staging: erofs: add some comments for xattr subsystem

As Dan Carpenter pointed out, it is better to document what
return values of these callbacks in `struct xattr_iter_handlers'
mean and why it->ofs is increased regardless of success or
failure in `xattr_foreach'.

Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Gao Xiang 2018-09-19 13:49:09 +08:00 committed by Greg Kroah-Hartman
parent 5fb76bb042
commit bdf30cef10

View File

@ -109,6 +109,13 @@ static int init_inode_xattrs(struct inode *inode)
return 0;
}
/*
* the general idea for these return values is
* if 0 is returned, go on processing the current xattr;
* 1 (> 0) is returned, skip this round to process the next xattr;
* -err (< 0) is returned, an error (maybe ENOXATTR) occurred
* and need to be handled
*/
struct xattr_iter_handlers {
int (*entry)(struct xattr_iter *, struct erofs_xattr_entry *);
int (*name)(struct xattr_iter *, unsigned int, char *, unsigned int);
@ -164,6 +171,10 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
return vi->xattr_isize - xattr_header_sz;
}
/*
* Regardless of success or failure, `xattr_foreach' will end up with
* `ofs' pointing to the next xattr item rather than an arbitrary position.
*/
static int xattr_foreach(struct xattr_iter *it,
const struct xattr_iter_handlers *op, unsigned int *tlimit)
{
@ -255,7 +266,7 @@ static int xattr_foreach(struct xattr_iter *it,
}
out:
/* we assume that ofs is aligned with 4 bytes */
/* xattrs should be 4-byte aligned (on-disk constraint) */
it->ofs = EROFS_XATTR_ALIGN(it->ofs);
return err;
}