diff options
Diffstat (limited to 'fs/cachefiles/namei.c')
| -rw-r--r-- | fs/cachefiles/namei.c | 771 |
1 files changed, 771 insertions, 0 deletions
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c new file mode 100644 index 000000000000..4ce818ae39ea --- /dev/null +++ b/fs/cachefiles/namei.c @@ -0,0 +1,771 @@ +/* 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" + +static int cachefiles_wait_bit(void *flags) +{ + schedule(); + return 0; +} + +/* + * record the fact that an object is now active + */ +static void 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)) + 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(""); + return; + + /* 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"); + printk(KERN_ERR "xobject: OBJ%x\n", + xobject->fscache.debug_id); + printk(KERN_ERR "xobjstate=%s\n", + fscache_object_states[xobject->fscache.state]); + printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags); + printk(KERN_ERR "xobjevent=%lx [%lx]\n", + xobject->fscache.events, xobject->fscache.event_mask); + printk(KERN_ERR "xops=%u inp=%u exc=%u\n", + xobject->fscache.n_ops, xobject->fscache.n_in_progress, + xobject->fscache.n_exclusive); + printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n", + xobject->fscache.cookie, + xobject->fscache.cookie->parent, + xobject->fscache.cookie->netfs_data, + xobject->fscache.cookie->flags); + printk(KERN_ERR "xparent=%p\n", + xobject->fscache.parent); + printk(KERN_ERR "object: OBJ%x\n", + object->fscache.debug_id); + printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n", + object->fscache.cookie, + object->fscache.cookie->parent, + object->fscache.cookie->netfs_data, + object->fscache.cookie->flags); + printk(KERN_ERR "parent=%p\n", + object->fscache.parent); + BUG(); + } + atomic_inc(&xobject->usage); + write_unlock(&cache->active_lock); + + _debug(">>> wait"); + wait_on_bit(&xobject->flags, CACHEFILES_OBJECT_ACTIVE, + cachefiles_wait_bit, TASK_UNINTERRUPTIBLE); + _debug("<<< waited"); + + cache->cache.ops->put_object(&xobject->fscache); + goto try_again; +} + +/* + * 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(&dir->d_inode->i_mutex); + 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(&dir->d_inode->i_mutex); + + 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 */ + cachefiles_mark_object_active(cache, object); + + mutex_unlock(&dir->d_inode->i_mutex); + dput(dir); + dir = NULL; + + _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; + +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); + + 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: + if (ret == -ENOSPC) + ret = -ENOBUFS; + + _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; +} |
