On Wed, 2009-04-29 at 15:58 +0200, Thomas Glanzmann wrote: > Hello Chris, > > > But, in your ioctls you want to deal with [file, offset, len], not > > directly with block numbers. COW means that blocks can move around > > without you knowing, and some of the btrfs internals will COW files in > > order to relocate storage. > > > So, what you want is a dedup file (or files) where your DB knows a given > > offset in the file has a given csum. > > how do I track if a certain block has already been deduplicated? > Your database should know, and the ioctl could check to see if the source and destination already point to the same thing before doing anything expensive. > So, if I only have file, offset, len and not the block number, is there > a way from userland to tell if two blocks are already point to the same > block? You can use the fiemap ioctl. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
