12 files changed, 84 insertions, 16 deletions

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index f48e0c6b4c42..0706d32a61e6 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -10,6 +10,7 @@ be able to use diff(1).
 --------------------------- dentry_operations --------------------------
 prototypes:
         int (*d_revalidate)(struct dentry *, unsigned int);
+        int (*d_weak_revalidate)(struct dentry *, unsigned int);
         int (*d_hash)(const struct dentry *, const struct inode *,
                         struct qstr *);
         int (*d_compare)(const struct dentry *, const struct inode *,
@@ -25,6 +26,7 @@ prototypes:
 locking rules:
                 rename_lock     ->d_lock        may block       rcu-walk
 d_revalidate:   no              no              yes (ref-walk)  maybe
+d_weak_revalidate:no            no              yes             no
 d_hash          no              no              no              maybe
 d_compare:      yes             no              no              maybe
 d_delete:       no              yes             no              no
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 0472c31c163b..4db22f6491e0 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -441,3 +441,7 @@ d_make_root() drops the reference to inode if dentry allocation fails.
 two, it gets "is it an O_EXCL or equivalent?" boolean argument.  Note that
 local filesystems can ignore tha argument - they are guaranteed that the
 object doesn't exist.  It's remote/distributed ones that might care...
+--
+[mandatory]
+        FS_REVAL_DOT is gone; if you used to have it, add ->d_weak_revalidate()
+in your dentry operations instead.
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index e3869098163e..bc4b06b3160a 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -900,6 +900,7 @@ defined:
 
 struct dentry_operations {
         int (*d_revalidate)(struct dentry *, unsigned int);
+        int (*d_weak_revalidate)(struct dentry *, unsigned int);
         int (*d_hash)(const struct dentry *, const struct inode *,
                         struct qstr *);
         int (*d_compare)(const struct dentry *, const struct inode *,
@@ -915,8 +916,13 @@ struct dentry_operations {
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This
         is called whenever a name look-up finds a dentry in the
-        dcache. Most filesystems leave this as NULL, because all their
-        dentries in the dcache are valid
+        dcache. Most local filesystems leave this as NULL, because all their
+        dentries in the dcache are valid. Network filesystems are different
+        since things can change on the server without the client necessarily
+        being aware of it.
+
+        This function should return a positive value if the dentry is still
+        valid, and zero or a negative error code if it isn't.
 
         d_revalidate may be called in rcu-walk mode (flags & LOOKUP_RCU).
         If in rcu-walk mode, the filesystem must revalidate the dentry without
@@ -927,6 +933,20 @@ struct dentry_operations {
         If a situation is encountered that rcu-walk cannot handle, return
         -ECHILD and it will be called again in ref-walk mode.
 
+ d_weak_revalidate: called when the VFS needs to revalidate a "jumped" dentry.
+        This is called when a path-walk ends at dentry that was not acquired by
+        doing a lookup in the parent directory. This includes "/", "." and "..",
+        as well as procfs-style symlinks and mountpoint traversal.
+
+        In this case, we are less concerned with whether the dentry is still
+        fully correct, but rather that the inode is still valid. As with
+        d_revalidate, most local filesystems will set this to NULL since their
+        dcache entries are always valid.
+
+        This function has the same return code semantics as d_revalidate.
+
+        d_weak_revalidate is only called after leaving rcu-walk mode.
+
   d_hash: called when the VFS adds a dentry to the hash table. The first
         dentry passed to d_hash is the parent directory that the name is
         to be hashed into. The inode is the dentry's inode.
diff --git a/fs/9p/vfs_dentry.c b/fs/9p/vfs_dentry.c
index 64600b5d0522..9ad68628522c 100644
--- a/fs/9p/vfs_dentry.c
+++ b/fs/9p/vfs_dentry.c
@@ -137,6 +137,7 @@ out_valid:
 
