In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.

Rename vfs_create as __vfs_create, make it static, and add a new
delegated_inode parameter. Fix do_mknodat to call __vfs_create and wait
for a delegation break if there is one. Add a new exported vfs_create
wrapper that passes in NULL for delegated_inode.

Signed-off-by: Jeff Layton <[email protected]>
---
 fs/namei.c | 55 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 36 insertions(+), 19 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 
903b70a82530938a0fdf10508529a1b7cc38136d..d4b8330a3eb97e205dc2e71766fed1e45503323b
 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3370,6 +3370,32 @@ static inline umode_t vfs_prepare_mode(struct mnt_idmap 
*idmap,
        return mode;
 }
 
+static int __vfs_create(struct mnt_idmap *idmap, struct inode *dir,
+                       struct dentry *dentry, umode_t mode, bool want_excl,
+                       struct inode **delegated_inode)
+{
+       int error;
+
+       error = may_create(idmap, dir, dentry);
+       if (error)
+               return error;
+
+       if (!dir->i_op->create)
+               return -EACCES; /* shouldn't it be ENOSYS? */
+
+       mode = vfs_prepare_mode(idmap, dir, mode, S_IALLUGO, S_IFREG);
+       error = security_inode_create(dir, dentry, mode);
+       if (error)
+               return error;
+       error = try_break_deleg(dir, delegated_inode);
+       if (error)
+               return error;
+       error = dir->i_op->create(idmap, dir, dentry, mode, want_excl);
+       if (!error)
+               fsnotify_create(dir, dentry);
+       return error;
+}
+
 /**
  * vfs_create - create new file
  * @idmap:     idmap of the mount the inode was found from
@@ -3389,23 +3415,7 @@ static inline umode_t vfs_prepare_mode(struct mnt_idmap 
*idmap,
 int vfs_create(struct mnt_idmap *idmap, struct inode *dir,
               struct dentry *dentry, umode_t mode, bool want_excl)
 {
-       int error;
-
-       error = may_create(idmap, dir, dentry);
-       if (error)
-               return error;
-
-       if (!dir->i_op->create)
-               return -EACCES; /* shouldn't it be ENOSYS? */
-
-       mode = vfs_prepare_mode(idmap, dir, mode, S_IALLUGO, S_IFREG);
-       error = security_inode_create(dir, dentry, mode);
-       if (error)
-               return error;
-       error = dir->i_op->create(idmap, dir, dentry, mode, want_excl);
-       if (!error)
-               fsnotify_create(dir, dentry);
-       return error;
+       return __vfs_create(idmap, dir, dentry, mode, want_excl, NULL);
 }
 EXPORT_SYMBOL(vfs_create);
 
@@ -4278,6 +4288,7 @@ static int do_mknodat(int dfd, struct filename *name, 
umode_t mode,
        struct path path;
        int error;
        unsigned int lookup_flags = 0;
+       struct inode *delegated_inode = NULL;
 
        error = may_mknod(mode);
        if (error)
@@ -4296,8 +4307,9 @@ static int do_mknodat(int dfd, struct filename *name, 
umode_t mode,
        idmap = mnt_idmap(path.mnt);
        switch (mode & S_IFMT) {
                case 0: case S_IFREG:
-                       error = vfs_create(idmap, path.dentry->d_inode,
-                                          dentry, mode, true);
+                       error = __vfs_create(idmap, path.dentry->d_inode,
+                                            dentry, mode, true,
+                                            &delegated_inode);
                        if (!error)
                                security_path_post_mknod(idmap, dentry);
                        break;
@@ -4312,6 +4324,11 @@ static int do_mknodat(int dfd, struct filename *name, 
umode_t mode,
        }
 out2:
        done_path_create(&path, dentry);
+       if (delegated_inode) {
+               error = break_deleg_wait(&delegated_inode);
+               if (!error)
+                       goto retry;
+       }
        if (retry_estale(error, lookup_flags)) {
                lookup_flags |= LOOKUP_REVAL;
                goto retry;

-- 
2.51.0


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