linux/fs/cachefiles/namei.c
David Howells a5b3a80b89 CacheFiles: Provide read-and-reset release counters for cachefilesd
Provide read-and-reset objects- and blocks-released counters for cachefilesd
to use to work out whether there's anything new that can be culled.

One of the problems cachefilesd has is that if all the objects in the cache
are pinned by inodes lying dormant in the kernel inode cache, there isn't
anything for it to cull.  In such a case, it just spins around walking the
filesystem tree and scanning for something to cull.  This eats up a lot of
CPU time.

By telling cachefilesd if there have been any releases, the daemon can
sleep until there is the possibility of something to do.

cachefilesd finds this information by the following means:

 (1) When the control fd is read, the kernel presents a list of values of
     interest.  "freleased=N" and "breleased=N" are added to this list to
     indicate the number of files released and number of blocks released
     since the last read call.  At this point the counters are reset.

 (2) POLLIN is signalled if the number of files released becomes greater
     than 0.

Note that by 'released' it just means that the kernel has released its
interest in those files for the moment, not necessarily that the files
should be deleted from the cache.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-02-01 12:30:10 -05:00

1008 lines
25 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 <linux/slab.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;
pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
prefix, object->fscache.state->name,
object->fscache.flags, work_busy(&object->fscache.work),
object->fscache.events, object->fscache.event_mask);
pr_err("%sops=%u inp=%u exc=%u\n",
prefix, object->fscache.n_ops, object->fscache.n_in_progress,
object->fscache.n_exclusive);
pr_err("%sparent=%p\n",
prefix, object->fscache.parent);
spin_lock(&object->fscache.lock);
cookie = object->fscache.cookie;
if (cookie) {
pr_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 && cookie->def)
keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
CACHEFILES_KEYBUF_SIZE);
else
keylen = 0;
} else {
pr_err("%scookie=NULL\n", prefix);
keylen = 0;
}
spin_unlock(&object->fscache.lock);
if (keylen) {
pr_err("%skey=[%u] '", prefix, keylen);
for (loop = 0; loop < keylen; loop++)
pr_cont("%02x", keybuf[loop]);
pr_cont("'\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);
}
/*
* mark the owner of a dentry, if there is one, to indicate that that dentry
* has been preemptively deleted
* - the caller must hold the i_mutex on the dentry's parent as required to
* call vfs_unlink(), vfs_rmdir() or vfs_rename()
*/
static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
struct dentry *dentry,
enum fscache_why_object_killed why)
{
struct cachefiles_object *object;
struct rb_node *p;
_enter(",'%pd'", dentry);
write_lock(&cache->active_lock);
p = cache->active_nodes.rb_node;
while (p) {
object = rb_entry(p, struct cachefiles_object, active_node);
if (object->dentry > dentry)
p = p->rb_left;
else if (object->dentry < dentry)
p = p->rb_right;
else
goto found_dentry;
}
write_unlock(&cache->active_lock);
_leave(" [no owner]");
return;
/* found the dentry for */
found_dentry:
kdebug("preemptive burial: OBJ%x [%s] %p",
object->fscache.debug_id,
object->fscache.state->name,
dentry);
if (fscache_object_is_live(&object->fscache)) {
pr_err("\n");
pr_err("Error: Can't preemptively bury live object\n");
cachefiles_printk_object(object, NULL);
} else {
if (why != FSCACHE_OBJECT_IS_STALE)
fscache_object_mark_killed(&object->fscache, why);
}
write_unlock(&cache->active_lock);
_leave(" [owner marked]");
}
/*
* 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)) {
pr_err("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 (fscache_object_is_live(&xobject->fscache)) {
pr_err("\n");
pr_err("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 (work_pending(&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 fscache_object is congested */
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 = fscache_object_sleep_till_congested(&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) {
pr_err("\n");
pr_err("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;
}
/*
* Mark an object as being inactive.
*/
void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
struct cachefiles_object *object)
{
write_lock(&cache->active_lock);
rb_erase(&object->active_node, &cache->active_nodes);
clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
write_unlock(&cache->active_lock);
wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
/* This object can now be culled, so we need to let the daemon know
* that there is something it can remove if it needs to.
