forked from Minki/linux
f29507ce66
When a cookie is allocated that causes fscache_object structs to be
allocated, those objects are initialised with the cookie pointer, but
aren't blessed with a ref on that cookie unless the attachment is
successfully completed in fscache_attach_object().
If attachment fails because the parent object was dying or there was a
collision, fscache_attach_object() returns without incrementing the cookie
counter - but upon failure of this function, the object is released which
then puts the cookie, whether or not a ref was taken on the cookie.
Fix this by taking a ref on the cookie when it is assigned in
fscache_object_init(), even when we're creating a root object.
Analysis from Kiran Kumar:
This bug has been seen in 4.4.0-124-generic #148-Ubuntu kernel
BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1776277
fscache cookie ref count updated incorrectly during fscache object
allocation resulting in following Oops.
kernel BUG at /build/linux-Y09MKI/linux-4.4.0/fs/fscache/internal.h:321!
kernel BUG at /build/linux-Y09MKI/linux-4.4.0/fs/fscache/cookie.c:639!
[Cause]
Two threads are trying to do operate on a cookie and two objects.
(1) One thread tries to unmount the filesystem and in process goes over a
huge list of objects marking them dead and deleting the objects.
cookie->usage is also decremented in following path:
nfs_fscache_release_super_cookie
-> __fscache_relinquish_cookie
->__fscache_cookie_put
->BUG_ON(atomic_read(&cookie->usage) <= 0);
(2) A second thread tries to lookup an object for reading data in following
path:
fscache_alloc_object
1) cachefiles_alloc_object
-> fscache_object_init
-> assign cookie, but usage not bumped.
2) fscache_attach_object -> fails in cant_attach_object because the
cookie's backing object or cookie's->parent object are going away
3) fscache_put_object
-> cachefiles_put_object
->fscache_object_destroy
->fscache_cookie_put
->BUG_ON(atomic_read(&cookie->usage) <= 0);
[NOTE from dhowells] It's unclear as to the circumstances in which (2) can
take place, given that thread (1) is in nfs_kill_super(), however a
conflicting NFS mount with slightly different parameters that creates a
different superblock would do it. A backtrace from Kiran seems to show
that this is a possibility:
kernel BUG at/build/linux-Y09MKI/linux-4.4.0/fs/fscache/cookie.c:639!
...
RIP: __fscache_cookie_put+0x3a/0x40 [fscache]
Call Trace:
__fscache_relinquish_cookie+0x87/0x120 [fscache]
nfs_fscache_release_super_cookie+0x2d/0xb0 [nfs]
nfs_kill_super+0x29/0x40 [nfs]
deactivate_locked_super+0x48/0x80
deactivate_super+0x5c/0x60
cleanup_mnt+0x3f/0x90
__cleanup_mnt+0x12/0x20
task_work_run+0x86/0xb0
exit_to_usermode_loop+0xc2/0xd0
syscall_return_slowpath+0x4e/0x60
int_ret_from_sys_call+0x25/0x9f
[Fix] Bump up the cookie usage in fscache_object_init, when it is first
being assigned a cookie atomically such that the cookie is added and bumped
up if its refcount is not zero. Remove the assignment in
fscache_attach_object().
[Testcase]
I have run ~100 hours of NFS stress tests and not seen this bug recur.
[Regression Potential]
- Limited to fscache/cachefiles.
Fixes: ccc4fc3d11
("FS-Cache: Implement the cookie management part of the netfs API")
Signed-off-by: Kiran Kumar Modukuri <kiran.modukuri@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
976 lines
26 KiB
C
976 lines
26 KiB
C
/* netfs cookie management
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|
*
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* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
|
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
|
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* See Documentation/filesystems/caching/netfs-api.txt for more information on
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* the netfs API.
