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linux/fs/fscache/object-list.c
David Howells 402cb8dda9 fscache: Attach the index key and aux data to the cookie 
Attach copies of the index key and auxiliary data to the fscache cookie so
that:

 (1) The callbacks to the netfs for this stuff can be eliminated.  This
     can simplify things in the cache as the information is still
     available, even after the cache has relinquished the cookie.

 (2) Simplifies the locking requirements of accessing the information as we
     don't have to worry about the netfs object going away on us.

 (3) The cache can do lazy updating of the coherency information on disk.
     As long as the cache is flushed before reboot/poweroff, there's no
     need to update the coherency info on disk every time it changes.

 (4) Cookies can be hashed or put in a tree as the index key is easily
     available.  This allows:

     (a) Checks for duplicate cookies can be made at the top fscache layer
     	 rather than down in the bowels of the cache backend.

     (b) Caching can be added to a netfs object that has a cookie if the
     	 cache is brought online after the netfs object is allocated.

A certain amount of space is made in the cookie for inline copies of the
data, but if it won't fit there, extra memory will be allocated for it.

The downside of this is that live cache operation requires more memory.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>
2018-04-04 13:41:28 +01:00

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/* Global fscache object list maintainer and viewer
*
* Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define FSCACHE_DEBUG_LEVEL COOKIE
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/key.h>
#include <keys/user-type.h>
#include "internal.h"
static struct rb_root fscache_object_list;
static DEFINE_RWLOCK(fscache_object_list_lock);
struct fscache_objlist_data {
unsigned long config; /* display configuration */
#define FSCACHE_OBJLIST_CONFIG_KEY 0x00000001 /* show object keys */
#define FSCACHE_OBJLIST_CONFIG_AUX 0x00000002 /* show object auxdata */
#define FSCACHE_OBJLIST_CONFIG_COOKIE 0x00000004 /* show objects with cookies */
#define FSCACHE_OBJLIST_CONFIG_NOCOOKIE 0x00000008 /* show objects without cookies */
#define FSCACHE_OBJLIST_CONFIG_BUSY 0x00000010 /* show busy objects */
#define FSCACHE_OBJLIST_CONFIG_IDLE 0x00000020 /* show idle objects */
#define FSCACHE_OBJLIST_CONFIG_PENDWR 0x00000040 /* show objects with pending writes */
#define FSCACHE_OBJLIST_CONFIG_NOPENDWR 0x00000080 /* show objects without pending writes */
#define FSCACHE_OBJLIST_CONFIG_READS 0x00000100 /* show objects with active reads */
#define FSCACHE_OBJLIST_CONFIG_NOREADS 0x00000200 /* show objects without active reads */
#define FSCACHE_OBJLIST_CONFIG_EVENTS 0x00000400 /* show objects with events */
#define FSCACHE_OBJLIST_CONFIG_NOEVENTS 0x00000800 /* show objects without no events */
#define FSCACHE_OBJLIST_CONFIG_WORK 0x00001000 /* show objects with work */
#define FSCACHE_OBJLIST_CONFIG_NOWORK 0x00002000 /* show objects without work */
};
/*
* Add an object to the object list
* - we use the address of the fscache_object structure as the key into the
* tree
*/
void fscache_objlist_add(struct fscache_object *obj)
{
struct fscache_object *xobj;
struct rb_node **p = &fscache_object_list.rb_node, *parent = NULL;
ASSERT(RB_EMPTY_NODE(&obj->objlist_link));
write_lock(&fscache_object_list_lock);
while (*p) {
parent = *p;
xobj = rb_entry(parent, struct fscache_object, objlist_link);
if (obj < xobj)
p = &(*p)->rb_left;
else if (obj > xobj)
p = &(*p)->rb_right;
else
BUG();
}
rb_link_node(&obj->objlist_link, parent, p);
rb_insert_color(&obj->objlist_link, &fscache_object_list);
write_unlock(&fscache_object_list_lock);
}
/*
* Remove an object from the object list.
*/
void fscache_objlist_remove(struct fscache_object *obj)
{
if (RB_EMPTY_NODE(&obj->objlist_link))
return;
write_lock(&fscache_object_list_lock);
BUG_ON(RB_EMPTY_ROOT(&fscache_object_list));