*/
atomic_long_add(d_backing_inode(object->dentry)->i_blocks,
&cache->b_released);
if (atomic_inc_return(&cache->f_released))
cachefiles_state_changed(cache);
}
/*
* 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,
bool preemptive,
enum fscache_why_object_killed why)
{
struct dentry *grave, *trap;
struct path path, path_to_graveyard;
char nbuffer[8 + 8 + 1];
int ret;
_enter(",'%pd','%pd'", dir, rep);
_debug("remove %p from %p", rep, dir);
/* non-directories can just be unlinked */
if (!d_is_dir(rep)) {
_debug("unlink stale object");
path.mnt = cache->mnt;
path.dentry = dir;
ret = security_path_unlink(&path, rep);
if (ret < 0) {
cachefiles_io_error(cache, "Unlink security error");
} else {
ret = vfs_unlink(d_inode(dir), rep, NULL);
if (preemptive)
cachefiles_mark_object_buried(cache, rep, why);
}
inode_unlock(d_inode(dir));
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");
inode_unlock(d_inode(dir));
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 (!d_can_lookup(cache->graveyard)) {
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 (d_is_positive(grave)) {
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 */
path.mnt = cache->mnt;
path.dentry = dir;
path_to_graveyard.mnt = cache->mnt;
path_to_graveyard.dentry = cache->graveyard;
ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
if (ret < 0) {
cachefiles_io_error(cache, "Rename security error %d", ret);
} else {
ret = vfs_rename(d_inode(dir), rep,
d_inode(cache->graveyard), grave, NULL, 0);
if (ret != 0 && ret != -ENOMEM)
cachefiles_io_error(cache,
"Rename failed with error %d", ret);
if (preemptive)
cachefiles_mark_object_buried(cache, rep, why);
}
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(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
ASSERT(object->dentry);
ASSERT(d_backing_inode(object->dentry));
ASSERT(object->dentry->d_parent);
dir = dget_parent(object->dentry);
inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
/* object allocation for the same key preemptively deleted this
* object's file so that it could create its own file */
_debug("object preemptively buried");
inode_unlock(d_inode(dir));
ret = 0;
} else {
/* we need to check that our parent is _still_ our parent - it
* may have been renamed */
if (dir == object->dentry->d_parent) {
ret = cachefiles_bury_object(cache, dir,
object->dentry, false,
FSCACHE_OBJECT_WAS_RETIRED);
} else {
/* it got moved, presumably by cachefilesd culling it,
* so it's no longer in the key path and we can ignore
* it */
inode_unlock(d_inode(dir));
ret = 0;
}
}
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;
struct path path;
unsigned long start;
const char *name;
int ret, nlen;
_enter("OBJ%x{%p},OBJ%x,%s,",
parent->fscache.debug_id, parent->dentry,
object->fscache.debug_id, key);
cache = container_of(parent->fscache.cache,
struct cachefiles_cache, cache);
path.mnt = cache->mnt;
ASSERT(parent->dentry);
ASSERT(d_backing_inode(parent->dentry));
if (!(d_is_dir(parent->dentry))) {
// 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);
inode_lock_nested(d_inode(dir), 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, d_backing_inode(next) ? "positive" : "negative");
if (!key)
object->new = !d_backing_inode(next);
/* 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 (d_is_negative(next))
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 (d_is_negative(next)) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto no_space_error;
path.dentry = dir;
ret = security_path_mkdir(&path, next, 0);
if (ret < 0)
goto create_error;
start = jiffies;
ret = vfs_mkdir(d_inode(dir), next, 0);
cachefiles_hist(cachefiles_mkdir_histogram, start);
if (ret < 0)
goto create_error;
ASSERT(d_backing_inode(next));
_debug("mkdir -> %p{%p{ino=%lu}}",
next, d_backing_inode(next), d_backing_inode(next)->i_ino);
} else if (!d_can_lookup(next)) {
pr_err("inode %lu is not a directory\n",
d_backing_inode(next)->i_ino);
ret = -ENOBUFS;
goto error;
}
} else {
/* non-index objects start out life as files */
if (d_is_negative(next)) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto no_space_error;
path.dentry = dir;
ret = security_path_mknod(&path, next, S_IFREG, 0);
if (ret < 0)
goto create_error;
start = jiffies;
ret = vfs_create(d_inode(dir), next, S_IFREG, true);
cachefiles_hist(cachefiles_create_histogram, start);
if (ret < 0)
goto create_error;
ASSERT(d_backing_inode(next));
_debug("create -> %p{%p{ino=%lu}}",
next, d_backing_inode(next), d_backing_inode(next)->i_ino);
} else if (!d_can_lookup(next) &&
!d_is_reg(next)
) {
pr_err("inode %lu is not a file or directory\n",
d_backing_inode(next)->i_ino);
ret = -ENOBUFS;
goto error;
}
}
/* process the next component */
if (key) {
_debug("advance");
