devmnt: use c->iounit instead of msize-IOHDRSZ to chunk reads and writes, reduce memory overhead for Mntrpc, mntalloc lock

use the actual iounit returned from Ropen/Rcreate to chunk reads and writes
instead of c->mux->msize-IOHDRSZ.

dont preallocate the rpc buffers to msize, most 9p requests are rather small
(except Twrite of course). so we allocate the buffer on demand in mountio()
with some rounding to avoid frequent reallocations.

avoid malloc()/free() while holding mntalloc lock.

0 files changed, 0 insertions, 0 deletions