rb_erase(&obj->objlist_link, &fscache_object_list);
write_unlock(&fscache_object_list_lock);
}
/*
* find the object in the tree on or after the specified index
*/
static struct fscache_object *fscache_objlist_lookup(loff_t *_pos)
{
struct fscache_object *pobj, *obj = NULL, *minobj = NULL;
struct rb_node *p;
unsigned long pos;
if (*_pos >= (unsigned long) ERR_PTR(-ENOENT))
return NULL;
pos = *_pos;
/* banners (can't represent line 0 by pos 0 as that would involve
* returning a NULL pointer) */
if (pos == 0)
return (struct fscache_object *)(long)++(*_pos);
if (pos < 3)
return (struct fscache_object *)pos;
pobj = (struct fscache_object *)pos;
p = fscache_object_list.rb_node;
while (p) {
obj = rb_entry(p, struct fscache_object, objlist_link);
if (pobj < obj) {
if (!minobj || minobj > obj)
minobj = obj;
p = p->rb_left;
} else if (pobj > obj) {
p = p->rb_right;
} else {
minobj = obj;
break;
}
obj = NULL;
}
if (!minobj)
*_pos = (unsigned long) ERR_PTR(-ENOENT);
else if (minobj != obj)
*_pos = (unsigned long) minobj;
return minobj;
}
/*
* set up the iterator to start reading from the first line
*/
static void *fscache_objlist_start(struct seq_file *m, loff_t *_pos)
__acquires(&fscache_object_list_lock)
{
read_lock(&fscache_object_list_lock);
return fscache_objlist_lookup(_pos);
}
/*
* move to the next line
*/
static void *fscache_objlist_next(struct seq_file *m, void *v, loff_t *_pos)
{
(*_pos)++;
return fscache_objlist_lookup(_pos);
}
/*
* clean up after reading
*/
static void fscache_objlist_stop(struct seq_file *m, void *v)
__releases(&fscache_object_list_lock)
{
read_unlock(&fscache_object_list_lock);
}
/*
* display an object
*/
static int fscache_objlist_show(struct seq_file *m, void *v)
{
struct fscache_objlist_data *data = m->private;
struct fscache_object *obj = v;
struct fscache_cookie *cookie;
unsigned long config = data->config;
char _type[3], *type;
u8 *p;
if ((unsigned long) v == 1) {
seq_puts(m, "OBJECT PARENT STAT CHLDN OPS OOP IPR EX READS"
" EM EV FL S"
" | NETFS_COOKIE_DEF TY FL NETFS_DATA");
if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
FSCACHE_OBJLIST_CONFIG_AUX))
seq_puts(m, " ");
if (config & FSCACHE_OBJLIST_CONFIG_KEY)
seq_puts(m, "OBJECT_KEY");
if ((config & (FSCACHE_OBJLIST_CONFIG_KEY |
FSCACHE_OBJLIST_CONFIG_AUX)) ==
(FSCACHE_OBJLIST_CONFIG_KEY | FSCACHE_OBJLIST_CONFIG_AUX))
seq_puts(m, ", ");
if (config & FSCACHE_OBJLIST_CONFIG_AUX)
seq_puts(m, "AUX_DATA");
seq_puts(m, "\n");
return 0;
}
if ((unsigned long) v == 2) {
seq_puts(m, "======== ======== ==== ===== === === === == ====="
" == == == ="
" | ================ == == ================");
if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
FSCACHE_OBJLIST_CONFIG_AUX))
seq_puts(m, " ================");
seq_puts(m, "\n");
return 0;
}
/* filter out any unwanted objects */
#define FILTER(criterion, _yes, _no) \
do { \
unsigned long yes = FSCACHE_OBJLIST_CONFIG_##_yes; \
unsigned long no = FSCACHE_OBJLIST_CONFIG_##_no; \
if (criterion) { \
if (!(config & yes)) \
return 0; \
} else { \
if (!(config & no)) \
return 0; \
} \
} while(0)
cookie = obj->cookie;
if (~config) {
FILTER(cookie->def,
COOKIE, NOCOOKIE);
FILTER(fscache_object_is_active(obj) ||
obj->n_ops != 0 ||
obj->n_obj_ops != 0 ||
obj->flags ||
!list_empty(&obj->dependents),
BUSY, IDLE);
FILTER(test_bit(FSCACHE_OBJECT_PENDING_WRITE, &obj->flags),
PENDWR, NOPENDWR);
FILTER(atomic_read(&obj->n_reads),
READS, NOREADS);
FILTER(obj->events & obj->event_mask,
EVENTS, NOEVENTS);
FILTER(work_busy(&obj->work), WORK, NOWORK);
}
seq_printf(m,
"%8x %8x %s %5u %3u %3u %3u %2u %5u %2lx %2lx %2lx %1x | ",
obj->debug_id,
obj->parent ? obj->parent->debug_id : -1,
obj->state->short_name,
obj->n_children,
obj->n_ops,
obj->n_obj_ops,
obj->n_in_progress,
obj->n_exclusive,
atomic_read(&obj->n_reads),
obj->event_mask,
obj->events,
obj->flags,
work_busy(&obj->work));
if (fscache_use_cookie(obj)) {
uint16_t keylen = 0, auxlen = 0;
switch (cookie->type) {
case 0:
type = "IX";
break;
case 1:
type = "DT";
break;
default:
snprintf(_type, sizeof(_type), "%02u",
cookie->type);