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*/
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#define FSCACHE_DEBUG_LEVEL COOKIE
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#include <linux/module.h>
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#include <linux/slab.h>
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#include "internal.h"
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struct kmem_cache *fscache_cookie_jar;
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static atomic_t fscache_object_debug_id = ATOMIC_INIT(0);
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#define fscache_cookie_hash_shift 15
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static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
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static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
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loff_t object_size);
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static int fscache_alloc_object(struct fscache_cache *cache,
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struct fscache_cookie *cookie);
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static int fscache_attach_object(struct fscache_cookie *cookie,
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struct fscache_object *object);
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static void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
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{
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struct hlist_node *object;
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const u8 *k;
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unsigned loop;
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pr_err("%c-cookie c=%p [p=%p fl=%lx nc=%u na=%u]\n",
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prefix, cookie, cookie->parent, cookie->flags,
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atomic_read(&cookie->n_children),
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atomic_read(&cookie->n_active));
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pr_err("%c-cookie d=%p n=%p\n",
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prefix, cookie->def, cookie->netfs_data);
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object = READ_ONCE(cookie->backing_objects.first);
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if (object)
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pr_err("%c-cookie o=%p\n",
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prefix, hlist_entry(object, struct fscache_object, cookie_link));
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pr_err("%c-key=[%u] '", prefix, cookie->key_len);
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k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
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cookie->inline_key : cookie->key;
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for (loop = 0; loop < cookie->key_len; loop++)
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pr_cont("%02x", k[loop]);
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pr_cont("'\n");
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}
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void fscache_free_cookie(struct fscache_cookie *cookie)
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{
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if (cookie) {
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BUG_ON(!hlist_empty(&cookie->backing_objects));
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if (cookie->aux_len > sizeof(cookie->inline_aux))
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kfree(cookie->aux);
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if (cookie->key_len > sizeof(cookie->inline_key))
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kfree(cookie->key);
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kmem_cache_free(fscache_cookie_jar, cookie);
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}
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}
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/*
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* initialise an cookie jar slab element prior to any use
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*/
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void fscache_cookie_init_once(void *_cookie)
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{
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struct fscache_cookie *cookie = _cookie;
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memset(cookie, 0, sizeof(*cookie));
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spin_lock_init(&cookie->lock);
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spin_lock_init(&cookie->stores_lock);
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INIT_HLIST_HEAD(&cookie->backing_objects);
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}
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/*
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* Set the index key in a cookie. The cookie struct has space for a 12-byte
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* key plus length and hash, but if that's not big enough, it's instead a
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* pointer to a buffer containing 3 bytes of hash, 1 byte of length and then
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* the key data.
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*/
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static int fscache_set_key(struct fscache_cookie *cookie,
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const void *index_key, size_t index_key_len)
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{
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unsigned long long h;
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u32 *buf;
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int i;
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cookie->key_len = index_key_len;
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if (index_key_len > sizeof(cookie->inline_key)) {
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buf = kzalloc(index_key_len, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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cookie->key = buf;
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} else {
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buf = (u32 *)cookie->inline_key;
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buf[0] = 0;
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buf[1] = 0;
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buf[2] = 0;
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}
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memcpy(buf, index_key, index_key_len);
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/* Calculate a hash and combine this with the length in the first word
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* or first half word
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*/
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h = (unsigned long)cookie->parent;
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h += index_key_len + cookie->type;
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for (i = 0; i < (index_key_len + sizeof(u32) - 1) / sizeof(u32); i++)
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h += buf[i];
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cookie->key_hash = h ^ (h >> 32);
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return 0;
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}
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static long fscache_compare_cookie(const struct fscache_cookie *a,
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const struct fscache_cookie *b)
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{
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const void *ka, *kb;
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if (a->key_hash != b->key_hash)
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return (long)a->key_hash - (long)b->key_hash;
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if (a->parent != b->parent)
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return (long)a->parent - (long)b->parent;
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if (a->key_len != b->key_len)
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return (long)a->key_len - (long)b->key_len;
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if (a->type != b->type)
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return (long)a->type - (long)b->type;
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if (a->key_len <= sizeof(a->inline_key)) {
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ka = &a->inline_key;
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kb = &b->inline_key;
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} else {
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ka = a->key;
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kb = b->key;
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}
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return memcmp(ka, kb, a->key_len);
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}
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/*
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* Allocate a cookie.
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*/
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struct fscache_cookie *fscache_alloc_cookie(
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struct fscache_cookie *parent,
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const struct fscache_cookie_def *def,
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const void *index_key, size_t index_key_len,
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const void *aux_data, size_t aux_data_len,
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void *netfs_data,
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loff_t object_size)
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{
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struct fscache_cookie *cookie;
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/* allocate and initialise a cookie */
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cookie = kmem_cache_alloc(fscache_cookie_jar, GFP_KERNEL);
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if (!cookie)
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return NULL;
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cookie->key_len = index_key_len;
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cookie->aux_len = aux_data_len;
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if (fscache_set_key(cookie, index_key, index_key_len) < 0)
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goto nomem;
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if (cookie->aux_len <= sizeof(cookie->inline_aux)) {
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memcpy(cookie->inline_aux, aux_data, cookie->aux_len);
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} else {
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cookie->aux = kmemdup(aux_data, cookie->aux_len, GFP_KERNEL);
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if (!cookie->aux)
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goto nomem;
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}
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atomic_set(&cookie->usage, 1);
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atomic_set(&cookie->n_children, 0);
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/* We keep the active count elevated until relinquishment to prevent an
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* attempt to wake up every time the object operations queue quiesces.
