On Wed, 27 Jul 2011 01:04:15 +0900 Namhyung Kim <namhyung@xxxxxxxxx> wrote: > NeilBrown <neilb@xxxxxxx> writes: > > > It is only safe to choose not to write to a bad block if that bad > > block is safely recorded in metadata - i.e. if it has been > > 'acknowledged'. > > > > If it hasn't we need to wait for the acknowledgement. > > > > We support that using rdev->blocked wait and > > md_wait_for_blocked_rdev by introducing a new device flag > > 'BlockedBadBlock'. > > > > This flag is only advisory. > > It is cleared whenever we acknowledge a bad block, so that a waiter > > can re-check the particular bad blocks that it is interested it. > > > > It should be set by a caller when they find they need to wait. > > This (set after test) is inherently racy, but as > > md_wait_for_blocked_rdev already has a timeout, losing the race will > > have minimal impact. > > > > When we clear "Blocked" was also clear "BlockedBadBlocks" incase it > > was set incorrectly (see above race). > > > > We also modify the way we manage 'Blocked' to fit better with the new > > handling of 'BlockedBadBlocks' and to make it consistent between > > externally managed and internally managed metadata. This requires > > that each raidXd loop checks if the metadata needs to be written and > > triggers a write (md_check_recovery) if needed. Otherwise a queued > > write request might cause raidXd to wait for the metadata to write, > > and only that thread can write it. > > > > Before writing metadata, we set FaultRecorded for all devices that > > are Faulty, then after writing the metadata we clear Blocked for any > > device for which the Fault was certainly Recorded. > > > > The 'faulty' device flag now appears in sysfs if the device is faulty > > *or* it has unacknowledged bad blocks. So user-space which does not > > understand bad blocks can continue to function correctly. > > User space which does, should not assume a device is faulty until it > > sees the 'faulty' flag, and then sees the list of unacknowledged bad > > blocks is empty. > > > > Signed-off-by: NeilBrown <neilb@xxxxxxx> > > Probably you also need this patch: > > >From 76320c4fdaed91f26a083a9337bb5a5503300e0e Mon Sep 17 00:00:00 2001 > From: Namhyung Kim <namhyung@xxxxxxxxx> > Date: Wed, 27 Jul 2011 00:59:26 +0900 > Subject: [PATCH] md: update documentation for md/rdev/state sysfs interface > > Previous patches in the bad block series extended behavior of > rdev's 'state' interface but lacked documentation update. > Fix it. > > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxx> Applied, thanks. NeilBrown > --- > Documentation/md.txt | 14 +++++++++----- > 1 files changed, 9 insertions(+), 5 deletions(-) > > diff --git a/Documentation/md.txt b/Documentation/md.txt > index 923a6bddce7c..fc94770f44ab 100644 > --- a/Documentation/md.txt > +++ b/Documentation/md.txt > @@ -360,18 +360,20 @@ Each directory contains: > A file recording the current state of the device in the array > which can be a comma separated list of > faulty - device has been kicked from active use due to > - a detected fault > + a detected fault or it has unacknowledged bad > + blocks > in_sync - device is a fully in-sync member of the array > writemostly - device will only be subject to read > requests if there are no other options. > This applies only to raid1 arrays. > - blocked - device has failed, metadata is "external", > - and the failure hasn't been acknowledged yet. > + blocked - device has failed, and the failure hasn't been > + acknowledged yet by the metadata handler. > Writes that would write to this device if > it were not faulty are blocked. > spare - device is working, but not a full member. > This includes spares that are in the process > of being recovered to > + write_error - device has ever seen a write error. > This list may grow in future. > This can be written to. > Writing "faulty" simulates a failure on the device. > @@ -379,9 +381,11 @@ Each directory contains: > Writing "writemostly" sets the writemostly flag. > Writing "-writemostly" clears the writemostly flag. > Writing "blocked" sets the "blocked" flag. > - Writing "-blocked" clears the "blocked" flag and allows writes > - to complete. > + Writing "-blocked" clears the "blocked" flags and allows writes > + to complete and possibly simulates an error. > Writing "in_sync" sets the in_sync flag. > + Writing "write_error" sets writeerrorseen flag. > + Writing "-write_error" clears writeerrorseen flag. > > This file responds to select/poll. Any change to 'faulty' > or 'blocked' causes an event. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
