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[PATCH] teach seq_file to discard entries

Browse source 
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>
This commit is contained in:
Al Viro 2008-03-28 00:46:41 -04:00
parent 4e1b36fb48
commit 521b5d0c40
3 changed files with 15 additions and 4 deletions
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1
fs/pnode.h
View file

@ -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 */

16
fs/seq_file.c
View file

@ -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);
@ -140,9 +143,10 @@ Fill:
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 @@ 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) {

2
include/linux/seq_file.h
View file

@ -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);