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*/
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atomic_set(&cookie->n_active, 1);
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cookie->def = def;
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cookie->parent = parent;
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cookie->netfs_data = netfs_data;
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cookie->flags = (1 << FSCACHE_COOKIE_NO_DATA_YET);
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cookie->type = def->type;
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/* radix tree insertion won't use the preallocation pool unless it's
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* told it may not wait */
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INIT_RADIX_TREE(&cookie->stores, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
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return cookie;
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nomem:
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fscache_free_cookie(cookie);
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return NULL;
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}
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/*
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* Attempt to insert the new cookie into the hash. If there's a collision, we
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* return the old cookie if it's not in use and an error otherwise.
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*/
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struct fscache_cookie *fscache_hash_cookie(struct fscache_cookie *candidate)
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{
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struct fscache_cookie *cursor;
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struct hlist_bl_head *h;
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struct hlist_bl_node *p;
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unsigned int bucket;
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bucket = candidate->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
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h = &fscache_cookie_hash[bucket];
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hlist_bl_lock(h);
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hlist_bl_for_each_entry(cursor, p, h, hash_link) {
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if (fscache_compare_cookie(candidate, cursor) == 0)
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goto collision;
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}
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__set_bit(FSCACHE_COOKIE_ACQUIRED, &candidate->flags);
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fscache_cookie_get(candidate->parent, fscache_cookie_get_acquire_parent);
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atomic_inc(&candidate->parent->n_children);
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hlist_bl_add_head(&candidate->hash_link, h);
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hlist_bl_unlock(h);
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return candidate;
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collision:
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if (test_and_set_bit(FSCACHE_COOKIE_ACQUIRED, &cursor->flags)) {
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trace_fscache_cookie(cursor, fscache_cookie_collision,
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atomic_read(&cursor->usage));
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pr_err("Duplicate cookie detected\n");
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fscache_print_cookie(cursor, 'O');
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fscache_print_cookie(candidate, 'N');
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hlist_bl_unlock(h);
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return NULL;
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}
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fscache_cookie_get(cursor, fscache_cookie_get_reacquire);
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hlist_bl_unlock(h);
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return cursor;
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}
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/*
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* request a cookie to represent an object (index, datafile, xattr, etc)
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* - parent specifies the parent object
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* - the top level index cookie for each netfs is stored in the fscache_netfs
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* struct upon registration
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* - def points to the definition
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* - the netfs_data will be passed to the functions pointed to in *def
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* - all attached caches will be searched to see if they contain this object
|
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* - index objects aren't stored on disk until there's a dependent file that
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* needs storing
|
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* - other objects are stored in a selected cache immediately, and all the
|
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* indices forming the path to it are instantiated if necessary
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* - we never let on to the netfs about errors
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* - we may set a negative cookie pointer, but that's okay
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*/
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struct fscache_cookie *__fscache_acquire_cookie(
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struct fscache_cookie *parent,
