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authorHeinz Mauelshagen <heinzm@redhat.com>2017-01-14 03:53:07 +0100
committerMike Snitzer <snitzer@redhat.com>2017-01-25 12:49:06 +0100
commitc63ede3b4211e1e2489eda6a2efb0eb6fa26483a (patch)
tree5f3cc66a60cbb756d9b120f7a6322bc36ad9c6f6 /Documentation/device-mapper
parentLinux 4.10-rc5 (diff)
downloadlinux-c63ede3b4211e1e2489eda6a2efb0eb6fa26483a.tar.xz
linux-c63ede3b4211e1e2489eda6a2efb0eb6fa26483a.zip
dm raid: fix transient device failure processing
This fix addresses the following 3 failure scenarios: 1) If a (transiently) inaccessible metadata device is being passed into the constructor (e.g. a device tuple '254:4 254:5'), it is processed as if '- -' was given. This erroneously results in a status table line containing '- -', which mistakenly differs from what has been passed in. As a result, userspace libdevmapper puts the device tuple seperate from the RAID device thus not processing the dependencies properly. 2) False health status char 'A' instead of 'D' is emitted on the status status info line for the meta/data device tuple in this metadata device failure case. 3) If the metadata device is accessible when passed into the constructor but the data device (partially) isn't, that leg may be set faulty by the raid personality on access to the (partially) unavailable leg. Restore tried in a second raid device resume on such failed leg (status char 'D') fails after the (partial) leg returned. Fixes for aforementioned failure scenarios: - don't release passed in devices in the constructor thus allowing the status table line to e.g. contain '254:4 254:5' rather than '- -' - emit device status char 'D' rather than 'A' for the device tuple with the failed metadata device on the status info line - when attempting to restore faulty devices in a second resume, allow the device hot remove function to succeed by setting the device to not in-sync In case userspace intentionally passes '- -' into the constructor to avoid that device tuple (e.g. to split off a raid1 leg temporarily for later re-addition), the status table line will correctly show '- -' and the status info line will provide a '-' device health character for the non-defined device tuple. Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'Documentation/device-mapper')
-rw-r--r--Documentation/device-mapper/dm-raid.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index 5e3786fd9ea7..c84cdd220f9d 100644
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -314,3 +314,7 @@ Version History
1.9.0 Add support for RAID level takeover/reshape/region size
and set size reduction.
1.9.1 Fix activation of existing RAID 4/10 mapped devices
+1.9.2 Don't emit '- -' on the status table line in case the constructor
+ fails reading a superblock. Correctly emit 'maj:min1 maj:min2' and
+ 'D' on the status line. If '- -' is passed into the constructor, emit
+ '- -' on the table line and '-' as the status line health character.