NFS: Fix a few further cache consistency regressions

 Steve Dickson writes:
 Doing the following:
 1. On server:
 $ mkdir ~/t
 $ echo Hello > ~/t/tmp

 2. On client, wait for a string to appear in this file:
 $ until grep -q foo t/tmp ; do echo -n . ; sleep 1 ; done

 3. On server, create a *new* file with the same name containing that
 string:
 $ mv ~/t/tmp ~/t/tmp.old; echo foo > ~/t/tmp

 will show how the client will never (and I mean never ;-) ) see
 the updated file.

 The problem is that we do not update nfsi->cache_change_attribute when the
 file changes on the server (we only update it when our client makes the
 changes). This again means that functions like nfs_check_verifier() will
 fail to register when the parent directory has changed and should trigger
 a dentry lookup revalidation.

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

1 files changed, 20 insertions, 34 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index b551b19aa6e7..afd75d0463fd 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -54,7 +54,7 @@
 #define NFS_MAX_READAHEAD       (RPC_DEF_SLOT_TABLE - 1)
 
 static void nfs_invalidate_inode(struct inode *);
-static int nfs_update_inode(struct inode *, struct nfs_fattr *, unsigned long);
+static int nfs_update_inode(struct inode *, struct nfs_fattr *);
 
 static struct inode *nfs_alloc_inode(struct super_block *sb);
 static void nfs_destroy_inode(struct inode *);
@@ -1080,8 +1080,6 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
         int              status = -ESTALE;
         struct nfs_fattr fattr;
         struct nfs_inode *nfsi = NFS_I(inode);
-        unsigned long verifier;
-        unsigned long cache_validity;
 
         dfprintk(PAGECACHE, "NFS: revalidating (%s/%Ld)\n",
                 inode->i_sb->s_id, (long long)NFS_FILEID(inode));
@@ -1106,8 +1104,6 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
                 }
         }
 
-        /* Protect against RPC races by saving the change attribute */
-        verifier = nfs_save_change_attribute(inode);
         status = NFS_PROTO(inode)->getattr(server, NFS_FH(inode), &fattr);
         if (status != 0) {
                 dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) getattr failed, error=%d\n",
@@ -1122,7 +1118,7 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
         }
 
         spin_lock(&inode->i_lock);
-        status = nfs_update_inode(inode, &fattr, verifier);
+        status = nfs_update_inode(inode, &fattr);
         if (status) {
                 spin_unlock(&inode->i_lock);
                 dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) refresh failed, error=%d\n",
@@ -1130,20 +1126,11 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
                          (long long)NFS_FILEID(inode), status);
                 goto out;
         }
-        cache_validity = nfsi->cache_validity;
-        nfsi->cache_validity &= ~NFS_INO_REVAL_PAGECACHE;
-
-        /*
-         * We may need to keep the attributes marked as invalid if
-         * we raced with nfs_end_attr_update().
-         */
-        if (time_after_eq(verifier, nfsi->cache_change_attribute))
-                nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME);
         spin_unlock(&inode->i_lock);
 
         nfs_revalidate_mapping(inode, inode->i_mapping);
 
-        if (cache_validity & NFS_INO_INVALID_ACL)
+        if (nfsi->cache_validity & NFS_INO_INVALID_ACL)
                 nfs_zap_acl_cache(inode);
 
         dfprintk(PAGECACHE, "NFS: (%s/%Ld) revalidation complete\n",
@@ -1346,10 +1333,8 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
                 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);
+                status = nfs_update_inode(inode, fattr);
         else
                 status = nfs_check_inode_attributes(inode, fattr);
 
@@ -1375,10 +1360,7 @@ int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr)
                 nfsi->cache_validity |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS;
                 goto out;
         }
-        status = nfs_update_inode(inode, fattr, fattr->time_start);
-        if (time_after_eq(fattr->time_start, nfsi->cache_change_attribute))
-                nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME|NFS_INO_REVAL_PAGECACHE);
-        nfsi->cache_change_attribute = jiffies;
+        status = nfs_update_inode(inode, fattr);
 out:
         spin_unlock(&inode->i_lock);
         return status;
@@ -1396,12 +1378,12 @@ out:
  *
  * A very similar scenario holds for the dir cache.
  */
-static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsigned long verifier)
+static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 {
         struct nfs_inode *nfsi = NFS_I(inode);
         loff_t cur_isize, new_isize;
         unsigned int    invalid = 0;
-        int data_unstable;
+        int data_stable;
 
         dfprintk(VFS, "NFS: %s(%s/%ld ct=%d info=0x%x)\n",
                         __FUNCTION__, inode->i_sb->s_id, inode->i_ino,
@@ -1432,8 +1414,9 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
         nfsi->last_updated = jiffies;
 
         /* Are we racing with known updates of the metadata on the server? */
-        data_unstable = ! (nfs_verify_change_attribute(inode, verifier) ||
-                (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE));
+        data_stable = nfs_verify_change_attribute(inode, fattr->time_start);
+        if (data_stable)
+                nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME);
 
         /* Check if our cached file size is stale */
         new_isize = nfs_size_to_loff_t(fattr->size);
@@ -1442,7 +1425,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
                 /* Do we perhaps have any outstanding writes? */
                 if (nfsi->npages == 0) {
                         /* No, but did we race with nfs_end_data_update()? */
-                        if (time_after_eq(verifier,  nfsi->cache_change_attribute)) {
+                        if (data_stable) {
                                 inode->i_size = new_isize;
                                 invalid |= NFS_INO_INVALID_DATA;
                         }
@@ -1451,6 +1434,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
                         inode->i_size = new_isize;
                         invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
                 }
+                nfsi->cache_change_attribute = jiffies;
                 dprintk("NFS: isize change on server for file %s/%ld\n",
                                 inode->i_sb->s_id, inode->i_ino);
         }
@@ -1460,8 +1444,8 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
                 memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
                 dprintk("NFS: mtime change on server for file %s/%ld\n",
                                 inode->i_sb->s_id, inode->i_ino);
-                if (!data_unstable)
-                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
+                invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
+                nfsi->cache_change_attribute = jiffies;
         }
 
         if ((fattr->valid & NFS_ATTR_FATTR_V4)
@@ -1469,15 +1453,15 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
                 dprintk("NFS: change_attr change on server for file %s/%ld\n",
                        inode->i_sb->s_id, inode->i_ino);
                 nfsi->change_attr = fattr->change_attr;
-                if (!data_unstable)
-                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
+                invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
+                nfsi->cache_change_attribute = jiffies;
         }
 
         /* If ctime has changed we should definitely clear access+acl caches */
         if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) {
-                if (!data_unstable)
-                        invalid |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
+                invalid |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                 memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
+                nfsi->cache_change_attribute = jiffies;
         }
         memcpy(&inode->i_atime, &fattr->atime, sizeof(inode->i_atime));
 
@@ -1515,6 +1499,8 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr, unsign
         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)
                                 || S_ISLNK(inode->i_mode)))
                 invalid &= ~NFS_INO_INVALID_DATA;
+        if (data_stable)
+                invalid &= ~(NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ATIME|NFS_INO_REVAL_PAGECACHE);
         if (!nfs_have_delegation(inode, FMODE_READ))
                 nfsi->cache_validity |= invalid;