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Subject[PATCH 5/6] staging: erofs: add some comments for xattr subsystem
Date
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>
---
drivers/staging/erofs/xattr.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index 4942ca1..7b1367e 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -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;
}
--
1.9.1
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