[lttng-tools.git] / src / common / fd-tracker / inode.cpp

/*
 * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#include "inode.hpp"

#include <common/defaults.hpp>
#include <common/error.hpp>
#include <common/hashtable/utils.hpp>
#include <common/macros.hpp>
#include <common/optional.hpp>
#include <common/string-utils/format.hpp>
#include <common/utils.hpp>

#include <lttng/constant.h>

#include <inttypes.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <urcu.h>
#include <urcu/rculfhash.h>
#include <urcu/ref.h>

namespace {
struct inode_id {
	dev_t device;
	ino_t inode;
};
} /* namespace */

struct lttng_inode_registry {
	/* Hashtable of inode_id to lttng_inode. */
	struct cds_lfht *inodes;
};

struct lttng_inode {
	struct inode_id id;
	/* Node in the lttng_inode_registry's ht. */
	struct cds_lfht_node registry_node;
	/* Weak reference to ht containing the node. */
	struct cds_lfht *registry_ht;
	struct urcu_ref ref;
	struct rcu_head rcu_head;
	/* Location from which this file can be opened. */
	struct {
		struct lttng_directory_handle *directory_handle;
		char *path;
	} location;
	/* Unlink the underlying file at the release of the inode. */
	bool unlink_pending;
	LTTNG_OPTIONAL(unsigned int) unlinked_id;
	/* Weak reference. */
	struct lttng_unlinked_file_pool *unlinked_file_pool;
};

struct lttng_unlinked_file_pool {
	struct lttng_directory_handle *unlink_directory_handle;
	char *unlink_directory_path;
	unsigned int file_count;
	unsigned int next_id;
};

namespace {
struct {
	pthread_mutex_t lock;
	bool initialized;
	unsigned long value;
} seed = {
	.lock = PTHREAD_MUTEX_INITIALIZER,
	.initialized = false,
	.value = 0,
};
} /* namespace */

static unsigned long lttng_inode_id_hash(const struct inode_id *id)
{
	uint64_t device = id->device, inode_no = id->inode;

	return hash_key_u64(&device, seed.value) ^ hash_key_u64(&inode_no, seed.value);
}

static int lttng_inode_match(struct cds_lfht_node *node, const void *key)
{
	const struct inode_id *id = (inode_id *) key;
	const struct lttng_inode *inode =
		lttng::utils::container_of(node, &lttng_inode::registry_node);

	return inode->id.device == id->device && inode->id.inode == id->inode;
}

static void lttng_inode_free(struct rcu_head *head)
{
	struct lttng_inode *inode = lttng::utils::container_of(head, &lttng_inode::rcu_head);

	free(inode);
}

static int lttng_unlinked_file_pool_add_inode(struct lttng_unlinked_file_pool *pool,
					      struct lttng_inode *inode)
{
	int ret;
	const unsigned int unlinked_id = pool->next_id++;
	char *inode_unlinked_name;
	bool reference_acquired;

	DBG("Adding inode of %s to unlinked file pool as id %u", inode->location.path, unlinked_id);
	ret = asprintf(&inode_unlinked_name, "%u", unlinked_id);
	if (ret < 0) {
		ERR("Failed to format unlinked inode name");
		ret = -1;
		goto end;
	}

	if (pool->file_count == 0) {
		DBG("Creating unlinked files directory at %s", pool->unlink_directory_path);
		LTTNG_ASSERT(!pool->unlink_directory_handle);
		ret = utils_mkdir(pool->unlink_directory_path, S_IRWXU | S_IRWXG, -1, -1);
		if (ret) {
			if (errno == EEXIST) {
				/*
				 * Unexpected (previous crash?), but not an
				 * error.
				 */
				DBG("Unlinked file directory \"%s\" already exists",
				    pool->unlink_directory_path);
			} else {
				PERROR("Failed to create unlinked files directory at %s",
				       pool->unlink_directory_path);
				goto end;
			}
		}
		pool->unlink_directory_handle =
			lttng_directory_handle_create(pool->unlink_directory_path);
		if (!pool->unlink_directory_handle) {
			ERR("Failed to create directory handle to unlinked file pool at %s",
			    pool->unlink_directory_path);
			ret = -1;
			goto end;
		}
	}

	ret = lttng_directory_handle_rename(inode->location.directory_handle,
					    inode->location.path,
					    pool->unlink_directory_handle,
					    inode_unlinked_name);
	if (ret) {
		goto end;
	}

	lttng_directory_handle_put(inode->location.directory_handle);
	inode->location.directory_handle = nullptr;
	reference_acquired = lttng_directory_handle_get(pool->unlink_directory_handle);
	LTTNG_ASSERT(reference_acquired);
	inode->location.directory_handle = pool->unlink_directory_handle;

	free(inode->location.path);
	inode->location.path = inode_unlinked_name;
	inode_unlinked_name = nullptr;
	LTTNG_OPTIONAL_SET(&inode->unlinked_id, unlinked_id);
	pool->file_count++;
end:
	free(inode_unlinked_name);
	return ret;
}

static int lttng_unlinked_file_pool_remove_inode(struct lttng_unlinked_file_pool *pool,
						 struct lttng_inode *inode)
{
	int ret;