 const struct dentry_operations v9fs_cached_dentry_operations = {
         .d_revalidate = v9fs_lookup_revalidate,
+        .d_weak_revalidate = v9fs_lookup_revalidate,
         .d_delete = v9fs_cached_dentry_delete,
         .d_release = v9fs_dentry_release,
 };
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 137d50396898..91dad63e5a2d 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -363,5 +363,5 @@ struct file_system_type v9fs_fs_type = {
         .mount = v9fs_mount,
         .kill_sb = v9fs_kill_super,
         .owner = THIS_MODULE,
-        .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT,
+        .fs_flags = FS_RENAME_DOES_D_MOVE,
 };
diff --git a/fs/dcache.c b/fs/dcache.c
index ebab049826c0..68220dd0c135 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1358,6 +1358,7 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
         WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH  |
                                 DCACHE_OP_COMPARE       |
                                 DCACHE_OP_REVALIDATE    |
+                                DCACHE_OP_WEAK_REVALIDATE       |
                                 DCACHE_OP_DELETE ));
         dentry->d_op = op;
         if (!op)
@@ -1368,6 +1369,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
                 dentry->d_flags |= DCACHE_OP_COMPARE;
         if (op->d_revalidate)
                 dentry->d_flags |= DCACHE_OP_REVALIDATE;
+        if (op->d_weak_revalidate)
+                dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE;
         if (op->d_delete)
                 dentry->d_flags |= DCACHE_OP_DELETE;
         if (op->d_prune)
diff --git a/fs/namei.c b/fs/namei.c
index 052c095c2808..dc984fee5532 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -600,14 +600,10 @@ static int complete_walk(struct nameidata *nd)
         if (likely(!(nd->flags & LOOKUP_JUMPED)))
                 return 0;
 
-        if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
+        if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE)))
                 return 0;
 
-        if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
-                return 0;
-
-        /* Note: we do not d_invalidate() */
-        status = d_revalidate(dentry, nd->flags);
+        status = dentry->d_op->d_weak_revalidate(dentry, nd->flags);
         if (status > 0)
                 return 0;
 
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index a8bd28cde7e2..f23f455be42b 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1136,6 +1136,45 @@ out_error:
 }
 
 /*
+ * A weaker form of d_revalidate for revalidating just the dentry->d_inode
+ * when we don't really care about the dentry name. This is called when a
+ * pathwalk ends on a dentry that was not found via a normal lookup in the
+ * parent dir (e.g.: ".", "..", procfs symlinks or mountpoint traversals).
+ *
+ * In this situation, we just want to verify that the inode itself is OK
+ * since the dentry might have changed on the server.
+ */
+static int nfs_weak_revalidate(struct dentry *dentry, unsigned int flags)
+{
+        int error;
+        struct inode *inode = dentry->d_inode;
+
+        /*
+         * I believe we can only get a negative dentry here in the case of a
+         * procfs-style symlink. Just assume it's correct for now, but we may
+         * eventually need to do something more here.
+         */
+        if (!inode) {
+                dfprintk(LOOKUPCACHE, "%s: %s/%s has negative inode\n",
+                                __func__, dentry->d_parent->d_name.name,
+                                dentry->d_name.name);
+                return 1;
+        }
+
+        if (is_bad_inode(inode)) {
+                dfprintk(LOOKUPCACHE, "%s: %s/%s has dud inode\n",
+                                __func__, dentry->d_parent->d_name.name,
+                                dentry->d_name.name);
+                return 0;
+        }
+
+        error = nfs_revalidate_inode(NFS_SERVER(inode), inode);
+        dfprintk(LOOKUPCACHE, "NFS: %s: inode %lu is %s\n",
+                        __func__, inode->i_ino, error ? "invalid" : "valid");
+        return !error;
+}
+
+/*
  * This is called from dput() when d_count is going to 0.
  */
 static int nfs_dentry_delete(const struct dentry *dentry)
@@ -1202,6 +1241,7 @@ static void nfs_d_release(struct dentry *dentry)
 
