From: Dave Hansen A little helper that we use in the hotplug code. Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton --- include/linux/mmzone.h | 25 +++++++++++++++++++++++++ 1 files changed, 25 insertions(+) diff -puN include/linux/mmzone.h~memory-hotplug-prep-__section_nr-helper include/linux/mmzone.h --- devel/include/linux/mmzone.h~memory-hotplug-prep-__section_nr-helper 2005-09-07 20:10:27.000000000 -0700 +++ devel-akpm/include/linux/mmzone.h 2005-09-07 20:10:27.000000000 -0700 @@ -513,6 +513,31 @@ static inline struct mem_section *__nr_t } /* + * Although written for the SPARSEMEM_EXTREME case, this happens + * to also work for the flat array case becase + * NR_SECTION_ROOTS==NR_MEM_SECTIONS. + */ +static inline int __section_nr(struct mem_section* ms) +{ + unsigned long root_nr; + struct mem_section* root; + + for (root_nr = 0; + root_nr < NR_MEM_SECTIONS; + root_nr += SECTIONS_PER_ROOT) { + root = __nr_to_section(root_nr); + + if (!root) + continue; + + if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT))) + break; + } + + return (root_nr * SECTIONS_PER_ROOT) + (ms - root); +} + +/* * We use the lower bits of the mem_map pointer to store * a little bit of information. There should be at least * 3 bits here due to 32-bit alignment. _