On Tue, 31 May 2011, Dan Magenheimer wrote: > > > > truncate_inode_pages_range() and invalidate_inode_pages2_range() > > call cleancache_flush_inode(mapping) before and after: shouldn't > > invalidate_mapping_pages() be doing the same? > > I don't claim to be an expert on VFS, and so I have cc'ed > Chris Mason who originally placed the cleancache hooks > in VFS, but I think this patch is unnecessary. Instead > of flushing ALL of the cleancache pages belonging to > the inode with cleancache_flush_inode, the existing code > eventually calls __delete_from_page_cache on EACH page > that is being invalidated. On each one that's in pagecache (and satisfies the other "can we do it easily?" conditions peculiar to invalidate_mapping_pages()). But there may be other slots in the range that don't reach __delete_from_page_cache() e.g. because not currently in pagecache, but whose cleancache ought to be flushed. I think that's what a caller of invalidate_mapping_pages(), e.g. drop caches, expects. > And since __delete_from_page_cache > calls cleancache_flush_page, only that subset of pages > in the mapping that invalidate_mapping_pages() would > invalidate (which, from the comment above the routine > indicates, is only *unlocked* pages) is removed from > cleancache. It's nice to target the particular range asked for, rather than throwing away all the cleancache for the whole mapping, I can see that (though that's a defect in the cleancache_flush_inode() interface). But then why do truncate_inode_pages_range() and invalidate_inode_pages2_range() throw it all away, despite going down to __delete_from_page_cache on individual pages found? Maybe the right patch is to remove cleancache_flush_inode() from the two instead of adding it to the one? But I think not. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>