maple_tree: add write lock checking with lockdep sequence numbers

Use the lockdep sequence numbers to ensure the write lock is not dropped
between write operations.  The lockdep sequence is recorded on any walk
that starts from the top of the tree and re-checked prior to any operation
using an active node.

When lockdep detects an issue, it sets debug_locks to 0 disabling further
reports.  __lock_sequnece() will return u32 ~0 when debug_locks is zero,
and the real sequnece count cannot return such a high value as it is less
than 32bits.

By always updating the sequence number, regardless of lock state and by
ignoring ~0 value in the sequence number will avoid ever printing a
WARN_ON when lockdep sets debug_locks to 0.

Link: https://lore.kernel.org/20260821192627.4085470-4-liam@infradead.org
Signed-off-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Cc: Breno Leitao <leitao@debian.org>
Tested-by: Breno Leitao <leitao@debian.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Chris Mason <clm@meta.com>
Cc: Chuck Lever <cel@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joe Perches <joe@perches.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions