linux-toradex.git/drivers/md/persistent-data/dm-space-map-common.c, branch v5.11-rc2

dm space map common: fix to ensure new block isn't already in use

2020-01-15T01:15:53+00:00

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 
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer

dm space map common: remove check for impossible sm_find_free() return value

2019-08-26T19:39:53+00:00

The function sm_find_free() just returns -ENOSPC and 0.
So remove lone caller's check for some other error.

Signed-off-by: ZhangXiaoxu 
Signed-off-by: Mike Snitzer

dm space map common: zero entire ll_disk

2019-04-18T20:18:32+00:00

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

dm: Avoid namespace collision with bitmap API

2018-08-01T22:49:38+00:00

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 
Signed-off-by: Andy Shevchenko 
Acked-by: Mike Snitzer 
Signed-off-by: Dmitry Torokhov

dm space map common: memcpy the disk root to ensure it's arch aligned

2017-02-16T18:02:54+00:00

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 
Signed-off-by: Mike Snitzer

dm space map: always set ev if sm_ll_mutate() succeeds

2016-12-08T19:13:15+00:00

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 
Acked-by: Joe Thornber 
Signed-off-by: Mike Snitzer

dm space map metadata: skip useless memcpy in metadata_ll_init_index()

2016-12-08T19:13:15+00:00

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 
Signed-off-by: Mike Snitzer

dm persistent data: eliminate unnecessary return values

2015-10-31T23:06:02+00:00

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 
Signed-off-by: Mike Snitzer

dm space map common: make sure new space is used during extend

2014-01-08T02:05:17+00:00

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 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org

dm space map: disallow decrementing a reference count below zero

2013-12-13T19:22:09+00:00

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 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # 3.12+