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const struct fscache_cookie_def *def,
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const void *index_key, size_t index_key_len,
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const void *aux_data, size_t aux_data_len,
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void *netfs_data,
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loff_t object_size,
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bool enable)
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{
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struct fscache_cookie *candidate, *cookie;
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BUG_ON(!def);
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_enter("{%s},{%s},%p,%u",
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parent ? (char *) parent->def->name : "<no-parent>",
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def->name, netfs_data, enable);
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|
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if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
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return NULL;
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if (!aux_data || !aux_data_len) {
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aux_data = NULL;
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aux_data_len = 0;
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}
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fscache_stat(&fscache_n_acquires);
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|
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/* if there's no parent cookie, then we don't create one here either */
|
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if (!parent) {
|
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fscache_stat(&fscache_n_acquires_null);
|
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_leave(" [no parent]");
|
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return NULL;
|
|
}
|
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|
|
/* validate the definition */
|
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BUG_ON(!def->name[0]);
|
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BUG_ON(def->type == FSCACHE_COOKIE_TYPE_INDEX &&
|
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parent->type != FSCACHE_COOKIE_TYPE_INDEX);
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|
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candidate = fscache_alloc_cookie(parent, def,
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index_key, index_key_len,
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aux_data, aux_data_len,
|
|
netfs_data, object_size);
|
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if (!candidate) {
|
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fscache_stat(&fscache_n_acquires_oom);
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_leave(" [ENOMEM]");
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return NULL;
|
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}
|
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|
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cookie = fscache_hash_cookie(candidate);
|
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if (!cookie) {
|
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trace_fscache_cookie(candidate, fscache_cookie_discard, 1);
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|
goto out;
|
|
}
|
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|
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if (cookie == candidate)
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candidate = NULL;
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|
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switch (cookie->type) {
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case FSCACHE_COOKIE_TYPE_INDEX:
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fscache_stat(&fscache_n_cookie_index);
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break;
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case FSCACHE_COOKIE_TYPE_DATAFILE:
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fscache_stat(&fscache_n_cookie_data);
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break;
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default:
|
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fscache_stat(&fscache_n_cookie_special);
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break;
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}
|
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|
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trace_fscache_acquire(cookie);
|
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|
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if (enable) {
|
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/* if the object is an index then we need do nothing more here
|
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* - we create indices on disk when we need them as an index
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* may exist in multiple caches */
|
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if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
|
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if (fscache_acquire_non_index_cookie(cookie, object_size) == 0) {
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set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
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} else {
|
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atomic_dec(&parent->n_children);
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fscache_cookie_put(cookie,
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fscache_cookie_put_acquire_nobufs);
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fscache_stat(&fscache_n_acquires_nobufs);
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_leave(" = NULL");
