- 根目录:
- fs
- cachefiles
- namei.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;
printk(KERN_ERR "%sobject: OBJ%x\n",
prefix, object->fscache.debug_id);
printk(KERN_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);
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 && cookie->def)
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);
}
/*
* 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)
{
struct cachefiles_object *object;
struct rb_node *p;
_enter(",'%*.*s'",
dentry->d_name.len, dentry->d_name.len, dentry->d_name.name);
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)) {
printk(KERN_ERR "\n");
printk(KERN_ERR "CacheFiles: Error:"
" Can't preemptively bury live object\n");
cachefiles_printk_object(object, NULL);
} else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
printk(KERN_ERR "CacheFiles: Error:"
" Object already preemptively buried\n");
}
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)) {
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 (fscache_object_is_live(&object->fscache)) {
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 (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) {
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,
bool preemptive)
{
struct dentry *grave, *trap;
struct path path, path_to_graveyard;
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);
_debug("remove %p from %p", rep, dir);
/* non-directories can just be unlinked */
if (!S_ISDIR(rep->d_inode->i_mode)) {
_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(dir->d_inode, rep, NULL);
if (preemptive)
cachefiles_mark_object_buried(cache, 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 */
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);
if (ret < 0) {
cachefiles_io_error(cache, "Rename security error %d", ret);
} else {
ret = vfs_rename(dir->d_inode, rep,
cache->graveyard->d_inode, grave, NULL);
if (ret != 0 && ret != -ENOMEM)
cachefiles_io_error(cache,
"Rename failed with error %d", ret);
if (preemptive)
cachefiles_mark_object_buried(cache, rep);
}
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(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);
if (test_bit(CACHEFILES_OBJECT_BURIED, &object->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");
mutex_unlock(&dir->d_inode->i_mutex);
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);
} else {
/* it got moved, presumably by cachefilesd culling it,
* so it's no longer in the key path and we can ignore
* it */
mutex_unlock(&dir->d_inode->i_mutex);
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(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;
path.dentry = dir;
ret = security_path_mkdir(&path, next, 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;
path.dentry = dir;
ret = security_path_mknod(&path, next, S_IFREG, 0);
if (ret < 0)
goto create_error;
start = jiffies;
ret = vfs_create(dir->d_inode, next, S_IFREG, true);
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, true);
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) */
path.dentry = next;
touch_atime(&path);
}
/* 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;
struct path path;
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");
path.mnt = cache->mnt;
path.dentry = dir;
ret = security_path_mkdir(&path, subdir, 0700);
if (ret < 0)
goto mkdir_error;
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, 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, 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, false);
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;
}