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Commit aa3ff3c1 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

ovl: copy up of disconnected dentries 



With NFS export, some operations on decoded file handles (e.g. open,
link, setattr, xattr_set) may call copy up with a disconnected non-dir.
In this case, we will copy up lower inode to index dir without
linking it to upper dir.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 829c28be

fs/overlayfs/copy_up.c

+41 −15
Original line number Diff line number Diff line
@@ -450,7 +450,10 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c) 
		}

	}

	inode_unlock(udir);

	ovl_set_nlink_upper(c->dentry);

	if (err)

		return err;



	err = ovl_set_nlink_upper(c->dentry);



	return err;

}
@@ -655,6 +658,9 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) 
		err = ovl_get_index_name(c->lowerpath.dentry, &c->destname);

		if (err)

			return err;

	} else if (WARN_ON(!c->parent)) {

		/* Disconnected dentry must be copied up to index dir */

		return -EIO;

	} else {

		/*

		 * Mark parent "impure" because it may now contain non-pure
@@ -677,12 +683,17 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) 
		}

	}



	if (!err && c->indexed)



	if (err)

		goto out;



	if (c->indexed)

		ovl_set_flag(OVL_INDEX, d_inode(c->dentry));



	if (to_index) {

		kfree(c->destname.name);

	} else if (!err) {

		/* Initialize nlink for copy up of disconnected dentry */

		err = ovl_set_nlink_upper(c->dentry);

	} else {

		struct inode *udir = d_inode(c->destdir);



		/* Restore timestamps on parent (best effort) */
@@ -693,6 +704,9 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) 
		ovl_dentry_set_upper_alias(c->dentry);

	}



out:

	if (to_index)

		kfree(c->destname.name);

	return err;

}
@@ -717,14 +731,17 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
	if (err)

		return err;



	if (parent) {

		ovl_path_upper(parent, &parentpath);

		ctx.destdir = parentpath.dentry;

		ctx.destname = dentry->d_name;



		err = vfs_getattr(&parentpath, &ctx.pstat,

			  STATX_ATIME | STATX_MTIME, AT_STATX_SYNC_AS_STAT);

				  STATX_ATIME | STATX_MTIME,

				  AT_STATX_SYNC_AS_STAT);

		if (err)

			return err;

	}



	/* maybe truncate regular file. this has no effect on dirs */

	if (flags & O_TRUNC)
@@ -745,7 +762,7 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
	} else {

		if (!ovl_dentry_upper(dentry))

			err = ovl_do_copy_up(&ctx);

		if (!err && !ovl_dentry_has_upper_alias(dentry))

		if (!err && parent && !ovl_dentry_has_upper_alias(dentry))

			err = ovl_link_up(&ctx);

		ovl_copy_up_end(dentry);

	}
@@ -758,10 +775,19 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags) 
{

	int err = 0;

	const struct cred *old_cred = ovl_override_creds(dentry->d_sb);

	bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);



	/*

	 * With NFS export, copy up can get called for a disconnected non-dir.

	 * In this case, we will copy up lower inode to index dir without

	 * linking it to upper dir.

	 */

	if (WARN_ON(disconnected && d_is_dir(dentry)))

		return -EIO;



	while (!err) {

		struct dentry *next;

		struct dentry *parent;

		struct dentry *parent = NULL;



		/*

		 * Check if copy-up has happened as well as for upper alias (in
@@ -777,12 +803,12 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags) 
		 *      with rename.

		 */

		if (ovl_dentry_upper(dentry) &&

		    ovl_dentry_has_upper_alias(dentry))

		    (ovl_dentry_has_upper_alias(dentry) || disconnected))

			break;



		next = dget(dentry);

		/* find the topmost dentry not yet copied up */

		for (;;) {

		for (; !disconnected;) {

			parent = dget_parent(next);



			if (ovl_dentry_upper(parent))

fs/overlayfs/inode.c

+3 −1
Original line number Diff line number Diff line
@@ -351,8 +351,10 @@ struct posix_acl *ovl_get_acl(struct inode *inode, int type) 


static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)

{

	/* Copy up of disconnected dentry does not set upper alias */

	if (ovl_dentry_upper(dentry) &&

	    ovl_dentry_has_upper_alias(dentry))

	    (ovl_dentry_has_upper_alias(dentry) ||

	     (dentry->d_flags & DCACHE_DISCONNECTED)))

		return false;



	if (special_file(d_inode(dentry)->i_mode))

fs/overlayfs/util.c

+4 −3
Original line number Diff line number Diff line
@@ -229,9 +229,10 @@ void ovl_dentry_set_opaque(struct dentry *dentry) 
}



/*

 * For hard links it's possible for ovl_dentry_upper() to return positive, while

 * there's no actual upper alias for the inode.  Copy up code needs to know

 * about the existence of the upper alias, so it can't use ovl_dentry_upper().

 * For hard links and decoded file handles, it's possible for ovl_dentry_upper()

 * to return positive, while there's no actual upper alias for the inode.

 * Copy up code needs to know about the existence of the upper alias, so it

 * can't use ovl_dentry_upper().

 */

bool ovl_dentry_has_upper_alias(struct dentry *dentry)

{