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>

6 files changed, 44 insertions, 20 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:
         /*
diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
index d91b69044a4d..59049e864ca7 100644
--- a/fs/nfs/nfs2xdr.c
+++ b/fs/nfs/nfs2xdr.c
@@ -143,7 +143,6 @@ xdr_decode_fattr(u32 *p, struct nfs_fattr *fattr)
                 fattr->mode = (fattr->mode & ~S_IFMT) | S_IFIFO;
                 fattr->rdev = 0;
         }
-        fattr->timestamp = jiffies;
         return p;
 }
 
diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index db4a904810a4..0498bd36602c 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -174,7 +174,6 @@ xdr_decode_fattr(u32 *p, struct nfs_fattr *fattr)
 
         /* Update the mode bits */
         fattr->valid |= (NFS_ATTR_FATTR | NFS_ATTR_FATTR_V3);
-        fattr->timestamp = jiffies;
         return p;
 }
 
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index cd762648fa9a..8b21de8a06fa 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -2799,10 +2799,8 @@ static int decode_getfattr(struct xdr_stream *xdr, struct nfs_fattr *fattr, cons
                 goto xdr_error;
         if ((status = decode_attr_time_modify(xdr, bitmap, &fattr->mtime)) != 0)
                 goto xdr_error;
-        if ((status = verify_attr_len(xdr, savep, attrlen)) == 0) {
+        if ((status = verify_attr_len(xdr, savep, attrlen)) == 0)
                 fattr->valid = NFS_ATTR_FATTR | NFS_ATTR_FATTR_V3 | NFS_ATTR_FATTR_V4;
-                fattr->timestamp = jiffies;
-        }
 xdr_error:
         if (status != 0)
                 printk(KERN_NOTICE "%s: xdr error %d!\n", __FUNCTION__, -status);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index abf890f5fbfb..faeaad666ca8 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -141,6 +141,7 @@ struct nfs_inode {
         unsigned long           attrtimeo_timestamp;
         __u64                   change_attr;            /* v4 only */
 
+        unsigned long           last_updated;
         /* "Generation counter" for the attribute cache. This is
          * bumped whenever we update the metadata on the
          * server.
@@ -319,6 +320,7 @@ extern u32 root_nfs_parse_addr(char *name); /*__init*/
 static inline void nfs_fattr_init(struct nfs_fattr *fattr)
 {
         fattr->valid = 0;
+        fattr->time_start = jiffies;
 }
 
 /*
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 60086dac11d5..aeaee7e7c51d 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -41,7 +41,7 @@ struct nfs_fattr {
         __u32                   bitmap[2];      /* NFSv4 returned attribute bitmap */
         __u64                   change_attr;    /* NFSv4 change attribute */
         __u64                   pre_change_attr;/* pre-op NFSv4 change attribute */
-        unsigned long           timestamp;
+        unsigned long           time_start;
 };
 
 #define NFS_ATTR_WCC            0x0001          /* pre-op WCC data    */