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author | Jonathan Brassow <jbrassow@redhat.com> | 2008-02-08 03:11:29 +0100 |
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committer | Alasdair G Kergon <agk@redhat.com> | 2008-02-08 03:11:29 +0100 |
commit | 72f4b314100bae85c75d8e4c6fec621ab44e777d (patch) | |
tree | 6dc5e860e8a4acab2e047f31391d0c8fdf366ff7 /sound/ac97_bus.c | |
parent | dm snapshot: combine consecutive exceptions in memory (diff) | |
download | linux-72f4b314100bae85c75d8e4c6fec621ab44e777d.tar.xz linux-72f4b314100bae85c75d8e4c6fec621ab44e777d.zip |
dm raid1: handle write failures
This patch gives mirror the ability to handle device failures
during normal write operations.
The 'write_callback' function is called when a write completes.
If all the writes failed or succeeded, we report failure or
success respectively. If some of the writes failed, we call
fail_mirror; which increments the error count for the device, notes
the type of error encountered (DM_RAID1_WRITE_ERROR), and
selects a new primary (if necessary). Note that the primary
device can never change while the mirror is not in-sync (IOW,
while recovery is happening.) This means that the scenario
where a failed write changes the primary and gives
recovery_complete a chance to misread the primary never happens.
The fact that the primary can change has necessitated the change
to the default_mirror field. We need to protect against reading
garbage while the primary changes. We then add the bio to a new
list in the mirror set, 'failures'. For every bio in the 'failures'
list, we call a new function, '__bio_mark_nosync', where we mark
the region 'not-in-sync' in the log and properly set the region
state as, RH_NOSYNC. Userspace must also be notified of the
failure. This is done by 'raising an event' (dm_table_event()).
If fail_mirror is called in process context the event can be raised
right away. If in interrupt context, the event is deferred to the
kmirrord thread - which raises the event if 'event_waiting' is set.
Backwards compatibility is maintained by ignoring errors if
the DM_FEATURES_HANDLE_ERRORS flag is not present.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'sound/ac97_bus.c')
0 files changed, 0 insertions, 0 deletions