The disk space map stores it's index entries in a btree, these are
accessed very frequently, so having a few cached makes a big difference
to performance.
With this change provisioning a new block takes roughly 20% less cpu.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
When we break sharing on btree nodes we typically need to increment
the reference counts to every value held in the node. This can
cause a lot of repeated calls to the space maps. Fix this by changing
the interface to the space map inc/dec methods to take ranges of
adjacent blocks to be operated on.
For installations that are using a lot of snapshots this will reduce
cpu overhead of fundamental operations such as provisioning a new block,
or deleting a snapshot, by as much as 10 times.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This division bug meant the search for free metadata space could skip
the final allocation bitmap's worth of entries. Fix affects DM thinp,
cache and era targets.
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Tested-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The space-maps track the reference counts for disk blocks allocated by
both the thin-provisioning and cache targets. There are variants for
tracking metadata blocks and data blocks.
Transactionality is implemented by never touching blocks from the
previous transaction, so we can rollback in the event of a crash.
When allocating a new block we need to ensure the block is free (has
reference count of 0) in both the current and previous transaction.
Prior to this fix we were doing this by searching for a free block in
the previous transaction, and relying on a 'begin' counter to track
where the last allocation in the current transaction was. This
'begin' field was not being updated in all code paths (eg, increment
of a data block reference count due to breaking sharing of a neighbour
block in the same btree leaf).
This fix keeps the 'begin' field, but now it's just a hint to speed up
the search. Instead the current transaction is searched for a free
block, and then the old transaction is double checked to ensure it's
free. Much simpler.
This fixes reports of sm_disk_new_block()'s BUG_ON() triggering when
DM thin-provisioning's snapshots are heavily used.
Reported-by: Eric Wheeler <dm-devel@lists.ewheeler.net>
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The function sm_find_free() just returns -ENOSPC and 0.
So remove lone caller's check for some other error.
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Otherwise, memory that is allocated (and potentially not previously
zeroed) will get written to disk as part of the space maps.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
bitmap API (include/linux/bitmap.h) has 'bitmap' prefix for its methods.
On the other hand DM bitmap API is special case.
Adding 'dm' prefix to it to avoid potential name space collision.
No functional changes intended.
Suggested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
The metadata_space_map_root passed to sm_ll_open_metadata() may or may
not be arch aligned, use memcpy to ensure it is. This is not a fast
path so the extra memcpy doesn't hurt us.
Long-term it'd be better to use the kernel's alignment infrastructure to
remove the memcpy()s that are littered across persistent-data (btree,
array, space-maps, etc).
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
If no block was allocated or freed, sm_ll_mutate() wasn't setting
*ev, leaving the variable unitialized. sm_ll_insert(),
sm_disk_inc_block(), and sm_disk_new_block() all check ev to see
if there was an allocation event in sm_ll_mutate(), possibly
reading unitialized data.
If no allocation event occured, sm_ll_mutate() should set *ev
to SM_NONE.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
When metadata_ll_init_index() is called by sm_ll_new_metadata(),
ll->mi_le hasn't been initialized yet. So, when
metadata_ll_init_index() copies the contents of ll->mi_le into the
newly allocated bitmap_root, it is just copying garbage. ll->mi_le
will be allocated later in sm_ll_extend() and copied into the
bitmap_root, in sm_ll_commit().
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
dm_bm_unlock and dm_tm_unlock return an integer value but the returned
value is always 0. The calling code sometimes checks the return value
and sometimes doesn't.
Eliminate these unnecessary return values and also the checks for them.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
When extending a low level space map we should update nr_blocks at
the start so the new space is used for the index entries.
Otherwise extend can fail, e.g.: sm_metadata_extend call sequence
that fails:
-> sm_ll_extend
-> dm_tm_new_block -> dm_sm_new_block -> sm_bootstrap_new_block
=> returns -ENOSPC because smm->begin == smm->ll.nr_blocks
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
The old behaviour, returning -EINVAL if a ref_count of 0 would be
decremented, was removed in commit f722063 ("dm space map: optimise
sm_ll_dec and sm_ll_inc"). To fix this regression we return an error
code from the mutator function pointer passed to sm_ll_mutate() and have
dec_ref_count() return -EINVAL if the old ref_count is 0.
Add a DMERR to reflect the potential seriousness of this error.
Also, add missing dm_tm_unlock() to sm_ll_mutate()'s error path.
With this fix the following dmts regression test now passes:
dmtest run --suite cache -n /metadata_use_kernel/
The next patch fixes the higher-level dm-array code that exposed this
regression.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.12+
Prior to this patch these methods did a lookup followed by an insert.
Instead they now call a common mutate function that adjusts the value
according to a callback function. This avoids traversing the data
structures twice and hence improves performance.
Also factor out sm_ll_lookup_big_ref_count() for use by both
sm_ll_lookup() and sm_ll_mutate().
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Nearly all of persistent-data is in the IO path so throttle error
messages with DMERR_LIMIT to limit the amount logged when
something has gone wrong.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Convert cpu_to_le32(le32_to_cpu(E1) + E2) to use le32_add_cpu().
dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch)
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Introduce bitmap_index_changed to track whether or not the index changed
then only commit a space map if it did.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Save space by removing entries from the space map ref_count tree if
they're no longer needed.
Ref counts are stored in two places: a bitmap if the ref_count is
below 3, or a btree of uint32_t if 3 or above.
When a ref_count that was above 3 drops below we can remove it from
the tree and save some metadata space. This removal was commented out
before because I was unsure why this was causing under-populated btree
nodes. Earlier patches have fixed this issue.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
The persistent-data library offers a re-usable framework for the storage
and management of on-disk metadata in device-mapper targets.
It's used by the thin-provisioning target in the next patch and in an
upcoming hierarchical storage target.
For further information, please read
Documentation/device-mapper/persistent-data.txt
Signed-off-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Joe Thornber