type = _type;
break;
}
seq_printf(m, "%-16s %s %2lx %16p",
cookie->def->name,
type,
cookie->flags,
cookie->netfs_data);
if (config & FSCACHE_OBJLIST_CONFIG_KEY)
keylen = cookie->key_len;
if (config & FSCACHE_OBJLIST_CONFIG_AUX)
auxlen = cookie->aux_len;
if (keylen > 0 || auxlen > 0) {
seq_puts(m, " ");
p = keylen <= sizeof(cookie->inline_key) ?
cookie->inline_key : cookie->key;
for (; keylen > 0; keylen--)
seq_printf(m, "%02x", *p++);
if (auxlen > 0) {
if (config & FSCACHE_OBJLIST_CONFIG_KEY)
seq_puts(m, ", ");
p = auxlen <= sizeof(cookie->inline_aux) ?
cookie->inline_aux : cookie->aux;
for (; auxlen > 0; auxlen--)
seq_printf(m, "%02x", *p++);
}
}
seq_puts(m, "\n");
fscache_unuse_cookie(obj);
} else {
seq_puts(m, "<no_netfs>\n");
}
return 0;
}
static const struct seq_operations fscache_objlist_ops = {
.start = fscache_objlist_start,
.stop = fscache_objlist_stop,
.next = fscache_objlist_next,
.show = fscache_objlist_show,
};
/*
* get the configuration for filtering the list
*/
static void fscache_objlist_config(struct fscache_objlist_data *data)
{
#ifdef CONFIG_KEYS
const struct user_key_payload *confkey;
unsigned long config;
struct key *key;
const char *buf;
int len;
key = request_key(&key_type_user, "fscache:objlist", NULL);
if (IS_ERR(key))
goto no_config;
config = 0;
rcu_read_lock();
confkey = user_key_payload_rcu(key);
if (!confkey) {
/* key was revoked */
rcu_read_unlock();
key_put(key);
goto no_config;
}
buf = confkey->data;
for (len = confkey->datalen - 1; len >= 0; len--) {
switch (buf[len]) {
case 'K': config |= FSCACHE_OBJLIST_CONFIG_KEY; break;
case 'A': config |= FSCACHE_OBJLIST_CONFIG_AUX; break;
case 'C': config |= FSCACHE_OBJLIST_CONFIG_COOKIE; break;
case 'c': config |= FSCACHE_OBJLIST_CONFIG_NOCOOKIE; break;
case 'B': config |= FSCACHE_OBJLIST_CONFIG_BUSY; break;
case 'b': config |= FSCACHE_OBJLIST_CONFIG_IDLE; break;
case 'W': config |= FSCACHE_OBJLIST_CONFIG_PENDWR; break;
case 'w': config |= FSCACHE_OBJLIST_CONFIG_NOPENDWR; break;
case 'R': config |= FSCACHE_OBJLIST_CONFIG_READS; break;
case 'r': config |= FSCACHE_OBJLIST_CONFIG_NOREADS; break;
case 'S': config |= FSCACHE_OBJLIST_CONFIG_WORK; break;
case 's': config |= FSCACHE_OBJLIST_CONFIG_NOWORK; break;
}
}
rcu_read_unlock();
key_put(key);
if (!(config & (FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE)))
config |= FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE;
if (!(config & (FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE)))
config |= FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE;
if (!(config & (FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR)))
config |= FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR;
if (!(config & (FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS)))
config |= FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS;
if (!(config & (FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS)))
config |= FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS;
if (!(config & (FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK)))
config |= FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK;
data->config = config;
return;
no_config:
#endif
data->config = ULONG_MAX;
}
/*
* open "/proc/fs/fscache/objects" to provide a list of active objects
* - can be configured by a user-defined key added to the caller's keyrings
*/
static int fscache_objlist_open(struct inode *inode, struct file *file)
{
struct fscache_objlist_data *data;
data = __seq_open_private(file, &fscache_objlist_ops, sizeof(*data));
if (!data)
return -ENOMEM;
/* get the configuration key */
fscache_objlist_config(data);
return 0;
}
/*
* clean up on close
*/
static int fscache_objlist_release(struct inode *inode, struct file *file)
{
struct seq_file *m = file->private_data;
kfree(m->private);
m->private = NULL;
return seq_release(inode, file);
}
const struct file_operations fscache_objlist_fops = {
.open = fscache_objlist_open,
.read = seq_read,
.llseek = seq_lseek,
.release = fscache_objlist_release,
};
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