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return NULL;
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}
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} else {
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set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
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}
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}
|
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|
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fscache_stat(&fscache_n_acquires_ok);
|
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|
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out:
|
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fscache_free_cookie(candidate);
|
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return cookie;
|
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}
|
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EXPORT_SYMBOL(__fscache_acquire_cookie);
|
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|
|
/*
|
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* Enable a cookie to permit it to accept new operations.
|
|
*/
|
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void __fscache_enable_cookie(struct fscache_cookie *cookie,
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const void *aux_data,
|
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loff_t object_size,
|
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bool (*can_enable)(void *data),
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void *data)
|
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{
|
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_enter("%p", cookie);
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|
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trace_fscache_enable(cookie);
|
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|
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wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
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TASK_UNINTERRUPTIBLE);
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|
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fscache_update_aux(cookie, aux_data);
|
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|
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if (test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
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goto out_unlock;
|
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|
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if (can_enable && !can_enable(data)) {
|
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/* The netfs decided it didn't want to enable after all */
|
|
} else if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
|
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/* Wait for outstanding disablement to complete */
|
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__fscache_wait_on_invalidate(cookie);
|
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|
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if (fscache_acquire_non_index_cookie(cookie, object_size) == 0)
|
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set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
|
|
} else {
|
|
set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
|
|
}
|
|
|
|
out_unlock:
|
|
clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
|
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
|
|
}
|
|
EXPORT_SYMBOL(__fscache_enable_cookie);
|
|
|
|
/*
|
|
* acquire a non-index cookie
|
|
* - this must make sure the index chain is instantiated and instantiate the
|
|
* object representation too
|
|
*/
|
|
static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
|
|
loff_t object_size)
|
|
{
|
|
struct fscache_object *object;
|
|
struct fscache_cache *cache;
|
|
int ret;
|
|
|
|
_enter("");
|
|
|
|
set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
|
|
|
|
/* now we need to see whether the backing objects for this cookie yet
|
|
* exist, if not there'll be nothing to search */
|
|
down_read(&fscache_addremove_sem);
|
|
|
|
if (list_empty(&fscache_cache_list)) {
|
|
up_read(&fscache_addremove_sem);
|
|
_leave(" = 0 [no caches]");
|
|
return 0;
|
|
}
|
|
|
|
/* select a cache in which to store the object */
|
|
cache = fscache_select_cache_for_object(cookie->parent);
|
|
if (!cache) {
|
|
up_read(&fscache_addremove_sem);
|
|
fscache_stat(&fscache_n_acquires_no_cache);
|
|
_leave(" = -ENOMEDIUM [no cache]");
|
|
return -ENOMEDIUM;
|
|
}
|
|
|
|
_debug("cache %s", cache->tag->name);
|
|
|
|
set_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
|
|
|
|
/* ask the cache to allocate objects for this cookie and its parent
|
|
* chain */
|
|
ret = fscache_alloc_object(cache, cookie);
|
|
if (ret < 0) {
|
|
up_read(&fscache_addremove_sem);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
spin_lock(&cookie->lock);
|
|
if (hlist_empty(&cookie->backing_objects)) {
|
|
spin_unlock(&cookie->lock);
|
|
goto unavailable;
|
|
}
|
|
|
|
object = hlist_entry(cookie->backing_objects.first,
|
|
struct fscache_object, cookie_link);
|
|
|
|
fscache_set_store_limit(object, object_size);
|
|
|
|
/* initiate the process of looking up all the objects in the chain
|
|
* (done by fscache_initialise_object()) */
|
|
fscache_raise_event(object, FSCACHE_OBJECT_EV_NEW_CHILD);
|
|
|
|
spin_unlock(&cookie->lock);
|
|
|
|
/* we may be required to wait for lookup to complete at this point */
|
|
if (!fscache_defer_lookup) {
|
|
_debug("non-deferred lookup %p", &cookie->flags);
|
|
wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
|
|
TASK_UNINTERRUPTIBLE);
|
|
_debug("complete");
|
|
if (test_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags))
|
|
goto unavailable;
|
|
}
|
|
|
|
up_read(&fscache_addremove_sem);
|
|
_leave(" = 0 [deferred]");
|
|
return 0;
|
|
|
|
unavailable:
|
|
up_read(&fscache_addremove_sem);
|
|
_leave(" = -ENOBUFS");
|
|
return -ENOBUFS;
|
|
}
|
|
|
|
/*
|
|
* recursively allocate cache object records for a cookie/cache combination
|
|
* - caller must be holding the addremove sem
