nfs: fix congestion control: use atomic_longs

Change the atomic_t in struct nfs_server to atomic_long_t in anticipation
of machines that can handle 8+TB of (4K) pages under writeback.

However I suspect other things in NFS will start going *bang* by then.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 522cd41..de92b95 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -224,7 +224,7 @@ static int nfs_set_page_writeback(struct page *page)
                struct inode *inode = page->mapping->host;
                struct nfs_server *nfss = NFS_SERVER(inode);
 
-               if (atomic_inc_return(&nfss->writeback) >
+               if (atomic_long_inc_return(&nfss->writeback) >
                                NFS_CONGESTION_ON_THRESH)
                        set_bdi_congested(&nfss->backing_dev_info, WRITE);
        }
@@ -237,7 +237,7 @@ static void nfs_end_page_writeback(struct page *page)
        struct nfs_server *nfss = NFS_SERVER(inode);
 
        end_page_writeback(page);
-       if (atomic_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) {
+       if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH) {
                clear_bdi_congested(&nfss->backing_dev_info, WRITE);
                congestion_end(WRITE);
        }

diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index c95d5e6..52b4378 100644 (file)
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -82,7 +82,7 @@ struct nfs_server {
        struct rpc_clnt *       client_acl;     /* ACL RPC client handle */
        struct nfs_iostats *    io_stats;       /* I/O statistics */
        struct backing_dev_info backing_dev_info;
-       atomic_t                writeback;      /* number of writeback pages */
+       atomic_long_t           writeback;      /* number of writeback pages */
        int                     flags;          /* various flags */
        unsigned int            caps;           /* server capabilities */
        unsigned int            rsize;          /* read size */