[PATCH md 0 of 2] Introduction

[PATCH md 0 of 2] Introduction

[NeilBrown]

Two patches for md in 2.6.9-rc1-mm2

The first adds support for notifying user-space of events in md.

The mechanism is very simple.  A reader of /proc/mdstat can select for
"exceptional" events.  When select/poll indicates one of these, the 
reader should re-read /proc/mdstat from the top looking for changes, and then
select again.

If the reader opens for write as well (O_RDWR) (only root can do
this), then it indicates that it is prepared to take remedial action.
This is currently only relevant for multipath.  On last-drive-failure,
if there is a reader of /proc/mdstat that has an open for write, then
multipath will wait for that reader to add a new drive or take other
action before resubmitting the failed requests.

The second patch just fixes a counter in raid5/6 which could get out-by-one, and so
produce confusing messages.

(I think I sent a single item of junk just before this, sorry about that.  Please
ignore it).

NeilBrown

[PATCH md 0 of 2] Introduction

[NeilBrown]

Following are two patches for md/linear.c in 2.6.10-rc1-mm5

The first fixes a bug that was recently introduced, that affects linear arrays
where the components aren't all the same size (I didn't test that case :-( ).
I would be good if this was in 2.6.10.

The second is a code cleanup and minor reduction in memory usage.
There is no particular hurry for this patch to go in.

NeilBrown

[PATCH md 0 of 2] Introduction

[NeilBrown]

Two patches for md/raid in 2.6.recent.

1/ Fix data corruption bug in raid10 when used on
   partitions.  raid10 is marked "experimental" but 
   it would be good to get this in 2.6.10
2/ Fix jiffies comparison during resync so it behaves
   correctly when jiffies wrap.  This bug has no
   performance, security, or data integrity impact.

NeilBrown

[PATCH md 2 of 2] RAID Kconfig cleanups, remove experimental tag from RAID-6

[NeilBrown]

This patch removes the experimental tag from RAID-6 (unfortunately the 
damage is already done...:-|) and cleans up a few more things in the 
Kconfig file.

Signed-Off-By: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>

### Diffstat output
 ./drivers/md/Kconfig |   19 ++++++++-----------
 1 files changed, 8 insertions(+), 11 deletions(-)

diff ./drivers/md/Kconfig~current~ ./drivers/md/Kconfig
--- ./drivers/md/Kconfig~current~	2005-02-09 14:32:06.000000000 +1100
+++ ./drivers/md/Kconfig	2005-02-09 14:32:06.000000000 +1100
@@ -93,7 +93,7 @@ config MD_RAID10
 	  mirroring (RAID-1) with easier configuration and more flexable
 	  layout.
 	  Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
-	  be the same size (or atleast, only as much as the smallest device
+	  be the same size (or at least, only as much as the smallest device
 	  will be used).
 	  RAID-10 provides a variety of layouts that provide different levels
 	  of redundancy and performance.
@@ -102,6 +102,7 @@ config MD_RAID10
 
 	  ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
 
+	  If unsure, say Y.
 
 config MD_RAID5
 	tristate "RAID-4/RAID-5 mode"
@@ -120,20 +121,16 @@ config MD_RAID5
 	  <http://www.tldp.org/docs.html#howto>. There you will also
 	  learn where to get the supporting user space utilities raidtools.
 
-	  If you want to use such a RAID-4/RAID-5 set, say Y.  To compile
-	  this code as a module, choose M here: the module will be called raid5.
+	  If you want to use such a RAID-4/RAID-5 set, say Y.  To
+	  compile this code as a module, choose M here: the module
+	  will be called raid5.
 
 	  If unsure, say Y.
 
 config MD_RAID6
-	tristate "RAID-6 mode (EXPERIMENTAL)"
-	depends on BLK_DEV_MD && EXPERIMENTAL
+	tristate "RAID-6 mode"
+	depends on BLK_DEV_MD
 	---help---
-	  WARNING: RAID-6 is currently highly experimental.  If you
-	  use it, there is no guarantee whatsoever that it won't
-	  destroy your data, eat your disk drives, insult your mother,
-	  or re-appoint George W. Bush.
-
 	  A RAID-6 set of N drives with a capacity of C MB per drive
 	  provides the capacity of C * (N - 2) MB, and protects
 	  against a failure of any two drives. For a given sector
@@ -150,7 +147,7 @@ config MD_RAID6
 	  this code as a module, choose M here: the module will be
 	  called raid6.
 
-	  If unsure, say N.
+	  If unsure, say Y.
 
 config MD_MULTIPATH
 	tristate "Multipath I/O support"

[PATCH md 0 of 2] Introduction

[NeilBrown]

Two more little patches for md (sorry for the dribs-and-drabs).

Feel free to leave them until post-2.6.11, though the first is really trivial
and allows md/multipath arrays be assembled (without it they just won't work).

- Fix typo for multipat assembly with will
- Mark raid6 non-experimental and tidy up bits of Kconfig

NeilBrown

[PATCH md 1 of 2] Fix multipath assembly bug

[NeilBrown]

In md, there are "level" number and "personality" numbers.
LEVEL_MULTIPATH is the level number for multipath.
MULTIPATH is the personality number for multipath.

In one place, we compare the level with a personality
... bad

This makes it impossible to assemble multipath arrays.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>

### Diffstat output
 ./drivers/md/md.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~	2005-02-09 11:27:25.000000000 +1100
+++ ./drivers/md/md.c	2005-02-09 14:22:16.000000000 +1100
@@ -572,7 +572,7 @@ static int super_90_load(mdk_rdev_t *rde
 	rdev->preferred_minor = sb->md_minor;
 	rdev->data_offset = 0;
 
-	if (sb->level == MULTIPATH)
+	if (sb->level == LEVEL_MULTIPATH)
 		rdev->desc_nr = -1;
 	else
 		rdev->desc_nr = sb->this_disk.number;

Re: [PATCH md 1 of 2] Fix multipath assembly bug

[Michael Tokarev]

NeilBrown wrote:
> In md, there are "level" number and "personality" numbers.
> LEVEL_MULTIPATH is the level number for multipath.
> MULTIPATH is the personality number for multipath.

BTW, why the two in the first place?  Isn't it nice to
eliminate one of them?

/mjt

Re: [PATCH md 1 of 2] Fix multipath assembly bug

[Neil Brown]

On Thursday February 10, mjt@tls.msk.ru wrote:
> NeilBrown wrote:
> > In md, there are "level" number and "personality" numbers.
> > LEVEL_MULTIPATH is the level number for multipath.
> > MULTIPATH is the personality number for multipath.
> 
> BTW, why the two in the first place?  Isn't it nice to
> eliminate one of them?

Historical reasons....

The "Level" number corresponds to the common names of the raid levels:
 0, 1, 4, 5, 6 ...
There is also "-1" for "linear", which is a bit of a hack.

The personality numbers are dense small integers: 0 1 2 3 4 ...
and are used for indexing.

You are right: the personality number isn't needed and could be
eliminated, however it isn't a priority for me yet.  Patches welcome
....

NeilBrown