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authorMatthew Wilcox <willy@linux.intel.com>2016-05-20 17:03:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-20 17:58:30 -0700
commit3bcadd6fa6c4fd07ace3626357c824eb532488a6 (patch)
tree4e0fee97bdc25e76f7a786e1049a9aab6208d518 /arch/sparc/Kconfig
parent78a9be0a0a3367b94af242632c525d22b26f1a87 (diff)
downloadlinux-3bcadd6fa6c4fd07ace3626357c824eb532488a6.tar.gz
radix-tree: free up the bottom bit of exceptional entries for reuse
We are guaranteed that pointers to radix_tree_nodes always have the bottom two bits clear (because they come from a slab cache, and slab caches have a minimum alignment of sizeof(void *)), so we can redefine 'radix_tree_is_internal_node' to only return true if the bottom two bits have value '01'. This frees up one quarter of the potential values for use by the user. Idea from Neil Brown. Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Suggested-by: Neil Brown <neilb@suse.de> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Jan Kara <jack@suse.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/sparc/Kconfig')
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