Commit 521b5d0c authored by Al Viro's avatar Al Viro
Browse files

[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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 4e1b36fb

fs/pnode.h

+1 −0
Original line number Diff line number Diff line
@@ -35,4 +35,5 @@ int propagate_mnt(struct vfsmount *, struct dentry *, struct vfsmount *, 
		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 */

fs/seq_file.c

+12 −4
Original line number Diff line number Diff line
@@ -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 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) 
		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);
@@ -140,8 +143,9 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) 
			break;

		}

		err = m->op->show(m, p);

		if (err || m->count == m->size) {

		if (m->count == m->size || err) {

			m->count = offs;

			if (likely(err <= 0))

				break;

		}

		pos = next;
@@ -199,8 +203,12 @@ static int traverse(struct seq_file *m, loff_t offset) 
		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) {

include/linux/seq_file.h

+2 −0
Original line number Diff line number Diff line
@@ -30,6 +30,8 @@ struct seq_operations { 
	int (*show) (struct seq_file *m, void *v);

};



#define SEQ_SKIP 1



int seq_open(struct file *, const struct seq_operations *);

ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);

loff_t seq_lseek(struct file *, loff_t, int);