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linux-next/fs/cachefiles/namei.c
David Howells fee096deb4 CacheFiles: Catch an overly long wait for an old active object
Catch an overly long wait for an old, dying active object when we want to
replace it with a new one.  The probability is that all the slow-work threads
are hogged, and the delete can't get a look in.

What we do instead is:

 (1) if there's nothing in the slow work queue, we sleep until either the dying
     object has finished dying or there is something in the slow work queue
     behind which we can queue our object.

 (2) if there is something in the slow work queue, we return ETIMEDOUT to
     fscache_lookup_object(), which then puts us back on the slow work queue,
     presumably behind the deletion that we're blocked by.  We are then
     deferred for a while until we work our way back through the queue -
     without blocking a slow-work thread unnecessarily.

A backtrace similar to the following may appear in the log without this patch:

	INFO: task kslowd004:5711 blocked for more than 120 seconds.
	"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
	kslowd004     D 0000000000000000     0  5711      2 0x00000080
	 ffff88000340bb80 0000000000000046 ffff88002550d000 0000000000000000
	 ffff88002550d000 0000000000000007 ffff88000340bfd8 ffff88002550d2a8
	 000000000000ddf0 00000000000118c0 00000000000118c0 ffff88002550d2a8
	Call Trace:
	 [<ffffffff81058e21>] ? trace_hardirqs_on+0xd/0xf
	 [<ffffffffa011c4d8>] ? cachefiles_wait_bit+0x0/0xd [cachefiles]
	 [<ffffffffa011c4e1>] cachefiles_wait_bit+0x9/0xd [cachefiles]
	 [<ffffffff81353153>] __wait_on_bit+0x43/0x76
	 [<ffffffff8111ae39>] ? ext3_xattr_get+0x1ec/0x270
	 [<ffffffff813531ef>] out_of_line_wait_on_bit+0x69/0x74
	 [<ffffffffa011c4d8>] ? cachefiles_wait_bit+0x0/0xd [cachefiles]
	 [<ffffffff8104c125>] ? wake_bit_function+0x0/0x2e
	 [<ffffffffa011bc79>] cachefiles_mark_object_active+0x203/0x23b [cachefiles]
	 [<ffffffffa011c209>] cachefiles_walk_to_object+0x558/0x827 [cachefiles]
	 [<ffffffffa011a429>] cachefiles_lookup_object+0xac/0x12a [cachefiles]
	 [<ffffffffa00aa1e9>] fscache_lookup_object+0x1c7/0x214 [fscache]
	 [<ffffffffa00aafc5>] fscache_object_state_machine+0xa5/0x52d [fscache]
	 [<ffffffffa00ab4ac>] fscache_object_slow_work_execute+0x5f/0xa0 [fscache]
	 [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1
	 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308
	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
	 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308
	 [<ffffffff8104be91>] kthread+0x7a/0x82
	 [<ffffffff8100beda>] child_rip+0xa/0x20
	 [<ffffffff8100b87c>] ? restore_args+0x0/0x30
	 [<ffffffff8104be17>] ? kthread+0x0/0x82
	 [<ffffffff8100bed0>] ? child_rip+0x0/0x20
	1 lock held by kslowd004/5711:
	 #0:  (&sb->s_type->i_mutex_key#7/1){+.+.+.}, at: [<ffffffffa011be64>] cachefiles_walk_to_object+0x1b3/0x827 [cachefiles]

Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19 18:12:05 +00:00

869 lines
21 KiB
C

/* CacheFiles path walking and related routines
*
* Copyright (C) 2007 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.
