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Commit 26b6c984 authored by Al Viro's avatar Al Viro
Browse files

libfs: take cursors out of list when moving past the end of directory 



that eliminates the last place where we accessed the tail of ->d_subdirs

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent d4f4de5e

fs/libfs.c

+25 −24
Original line number Diff line number Diff line
@@ -92,14 +92,13 @@ EXPORT_SYMBOL(dcache_dir_close); 
/*

 * Returns an element of siblings' list.

 * We are looking for <count>th positive after <p>; if

 * found, dentry is grabbed and passed to caller via *<res>.

 * If no such element exists, the anchor of list is returned

 * and *<res> is set to NULL.

 * found, dentry is grabbed and returned to caller.

 * If no such element exists, NULL is returned.

 */

static struct list_head *scan_positives(struct dentry *cursor,

static struct dentry *scan_positives(struct dentry *cursor,

					struct list_head *p,

					loff_t count,

					struct dentry **res)

					struct dentry *last)

{

	struct dentry *dentry = cursor->d_parent, *found = NULL;
@@ -127,9 +126,8 @@ static struct list_head *scan_positives(struct dentry *cursor, 
		}

	}

	spin_unlock(&dentry->d_lock);

	dput(*res);

	*res = found;

	return p;

	dput(last);

	return found;

}



loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
@@ -149,25 +147,22 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) 
	if (offset != file->f_pos) {

		struct dentry *cursor = file->private_data;

		struct dentry *to = NULL;

		struct list_head *p;



		file->f_pos = offset;

		inode_lock_shared(dentry->d_inode);



		if (file->f_pos > 2) {

			p = scan_positives(cursor, &dentry->d_subdirs,

					   file->f_pos - 2, &to);

			spin_lock(&dentry->d_lock);

			list_move(&cursor->d_child, p);

			spin_unlock(&dentry->d_lock);

		} else {

		if (offset > 2)

			to = scan_positives(cursor, &dentry->d_subdirs,

					    offset - 2, NULL);

		spin_lock(&dentry->d_lock);

		if (to)

			list_move(&cursor->d_child, &to->d_child);

		else

			list_del_init(&cursor->d_child);

		spin_unlock(&dentry->d_lock);

		}



		dput(to);



		file->f_pos = offset;



		inode_unlock_shared(dentry->d_inode);

	}

	return offset;
@@ -199,17 +194,23 @@ int dcache_readdir(struct file *file, struct dir_context *ctx) 


	if (ctx->pos == 2)

		p = anchor;

	else

	else if (!list_empty(&cursor->d_child))

		p = &cursor->d_child;

	else

		return 0;



	while ((p = scan_positives(cursor, p, 1, &next)) != anchor) {

	while ((next = scan_positives(cursor, p, 1, next)) != NULL) {

		if (!dir_emit(ctx, next->d_name.name, next->d_name.len,

			      d_inode(next)->i_ino, dt_type(d_inode(next))))

			break;

		ctx->pos++;

		p = &next->d_child;

	}

	spin_lock(&dentry->d_lock);

	list_move_tail(&cursor->d_child, p);

	if (next)

		list_move_tail(&cursor->d_child, &next->d_child);

	else

		list_del_init(&cursor->d_child);

	spin_unlock(&dentry->d_lock);

	dput(next);