[PATCH RFC 08/24] vfs: make vfs_mknod break delegations on parent directory

[Jeff Layton]

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.

Add a new delegated_inode parameter to vfs_mknod. Most callers will
set that to NULL, but do_mknodat can use that to synchronously wait
for the delegation break to complete.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 drivers/base/devtmpfs.c  |  2 +-
 fs/ecryptfs/inode.c      |  2 +-
 fs/init.c                |  2 +-
 fs/namei.c               | 11 ++++++++---
 fs/nfsd/vfs.c            |  2 +-
 fs/overlayfs/overlayfs.h |  2 +-
 include/linux/fs.h       |  4 ++--
 net/unix/af_unix.c       |  2 +-
 8 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index c00126796f79..8c0a872e3165 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -217,7 +217,7 @@ static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
 		return PTR_ERR(dentry);
 
 	err = vfs_mknod(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode,
-			dev->devt);
+			dev->devt, NULL);
 	if (!err) {
 		struct iattr newattrs;
 
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index a99b1e264c46..c6442b8caa2f 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -566,7 +566,7 @@ ecryptfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
 	rc = lock_parent(dentry, &lower_dentry, &lower_dir);
 	if (!rc)
 		rc = vfs_mknod(&nop_mnt_idmap, lower_dir,
-			       lower_dentry, mode, dev);
+			       lower_dentry, mode, dev, NULL);
 	if (rc || d_really_is_negative(lower_dentry))
 		goto out;
 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
diff --git a/fs/init.c b/fs/init.c
index 325c9e4d9b20..99c6b413adad 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -157,7 +157,7 @@ int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
 	error = security_path_mknod(&path, dentry, mode, dev);
 	if (!error)
 		error = vfs_mknod(mnt_idmap(path.mnt), path.dentry->d_inode,
-				  dentry, mode, new_decode_dev(dev));
+				  dentry, mode, new_decode_dev(dev), NULL);
 	done_path_create(&path, dentry);
 	return error;
 }
diff --git a/fs/namei.c b/fs/namei.c
index 01e04cf155eb..a185974c1a55 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3996,7 +3996,8 @@ EXPORT_SYMBOL(user_path_create);
  * raw inode simply pass @nop_mnt_idmap.
  */
 int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
-	      struct dentry *dentry, umode_t mode, dev_t dev)
+	      struct dentry *dentry, umode_t mode, dev_t dev,
+	      struct inode **delegated_inode)
 {
 	bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV;
 	int error = may_create(idmap, dir, dentry);
@@ -4020,6 +4021,10 @@ int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
 	if (error)
 		return error;
 
+	error = try_break_deleg(dir, delegated_inode);
+	if (error)
+		return error;
+
 	error = dir->i_op->mknod(idmap, dir, dentry, mode, dev);
 	if (!error)
 		fsnotify_create(dir, dentry);
@@ -4078,11 +4083,11 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode,
 			break;
 		case S_IFCHR: case S_IFBLK:
 			error = vfs_mknod(idmap, path.dentry->d_inode,
-					  dentry, mode, new_decode_dev(dev));
+					  dentry, mode, new_decode_dev(dev), &delegated_inode);
 			break;
 		case S_IFIFO: case S_IFSOCK:
 			error = vfs_mknod(idmap, path.dentry->d_inode,
-					  dentry, mode, 0);
+					  dentry, mode, 0, &delegated_inode);
 			break;
 	}
 out2:
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 47b8ab1d4b17..fe088e7c49c8 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1525,7 +1525,7 @@ nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	case S_IFIFO:
 	case S_IFSOCK:
 		host_err = vfs_mknod(&nop_mnt_idmap, dirp, dchild,
-				     iap->ia_mode, rdev);
+				     iap->ia_mode, rdev, NULL);
 		break;
 	default:
 		printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index be2518e6da95..26cdef6c3579 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -251,7 +251,7 @@ static inline int ovl_do_mknod(struct ovl_fs *ofs,
 			       struct inode *dir, struct dentry *dentry,
 			       umode_t mode, dev_t dev)
 {
-	int err = vfs_mknod(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, dev);
+	int err = vfs_mknod(ovl_upper_mnt_idmap(ofs), dir, dentry, mode, dev, NULL);
 
 	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
 	return err;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8fb4101fea49..4b396c9a7a84 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1841,7 +1841,7 @@ int vfs_create(struct mnt_idmap *, struct inode *,
 int vfs_mkdir(struct mnt_idmap *, struct inode *,
 	      struct dentry *, umode_t, struct inode **);
 int vfs_mknod(struct mnt_idmap *, struct inode *, struct dentry *,
-              umode_t, dev_t);
+              umode_t, dev_t, struct inode **);
 int vfs_symlink(struct mnt_idmap *, struct inode *,
 		struct dentry *, const char *);
 int vfs_link(struct dentry *, struct mnt_idmap *, struct inode *,
@@ -1879,7 +1879,7 @@ static inline int vfs_whiteout(struct mnt_idmap *idmap,
 			       struct inode *dir, struct dentry *dentry)
 {
 	return vfs_mknod(idmap, dir, dentry, S_IFCHR | WHITEOUT_MODE,
-			 WHITEOUT_DEV);
+			 WHITEOUT_DEV, NULL);
 }
 
 struct file *kernel_tmpfile_open(struct mnt_idmap *idmap,
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 0748e7ea5210..34fbcc90c984 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1227,7 +1227,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
 	idmap = mnt_idmap(parent.mnt);
 	err = security_path_mknod(&parent, dentry, mode, 0);
 	if (!err)
-		err = vfs_mknod(idmap, d_inode(parent.dentry), dentry, mode, 0);
+		err = vfs_mknod(idmap, d_inode(parent.dentry), dentry, mode, 0, NULL);
 	if (err)
 		goto out_path;
 	err = mutex_lock_interruptible(&u->bindlock);

-- 
2.44.0