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/quotaops.h>
#include <linux/xattr.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/security.h>
#include "internal.h"
#define CACHEFILES_KEYBUF_SIZE 512
/*
* dump debugging info about an object
*/
static noinline
void __cachefiles_printk_object(struct cachefiles_object *object,
const char *prefix,
u8 *keybuf)
{
struct fscache_cookie *cookie;
unsigned keylen, loop;
printk(KERN_ERR "%sobject: OBJ%x\n",
prefix, object->fscache.debug_id);
printk(KERN_ERR "%sobjstate=%s fl=%lx swfl=%lx ev=%lx[%lx]\n",
prefix, fscache_object_states[object->fscache.state],
object->fscache.flags, object->fscache.work.flags,
object->fscache.events,
object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
prefix, object->fscache.n_ops, object->fscache.n_in_progress,
object->fscache.n_exclusive);
printk(KERN_ERR "%sparent=%p\n",
prefix, object->fscache.parent);
spin_lock(&object->fscache.lock);
cookie = object->fscache.cookie;
if (cookie) {
printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
prefix,
object->fscache.cookie,
object->fscache.cookie->parent,
object->fscache.cookie->netfs_data,
object->fscache.cookie->flags);
if (keybuf)
keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
CACHEFILES_KEYBUF_SIZE);
else
keylen = 0;
} else {
printk(KERN_ERR "%scookie=NULL\n", prefix);
keylen = 0;
}
spin_unlock(&object->fscache.lock);
if (keylen) {
printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
for (loop = 0; loop < keylen; loop++)
printk("%02x", keybuf[loop]);
printk("'\n");
}
}
/*
* dump debugging info about a pair of objects
*/
static noinline void cachefiles_printk_object(struct cachefiles_object *object,
struct cachefiles_object *xobject)
{
u8 *keybuf;
keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
if (object)
__cachefiles_printk_object(object, "", keybuf);
if (xobject)
__cachefiles_printk_object(xobject, "x", keybuf);
kfree(keybuf);
}
/*
* record the fact that an object is now active
*/
static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
struct cachefiles_object *object)
{
struct cachefiles_object *xobject;
struct rb_node **_p, *_parent = NULL;
struct dentry *dentry;
_enter(",%p", object);
try_again:
write_lock(&cache->active_lock);
if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
printk(KERN_ERR "CacheFiles: Error: Object already active\n");
cachefiles_printk_object(object, NULL);
BUG();
}
dentry = object->dentry;
_p = &cache->active_nodes.rb_node;
while (*_p) {
_parent = *_p;
xobject = rb_entry(_parent,
struct cachefiles_object, active_node);
ASSERT(xobject != object);
if (xobject->dentry > dentry)
_p = &(*_p)->rb_left;
else if (xobject->dentry < dentry)
_p = &(*_p)->rb_right;
else
goto wait_for_old_object;
}
rb_link_node(&object->active_node, _parent, _p);
rb_insert_color(&object->active_node, &cache->active_nodes);
write_unlock(&cache->active_lock);
_leave(" = 0");
return 0;
/* an old object from a previous incarnation is hogging the slot - we
* need to wait for it to be destroyed */
wait_for_old_object:
if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
printk(KERN_ERR "\n");
printk(KERN_ERR "CacheFiles: Error:"
" Unexpected object collision\n");
cachefiles_printk_object(object, xobject);
BUG();
}
atomic_inc(&xobject->usage);
write_unlock(&cache->active_lock);
if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
wait_queue_head_t *wq;
signed long timeout = 60 * HZ;
wait_queue_t wait;
bool requeue;
/* if the object we're waiting for is queued for processing,
* then just put ourselves on the queue behind it */
if (slow_work_is_queued(&xobject->fscache.work)) {
_debug("queue OBJ%x behind OBJ%x immediately",
object->fscache.debug_id,
xobject->fscache.debug_id);
goto requeue;
}
/* otherwise we sleep until either the object we're waiting for
* is done, or the slow-work facility wants the thread back to
* do other work */
wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
init_wait(&wait);
requeue = false;
do {
prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
break;
requeue = slow_work_sleep_till_thread_needed(
&object->fscache.work, &timeout);
} while (timeout > 0 && !requeue);
finish_wait(wq, &wait);
if (requeue &&
test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
_debug("queue OBJ%x behind OBJ%x after wait",
object->fscache.debug_id,
xobject->fscache.debug_id);
goto requeue;
}
if (timeout <= 0) {
printk(KERN_ERR "\n");
printk(KERN_ERR "CacheFiles: Error: Overlong"
" wait for old active object to go away\n");
cachefiles_printk_object(object, xobject);
goto requeue;
}
}
ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
cache->cache.ops->put_object(&xobject->fscache);
goto try_again;
requeue:
clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
cache->cache.ops->put_object(&xobject->fscache);
_leave(" = -ETIMEDOUT");
return -ETIMEDOUT;
}
/*
* delete an object representation from the cache
* - file backed objects are unlinked
* - directory backed objects are stuffed into the graveyard for userspace to
* delete
* - unlocks the directory mutex
*/
static int cachefiles_bury_object(struct cachefiles_cache *cache,
struct dentry *dir,
struct dentry *rep)
{
struct dentry *grave, *trap;
char nbuffer[8 + 8 + 1];
int ret;
_enter(",'%*.*s','%*.*s'",
dir->d_name.len, dir->d_name.len, dir->d_name.name,
rep->d_name.len, rep->d_name.len, rep->d_name.name);
/* non-directories can just be unlinked */
if (!S_ISDIR(rep->d_inode->i_mode)) {
_debug("unlink stale object");
ret = vfs_unlink(dir->d_inode, rep);
mutex_unlock(&dir->d_inode->i_mutex);
if (ret == -EIO)
cachefiles_io_error(cache, "Unlink failed");
_leave(" = %d", ret);
return ret;
}
/* directories have to be moved to the graveyard */
_debug("move stale object to graveyard");
mutex_unlock(&dir->d_inode->i_mutex);
try_again:
/* first step is to make up a grave dentry in the graveyard */
sprintf(nbuffer, "%08x%08x",
(uint32_t) get_seconds(),
(uint32_t) atomic_inc_return(&cache->gravecounter));
/* do the multiway lock magic */
trap = lock_rename(cache->graveyard, dir);
/* do some checks before getting the grave dentry */
if (rep->d_parent != dir) {
/* the entry was probably culled when we dropped the parent dir
* lock */
unlock_rename(cache->graveyard, dir);
_leave(" = 0 [culled?]");
return 0;
}
if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
unlock_rename(cache->graveyard, dir);
cachefiles_io_error(cache, "Graveyard no longer a directory");
return -EIO;
}
if (trap == rep) {
unlock_rename(cache->graveyard, dir);
cachefiles_io_error(cache, "May not make directory loop");
return -EIO;
}
if (d_mountpoint(rep)) {
unlock_rename(cache->graveyard, dir);
cachefiles_io_error(cache, "Mountpoint in cache");
return -EIO;
}
grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
if (IS_ERR(grave)) {
unlock_rename(cache->graveyard, dir);
if (PTR_ERR(grave) == -ENOMEM) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
cachefiles_io_error(cache, "Lookup error %ld",
PTR_ERR(grave));
return -EIO;
}
if (grave->d_inode) {
unlock_rename(cache->graveyard, dir);
dput(grave);
grave = NULL;
cond_resched();
goto try_again;
}
if (d_mountpoint(grave)) {
unlock_rename(cache->graveyard, dir);
dput(grave);
cachefiles_io_error(cache, "Mountpoint in graveyard");
return -EIO;
}
/* target should not be an ancestor of source */
if (trap == grave) {
unlock_rename(cache->graveyard, dir);
dput(grave);
cachefiles_io_error(cache, "May not make directory loop");
return -EIO;
}
/* attempt the rename */
ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
if (ret != 0 && ret != -ENOMEM)
cachefiles_io_error(cache, "Rename failed with error %d", ret);
unlock_rename(cache->graveyard, dir);
dput(grave);
_leave(" = 0");
return 0;
}
/*
* delete an object representation from the cache
*/
int cachefiles_delete_object(struct cachefiles_cache *cache,
