If we are to allow bitmaps to be resized when the array is resized,
we need to know how much space there is.
So create an attribute to store this information and set appropriate
defaults.
It can be set more precisely via sysfs, or future metadata extensions
may allow it to be recorded.
Signed-off-by: NeilBrown <neilb@suse.de>
There are two different 'pending' concepts in the handling of the
write intent bitmap.
Firstly, a 'page' from the bitmap (which container PAGE_SIZE*8 bits)
may have changes (bits cleared) that should be written in due course.
There is no hurry for these and the page will transition from
PENDING to NEEDWRITE and will then be written, though if it ever
becomes DIRTY it will be written much sooner and PENDING will be
cleared.
Secondly, a page of counters - which contains PAGE_SIZE/2 counters, one
for each bit, can usefully have a 'pending' flag which indicates if
any of the counters are low (2 or 1) and ready to be processed by
bitmap_daemon_work(). If this flag is clear we can skip the whole
page.
These two concepts are currently combined in the bitmap-file flag.
This causes a tighter connection between the counters and the bitmap
file than I would like - as I want to add some flexibility to the
bitmap file.
So introduce a new flag with the page-of-counters, and rewrite
bitmap_daemon_work() so that it handles the two different 'pending'
concepts separately.
This also allows us to clear BITMAP_PAGE_PENDING when we write out
a dirty page, which may occasionally reduce the number of times we
write a page.
Signed-off-by: NeilBrown <neilb@suse.de>
commit 61a0d80c "md/bitmap: discard CHUNK_BLOCK_SHIFT macro"
replaced CHUNK_BLOCK_RATIO() by the same text that was
replacing CHUNK_BLOCK_SHIFT() - which is clearly wrong.
The result is that 'chunks' is often too small by 1,
which can sometimes result in a crash (not sure how).
So use the correct replacement, and get rid of CHUNK_BLOCK_RATIO
which is no longe used.
Reported-by: Karl Newman <siliconfiend@gmail.com>
Tested-by: Karl Newman <siliconfiend@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
If a bitmap is added while the array is active, it is possible
for bitmap_daemon_work to run while the bitmap is being
initialised.
This is particularly a problem if bitmap_daemon_work sees
bitmap->filemap as non-NULL before it has been filled in properly.
So hold bitmap_info.mutex while filling in ->filemap
to prevent problems.
This patch is suitable for any -stable kernel, though it might not
apply cleanly before about 3.1.
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
bitmap_new_disk_sb() would still create V3 bitmap superblock
with host-endian layout.
Perhaps I'm confused, but shouldn't bitmap_new_disk_sb() be
creating a V4 bitmap superblock instead, that is portable,
as per comment in bitmap.h?
Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Pull md updates for 3.4 from Neil Brown:
"Mostly tidying up code in preparation for some bigger changes next
time.
A few bug fixes tagged for -stable.
Main functionality change is that some RAID10 arrays can now grow to
use extra space that may have been made available on the individual
devices."
Fixed up trivial conflicts with the k[un]map_atomic() cleanups in
drivers/md/bitmap.c.
* tag 'md-3.4' of git://neil.brown.name/md: (22 commits)
md: Add judgement bb->unacked_exist in function md_ack_all_badblocks().
md: fix clearing of the 'changed' flags for the bad blocks list.
md/bitmap: discard CHUNK_BLOCK_SHIFT macro
md/bitmap: remove unnecessary indirection when allocating.
md/bitmap: remove some pointless locking.
md/bitmap: change a 'goto' to a normal 'if' construct.
md/bitmap: move printing of bitmap status to bitmap.c
md/bitmap: remove some unused noise from bitmap.h
md/raid10 - support resizing some RAID10 arrays.
md/raid1: handle merge_bvec_fn in member devices.
md/raid10: handle merge_bvec_fn in member devices.
md: add proper merge_bvec handling to RAID0 and Linear.
md: tidy up rdev_for_each usage.
md/raid1,raid10: avoid deadlock during resync/recovery.
md/bitmap: ensure to load bitmap when creating via sysfs.
md: don't set md arrays to readonly on shutdown.
md: allow re-add to failed arrays.
md/raid5: use atomic_dec_return() instead of atomic_dec() and atomic_read().
md: Use existed macros instead of numbers
md/raid5: removed unused 'added_devices' variable.
...
Be redefining ->chunkshift as the shift from sectors to chunks rather
than bytes to chunks, we can just use "bitmap->chunkshift" which is
shorter than the macro call, and less indirect.
Signed-off-by: NeilBrown <neilb@suse.de>
These funcitons don't add anything useful except possibly the trace
points, and I don't think they are worth the extra indirection.
So remove them.
Signed-off-by: NeilBrown <neilb@suse.de>
There is nothing gained by holding a lock while we check if a pointer
is NULL or not. If there could be a race, then it could become NULL
immediately after the unlock - but there is no race here.
So just remove the locking.
Signed-off-by: NeilBrown <neilb@suse.de>
The use of a goto makes the control flow more obscure here.
So make it a normal:
if (x) {
Y;
}
No functional change.
