Re: [PATCH] radix-tree: fix comment about "exceptional" bits

The bottom two bits of radix tree entries are reserved for special use by the radix tree code itself. A comment detailing their usage was added by: commit 3bcadd6fa6c4 ("radix-tree: free up the bottom bit of exceptional entries for reuse") This comment states that if the bottom two bits are '11', this means that this is a locked exceptional entry. It turns out that this bit combination was never actually used. Radix tree locking for DAX was indeed implemented, but it actually used the third LSB: /* We use lowest available exceptional entry bit for locking */ #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT) This locking code was also made specific to the DAX code instead of being generally implemented in radix-tree.h. So, fix the comment. Signed-off-by: Ross Zwisler <ross.zwisler(a)linux.intel.com&gt;