locks: break delegations on rename

Cc: David Howells <dhowells@redhat.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>

7 files changed, 51 insertions, 11 deletions

diff --git a/drivers/staging/lustre/lustre/include/linux/lustre_compat25.h b/drivers/staging/lustre/lustre/include/linux/lustre_compat25.h
index 9243dfab43d3..80b019bf969c 100644
--- a/drivers/staging/lustre/lustre/include/linux/lustre_compat25.h
+++ b/drivers/staging/lustre/lustre/include/linux/lustre_compat25.h
@@ -105,8 +105,8 @@ static inline void ll_set_fs_pwd(struct fs_struct *fs, struct vfsmount *mnt,
 #define ll_vfs_unlink(inode,entry,mnt)    vfs_unlink(inode,entry)
 #define ll_vfs_mknod(dir,entry,mnt,mode,dev)    vfs_mknod(dir,entry,mode,dev)
 #define ll_security_inode_unlink(dir,entry,mnt) security_inode_unlink(dir,entry)
-#define ll_vfs_rename(old,old_dir,mnt,new,new_dir,mnt1) \
-                vfs_rename(old,old_dir,new,new_dir)
+#define ll_vfs_rename(old,old_dir,mnt,new,new_dir,mnt1,delegated_inode) \
+                vfs_rename(old,old_dir,new,new_dir,delegated_inode)
 
 #define cfs_bio_io_error(a,b)   bio_io_error((a))
 #define cfs_bio_endio(a,b,c)    bio_endio((a),(c))
diff --git a/drivers/staging/lustre/lustre/lvfs/lvfs_linux.c b/drivers/staging/lustre/lustre/lvfs/lvfs_linux.c
index 18e1b47a1d65..4ed7c9f0a8be 100644
--- a/drivers/staging/lustre/lustre/lvfs/lvfs_linux.c
+++ b/drivers/staging/lustre/lustre/lvfs/lvfs_linux.c
@@ -220,7 +220,7 @@ int lustre_rename(struct dentry *dir, struct vfsmount *mnt,
                 GOTO(put_old, err = PTR_ERR(dchild_new));
 
         err = ll_vfs_rename(dir->d_inode, dchild_old, mnt,
-                            dir->d_inode, dchild_new, mnt);
+                            dir->d_inode, dchild_new, mnt, NULL);
 
         dput(dchild_new);
 put_old:
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 31d480c0e046..ca65f39dc8dc 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -396,7 +396,7 @@ try_again:
                 cachefiles_io_error(cache, "Rename security error %d", ret);
         } else {
                 ret = vfs_rename(dir->d_inode, rep,
-                                 cache->graveyard->d_inode, grave);
+                                 cache->graveyard->d_inode, grave, NULL);
                 if (ret != 0 && ret != -ENOMEM)
                         cachefiles_io_error(cache,
                                             "Rename failed with error %d", ret);
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index dc60b8bd09ec..c23b01bb7e04 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -640,7 +640,8 @@ ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                 goto out_lock;
         }
         rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
-                        lower_new_dir_dentry->d_inode, lower_new_dentry);
+                        lower_new_dir_dentry->d_inode, lower_new_dentry,
+                        NULL);
         if (rc)
                 goto out_lock;
         if (target_inode)
diff --git a/fs/namei.c b/fs/namei.c
index cfaeaae0f2db..ce7e580e4e14 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4022,7 +4022,8 @@ out:
 }
 
 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
-                            struct inode *new_dir, struct dentry *new_dentry)
+                            struct inode *new_dir, struct dentry *new_dentry,
+                            struct inode **delegated_inode)
 {
         struct inode *target = new_dentry->d_inode;
         struct inode *source = old_dentry->d_inode;
@@ -4039,6 +4040,14 @@ static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
         if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
                 goto out;
 
+        error = try_break_deleg(source, delegated_inode);
+        if (error)
+                goto out;
+        if (target) {
+                error = try_break_deleg(target, delegated_inode);
+                if (error)
+                        goto out;
+        }
         error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
         if (error)
                 goto out;
@@ -4053,8 +4062,30 @@ out:
         return error;
 }
 
+/**
+ * vfs_rename - rename a filesystem object
+ * @old_dir:    parent of source
+ * @old_dentry: source
+ * @new_dir:    parent of destination
+ * @new_dentry: destination
+ * @delegated_inode: returns an inode needing a delegation break
+ *
+ * The caller must hold multiple mutexes--see lock_rename()).
+ *
+ * If vfs_rename discovers a delegation in need of breaking at either
+ * the source or destination, it will return -EWOULDBLOCK and return a
+ * reference to the inode in delegated_inode.  The caller should then
+ * break the delegation and retry.  Because breaking a delegation may
+ * take a long time, the caller should drop all locks before doing
+ * so.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode.  This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported.
+ */
 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-               struct inode *new_dir, struct dentry *new_dentry)
+               struct inode *new_dir, struct dentry *new_dentry,
+               struct inode **delegated_inode)
 {
         int error;
         int is_dir = d_is_directory(old_dentry) || d_is_autodir(old_dentry);
@@ -4082,7 +4113,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
         if (is_dir)
                 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
         else
-                error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
+                error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry,delegated_inode);
         if (!error)
                 fsnotify_move(old_dir, new_dir, old_name, is_dir,
                               new_dentry->d_inode, old_dentry);
@@ -4098,6 +4129,7 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
         struct dentry *old_dentry, *new_dentry;
         struct dentry *trap;
         struct nameidata oldnd, newnd;
+        struct inode *delegated_inode = NULL;
         struct filename *from;
         struct filename *to;
         unsigned int lookup_flags = 0;
@@ -4137,6 +4169,7 @@ retry:
         newnd.flags &= ~LOOKUP_PARENT;
         newnd.flags |= LOOKUP_RENAME_TARGET;
 
+retry_deleg:
         trap = lock_rename(new_dir, old_dir);
 
         old_dentry = lookup_hash(&oldnd);
@@ -4173,13 +4206,19 @@ retry:
         if (error)
                 goto exit5;
         error = vfs_rename(old_dir->d_inode, old_dentry,
-                                   new_dir->d_inode, new_dentry);
+                                   new_dir->d_inode, new_dentry,
+                                   &delegated_inode);
 exit5:
         dput(new_dentry);
 exit4:
         dput(old_dentry);
 exit3:
         unlock_rename(new_dir, old_dir);
+        if (delegated_inode) {
+                error = break_deleg_wait(&delegated_inode);
+                if (!error)
+                        goto retry_deleg;
+        }
         mnt_drop_write(oldnd.path.mnt);
 exit2:
         if (retry_estale(error, lookup_flags))
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 7a810235d599..45bf0295894d 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1837,7 +1837,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
                 if (host_err)
                         goto out_dput_new;
         }
-        host_err = vfs_rename(fdir, odentry, tdir, ndentry);
+        host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL);
         if (!host_err) {
                 host_err = commit_metadata(tfhp);
                 if (!host_err)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 931f919f44e1..5bcff883fa90 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1456,7 +1456,7 @@ extern int vfs_symlink(struct inode *, struct dentry *, const char *);
 extern int vfs_link(struct dentry *, struct inode *, struct dentry *);
 extern int vfs_rmdir(struct inode *, struct dentry *);
 extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
-extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
+extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **);
 
 /*
  * VFS dentry helper functions.