NFSv4: Express delegation limit in units of pages

Since we're tracking modifications to the page cache on a per-page
basis, it makes sense to express the limit to how much we may cache
in units of pages.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

4 files changed, 14 insertions, 10 deletions

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 029d688a969f..cd503cc2251c 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -175,7 +175,7 @@ void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred,
                 if (delegation->inode != NULL) {
                         nfs4_stateid_copy(&delegation->stateid, &res->delegation);
                         delegation->type = res->delegation_type;
-                        delegation->maxsize = res->maxsize;
+                        delegation->pagemod_limit = res->pagemod_limit;
                         oldcred = delegation->cred;
                         delegation->cred = get_rpccred(cred);
                         clear_bit(NFS_DELEGATION_NEED_RECLAIM,
@@ -337,7 +337,7 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
                 return -ENOMEM;
         nfs4_stateid_copy(&delegation->stateid, &res->delegation);
         delegation->type = res->delegation_type;
-        delegation->maxsize = res->maxsize;
+        delegation->pagemod_limit = res->pagemod_limit;
         delegation->change_attr = inode->i_version;
         delegation->cred = get_rpccred(cred);
         delegation->inode = inode;
diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
index e3c20a3ccc93..554178a17376 100644
--- a/fs/nfs/delegation.h
+++ b/fs/nfs/delegation.h
@@ -18,7 +18,7 @@ struct nfs_delegation {
         struct inode *inode;
         nfs4_stateid stateid;
         fmode_t type;
-        loff_t maxsize;
+        unsigned long pagemod_limit;
         __u64 change_attr;
         unsigned long flags;
         spinlock_t lock;
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index ff4784c54e04..788adf3897c7 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4932,24 +4932,28 @@ static int decode_lookup(struct xdr_stream *xdr)
 }
 
 /* This is too sick! */
-static int decode_space_limit(struct xdr_stream *xdr, u64 *maxsize)
+static int decode_space_limit(struct xdr_stream *xdr,
+                unsigned long *pagemod_limit)
 {
         __be32 *p;
         uint32_t limit_type, nblocks, blocksize;
+        u64 maxsize = 0;
 
         p = xdr_inline_decode(xdr, 12);
         if (unlikely(!p))
                 goto out_overflow;
         limit_type = be32_to_cpup(p++);
         switch (limit_type) {
-        case 1:
-                xdr_decode_hyper(p, maxsize);
+        case NFS4_LIMIT_SIZE:
+                xdr_decode_hyper(p, &maxsize);
                 break;
-        case 2:
+        case NFS4_LIMIT_BLOCKS:
                 nblocks = be32_to_cpup(p++);
                 blocksize = be32_to_cpup(p);
-                *maxsize = (uint64_t)nblocks * (uint64_t)blocksize;
+                maxsize = (uint64_t)nblocks * (uint64_t)blocksize;
         }
+        maxsize >>= PAGE_CACHE_SHIFT;
+        *pagemod_limit = min_t(u64, maxsize, ULONG_MAX);
         return 0;
 out_overflow:
         print_overflow_msg(__func__, xdr);
@@ -4977,7 +4981,7 @@ static int decode_rw_delegation(struct xdr_stream *xdr,
                 break;
         case NFS4_OPEN_DELEGATE_WRITE:
                 res->delegation_type = FMODE_WRITE|FMODE_READ;
-                if (decode_space_limit(xdr, &res->maxsize) < 0)
+                if (decode_space_limit(xdr, &res->pagemod_limit) < 0)
                                 return -EIO;
         }
         return decode_ace(xdr, NULL, res->server->nfs_client);
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index b4392d86d157..52faf7e96c65 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -406,8 +406,8 @@ struct nfs_openres {
         const struct nfs_server *server;
         fmode_t                 delegation_type;
         nfs4_stateid            delegation;
+        unsigned long           pagemod_limit;
         __u32                   do_recall;
-        __u64                   maxsize;
         __u32                   attrset[NFS4_BITMAP_SIZE];
         struct nfs4_string      *owner;
         struct nfs4_string      *group_owner;