Commit 071bf501 authored by Al Viro's avatar Al Viro
Browse files

link_path_walk: nd->depth massage, part 1 



nd->stack[0] is unused until the handling of trailing symlinks and
we want to get rid of that.  Having fucked that transformation up
several times, I went for bloody pedantic series of provably equivalent
transformations.  Sorry.

Step 1: keep nd->depth higher by one in link_path_walk() - increment upon
entry, decrement on exits, adjust the arithmetics inside and surround the
calls of functions that care about nd->depth value (nd_alloc_stack(),
get_link(), put_link()) with decrement/increment pairs.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 894bc8c4

fs/namei.c

+17 −5
Original line number Diff line number Diff line
@@ -1763,6 +1763,7 @@ static int link_path_walk(const char *name, struct nameidata *nd) 
	if (!*name)

		return 0;



	nd->depth++;

	/* At this point we know we have a real path component. */

	for(;;) {

		u64 hash_len;
@@ -1823,15 +1824,18 @@ Walked: 
		if (err) {

			const char *s;



			nd->depth--;

			err = nd_alloc_stack(nd);

			nd->depth++;

			if (unlikely(err)) {

				path_to_nameidata(&nd->link, nd);

				break;

			}



			nd->depth++;



			nd->depth--;

			s = get_link(nd);

			nd->depth++;



			if (unlikely(IS_ERR(s))) {

				err = PTR_ERR(s);
@@ -1841,7 +1845,9 @@ Walked: 
			err = 0;

			if (unlikely(!s)) {

				/* jumped */

				nd->depth--;

				put_link(nd);

				nd->depth++;

				nd->depth--;

			} else {

				if (*s == '/') {
@@ -1855,7 +1861,7 @@ Walked: 
						;

				}

				nd->inode = nd->path.dentry->d_inode;

				nd->stack[nd->depth].name = name;

				nd->stack[nd->depth - 1].name = name;

				if (!*s)

					goto OK;

				name = s;
@@ -1869,19 +1875,25 @@ Walked: 
	}

	terminate_walk(nd);

Err:

	while (unlikely(nd->depth)) {

	while (unlikely(nd->depth > 1)) {

		nd->depth--;

		put_link(nd);

		nd->depth++;

		nd->depth--;

	}

	nd->depth--;

	return err;

OK:

	if (unlikely(nd->depth)) {

		name = nd->stack[nd->depth].name;

	if (unlikely(nd->depth > 1)) {

		name = nd->stack[nd->depth - 1].name;

		err = walk_component(nd, LOOKUP_FOLLOW);

		nd->depth--;

		put_link(nd);

		nd->depth++;

		nd->depth--;

		goto Walked;

	}

	nd->depth--;

	return 0;

}

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