|
|
*/
|
|
static int fscache_alloc_object(struct fscache_cache *cache,
|
|
struct fscache_cookie *cookie)
|
|
{
|
|
struct fscache_object *object;
|
|
int ret;
|
|
|
|
_enter("%p,%p{%s}", cache, cookie, cookie->def->name);
|
|
|
|
spin_lock(&cookie->lock);
|
|
hlist_for_each_entry(object, &cookie->backing_objects,
|
|
cookie_link) {
|
|
if (object->cache == cache)
|
|
goto object_already_extant;
|
|
}
|
|
spin_unlock(&cookie->lock);
|
|
|
|
/* ask the cache to allocate an object (we may end up with duplicate
|
|
* objects at this stage, but we sort that out later) */
|
|
fscache_stat(&fscache_n_cop_alloc_object);
|
|
object = cache->ops->alloc_object(cache, cookie);
|
|
fscache_stat_d(&fscache_n_cop_alloc_object);
|
|
if (IS_ERR(object)) {
|
|
fscache_stat(&fscache_n_object_no_alloc);
|
|
ret = PTR_ERR(object);
|
|
goto error;
|
|
}
|
|
|
|
ASSERTCMP(object->cookie, ==, cookie);
|
|
fscache_stat(&fscache_n_object_alloc);
|
|
|
|
object->debug_id = atomic_inc_return(&fscache_object_debug_id);
|
|
|
|
_debug("ALLOC OBJ%x: %s {%lx}",
|
|
object->debug_id, cookie->def->name, object->events);
|
|
|
|
ret = fscache_alloc_object(cache, cookie->parent);
|
|
if (ret < 0)
|
|
goto error_put;
|
|
|
|
/* only attach if we managed to allocate all we needed, otherwise
|
|
* discard the object we just allocated and instead use the one
|
|
* attached to the cookie */
|
|
if (fscache_attach_object(cookie, object) < 0) {
|
|
fscache_stat(&fscache_n_cop_put_object);
|
|
cache->ops->put_object(object, fscache_obj_put_attach_fail);
|
|
fscache_stat_d(&fscache_n_cop_put_object);
|
|
}
|
|
|
|
_leave(" = 0");
|
|
return 0;
|
|
|
|
object_already_extant:
|
|
ret = -ENOBUFS;
|
|
if (fscache_object_is_dying(object) ||
|
|
fscache_cache_is_broken(object)) {
|
|
spin_unlock(&cookie->lock);
|
|
goto error;
|
|
}
|
|
spin_unlock(&cookie->lock);
|
|
_leave(" = 0 [found]");
|
|
return 0;
|
|
|
|
error_put:
|
|
fscache_stat(&fscache_n_cop_put_object);
|
|
cache->ops->put_object(object, fscache_obj_put_alloc_fail);
|
|
fscache_stat_d(&fscache_n_cop_put_object);
|
|
error:
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* attach a cache object to a cookie
|
|
*/
|
|
static int fscache_attach_object(struct fscache_cookie *cookie,
|
|
struct fscache_object *object)
|
|
{
|
|
struct fscache_object *p;
|
|
struct fscache_cache *cache = object->cache;
|
|
int ret;
|
|
|
|
_enter("{%s},{OBJ%x}", cookie->def->name, object->debug_id);
|
|
|
|
ASSERTCMP(object->cookie, ==, cookie);
|
|
|
|
spin_lock(&cookie->lock);
|
|
|
|
/* there may be multiple initial creations of this object, but we only
|
|
* want one */
|
|
ret = -EEXIST;
|
|
hlist_for_each_entry(p, &cookie->backing_objects, cookie_link) {
|
|
if (p->cache == object->cache) {
|
|
if (fscache_object_is_dying(p))
|
|
ret = -ENOBUFS;
|
|
goto cant_attach_object;
|
|
}
|
|
}
|
|
|
|
/* pin the parent object */
|
|
spin_lock_nested(&cookie->parent->lock, 1);
|
|
hlist_for_each_entry(p, &cookie->parent->backing_objects,
|
|
cookie_link) {
|
|
if (p->cache == object->cache) {
|
|
if (fscache_object_is_dying(p)) {
|
|
ret = -ENOBUFS;
|
|
spin_unlock(&cookie->parent->lock);
|
|
goto cant_attach_object;
|
|
}
|
|
object->parent = p;
|
|
spin_lock(&p->lock);
|
|
p->n_children++;
|
|
spin_unlock(&p->lock);
|
|
break;
|
|
}
|
|
}
|
|
spin_unlock(&cookie->parent->lock);
|
|
|
|
/* attach to the cache's object list */
|
|
if (list_empty(&object->cache_link)) {
|
|
spin_lock(&cache->object_list_lock);
|
|
list_add(&object->cache_link, &cache->object_list);
|
|
spin_unlock(&cache->object_list_lock);
|
|
}
|
|
|
|
/* Attach to the cookie. The object already has a ref on it. */
|
|
hlist_add_head(&object->cookie_link, &cookie->backing_objects);
|
|
|
|
fscache_objlist_add(object);
|
|
ret = 0;
|
|
|
|
cant_attach_object:
|
|
spin_unlock(&cookie->lock);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Invalidate an object. Callable with spinlocks held.
|
|
*/
|
|
void __fscache_invalidate(struct fscache_cookie *cookie)
|
|
{
|
|
struct fscache_object *object;
|
|
|
|
_enter("{%s}", cookie->def->name);
|
|
|
|
fscache_stat(&fscache_n_invalidates);
|
|
|
|
/* Only permit invalidation of data files. Invalidating an index will
|
|
* require the caller to release all its attachments to the tree rooted
|
|
* there, and if it's doing that, it may as well just retire the
|
|
* cookie.
|
|
*/
|
|
ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
|
|
|
|
/* If there's an object, we tell the object state machine to handle the
|
|
* invalidation on our behalf, otherwise there's nothing to do.
|
|
*/
|
|
if (!hlist_empty(&cookie->backing_objects)) {
|
|
spin_lock(&cookie->lock);
|
|
|
|
if (fscache_cookie_enabled(cookie) &&
|
|
!hlist_empty(&cookie->backing_objects) &&
|
|
!test_and_set_bit(FSCACHE_COOKIE_INVALIDATING,
|
|
&cookie->flags)) {
|
|
object = hlist_entry(cookie->backing_objects.first,
|
|
struct fscache_object,
|
|
cookie_link);
|
|
if (fscache_object_is_live(object))
|
|
fscache_raise_event(
|
|
object, FSCACHE_OBJECT_EV_INVALIDATE);
|
|
}
|
|
|
|
spin_unlock(&cookie->lock);
|
|
}
|
|
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(__fscache_invalidate);
|
|
|
|
/*
|
|
* Wait for object invalidation to complete.
|
|
*/
|
|
void __fscache_wait_on_invalidate(struct fscache_cookie *cookie)
|
|
{
|
|
_enter("%p", cookie);
|
|
|
|
wait_on_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING,
|
|
TASK_UNINTERRUPTIBLE);
|
|
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(__fscache_wait_on_invalidate);
|
|
|
|
/*
|
|
* update the index entries backing a cookie
|
|
*/
|
|
void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data)
|
|
{
|
|
struct fscache_object *object;
|
|
|
|
fscache_stat(&fscache_n_updates);
|
|
|
|
if (!cookie) {
|
|
fscache_stat(&fscache_n_updates_null);
|
|
_leave(" [no cookie]");
|
|
return;
|
|
}
|
|
|
|
_enter("{%s}", cookie->def->name);
|
|
|
|
spin_lock(&cookie->lock);
|
|
|
|
fscache_update_aux(cookie, aux_data);
|
|
|
|
if (fscache_cookie_enabled(cookie)) {
|
|
/* update the index entry on disk in each cache backing this
|
|
* cookie.
