On Fri, Apr 26, 2019 at 04:28:16PM +1000, Dave Chinner wrote: > i.e. go look at how xfs_pnfs.c works to hand out block mappings to > remote pNFS clients so they can directly access the underlying > storage. Basically, anyone wanting to map blocks needs a file layout > lease and then to manage the filesystem state over that range via > these methods in the struct export_operations: > > int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset); > int (*map_blocks)(struct inode *inode, loff_t offset, > u64 len, struct iomap *iomap, > bool write, u32 *device_generation); > int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, > int nr_iomaps, struct iattr *iattr); Nipick: get_uuid isn't needed for the least itself, it just works around the fact that the original pNFS/block protocol is braindead. The pNFS/SCSI prototocol already switches to a device UUID, and other users that work locally shouldn't need it either.
