linux-toradex.git/drivers/md/persistent-data/dm-btree.c, branch v5.5

dm btree: fix order of block initialization in btree_split_beneath

2019-08-22T20:11:23+00:00

When btree_split_beneath() splits a node to two new children, it will
allocate two blocks: left and right.  If right block's allocation
failed, the left block will be unlocked and marked dirty.  If this
happened, the left block'ss content is zero, because it wasn't
initialized with the btree struct before the attempot to allocate the
right block.  Upon return, when flushing the left block to disk, the
validator will fail when check this block.  Then a BUG_ON is raised.

Fix this by completely initializing the left block before allocating and
initializing the right block.

Fixes: 4dcb8b57df359 ("dm btree: fix leak of bufio-backed block in btree_split_beneath error path")
Cc: stable@vger.kernel.org
Signed-off-by: ZhangXiaoxu 
Signed-off-by: Mike Snitzer

dm btree: fix serious bug in btree_split_beneath()

2018-01-17T14:07:55+00:00

When inserting a new key/value pair into a btree we walk down the spine of
btree nodes performing the following 2 operations:

  i) space for a new entry
  ii) adjusting the first key entry if the new key is lower than any in the node.

If the _root_ node is full, the function btree_split_beneath() allocates 2 new
nodes, and redistibutes the root nodes entries between them.  The root node is
left with 2 entries corresponding to the 2 new nodes.

btree_split_beneath() then adjusts the spine to point to one of the two new
children.  This means the first key is never adjusted if the new key was lower,
ie. operation (ii) gets missed out.  This can result in the new key being
'lost' for a period; until another low valued key is inserted that will uncover
it.

This is a serious bug, and quite hard to make trigger in normal use.  A
reproducing test case ("thin create devices-in-reverse-order") is
available as part of the thin-provision-tools project:
  https://github.com/jthornber/thin-provisioning-tools/blob/master/functional-tests/device-mapper/dm-tests.scm#L593

Fix the issue by changing btree_split_beneath() so it no longer adjusts
the spine.  Instead it unlocks both the new nodes, and lets the main
loop in btree_insert_raw() relock the appropriate one and make any
neccessary adjustments.

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

dm btree: fix for dm_btree_find_lowest_key()

2017-04-24T18:47:49+00:00

dm_btree_find_lowest_key() is giving incorrect results.  find_key()
traverses the btree correctly for finding the highest key, but there is
an error in the way it traverses the btree for retrieving the lowest
key.  dm_btree_find_lowest_key() fetches the first key of the rightmost
block of the btree instead of fetching the first key from the leftmost
block.

Fix this by conditionally passing the correct parameter to value64()
based on the @find_highest flag.

Cc: stable@vger.kernel.org
Signed-off-by: Erez Zadok 
Signed-off-by: Vinothkumar Raja 
Signed-off-by: Nidhi Panpalia 
Signed-off-by: Mike Snitzer

dm persistent data: add cursor skip functions to the cursor APIs

2017-02-16T18:12:50+00:00

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

dm btree: use GFP_NOFS in dm_btree_del()

2017-02-16T18:09:10+00:00

dm_btree_del() is called from an ioctl so don't recurse into FS.

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

dm btree: introduce cursor api

2016-09-22T15:15:04+00:00

This uses prefetching to speed up iteration through a btree.

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

dm btree: fix a bug in dm_btree_find_next_single()

2016-07-20T16:43:34+00:00

dm_btree_find_next_single() can short-circuit the search for a block
with a return of -ENODATA if all entries are higher than the search key
passed to lower_bound().

This hasn't been a problem because of the way the btree has been used by
DM thinp.  But it must be fixed now in preparation for fixing the race
in DM thinp's handling of simultaneous block discard vs allocation.
Otherwise, once that fix is in place, some of the blocks in a discard
would not be unmapped as expected.

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

dm btree: factor out need_insert() helper

2015-12-10T15:38:59+00:00

Eliminates code duplication within insert().

Signed-off-by: Mike Snitzer

dm btree: fix bufio buffer leaks in dm_btree_del() error path

2015-12-10T15:30:18+00:00

If dm_btree_del()'s call to push_frame() fails, e.g. due to
btree_node_validator finding invalid metadata, the dm_btree_del() error
path must unlock all frames (which have active dm-bufio buffers) that
were pushed onto the del_stack.

Otherwise, dm_bufio_client_destroy() will BUG_ON() because dm-bufio
buffers have leaked, e.g.:
  device-mapper: bufio: leaked buffer 3, hold count 1, list 0

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

dm thin metadata: fix bug in dm_thin_remove_range()

2015-12-02T18:26:49+00:00

dm_btree_remove_leaves() only unmaps a contiguous region so we need a
loop, in __remove_range(), to handle ranges that contain multiple
regions.

A new btree function, dm_btree_lookup_next(), is introduced which is
more efficiently able to skip over regions of the thin device which
aren't mapped.  __remove_range() uses dm_btree_lookup_next() for each
iteration of __remove_range()'s loop.

Also, improve description of dm_btree_remove_leaves().

Fixes: 6550f075 ("dm thin metadata: add dm_thin_remove_range()")
Signed-off-by: Joe Thornber 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # 4.1+