|
|
*/
|
|
hlist_for_each_entry(object,
|
|
&cookie->backing_objects, cookie_link) {
|
|
fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
|
|
}
|
|
}
|
|
|
|
spin_unlock(&cookie->lock);
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(__fscache_update_cookie);
|
|
|
|
/*
|
|
* Disable a cookie to stop it from accepting new requests from the netfs.
|
|
*/
|
|
void __fscache_disable_cookie(struct fscache_cookie *cookie,
|
|
const void *aux_data,
|
|
bool invalidate)
|
|
{
|
|
struct fscache_object *object;
|
|
bool awaken = false;
|
|
|
|
_enter("%p,%u", cookie, invalidate);
|
|
|
|
trace_fscache_disable(cookie);
|
|
|
|
ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
|
|
|
|
if (atomic_read(&cookie->n_children) != 0) {
|
|
pr_err("Cookie '%s' still has children\n",
|
|
cookie->def->name);
|
|
BUG();
|
|
}
|
|
|
|
wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
|
|
TASK_UNINTERRUPTIBLE);
|
|
|
|
fscache_update_aux(cookie, aux_data);
|
|
|
|
if (!test_and_clear_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
|
|
goto out_unlock_enable;
|
|
|
|
/* If the cookie is being invalidated, wait for that to complete first
|
|
* so that we can reuse the flag.
|
|
*/
|
|
__fscache_wait_on_invalidate(cookie);
|
|
|
|
/* Dispose of the backing objects */
|
|
set_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags);
|
|
|
|
spin_lock(&cookie->lock);
|
|
if (!hlist_empty(&cookie->backing_objects)) {
|
|
hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
|
|
if (invalidate)
|
|
set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
|
|
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
|
|
fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
|
|
}
|
|
} else {
|
|
if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
|
|
awaken = true;
|
|
}
|
|
spin_unlock(&cookie->lock);
|
|
if (awaken)
|
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
|
|
|
|
/* Wait for cessation of activity requiring access to the netfs (when
|
|
* n_active reaches 0). This makes sure outstanding reads and writes
|
|
* have completed.
|
|
*/
|
|
if (!atomic_dec_and_test(&cookie->n_active)) {
|
|
wait_var_event(&cookie->n_active,
|
|
!atomic_read(&cookie->n_active));
|
|
}
|
|
|
|
/* Make sure any pending writes are cancelled. */
|
|
if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX)
|
|
fscache_invalidate_writes(cookie);
|
|
|
|
/* Reset the cookie state if it wasn't relinquished */
|
|
if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags)) {
|
|
atomic_inc(&cookie->n_active);
|
|
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
|
|
}
|
|
|
|
out_unlock_enable:
|
|
clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
|
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(__fscache_disable_cookie);
|
|
|
|
/*
|
|
* release a cookie back to the cache
|
|
* - the object will be marked as recyclable on disk if retire is true
|
|
* - all dependents of this cookie must have already been unregistered
|
|
* (indices/files/pages)
|
|
*/
|
|
void __fscache_relinquish_cookie(struct fscache_cookie *cookie,
|
|
const void *aux_data,
|
|
bool retire)
|
|
{
|
|
fscache_stat(&fscache_n_relinquishes);
|
|
if (retire)
|
|
fscache_stat(&fscache_n_relinquishes_retire);
|
|
|
|
if (!cookie) {
|
|
fscache_stat(&fscache_n_relinquishes_null);
|
|
_leave(" [no cookie]");
|
|
return;
|
|
}
|
|
|
|
_enter("%p{%s,%p,%d},%d",
|
|
cookie, cookie->def->name, cookie->netfs_data,
|
|
atomic_read(&cookie->n_active), retire);
|
|
|
|
trace_fscache_relinquish(cookie, retire);
|
|
|
|
/* No further netfs-accessing operations on this cookie permitted */
|
|
if (test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags))
|
|
BUG();
|
|
|
|
__fscache_disable_cookie(cookie, aux_data, retire);
|
|
|
|
/* Clear pointers back to the netfs */
|
|
cookie->netfs_data = NULL;
|
|
cookie->def = NULL;
|
|
BUG_ON(!radix_tree_empty(&cookie->stores));
|
|
|
|
if (cookie->parent) {
|
|
ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
|
|
ASSERTCMP(atomic_read(&cookie->parent->n_children), >, 0);
|
|
atomic_dec(&cookie->parent->n_children);
|
|
}
|
|
|
|
/* Dispose of the netfs's link to the cookie */
|
|
ASSERTCMP(atomic_read(&cookie->usage), >, 0);
|
|
fscache_cookie_put(cookie, fscache_cookie_put_relinquish);
|
|
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(__fscache_relinquish_cookie);
|
|
|
|
/*
|
|
* Remove a cookie from the hash table.
