Unverified Commit 134796f4 authored by Jeff Layton's avatar Jeff Layton Committed by Christian Brauner
Browse files

vfs: break parent dir delegations in open(..., O_CREAT) codepath 



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 delegated_inode parameter to lookup_open and have it break the
delegation. Then, open_last_lookups can wait for the delegation break
and retry the call to lookup_open once it's done.

Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarNeilBrown <neil@brown.name>
Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-8-52f3feebb2f2@kernel.org


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 4fa76319

fs/namei.c

+18 −4
Original line number Diff line number Diff line
@@ -3697,7 +3697,7 @@ static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 
 */

static struct dentry *lookup_open(struct nameidata *nd, struct file *file,

				  const struct open_flags *op,

				  bool got_write)

				  bool got_write, struct delegated_inode *delegated_inode)

{

	struct mnt_idmap *idmap;

	struct dentry *dir = nd->path.dentry;
@@ -3786,6 +3786,11 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 


	/* Negative dentry, just create the file */

	if (!dentry->d_inode && (open_flag & O_CREAT)) {

		/* but break the directory lease first! */

		error = try_break_deleg(dir_inode, delegated_inode);

		if (error)

			goto out_dput;



		file->f_mode |= FMODE_CREATED;

		audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);

		if (!dir_inode->i_op->create) {
@@ -3848,6 +3853,7 @@ static struct dentry *lookup_fast_for_open(struct nameidata *nd, int open_flag) 
static const char *open_last_lookups(struct nameidata *nd,

		   struct file *file, const struct open_flags *op)

{

	struct delegated_inode delegated_inode = { };

	struct dentry *dir = nd->path.dentry;

	int open_flag = op->open_flag;

	bool got_write = false;
@@ -3879,7 +3885,7 @@ static const char *open_last_lookups(struct nameidata *nd, 
				return ERR_PTR(-ECHILD);

		}

	}



retry:

	if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {

		got_write = !mnt_want_write(nd->path.mnt);

		/*
@@ -3892,7 +3898,7 @@ static const char *open_last_lookups(struct nameidata *nd, 
		inode_lock(dir->d_inode);

	else

		inode_lock_shared(dir->d_inode);

	dentry = lookup_open(nd, file, op, got_write);

	dentry = lookup_open(nd, file, op, got_write, &delegated_inode);

	if (!IS_ERR(dentry)) {

		if (file->f_mode & FMODE_CREATED)

			fsnotify_create(dir->d_inode, dentry);
@@ -3907,8 +3913,16 @@ static const char *open_last_lookups(struct nameidata *nd, 
	if (got_write)

		mnt_drop_write(nd->path.mnt);



	if (IS_ERR(dentry))

	if (IS_ERR(dentry)) {

		if (is_delegated(&delegated_inode)) {

			int error = break_deleg_wait(&delegated_inode);



			if (!error)

				goto retry;

			return ERR_PTR(error);

		}

		return ERR_CAST(dentry);

	}



	if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) {

		dput(nd->path.dentry);