[PATCH] teach seq_file to discard entries
Allow ->show() return SEQ_SKIP; that will discard all
output from that element and move on.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/pnode.h b/fs/pnode.h
index f249be2..973c3f8 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -35,4 +35,5 @@
struct list_head *);
int propagate_umount(struct list_head *);
int propagate_mount_busy(struct vfsmount *, int);
+void mnt_release_group_id(struct vfsmount *);
#endif /* _LINUX_PNODE_H */
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 8537702..bf2bcfd 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -25,6 +25,7 @@
* into the buffer. In case of error ->start() and ->next() return
* ERR_PTR(error). In the end of sequence they return %NULL. ->show()
* returns 0 in case of success and negative number in case of error.
+ * Returning SEQ_SKIP means "discard this element and move on".
*/
int seq_open(struct file *file, const struct seq_operations *op)
{
@@ -114,8 +115,10 @@
if (!p || IS_ERR(p))
break;
err = m->op->show(m, p);
- if (err)
+ if (err < 0)
break;
+ if (unlikely(err))
+ m->count = 0;
if (m->count < m->size)
goto Fill;
m->op->stop(m, p);
@@ -140,9 +143,10 @@
break;
}
err = m->op->show(m, p);
- if (err || m->count == m->size) {
+ if (m->count == m->size || err) {
m->count = offs;
- break;
+ if (likely(err <= 0))
+ break;
}
pos = next;
}
@@ -199,8 +203,12 @@
if (IS_ERR(p))
break;
error = m->op->show(m, p);
- if (error)
+ if (error < 0)
break;
+ if (unlikely(error)) {
+ error = 0;
+ m->count = 0;
+ }
if (m->count == m->size)
goto Eoverflow;
if (pos + m->count > offset) {