 const struct dentry_operations nfs_dentry_operations = {
         .d_revalidate   = nfs_lookup_revalidate,
+        .d_weak_revalidate      = nfs_weak_revalidate,
         .d_delete       = nfs_dentry_delete,
         .d_iput         = nfs_dentry_iput,
         .d_automount    = nfs_d_automount,
diff --git a/fs/nfs/nfs4super.c b/fs/nfs/nfs4super.c
index 84d2e9e2f313..569b166cc050 100644
--- a/fs/nfs/nfs4super.c
+++ b/fs/nfs/nfs4super.c
@@ -28,7 +28,7 @@ static struct file_system_type nfs4_remote_fs_type = {
         .name           = "nfs4",
         .mount          = nfs4_remote_mount,
         .kill_sb        = nfs_kill_super,
-        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
 };
 
 static struct file_system_type nfs4_remote_referral_fs_type = {
@@ -36,7 +36,7 @@ static struct file_system_type nfs4_remote_referral_fs_type = {
         .name           = "nfs4",
         .mount          = nfs4_remote_referral_mount,
         .kill_sb        = nfs_kill_super,
-        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
 };
 
 struct file_system_type nfs4_referral_fs_type = {
@@ -44,7 +44,7 @@ struct file_system_type nfs4_referral_fs_type = {
         .name           = "nfs4",
         .mount          = nfs4_referral_mount,
         .kill_sb        = nfs_kill_super,
-        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
 };
 
 static const struct super_operations nfs4_sops = {
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 2e7e8c878e5d..92acc26f9c5f 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -292,7 +292,7 @@ struct file_system_type nfs_fs_type = {
         .name           = "nfs",
         .mount          = nfs_fs_mount,
         .kill_sb        = nfs_kill_super,
-        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
 };
 EXPORT_SYMBOL_GPL(nfs_fs_type);
 
@@ -301,7 +301,7 @@ struct file_system_type nfs_xdev_fs_type = {
         .name           = "nfs",
         .mount          = nfs_xdev_mount,
         .kill_sb        = nfs_kill_super,
-        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
 };
 
 const struct super_operations nfs_sops = {
@@ -331,7 +331,7 @@ struct file_system_type nfs4_fs_type = {
         .name           = "nfs4",
         .mount          = nfs_fs_mount,
         .kill_sb        = nfs_kill_super,
-        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+        .fs_flags       = FS_RENAME_DOES_D_MOVE|FS_BINARY_MOUNTDATA,
 };
 EXPORT_SYMBOL_GPL(nfs4_fs_type);
 
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 03d169288423..1a6bb81f0fe5 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -145,6 +145,7 @@ enum dentry_d_lock_class
 
 struct dentry_operations {
         int (*d_revalidate)(struct dentry *, unsigned int);
+        int (*d_weak_revalidate)(struct dentry *, unsigned int);
         int (*d_hash)(const struct dentry *, const struct inode *,
                         struct qstr *);
         int (*d_compare)(const struct dentry *, const struct inode *,
@@ -192,6 +193,8 @@ struct dentry_operations {
 #define DCACHE_GENOCIDE         0x0200
 #define DCACHE_SHRINK_LIST      0x0400
 
+#define DCACHE_OP_WEAK_REVALIDATE       0x0800
+
 #define DCACHE_NFSFS_RENAMED    0x1000
      /* this dentry has been "silly renamed" and has to be deleted on the last
       * dput() */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7f471520b88b..da94011ae83c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1807,7 +1807,6 @@ struct file_system_type {
 #define FS_HAS_SUBTYPE          4
 #define FS_USERNS_MOUNT         8       /* Can be mounted by userns root */
 #define FS_USERNS_DEV_MOUNT     16 /* A userns mount does not imply MNT_NODEV */
-#define FS_REVAL_DOT            16384   /* Check the paths ".", ".." for staleness */
 #define FS_RENAME_DOES_D_MOVE   32768   /* FS will handle d_move() during rename() internally. */
         struct dentry *(*mount) (struct file_system_type *, int,
                        const char *, void *);