struct cachefiles_object *object)
{
struct dentry *dir;
int ret;
_enter(",{%p}", object->dentry);
ASSERT(object->dentry);
ASSERT(object->dentry->d_inode);
ASSERT(object->dentry->d_parent);
dir = dget_parent(object->dentry);
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
ret = cachefiles_bury_object(cache, dir, object->dentry);
dput(dir);
_leave(" = %d", ret);
return ret;
}
/*
* walk from the parent object to the child object through the backing
* filesystem, creating directories as we go
*/
int cachefiles_walk_to_object(struct cachefiles_object *parent,
struct cachefiles_object *object,
const char *key,
struct cachefiles_xattr *auxdata)
{
struct cachefiles_cache *cache;
struct dentry *dir, *next = NULL;
unsigned long start;
const char *name;
int ret, nlen;
_enter("{%p},,%s,", parent->dentry, key);
cache = container_of(parent->fscache.cache,
struct cachefiles_cache, cache);
ASSERT(parent->dentry);
ASSERT(parent->dentry->d_inode);
if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
// TODO: convert file to dir
_leave("looking up in none directory");
return -ENOBUFS;
}
dir = dget(parent->dentry);
advance:
/* attempt to transit the first directory component */
name = key;
nlen = strlen(key);
/* key ends in a double NUL */
key = key + nlen + 1;
if (!*key)
key = NULL;
lookup_again:
/* search the current directory for the element name */
_debug("lookup '%s'", name);
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
start = jiffies;
next = lookup_one_len(name, dir, nlen);
cachefiles_hist(cachefiles_lookup_histogram, start);
if (IS_ERR(next))
goto lookup_error;
_debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
if (!key)
object->new = !next->d_inode;
/* if this element of the path doesn't exist, then the lookup phase
* failed, and we can release any readers in the certain knowledge that
* there's nothing for them to actually read */
if (!next->d_inode)
fscache_object_lookup_negative(&object->fscache);
/* we need to create the object if it's negative */
if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
/* index objects and intervening tree levels must be subdirs */
if (!next->d_inode) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto create_error;
start = jiffies;
ret = vfs_mkdir(dir->d_inode, next, 0);
cachefiles_hist(cachefiles_mkdir_histogram, start);
if (ret < 0)
goto create_error;
ASSERT(next->d_inode);
_debug("mkdir -> %p{%p{ino=%lu}}",
next, next->d_inode, next->d_inode->i_ino);
} else if (!S_ISDIR(next->d_inode->i_mode)) {
kerror("inode %lu is not a directory",
next->d_inode->i_ino);
ret = -ENOBUFS;
goto error;
}
} else {
/* non-index objects start out life as files */
if (!next->d_inode) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto create_error;
start = jiffies;
ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
cachefiles_hist(cachefiles_create_histogram, start);
if (ret < 0)
goto create_error;
ASSERT(next->d_inode);
_debug("create -> %p{%p{ino=%lu}}",
next, next->d_inode, next->d_inode->i_ino);
} else if (!S_ISDIR(next->d_inode->i_mode) &&
!S_ISREG(next->d_inode->i_mode)
) {
kerror("inode %lu is not a file or directory",
next->d_inode->i_ino);
ret = -ENOBUFS;
goto error;
}
}
/* process the next component */
if (key) {
_debug("advance");
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
dir = next;
next = NULL;
goto advance;
}
/* we've found the object we were looking for */
object->dentry = next;
/* if we've found that the terminal object exists, then we need to
* check its attributes and delete it if it's out of date */
if (!object->new) {
_debug("validate '%*.*s'",
next->d_name.len, next->d_name.len, next->d_name.name);
ret = cachefiles_check_object_xattr(object, auxdata);
if (ret == -ESTALE) {
/* delete the object (the deleter drops the directory
* mutex) */
object->dentry = NULL;
ret = cachefiles_bury_object(cache, dir, next);
dput(next);
next = NULL;
if (ret < 0)
