locks: break delegations on any attribute modification

NFSv4 uses leases to guarantee that clients can cache metadata as well
as data.

Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 18 insertions, 4 deletions

diff --git a/fs/open.c b/fs/open.c
index fffbed40dbe9..4b3e1edf2fe4 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -57,7 +57,8 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
                 newattrs.ia_valid |= ret | ATTR_FORCE;
 
         mutex_lock(&dentry->d_inode->i_mutex);
-        ret = notify_change(dentry, &newattrs);
+        /* Note any delegations or leases have already been broken: */
+        ret = notify_change(dentry, &newattrs, NULL);
         mutex_unlock(&dentry->d_inode->i_mutex);
         return ret;
 }
@@ -464,21 +465,28 @@ out:
 static int chmod_common(struct path *path, umode_t mode)
 {
         struct inode *inode = path->dentry->d_inode;
+        struct inode *delegated_inode = NULL;
         struct iattr newattrs;
         int error;
 
         error = mnt_want_write(path->mnt);
         if (error)
                 return error;
+retry_deleg:
         mutex_lock(&inode->i_mutex);
         error = security_path_chmod(path, mode);
         if (error)
                 goto out_unlock;
         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
-        error = notify_change(path->dentry, &newattrs);
+        error = notify_change(path->dentry, &newattrs, &delegated_inode);
 out_unlock:
         mutex_unlock(&inode->i_mutex);
+        if (delegated_inode) {
+                error = break_deleg_wait(&delegated_inode);
+                if (!error)
+                        goto retry_deleg;
+        }
         mnt_drop_write(path->mnt);
         return error;
 }
@@ -522,6 +530,7 @@ SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 static int chown_common(struct path *path, uid_t user, gid_t group)
 {
         struct inode *inode = path->dentry->d_inode;
+        struct inode *delegated_inode = NULL;
         int error;
         struct iattr newattrs;
         kuid_t uid;
@@ -546,12 +555,17 @@ static int chown_common(struct path *path, uid_t user, gid_t group)
         if (!S_ISDIR(inode->i_mode))
                 newattrs.ia_valid |=
                         ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
+retry_deleg:
         mutex_lock(&inode->i_mutex);
         error = security_path_chown(path, uid, gid);
         if (!error)
-                error = notify_change(path->dentry, &newattrs);
+                error = notify_change(path->dentry, &newattrs, &delegated_inode);
         mutex_unlock(&inode->i_mutex);
-
+        if (delegated_inode) {
+                error = break_deleg_wait(&delegated_inode);
+                if (!error)
+                        goto retry_deleg;
+        }
         return error;
 }