generated. Following that, we assume that when the machine
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# operator changes the ReIPL target, the new target is reachable
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# and in a good state at this point in time.
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PROGRAM!="chreipl-fcp-mpath-record-volume-identifier", \
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GOTO="chreipl_fcp_mpath_try_change_ipl_path"
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GOTO="chreipl_fcp_mpath_try_change_ipl_path"
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# If the even subject is not a direct match (not the sdev that is the current
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# ReIPL target, and not a mpath device that contains the current ReIPL target)
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LABEL="chreipl_fcp_mpath_not_direct_match"
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# While this sdev/mpath device doesn't directly correspond to the path
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# currently set as ReIPL target, it might still point to the same volume.
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#
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# For mpath devices this can happen if the original ReIPL target is completely
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# gone from the machine, and so there is no way we can successfully, directly
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# compare the ReIPL parameters to the sdevs of the mpath device.
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#
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# For cases like these we recorded the volume identifier, which we now can
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# compare, and so still decide whether we are addressing the correct volume.
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#
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# This covers scenarios:
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# (A) (b)/(c),
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# (B) (c)/(d)/(e)
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#
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# XXX: we recorded WWID, Device-Bus-ID, Remote WWPN, LUN of the ReIPL target at
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# the time; if the latter three don't match the current ReIPL setting
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# anymore, we have to assume that someone changed the ReIPL target
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# manually, and we cannot use the WWID anymore since we can't possibly
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# know whether that stayed the same when the change was done.
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PROGRAM!="chreipl-fcp-mpath-is-ipl-vol", GOTO="chreipl_fcp_mpath_end"
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# We are here because of scenarios:
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# (A) (a)/(b),
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# (B) (a)/(b)/(c)/(d)
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LABEL="chreipl_fcp_mpath_try_change_ipl_path"
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RUN{program}+="chreipl-fcp-mpath-try-change-ipl-path"
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LABEL="chreipl_fcp_mpath_end"
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