goto delete_error;
_debug("redo lookup");
goto lookup_again;
}
}
/* note that we're now using this object */
ret = cachefiles_mark_object_active(cache, object);
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
dir = NULL;
if (ret == -ETIMEDOUT)
goto mark_active_timed_out;
_debug("=== OBTAINED_OBJECT ===");
if (object->new) {
/* attach data to a newly constructed terminal object */
ret = cachefiles_set_object_xattr(object, auxdata);
if (ret < 0)
goto check_error;
} else {
/* always update the atime on an object we've just looked up
* (this is used to keep track of culling, and atimes are only
* updated by read, write and readdir but not lookup or
* open) */
touch_atime(cache->mnt, next);
}
/* open a file interface onto a data file */
if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
if (S_ISREG(object->dentry->d_inode->i_mode)) {
const struct address_space_operations *aops;
ret = -EPERM;
aops = object->dentry->d_inode->i_mapping->a_ops;
if (!aops->bmap)
goto check_error;
object->backer = object->dentry;
} else {
BUG(); // TODO: open file in data-class subdir
}
}
object->new = 0;
fscache_obtained_object(&object->fscache);
_leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
return 0;
create_error:
_debug("create error %d", ret);
if (ret == -EIO)
cachefiles_io_error(cache, "Create/mkdir failed");
goto error;
mark_active_timed_out:
_debug("mark active timed out");
goto release_dentry;
check_error:
_debug("check error %d", ret);
write_lock(&cache->active_lock);
rb_erase(&object->active_node, &cache->active_nodes);
clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
write_unlock(&cache->active_lock);
release_dentry:
dput(object->dentry);
object->dentry = NULL;
goto error_out;
delete_error:
_debug("delete error %d", ret);
goto error_out2;
lookup_error:
_debug("lookup error %ld", PTR_ERR(next));
ret = PTR_ERR(next);
if (ret == -EIO)
cachefiles_io_error(cache, "Lookup failed");
next = NULL;
error:
mutex_unlock(&dir->d_inode->i_mutex);
dput(next);
error_out2:
dput(dir);
error_out:
_leave(" = error %d", -ret);
return ret;
}
/*
* get a subdirectory
*/
struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
struct dentry *dir,
const char *dirname)
{
struct dentry *subdir;
unsigned long start;
int ret;
_enter(",,%s", dirname);
/* search the current directory for the element name */
mutex_lock(&dir->d_inode->i_mutex);
start = jiffies;
subdir = lookup_one_len(dirname, dir, strlen(dirname));
cachefiles_hist(cachefiles_lookup_histogram, start);
if (IS_ERR(subdir)) {
if (PTR_ERR(subdir) == -ENOMEM)
goto nomem_d_alloc;
goto lookup_error;
}
_debug("subdir -> %p %s",
subdir, subdir->d_inode ? "positive" : "negative");
/* we need to create the subdir if it doesn't exist yet */
if (!subdir->d_inode) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto mkdir_error;
_debug("attempt mkdir");
ret = vfs_mkdir(dir->d_inode, subdir, 0700);
if (ret < 0)
goto mkdir_error;
ASSERT(subdir->d_inode);
_debug("mkdir -> %p{%p{ino=%lu}}",
subdir,
subdir->d_inode,
subdir->d_inode->i_ino);
}
mutex_unlock(&dir->d_inode->i_mutex);
/* we need to make sure the subdir is a directory */
ASSERT(subdir->d_inode);
if (!S_ISDIR(subdir->d_inode->i_mode)) {
kerror("%s is not a directory", dirname);
ret = -EIO;
goto check_error;
}
ret = -EPERM;
if (!subdir->d_inode->i_op ||
!subdir->d_inode->i_op->setxattr ||
!subdir->d_inode->i_op->getxattr ||
!subdir->d_inode->i_op->lookup ||
!subdir->d_inode->i_op->mkdir ||
!subdir->d_inode->i_op->create ||
!subdir->d_inode->i_op->rename ||
!subdir->d_inode->i_op->rmdir ||
!subdir->d_inode->i_op->unlink)
goto check_error;
_leave(" = [%lu]", subdir->d_inode->i_ino);
return subdir;
check_error:
dput(subdir);
_leave(" = %d [check]", ret);
return ERR_PTR(ret);
mkdir_error:
mutex_unlock(&dir->d_inode->i_mutex);
dput(subdir);
kerror("mkdir %s failed with error %d", dirname, ret);
return ERR_PTR(ret);
lookup_error:
