NFS: Optimise inode attribute cache updates

 Allow nfs_refresh_inode() also to update attributes on the inode if the
 RPC call was sent after the last call to nfs_update_inode().

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

1 files changed, 40 insertions, 14 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 449df8c8aa31..b7d4f8f13ac2 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -785,7 +785,8 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
                 else
                         init_special_inode(inode, inode->i_mode, fattr->rdev);
 
-                nfsi->read_cache_jiffies = fattr->timestamp;
+                nfsi->read_cache_jiffies = fattr->time_start;
+                nfsi->last_updated = jiffies;
                 inode->i_atime = fattr->atime;
                 inode->i_mtime = fattr->mtime;
                 inode->i_ctime = fattr->ctime;
@@ -1120,14 +1121,15 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
                 goto out;
         }
 
+        spin_lock(&inode->i_lock);
         status = nfs_update_inode(inode, &fattr, verifier);
         if (status) {
+                spin_unlock(&inode->i_lock);
                 dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) refresh failed, error=%d\n",
                          inode->i_sb->s_id,
                          (long long)NFS_FILEID(inode), status);
                 goto out;
         }
-        spin_lock(&inode->i_lock);
         cache_validity = nfsi->cache_validity;
         nfsi->cache_validity &= ~NFS_INO_REVAL_PAGECACHE;
 
@@ -1247,7 +1249,7 @@ void nfs_end_data_update(struct inode *inode)
 }
 
 /**
- * nfs_refresh_inode - verify consistency of the inode attribute cache
+ * nfs_check_inode_attributes - verify consistency of the inode attribute cache
  * @inode - pointer to inode
  * @fattr - updated attributes
  *
@@ -1255,13 +1257,12 @@ void nfs_end_data_update(struct inode *inode)
  * so that fattr carries weak cache consistency data, then it may
  * also update the ctime/mtime/change_attribute.
  */
-int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
+static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fattr)
 {
         struct nfs_inode *nfsi = NFS_I(inode);
         loff_t cur_size, new_isize;
         int data_unstable;
 
-        spin_lock(&inode->i_lock);
 
         /* Are we in the process of updating data on the server? */
         data_unstable = nfs_caches_unstable(inode);
@@ -1325,11 +1326,40 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
         if (!timespec_equal(&inode->i_atime, &fattr->atime))
                 nfsi->cache_validity |= NFS_INO_INVALID_ATIME;
 
-        nfsi->read_cache_jiffies = fattr->timestamp;
-        spin_unlock(&inode->i_lock);
+        nfsi->read_cache_jiffies = fattr->time_start;
         return 0;
 }
 
+/**
+ * nfs_refresh_inode - try to update the inode attribute cache
+ * @inode - pointer to inode
+ * @fattr - updated attributes
+ *
+ * Check that an RPC call that returned attributes has not overlapped with
+ * other recent updates of the inode metadata, then decide whether it is
+ * safe to do a full update of the inode attributes, or whether just to
+ * call nfs_check_inode_attributes.
+ */
+int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+        int status;
+
+        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
+                return 0;
+        spin_lock(&inode->i_lock);
+        nfsi->cache_validity &= ~NFS_INO_REVAL_PAGECACHE;
+        if (nfs_verify_change_attribute(inode, fattr->time_start))
+                nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME);
+        if (time_after(fattr->time_start, nfsi->last_updated))
+                status = nfs_update_inode(inode, fattr, fattr->time_start);
+        else
+                status = nfs_check_inode_attributes(inode, fattr);
+
+        spin_unlock(&inode->i_lock);
+        return status;
+}
+
 /*
  * Many nfs protocol calls return the new file attributes after
  * an operation.  Here we update the inode to reflect the state
@@ -1365,20 +1395,17 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
                 goto out_err;
         }
 
-        spin_lock(&inode->i_lock);
-
         /*
          * Make sure the inode's type hasn't changed.
          */
-        if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT)) {
-                spin_unlock(&inode->i_lock);
+        if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
                 goto out_changed;
-        }
 
         /*
          * Update the read time so we don't revalidate too often.
          */
-        nfsi->read_cache_jiffies = fattr->timestamp;
+        nfsi->read_cache_jiffies = fattr->time_start;
+        nfsi->last_updated = jiffies;
 
         /* Are we racing with known updates of the metadata on the server? */
         data_unstable = ! (nfs_verify_change_attribute(inode, verifier) ||
@@ -1467,7 +1494,6 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
         if (!nfs_have_delegation(inode, FMODE_READ))
                 nfsi->cache_validity |= invalid;
 
-        spin_unlock(&inode->i_lock);
         return 0;
  out_changed:
         /*