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| author | NeilBrown <neilb@suse.de> | 2006-04-10 22:52:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-04-11 06:18:30 -0700 |
| commit | 6f91fe88e4e28b40b4f08d99e0ea6d17b70e9567 (patch) | |
| tree | 035ac07180e058579ee8023ed0fcb12e40315594 | |
| parent | 54404e72cd3758e465fb6362f6d71e22b705c589 (diff) | |
| download | lwn-6f91fe88e4e28b40b4f08d99e0ea6d17b70e9567.tar.gz lwn-6f91fe88e4e28b40b4f08d99e0ea6d17b70e9567.zip | |
[PATCH] md: make sure 64bit fields in version-1 metadata are 64-bit aligned
reshape_position is a 64bit field that was not 64bit aligned. So swap with
new_level.
NOTE: this is a user-visible change. However:
- The bad code has not appeared in a released kernel
- This code is still marked 'experimental'
- This only affects version-1 superblock, which are not in wide use
- These field are only used (rather than simply reported) by user-space
tools in extemely rare circumstances : after a reshape crashes in the
first second of the reshape process.
So I believe that, at this stage, the change is safe. Especially if people
heed the 'help' message on use mdadm-2.4.1.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | drivers/md/Kconfig | 11 | ||||
| -rw-r--r-- | include/linux/raid/md_p.h | 2 |
2 files changed, 7 insertions, 6 deletions
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index fd2aae150ccc..ac25a48362ac 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -139,11 +139,12 @@ config MD_RAID5_RESHAPE is online. However it is still EXPERIMENTAL code. It should work, but please be sure that you have backups. - You will need a version of mdadm newer than 2.3.1. During the - early stage of reshape there is a critical section where live data - is being over-written. A crash during this time needs extra care - for recovery. The newer mdadm takes a copy of the data in the - critical section and will restore it, if necessary, after a crash. + You will need mdadm verion 2.4.1 or later to use this + feature safely. During the early stage of reshape there is + a critical section where live data is being over-written. A + crash during this time needs extra care for recovery. The + newer mdadm takes a copy of the data in the critical section + and will restore it, if necessary, after a crash. The mdadm usage is e.g. mdadm --grow /dev/md1 --raid-disks=6 diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h index 774e1acfb8c4..f1fbae7e390e 100644 --- a/include/linux/raid/md_p.h +++ b/include/linux/raid/md_p.h @@ -227,8 +227,8 @@ struct mdp_superblock_1 { */ /* These are only valid with feature bit '4' */ - __u64 reshape_position; /* next address in array-space for reshape */ __u32 new_level; /* new level we are reshaping to */ + __u64 reshape_position; /* next address in array-space for reshape */ __u32 delta_disks; /* change in number of raid_disks */ __u32 new_layout; /* new layout */ __u32 new_chunk; /* new chunk size (bytes) */ |