|
|
*/
|
|
static void fscache_unhash_cookie(struct fscache_cookie *cookie)
|
|
{
|
|
struct hlist_bl_head *h;
|
|
unsigned int bucket;
|
|
|
|
bucket = cookie->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
|
|
h = &fscache_cookie_hash[bucket];
|
|
|
|
hlist_bl_lock(h);
|
|
hlist_bl_del(&cookie->hash_link);
|
|
hlist_bl_unlock(h);
|
|
}
|
|
|
|
/*
|
|
* Drop a reference to a cookie.
|
|
*/
|
|
void fscache_cookie_put(struct fscache_cookie *cookie,
|
|
enum fscache_cookie_trace where)
|
|
{
|
|
struct fscache_cookie *parent;
|
|
int usage;
|
|
|
|
_enter("%p", cookie);
|
|
|
|
do {
|
|
usage = atomic_dec_return(&cookie->usage);
|
|
trace_fscache_cookie(cookie, where, usage);
|
|
|
|
if (usage > 0)
|
|
return;
|
|
BUG_ON(usage < 0);
|
|
|
|
parent = cookie->parent;
|
|
fscache_unhash_cookie(cookie);
|
|
fscache_free_cookie(cookie);
|
|
|
|
cookie = parent;
|
|
where = fscache_cookie_put_parent;
|
|
} while (cookie);
|
|
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* check the consistency between the netfs inode and the backing cache
|
|
*
|
|
* NOTE: it only serves no-index type
|
|
*/
|
|
int __fscache_check_consistency(struct fscache_cookie *cookie,
|
|
const void *aux_data)
|
|
{
|
|
struct fscache_operation *op;
|
|
struct fscache_object *object;
|
|
bool wake_cookie = false;
|
|
int ret;
|
|
|
|
_enter("%p,", cookie);
|
|
|
|
ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
|
|
|
|
if (fscache_wait_for_deferred_lookup(cookie) < 0)
|
|
return -ERESTARTSYS;
|
|
|
|
if (hlist_empty(&cookie->backing_objects))
|
|
return 0;
|
|
|
|
op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
|
|
if (!op)
|
|
return -ENOMEM;
|
|
|
|
fscache_operation_init(cookie, op, NULL, NULL, NULL);
|
|
op->flags = FSCACHE_OP_MYTHREAD |
|
|
(1 << FSCACHE_OP_WAITING) |
|
|
(1 << FSCACHE_OP_UNUSE_COOKIE);
|
|
trace_fscache_page_op(cookie, NULL, op, fscache_page_op_check_consistency);
|
|
|
|
spin_lock(&cookie->lock);
|
|
|
|
fscache_update_aux(cookie, aux_data);
|
|
|
|
if (!fscache_cookie_enabled(cookie) ||
|
|
hlist_empty(&cookie->backing_objects))
|
|
goto inconsistent;
|
|
object = hlist_entry(cookie->backing_objects.first,
|
|
struct fscache_object, cookie_link);
|
|
if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
|
|
goto inconsistent;
|
|
|
|
op->debug_id = atomic_inc_return(&fscache_op_debug_id);
|
|
|
|
__fscache_use_cookie(cookie);
|
|
if (fscache_submit_op(object, op) < 0)
|
|
goto submit_failed;
|
|
|
|
/* the work queue now carries its own ref on the object */
|
|
spin_unlock(&cookie->lock);
|
|
|
|
ret = fscache_wait_for_operation_activation(object, op, NULL, NULL);
|
|
if (ret == 0) {
|
|
/* ask the cache to honour the operation */
|
|
ret = object->cache->ops->check_consistency(op);
|
|
fscache_op_complete(op, false);
|
|
} else if (ret == -ENOBUFS) {
|
|
ret = 0;
|
|
}
|
|
|
|
fscache_put_operation(op);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
|
|
submit_failed:
|
|
wake_cookie = __fscache_unuse_cookie(cookie);
|
|
inconsistent:
|
|
spin_unlock(&cookie->lock);
|
|
if (wake_cookie)
|
|
__fscache_wake_unused_cookie(cookie);
|
|
kfree(op);
|
|
_leave(" = -ESTALE");
|
|
return -ESTALE;
|
|
}
|
|
EXPORT_SYMBOL(__fscache_check_consistency);
|