Commit Graph

21 Commits

Author SHA1 Message Date
NeilBrown
72626685dc [PATCH] md: add write-intent-bitmap support to raid5
Most awkward part of this is delaying write requests until bitmap updates have
been flushed.

To achieve this, we have a sequence number (seq_flush) which is incremented
each time the raid5 is unplugged.

If the raid thread notices that this has changed, it flushes bitmap changes,
and assigned the value of seq_flush to seq_write.

When a write request arrives, it is given the number from seq_write, and that
write request may not complete until seq_flush is larger than the saved seq
number.

We have a new queue for storing stripes which are waiting for a bitmap flush
and an extra flag for stripes to record if the write was 'degraded' and so
should not clear the a bit in the bitmap.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:12 -07:00
NeilBrown
0002b2718d [PATCH] md: limit size of sb read/written to appropriate amount
version-1 superblocks are not (normally) 4K long, and can be of variable size.
 Writing the full 4K can cause corruption (but only in non-default
configurations).

With this patch the super-block-flavour can choose a size to read, and set a
size to write based on what it finds.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:12 -07:00
NeilBrown
773f783442 [PATCH] md: remove old cruft from md_k.h header file
These inlines haven't been used for ages, they should go.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:12 -07:00
NeilBrown
71c0805cb4 [PATCH] md: allow md to load a superblock with feature-bit '1' set
As this is used to flag an internal bitmap.

Also, introduce symbolic names for feature bits.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:11 -07:00
NeilBrown
15945fee6f [PATCH] md: support md/linear array with components greater than 2 terabytes.
linear currently uses division by the size of the smallest componenet device
to find which device a request goes to.  If that smallest device is larger
than 2 terabytes, then the division will not work on some systems.

So we introduce a pre-shift, and take care not to make the hash table too
large, much like the code in raid0.

Also get rid of conf->nr_zones, which is not needed.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:10 -07:00
NeilBrown
4b6d287f62 [PATCH] md: add write-behind support for md/raid1
If a device is flagged 'WriteMostly' and the array has a bitmap, and the
bitmap superblock indicates that write_behind is allowed, then write_behind is
enabled for WriteMostly devices.

Write requests will be acknowledges as complete to the caller (via b_end_io)
when all non-WriteMostly devices have completed the write, but will not be
cleared from the bitmap until all devices complete.

This requires memory allocation to make a local copy of the data being
written.  If there is insufficient memory, then we fall-back on normal write
semantics.

Signed-Off-By: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:10 -07:00
NeilBrown
8ddf9efe67 [PATCH] md: support write-mostly device in raid1
This allows a device in a raid1 to be marked as "write mostly".  Read requests
will only be sent if there is no other option.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:10 -07:00
NeilBrown
36fa30636f [PATCH] md: all hot-add and hot-remove of md intent logging bitmaps
Both file-bitmaps and superblock bitmaps are supported.

If you add a bitmap file on the array device, you lose.

This introduces a 'default_bitmap_offset' field in mddev, as the ioctl used
for adding a superblock bitmap doesn't have room for giving an offset.  Later,
this value will be setable via sysfs.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 16:39:10 -07:00
NeilBrown
6b8b3e8a8b [PATCH] md: make sure md bitmap updates are flushed when array is stopped.
The recent change to never ignore the bitmap, revealed that the bitmap isn't
begin flushed properly when an array is stopped.

We call bitmap_daemon_work three times as there is a three-stage pipeline for
flushing updates to the bitmap file.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-04 13:00:54 -07:00
NeilBrown
6a806c510d [PATCH] md/raid1: clear bitmap when fullsync completes
We need to be careful differentiating between a resync of a complete array,
in which we can clear the bitmap, and a resync of a degraded array, in
which we cannot.

This patch cleans all that up.

Cc: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-15 09:54:51 -07:00
NeilBrown
39730960d9 [PATCH] Two small fixes for md verion-1 superblocks.
1/ Must typecast int to (sector_t) before inverting or we
 might not invert enough bits.

2/ When "bitmap_offset" was added to mdp_superblock_1, we didn't increase
   the count of words-used (96 to 100).