inode_unlock(d_inode(dir));
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 '%pd'", next);
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, true,
FSCACHE_OBJECT_IS_STALE);
dput(next);
next = NULL;
if (ret < 0)
goto delete_error;
_debug("redo lookup");
fscache_object_retrying_stale(&object->fscache);
goto lookup_again;
}
}
/* note that we're now using this object */
ret = cachefiles_mark_object_active(cache, object);
inode_unlock(d_inode(dir));
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) */
path.dentry = next;
touch_atime(&path);
}
/* open a file interface onto a data file */
if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
if (d_is_reg(object->dentry)) {
const struct address_space_operations *aops;
ret = -EPERM;
aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
if (!aops->bmap)
goto check_error;
if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
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]", d_backing_inode(object->dentry)->i_ino);
return 0;
no_space_error:
fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
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);
cachefiles_mark_object_inactive(cache, object);
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:
inode_unlock(d_inode(dir));
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;
struct path path;
int ret;
_enter(",,%s", dirname);
/* search the current directory for the element name */
inode_lock(d_inode(dir));
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, d_backing_inode(subdir) ? "positive" : "negative");
/* we need to create the subdir if it doesn't exist yet */
if (d_is_negative(subdir)) {
ret = cachefiles_has_space(cache, 1, 0);
if (ret < 0)
goto mkdir_error;
_debug("attempt mkdir");
path.mnt = cache->mnt;
path.dentry = dir;
ret = security_path_mkdir(&path, subdir, 0700);
if (ret < 0)
goto mkdir_error;
ret = vfs_mkdir(d_inode(dir), subdir, 0700);
if (ret < 0)
goto mkdir_error;
ASSERT(d_backing_inode(subdir));
_debug("mkdir -> %p{%p{ino=%lu}}",
subdir,
d_backing_inode(subdir),
d_backing_inode(subdir)->i_ino);
}
inode_unlock(d_inode(dir));
/* we need to make sure the subdir is a directory */
ASSERT(d_backing_inode(subdir));
if (!d_can_lookup(subdir)) {
pr_err("%s is not a directory\n", dirname);
ret = -EIO;
goto check_error;
}
ret = -EPERM;
if (!d_backing_inode(subdir)->i_op->setxattr ||
!d_backing_inode(subdir)->i_op->getxattr ||
!d_backing_inode(subdir)->i_op->lookup ||
!d_backing_inode(subdir)->i_op->mkdir ||
!d_backing_inode(subdir)->i_op->create ||
(!d_backing_inode(subdir)->i_op->rename &&
!d_backing_inode(subdir)->i_op->rename2) ||
!d_backing_inode(subdir)->i_op->rmdir ||
!d_backing_inode(subdir)->i_op->unlink)
goto check_error;
_leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
return subdir;
check_error:
dput(subdir);
_leave(" = %d [check]", ret);
return ERR_PTR(ret);
mkdir_error:
inode_unlock(d_inode(dir));
dput(subdir);
pr_err("mkdir %s failed with error %d\n", dirname, ret);
return ERR_PTR(ret);
lookup_error:
inode_unlock(d_inode(dir));
ret = PTR_ERR(subdir);
pr_err("Lookup %s failed with error %d\n", dirname, ret);
return ERR_PTR(ret);
nomem_d_alloc:
inode_unlock(d_inode(dir));
_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(",%pd/,%s",
// dir, filename);
/* look up the victim */
inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
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, d_backing_inode(victim) ? "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 (d_is_negative(victim)) {
inode_unlock(d_inode(dir));
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);
inode_unlock(d_inode(dir));
dput(victim);
//_leave(" = -EBUSY [in use]");
return ERR_PTR(-EBUSY);
lookup_error:
inode_unlock(d_inode(dir));
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) {
pr_err("Internal error: %d\n", 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(",%pd/,%s", dir, filename);
victim = cachefiles_check_active(cache, dir, filename);
if (IS_ERR(victim))
return PTR_ERR(victim);
_debug("victim -> %p %s",
victim, d_backing_inode(victim) ? "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, false,
FSCACHE_OBJECT_WAS_CULLED);
if (ret < 0)
goto error;
dput(victim);
_leave(" = 0");
return 0;
error_unlock:
inode_unlock(d_inode(dir));
error:
dput(victim);
if (ret == -ENOENT) {
/* file or dir now absent - probably retired by netfs */
_leave(" = -ESTALE [absent]");
return -ESTALE;
}
if (ret != -ENOMEM) {
pr_err("Internal error: %d\n", 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(",%pd/,%s",
// dir, filename);
victim = cachefiles_check_active(cache, dir, filename);
if (IS_ERR(victim))
return PTR_ERR(victim);
inode_unlock(d_inode(dir));
dput(victim);
//_leave(" = 0");
return 0;
}