pNFS: Handle RPC size limit for layoutcommits

pNFS: Handle RPC size limit for layoutcommits

When there are too many block extents for a layoutcommit, they may not
all fit into the maximum-sized RPC. This patch allows the generic pnfs
code to properly handle -ENOSPC returned by the block/scsi layout driver
and trigger additional layoutcommits if necessary.

Co-developed-by: Konstantin Evtushenko <koevtushenko@yandex.com>
Signed-off-by: Konstantin Evtushenko <koevtushenko@yandex.com>
Signed-off-by: Sergey Bashirov <sergeybashirov@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250630183537.196479-5-sergeybashirov@gmail.com
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>