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:47 -07:00
NeilBrown
7bfa19f274 [PATCH] md: allow md to update multiple superblocks in parallel.
currently, md updates all superblocks (one on each device) in series.  It
waits for one write to complete before starting the next.  This isn't a big
problem as superblock updates don't happen that often.

However it is neater to do it in parallel, and if the drives in the array have
gone to "sleep" after a period of idleness, then waking them is parallel is
faster (and someone else should be worrying about power drain).

Futher, we will need parallel superblock updates for a future patch which
keeps the intent-logging bitmap near the superblock.

Also remove the silly code that retired superblock updates 100 times.  This
simply never made sense.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:47 -07:00
NeilBrown
a654b9d8f8 [PATCH] md: allow md intent bitmap to be stored near the superblock.
This provides an alternate to storing the bitmap in a separate file.  The
bitmap can be stored at a given offset from the superblock.  Obviously the
creator of the array must make sure this doesn't intersect with data....
After is good for version-0.90 superblocks.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:47 -07:00
NeilBrown
3d310eb7b3 [PATCH] md: fix deadlock due to md thread processing delayed requests.
Before completing a 'write' the md superblock might need to be updated.
This is best done by the md_thread.

The current code schedules this up and queues the write request for later
handling by the md_thread.

However some personalities (Raid5/raid6) will deadlock if the md_thread
tries to submit requests to its own array.

So this patch changes things so the processes submitting the request waits
for the superblock to be written and then submits the request itself.

This fixes a recently-created deadlock in raid5/raid6

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:46 -07:00
NeilBrown
41158c7eb2 [PATCH] md: optimise reconstruction when re-adding a recently failed drive.
When an array is degraded, bit in the intent-bitmap are never cleared.  So if
a recently failed drive is re-added, we only need to reconstruct the block
that are still reflected in the bitmap.

This patch adds support for this re-adding.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:46 -07:00
NeilBrown
191ea9b2c7 [PATCH] md: raid1 support for bitmap intent logging
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:46 -07:00
NeilBrown
77ad4bc706 [PATCH] md: enable the bitmap write-back daemon and wait for it.
Currently we don't wait for updates to the bitmap to be flushed to disk
properly.  The infrastructure all there, but it isn't being used....

A separate kernel thread (bitmap_writeback_daemon) is needed to wait for each
page as we cannot get callbacks when a page write completes.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:45 -07:00
NeilBrown
32a7627cf3 [PATCH] md: optimised resync using Bitmap based intent logging
With this patch, the intent to write to some block in the array can be logged
to a bitmap file.  Each bit represents some number of sectors and is set
before any update happens, and only cleared when all writes relating to all
sectors are complete.

After an unclean shutdown, information in this bitmap can be used to optimise
resync - only sectors which could be out-of-sync need to be updated.

Also if a drive is removed and then added back into an array, the recovery can
make use of the bitmap to optimise reconstruction.  This is not implemented in
this patch.

Currently the bitmap is stored in a file which must (obviously) be stored on a
separate device.

The patch only provided infrastructure.  It does not update any personalities
to bitmap intent logging.

Md arrays can still be used with no bitmap file.  This patch has minimal
impact on such arrays.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:43 -07:00
NeilBrown
57afd89f98 [PATCH] md: improve the interface to sync_request
1/ change the return value (which is number-of-sectors synced)
 from 'int' to 'sector_t'.
 The number of sectors is usually easily small enough to fit
 in an int, but if resync needs to abort, it may want to return
 the total number of remaining sectors, which could be large.
 Also errors cannot be returned as negative numbers now, so use
 0 instead
2/ Add a 'skipped' return parameter to allow the array to report
 that it skipped the sectors.  This allows md to take this into account
 in the speed calculations.
 Currently there is no important skipping, but the bitmap-based-resync
 that is coming will use this.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:43 -07:00
NeilBrown
06d91a5fe0 [PATCH] md: improve locking on 'safemode' and move superblock writes
When md marks the superblock dirty before a write, it calls
generic_make_request (to write the superblock) from within
generic_make_request (to write the first dirty block), which could cause
problems later.

With this patch, the superblock write is always done by the helper thread, and
write request are delayed until that write completes.

Also, the locking around marking the array dirty and writing the superblock is
improved to avoid possible races.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21 19:07:43 -07:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00