fs/overlayfs/export.c

36  * Before encoding a non-upper directory file handle from real layer N, we need
48  * copied up and renamed, upper dir /a will be indexed by lower dir /a from
88 	/* We can get upper/overlay path from indexed/lower dentry */
154  * encoding also after copy up. If non-pure upper is not indexed, then it was
156  * about staying consistent with pre copy up encoding and we encode an upper
157  * file handle. Overlay root dentry is a private case of non-indexed upper.
164  *  Pure upper		| U
165  *  Non-indexed upper	| U
166  *  Indexed upper	| L (*)
167  *  Non-upper		| L (*)
169  * U = upper file handle
175  * of a decodable file handle for non-upper dir.
177  * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
184 	/* Lower file handle for non-upper non-decodable */
188 	/* Upper file handle for pure upper */
193 	 * Root is never indexed, so if there's an upper layer, encode upper for
200 	 * Upper decodable file handle for non-indexed upper.
208 	 * lower dir or under a non-indexed upper is not always possible.
215 	/* Lower file handle for indexed and non-upper dir/non-dir */
227 	 * Check if we should encode a lower or upper file handle and maybe
234 	/* Encode an upper or lower file handle */
291 	struct dentry *upper = upper_alias ?: index;
299 	if (d_is_dir(upper ?: lower))
306 	oip.upperdentry = dget(upper);
315 		dput(upper);
319 	if (upper)
325 /* Get the upper or lower dentry in stack whose on layer @idx */
345  * dentry is @real. If @real is on upper layer, we lookup a child overlay
427 	 * Decoding upper dir from index is expensive, so first try to lookup
448 	/* Get connected upper overlay dir from index */
450 		struct dentry *upper = ovl_index_upper(ofs, index, true);
453 		if (IS_ERR_OR_NULL(upper))
454 			return upper;
458 		 * ovl_lookup_real() in upper layer. The first level call walks
460 		 * recursive call walks back from indexed upper to the topmost
461 		 * connected/hashed upper parent (or up to root).
463 		this = ovl_lookup_real(sb, upper, &ofs->layers[0]);
464 		dput(upper);
532  * If @real is on upper layer, we lookup a child overlay dentry with the same
635  * Get an overlay dentry from upper/lower real dentries and index.
638 				     struct dentry *upper,
643 	const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;
644 	struct dentry *real = upper ?: (index ?: lowerpath->dentry);
651 		return ovl_obtain_alias(sb, upper, lowerpath, index);
669 	struct dentry *upper;
674 	upper = ovl_decode_real_fh(ofs, fh, ovl_upper_mnt(ofs), true);
675 	if (IS_ERR_OR_NULL(upper))
676 		return upper;
678 	dentry = ovl_get_dentry(sb, upper, NULL, NULL);
679 	dput(upper);
714 	/* Then lookup indexed upper/whiteout by origin fh */
724 	/* Then try to get a connected upper dir by index */
726 		struct dentry *upper = ovl_index_upper(ofs, index, true);
728 		err = PTR_ERR(upper);
729 		if (IS_ERR_OR_NULL(upper))
732 		dentry = ovl_get_dentry(sb, upper, NULL, NULL);
733 		dput(upper);
751 	/* Get a connected non-upper dir or disconnected non-dir */