tree fa64dac28c47940dd730fff68f692fd5bbd73d78
parent 5b7a1b9f9214cb89dd164b43ca3fab7af4058e06
author Trond Myklebust <Trond.Myklebust@netapp.com> 1249845268 -0400
committer Trond Myklebust <Trond.Myklebust@netapp.com> 1249845268 -0400

SUNRPC: Remove the global temporary write buffer in net/sunrpc/cache.c

While we do want to protect against multiple concurrent readers and writers
on each upcall/downcall pipe, we don't want to limit concurrent reading and
writing to separate caches.

This patch therefore replaces the static buffer 'write_buf', which can only
be used by one writer at a time, with use of the page cache as the
temporary buffer for downcalls. We still fall back to using the the old
global buffer if the downcall is larger than PAGE_CACHE_SIZE, since this is
apparently needed by the SPKM security context initialisation.

It then replaces the use of the global 'queue_io_mutex' with the
inode->i_mutex in cache_read() and cache_write().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>