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Commit c7999c36 authored by Al Viro's avatar Al Viro
Browse files

reduce m_start() cost... 



Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent f2ebb3a9

fs/mount.h

+4 −1
Original line number Diff line number Diff line
@@ -10,7 +10,7 @@ struct mnt_namespace { 
	struct user_namespace	*user_ns;

	u64			seq;	/* Sequence number to prevent loops */

	wait_queue_head_t poll;

	int event;

	u64 event;

};



struct mnt_pcp {
@@ -104,6 +104,9 @@ struct proc_mounts { 
	struct mnt_namespace *ns;

	struct path root;

	int (*show)(struct seq_file *, struct vfsmount *);

	void *cached_mount;

	u64 cached_event;

	loff_t cached_index;

};



#define proc_mounts(p) (container_of((p), struct proc_mounts, m))

fs/namespace.c

+18 −3
Original line number Diff line number Diff line
@@ -52,7 +52,7 @@ static int __init set_mphash_entries(char *str) 
}

__setup("mphash_entries=", set_mphash_entries);



static int event;

static u64 event;

static DEFINE_IDA(mnt_id_ida);

static DEFINE_IDA(mnt_group_ida);

static DEFINE_SPINLOCK(mnt_id_lock);
@@ -1100,14 +1100,29 @@ static void *m_start(struct seq_file *m, loff_t *pos) 
	struct proc_mounts *p = proc_mounts(m);



	down_read(&namespace_sem);

	return seq_list_start(&p->ns->list, *pos);

	if (p->cached_event == p->ns->event) {

		void *v = p->cached_mount;

		if (*pos == p->cached_index)

			return v;

		if (*pos == p->cached_index + 1) {

			v = seq_list_next(v, &p->ns->list, &p->cached_index);

			return p->cached_mount = v;

		}

	}



	p->cached_event = p->ns->event;

	p->cached_mount = seq_list_start(&p->ns->list, *pos);

	p->cached_index = *pos;

	return p->cached_mount;

}



static void *m_next(struct seq_file *m, void *v, loff_t *pos)

{

	struct proc_mounts *p = proc_mounts(m);



	return seq_list_next(v, &p->ns->list, pos);

	p->cached_mount = seq_list_next(v, &p->ns->list, pos);

	p->cached_index = *pos;

	return p->cached_mount;

}



static void m_stop(struct seq_file *m, void *v)

fs/proc_namespace.c

+1 −0
Original line number Diff line number Diff line
@@ -267,6 +267,7 @@ static int mounts_open_common(struct inode *inode, struct file *file, 
	p->root = root;

	p->m.poll_event = ns->event;

	p->show = show;

	p->cached_event = ~0ULL;



	return 0;