diff options
Diffstat (limited to 'fs/cachefiles/namei.c')
| -rw-r--r-- | fs/cachefiles/namei.c | 1031 |
1 files changed, 1031 insertions, 0 deletions
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c new file mode 100644 index 000000000..5ab411d4b --- /dev/null +++ b/fs/cachefiles/namei.c @@ -0,0 +1,1031 @@ +/* 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 <linux/xattr.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) +{ + struct fscache_cookie *cookie; + const u8 *k; + unsigned 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); + pr_err("%skey=[%u] '", prefix, cookie->key_len); + k = (cookie->key_len <= sizeof(cookie->inline_key)) ? + cookie->inline_key : cookie->key; + for (loop = 0; loop < cookie->key_len; loop++) + pr_cont("%02x", k[loop]); + pr_cont("'\n"); + } else { + pr_err("%scookie=NULL\n", prefix); + } + spin_unlock(&object->fscache.lock); +} + +/* + * dump debugging info about a pair of objects + */ +static noinline void cachefiles_printk_object(struct cachefiles_object *object, + struct cachefiles_object *xobject) +{ + if (object) + __cachefiles_printk_object(object, ""); + if (xobject) + __cachefiles_printk_object(xobject, "x"); +} + +/* + * 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); + trace_cachefiles_mark_buried(NULL, dentry, why); + _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); + + trace_cachefiles_mark_buried(object, dentry, why); + + 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); + + dentry = object->dentry; + trace_cachefiles_mark_active(object, dentry); + + if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) { + pr_err("Error: Object already active\n"); + cachefiles_printk_object(object, NULL); + BUG(); + } + + _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: + trace_cachefiles_wait_active(object, dentry, xobject); + clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags); + + if (fscache_object_is_live(&xobject->fscache)) { + pr_err("\n"); + pr_err("Error: Unexpected object collision\n"); + cachefiles_printk_object(object, xobject); + } + 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_entry_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, + (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry); + goto try_again; + +requeue: + cache->cache.ops->put_object(&xobject->fscache, + (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo); + _leave(" = -ETIMEDOUT"); + return -ETIMEDOUT; +} + +/* + * Mark an object as being inactive. + */ +void cachefiles_mark_object_inactive(struct cachefiles_cache *cache, + struct cachefiles_object *object, + blkcnt_t i_blocks) +{ + struct dentry *dentry = object->dentry; + struct inode *inode = d_backing_inode(dentry); + + trace_cachefiles_mark_inactive(object, dentry, inode); + + 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(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 cachefiles_object *object, + 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 { + trace_cachefiles_unlink(object, rep, why); + 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 || IS_DEADDIR(d_inode(rep))) { + /* 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 { + trace_cachefiles_rename(object, rep, grave, why); + 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, object, 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 inode *inode; + 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)) { + trace_cachefiles_lookup(object, next, NULL); + goto lookup_error; + } + + inode = d_backing_inode(next); + trace_cachefiles_lookup(object, next, inode); + _debug("next -> %p %s", next, inode ? "positive" : "negative"); + + if (!key) + object->new = !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 (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 (!key) + trace_cachefiles_mkdir(object, next, ret); + if (ret < 0) + goto create_error; + + if (unlikely(d_unhashed(next))) { + dput(next); + inode_unlock(d_inode(dir)); + goto lookup_again; + } + 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); + trace_cachefiles_create(object, next, ret); + 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, object, 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, d_backing_inode(object->dentry)->i_blocks); +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)); + +retry: + 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; + + if (unlikely(d_unhashed(subdir))) { + dput(subdir); + goto retry; + } + 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_opflags & IOP_XATTR) || + !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->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, NULL, 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; +} |