summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/locking.h
diff options
context:
space:
mode:
authorJosef Bacik <josef@toxicpanda.com>2020-08-20 11:46:04 -0400
committerDavid Sterba <dsterba@suse.com>2020-10-07 12:12:16 +0200
commitbf77467a93bdf11d815f5c5f25206a0d058da8de (patch)
treede61ced135cc6209b53edc8829335969cb9c8ec8 /fs/btrfs/locking.h
parent9631e4cc1a030aa71dea588cc9a57533b657489f (diff)
downloadlinux-bf77467a93bdf11d815f5c5f25206a0d058da8de.tar.gz
linux-bf77467a93bdf11d815f5c5f25206a0d058da8de.tar.bz2
linux-bf77467a93bdf11d815f5c5f25206a0d058da8de.zip
btrfs: introduce BTRFS_NESTING_LEFT/BTRFS_NESTING_RIGHT
Our lockdep maps are based on rootid+level, however in some cases we will lock adjacent blocks on the same level, namely in searching forward or in split/balance. Because of this lockdep will complain, so we need a separate subclass to indicate to lockdep that these are different locks. lock leaf -> BTRFS_NESTING_NORMAL cow leaf -> BTRFS_NESTING_COW split leaf lock left -> BTRFS_NESTING_LEFT lock right -> BTRFS_NESTING_RIGHT The above graph illustrates the need for this new nesting subclass. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/locking.h')
-rw-r--r--fs/btrfs/locking.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index 8b47ba34fb03..5844bc1c8410 100644
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -33,6 +33,18 @@ enum btrfs_lock_nesting {
BTRFS_NESTING_COW,
/*
+ * Oftentimes we need to lock adjacent nodes on the same level while
+ * still holding the lock on the original node we searched to, such as
+ * for searching forward or for split/balance.
+ *
+ * Because of this we need to indicate to lockdep that this is
+ * acceptable by having a different subclass for each of these
+ * operations.
+ */
+ BTRFS_NESTING_LEFT,
+ BTRFS_NESTING_RIGHT,
+
+ /*
* We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so
* add this in here and add a static_assert to keep us from going over
* the limit. As of this writing we're limited to 8, and we're