Signed-off-by: NeilBrown <neilb@suse.de>
The part of /proc/mdstat which describes the bitmap should really
be generated by code in bitmap.c. So move it there.
Signed-off-by: NeilBrown <neilb@suse.de>
md.h has an 'rdev_for_each()' macro for iterating the rdevs in an
mddev. However it uses the 'safe' version of list_for_each_entry,
and so requires the extra variable, but doesn't include 'safe' in the
name, which is useful documentation.
Consequently some places use this safe version without needing it, and
many use an explicity list_for_each entry.
So:
- rename rdev_for_each to rdev_for_each_safe
- create a new rdev_for_each which uses the plain
list_for_each_entry,
- use the 'safe' version only where needed, and convert all other
list_for_each_entry calls to use rdev_for_each.
Signed-off-by: NeilBrown <neilb@suse.de>
When commit 69e51b449d (md/bitmap: separate out loading a bitmap...)
created bitmap_load, it missed calling it after bitmap_create when a
bitmap is created through the sysfs interface.
So if a bitmap is added this way, we don't allocate memory properly
and can crash.
This is suitable for any -stable release since 2.6.35.
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
For each active region corresponding to a bit in the bitmap with have
a 14bit counter (and some flags).
This counts
number of active writes + bit in the on-disk bitmap + delay-needed.
The "delay-needed" is because we always want a delay before clearing a
bit. So the number here is normally number of active writes plus 2.
If there have been no writes for a while, we drop to 1.
If still no writes we clear the bit and drop to 0.
So for consistency, when setting bit from the on-disk bitmap or by
request from user-space it is best to set the counter to '2' to start
with.
In particular we might also set the NEEDED_MASK flag at this time, and
in all other cases NEEDED_MASK is only set when the counter is 2 or
more.
Signed-off-by: NeilBrown <neilb@suse.de>
We have a variable 'mddev' in this function, but repeatedly get the
same value by dereferencing bitmap->mddev.
There is room for simplification here...
Signed-off-by: NeilBrown <neilb@suse.de>
commit d0a4bb4927 introduced a
regression which is annoying but fairly harmless.
When writing to an array that is undergoing recovery (a spare
in being integrated into the array), writing to the array will
set bits in the bitmap, but they will not be cleared when the
write completes.
For bits covering areas that have not been recovered yet this is not a
problem as the recovery will clear the bits. However bits set in
already-recovered region will stay set and never be cleared.
This doesn't risk data integrity. The only negatives are:
- next time there is a crash, more resyncing than necessary will
be done.
- the bitmap doesn't look clean, which is confusing.
While an array is recovering we don't want to update the
'events_cleared' setting in the bitmap but we do still want to clear
bits that have very recently been set - providing they were written to
the recovering device.
So split those two needs - which previously both depended on 'success'
and always clear the bit of the write went to all devices.
Signed-off-by: NeilBrown <neilb@suse.de>
Page attributes are set using __set_bit rather than set_bit as
it normally called under a spinlock so the extra atomicity is not
needed.
However there are two places where we might set or clear page
attributes without holding the spinlock.
So add the spinlock in those cases.
This might be the cause of occasional reports that bits a aren't
getting clear properly - theory is that BITMAP_PAGE_PENDING gets lost
when BITMAP_PAGE_NEEDWRITE is set or cleared. This is an
inconvenience, not a threat to data safety.
Signed-off-by: NeilBrown <neilb@suse.de>
The typedefs are just annoying. 'mdk' probably refers to 'md_k.h'
which used to be an include file that defined this thing.
Signed-off-by: NeilBrown <neilb@suse.de>
The 'allclean' flag is used to cache the fact that there is nothing to
do, so we can avoid waking up and scanning the bitmap regularly.
The two sorts of pages that might need the attention of the bitmap
daemon are BITMAP_PAGE_PENDING and BITMAP_PAGE_NEEDWRITE pages.
So make sure allclean reflects exactly when there are none of those.
So:
set it before scanning all pages with either bit set.
clear it whenever these bits are set
clear it when we desire not to clear one of these bits.
don't clear it any other time.
Signed-off-by: NeilBrown <neilb@suse.de>
The flag 'BITMAP_PAGE_CLEAN' has a confusing name as it doesn't mean
that the page is clean, but rather that there are counters in the page
which allow bits in the bitmap to be cleared - i.e. maybe cleaning can
happen.
So change it to BITMAP_PAGE_PENDING and fix some irregularities:
- Don't set it in bitmap_init_from_disk as bitmap_set_memory_bits
sets it when needed
- in bitmap_daemon_work, if we find a counter that is '1', but
need_sync is set, then set BITMAP_PAGE_PENDING again (it was
recently cleared) to ensure we don't forget about this bit.
Signed-off-by: NeilBrown <neilb@suse.de>
Revert most of commit e384e58549
md/bitmap: prepare for storing write-intent-bitmap via dm-dirty-log.
MD should not need to use DM's dirty log - we decided to use md's
bitmaps instead.
Keeping the DIV_ROUND_UP clean-ups that were part of commit
e384e58549, however.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
NeilBrown
Andrei Warkentin
Linus Torvalds
Cong Wang
Jonathan Brassow