1 files changed, 51 insertions, 16 deletions

diff --git a/fs/stat.c b/fs/stat.c
index eae494630a3..ae0c3cef992 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -37,22 +37,41 @@ void generic_fillattr(struct inode *inode, struct kstat *stat)
 
 EXPORT_SYMBOL(generic_fillattr);
 
-int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+/**
+ * vfs_getattr_nosec - getattr without security checks
+ * @path: file to get attributes from
+ * @stat: structure to return attributes in
+ *
+ * Get attributes without calling security_inode_getattr.
+ *
+ * Currently the only caller other than vfs_getattr is internal to the
+ * filehandle lookup code, which uses only the inode number and returns
+ * no attributes to any user.  Any other code probably wants
+ * vfs_getattr.
+ */
+int vfs_getattr_nosec(struct path *path, struct kstat *stat)
 {
-	struct inode *inode = dentry->d_inode;
-	int retval;
-
-	retval = security_inode_getattr(mnt, dentry);
-	if (retval)
-		return retval;
+	struct inode *inode = path->dentry->d_inode;
 
 	if (inode->i_op->getattr)
-		return inode->i_op->getattr(mnt, dentry, stat);
+		return inode->i_op->getattr(path->mnt, path->dentry, stat);
 
 	generic_fillattr(inode, stat);
 	return 0;
 }
 
+EXPORT_SYMBOL(vfs_getattr_nosec);
+
+int vfs_getattr(struct path *path, struct kstat *stat)
+{
+	int retval;
+
+	retval = security_inode_getattr(path->mnt, path->dentry);
+	if (retval)
+		return retval;
+	return vfs_getattr_nosec(path, stat);
+}
+
 EXPORT_SYMBOL(vfs_getattr);
 
 int vfs_fstat(unsigned int fd, struct kstat *stat)
@@ -61,8 +80,7 @@ int vfs_fstat(unsigned int fd, struct kstat *stat)
 	int error = -EBADF;
 
 	if (f.file) {
-		error = vfs_getattr(f.file->f_path.mnt, f.file->f_path.dentry,
-				    stat);
+		error = vfs_getattr(&f.file->f_path, stat);
 		fdput(f);
 	}
 	return error;
@@ -74,7 +92,7 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 {
 	struct path path;
 	int error = -EINVAL;
-	int lookup_flags = 0;
+	unsigned int lookup_flags = 0;
 
 	if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 		      AT_EMPTY_PATH)) != 0)
@@ -84,13 +102,17 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 		lookup_flags |= LOOKUP_FOLLOW;
 	if (flag & AT_EMPTY_PATH)
 		lookup_flags |= LOOKUP_EMPTY;
-
+retry:
 	error = user_path_at(dfd, filename, lookup_flags, &path);
 	if (error)
 		goto out;
 
-	error = vfs_getattr(path.mnt, path.dentry, stat);
+	error = vfs_getattr(&path, stat);
 	path_put(&path);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
+	}
 out:
 	return error;
 }
@@ -296,11 +318,13 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 	struct path path;
 	int error;
 	int empty = 0;
+	unsigned int lookup_flags = LOOKUP_EMPTY;
 
 	if (bufsiz <= 0)
 		return -EINVAL;
 
-	error = user_path_at_empty(dfd, pathname, LOOKUP_EMPTY, &path, &empty);
+retry:
+	error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
 	if (!error) {
 		struct inode *inode = path.dentry->d_inode;
 
@@ -314,6 +338,10 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 			}
 		}
 		path_put(&path);
+		if (retry_estale(error, lookup_flags)) {
+			lookup_flags |= LOOKUP_REVAL;
+			goto retry;
+		}
 	}
 	return error;
 }
@@ -438,9 +466,8 @@ void inode_add_bytes(struct inode *inode, loff_t bytes)
 
 EXPORT_SYMBOL(inode_add_bytes);
 
-void inode_sub_bytes(struct inode *inode, loff_t bytes)
+void __inode_sub_bytes(struct inode *inode, loff_t bytes)
 {
-	spin_lock(&inode->i_lock);
 	inode->i_blocks -= bytes >> 9;
 	bytes &= 511;
 	if (inode->i_bytes < bytes) {
@@ -448,6 +475,14 @@ void inode_sub_bytes(struct inode *inode, loff_t bytes)
 		inode->i_bytes += 512;
 	}
 	inode->i_bytes -= bytes;
+}
+
+EXPORT_SYMBOL(__inode_sub_bytes);
+
+void inode_sub_bytes(struct inode *inode, loff_t bytes)
+{
+	spin_lock(&inode->i_lock);
+	__inode_sub_bytes(inode, bytes);
 	spin_unlock(&inode->i_lock);
 }