mutex_unlock(&dir->d_inode->i_mutex);
ret = PTR_ERR(subdir);
kerror("Lookup %s failed with error %d", dirname, ret);
return ERR_PTR(ret);
nomem_d_alloc:
mutex_unlock(&dir->d_inode->i_mutex);
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
/*
* find out if an object is in use or not
* - if finds object and it's not in use:
* - returns a pointer to the object and a reference on it
* - returns with the directory locked
*/
static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
struct dentry *dir,
char *filename)
{
struct cachefiles_object *object;
struct rb_node *_n;
struct dentry *victim;
unsigned long start;
int ret;
//_enter(",%*.*s/,%s",
// dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
/* look up the victim */
mutex_lock_nested(&dir->d_inode->i_mutex, 1);
start = jiffies;
victim = lookup_one_len(filename, dir, strlen(filename));
cachefiles_hist(cachefiles_lookup_histogram, start);
if (IS_ERR(victim))
goto lookup_error;
//_debug("victim -> %p %s",
// victim, victim->d_inode ? "positive" : "negative");
/* if the object is no longer there then we probably retired the object
* at the netfs's request whilst the cull was in progress
*/
if (!victim->d_inode) {
mutex_unlock(&dir->d_inode->i_mutex);
dput(victim);
_leave(" = -ENOENT [absent]");
return ERR_PTR(-ENOENT);
}
/* check to see if we're using this object */
read_lock(&cache->active_lock);
_n = cache->active_nodes.rb_node;
while (_n) {
object = rb_entry(_n, struct cachefiles_object, active_node);
if (object->dentry > victim)
_n = _n->rb_left;
else if (object->dentry < victim)
_n = _n->rb_right;
else
goto object_in_use;
}
read_unlock(&cache->active_lock);
//_leave(" = %p", victim);
return victim;
object_in_use:
read_unlock(&cache->active_lock);
mutex_unlock(&dir->d_inode->i_mutex);
dput(victim);
//_leave(" = -EBUSY [in use]");
return ERR_PTR(-EBUSY);
lookup_error:
mutex_unlock(&dir->d_inode->i_mutex);
ret = PTR_ERR(victim);
if (ret == -ENOENT) {
/* file or dir now absent - probably retired by netfs */
_leave(" = -ESTALE [absent]");
return ERR_PTR(-ESTALE);
}
if (ret == -EIO) {
cachefiles_io_error(cache, "Lookup failed");
} else if (ret != -ENOMEM) {
kerror("Internal error: %d", ret);
ret = -EIO;
}
_leave(" = %d", ret);
return ERR_PTR(ret);
}
/*
* cull an object if it's not in use
* - called only by cache manager daemon
*/
int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
char *filename)
{
struct dentry *victim;
int ret;
_enter(",%*.*s/,%s",
dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
victim = cachefiles_check_active(cache, dir, filename);
if (IS_ERR(victim))
return PTR_ERR(victim);
_debug("victim -> %p %s",
victim, victim->d_inode ? "positive" : "negative");
/* okay... the victim is not being used so we can cull it
* - start by marking it as stale
*/
_debug("victim is cullable");
ret = cachefiles_remove_object_xattr(cache, victim);
if (ret < 0)
goto error_unlock;
/* actually remove the victim (drops the dir mutex) */
_debug("bury");
ret = cachefiles_bury_object(cache, dir, victim);
if (ret < 0)
goto error;
dput(victim);
_leave(" = 0");
return 0;
error_unlock:
mutex_unlock(&dir->d_inode->i_mutex);
error:
dput(victim);
if (ret == -ENOENT) {
/* file or dir now absent - probably retired by netfs */
_leave(" = -ESTALE [absent]");
return -ESTALE;
}
if (ret != -ENOMEM) {
kerror("Internal error: %d", ret);
ret = -EIO;
}
_leave(" = %d", ret);
return ret;
}
/*
* find out if an object is in use or not
* - called only by cache manager daemon
* - returns -EBUSY or 0 to indicate whether an object is in use or not
*/
int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
char *filename)
{
struct dentry *victim;
//_enter(",%*.*s/,%s",
// dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
victim = cachefiles_check_active(cache, dir, filename);
if (IS_ERR(victim))
return PTR_ERR(victim);
mutex_unlock(&dir->d_inode->i_mutex);
dput(victim);
//_leave(" = 0");
return 0;
}