	DBG("Removing inode with unlinked id %u from unlinked file pool",
	    LTTNG_OPTIONAL_GET(inode->unlinked_id));

	ret = lttng_directory_handle_unlink_file(inode->location.directory_handle,
						 inode->location.path);
	if (ret) {
		PERROR("Failed to unlink file %s from unlinked file directory",
		       inode->location.path);
		goto end;
	}
	free(inode->location.path);
	inode->location.path = nullptr;
	lttng_directory_handle_put(inode->location.directory_handle);
	inode->location.directory_handle = nullptr;

	pool->file_count--;
	if (pool->file_count == 0) {
		ret = utils_recursive_rmdir(pool->unlink_directory_path);
		if (ret) {
			/*
			 * There is nothing the caller can do, don't report an
			 * error except through logging.
			 */
			PERROR("Failed to remove unlinked files directory at %s",
			       pool->unlink_directory_path);
		}
		lttng_directory_handle_put(pool->unlink_directory_handle);
		pool->unlink_directory_handle = nullptr;
	}
end:
	return ret;
}

static void lttng_inode_destroy(struct lttng_inode *inode)
{
	if (!inode) {
		return;
	}

	rcu_read_lock();
	cds_lfht_del(inode->registry_ht, &inode->registry_node);
	rcu_read_unlock();

	if (inode->unlink_pending) {
		int ret;

		LTTNG_ASSERT(inode->location.directory_handle);
		LTTNG_ASSERT(inode->location.path);
		DBG("Removing %s from unlinked file pool", inode->location.path);
		ret = lttng_unlinked_file_pool_remove_inode(inode->unlinked_file_pool, inode);
		if (ret) {
			PERROR("Failed to unlink %s", inode->location.path);
		}
	}

	lttng_directory_handle_put(inode->location.directory_handle);
	inode->location.directory_handle = nullptr;
	free(inode->location.path);
	inode->location.path = nullptr;
	call_rcu(&inode->rcu_head, lttng_inode_free);
}

static void lttng_inode_release(struct urcu_ref *ref)
{
	lttng_inode_destroy(lttng::utils::container_of(ref, &lttng_inode::ref));
}

static void lttng_inode_get(struct lttng_inode *inode)
{
	urcu_ref_get(&inode->ref);
}

struct lttng_unlinked_file_pool *lttng_unlinked_file_pool_create(const char *path)
{
	struct lttng_unlinked_file_pool *pool = zmalloc<lttng_unlinked_file_pool>();

	if (!pool) {
		goto error;
	}

	if (!path || *path != '/') {
		ERR("Unlinked file pool must be created with an absolute path, path = \"%s\"",
		    path ? path : "NULL");
		goto error;
	}

	pool->unlink_directory_path = strdup(path);
	if (!pool->unlink_directory_path) {
		PERROR("Failed to allocation unlinked file pool path");
		goto error;
	}
	DBG("Unlinked file pool created at: %s", path);
	return pool;
error:
	lttng_unlinked_file_pool_destroy(pool);
	return nullptr;
}

void lttng_unlinked_file_pool_destroy(struct lttng_unlinked_file_pool *pool)
{
	if (!pool) {
		return;
	}

	LTTNG_ASSERT(pool->file_count == 0);
	lttng_directory_handle_put(pool->unlink_directory_handle);
	free(pool->unlink_directory_path);
	free(pool);
}

void lttng_inode_put(struct lttng_inode *inode)
{
	urcu_ref_put(&inode->ref, lttng_inode_release);
}

struct lttng_directory_handle *lttng_inode_get_location_directory_handle(struct lttng_inode *inode)
{
	if (inode->location.directory_handle) {
		const bool reference_acquired =
			lttng_directory_handle_get(inode->location.directory_handle);

		LTTNG_ASSERT(reference_acquired);
	}
	return inode->location.directory_handle;
}

void lttng_inode_borrow_location(struct lttng_inode *inode,
				 const struct lttng_directory_handle **out_directory_handle,
				 const char **out_path)
{
	if (out_directory_handle) {
		*out_directory_handle = inode->location.directory_handle;
	}
	if (out_path) {
		*out_path = inode->location.path;
	}
}

int lttng_inode_rename(struct lttng_inode *inode,
		       struct lttng_directory_handle *old_directory_handle,
		       const char *old_path,
		       struct lttng_directory_handle *new_directory_handle,
		       const char *new_path,
		       bool overwrite)
{
	int ret = 0;
	char *new_path_copy = strdup(new_path);
	bool reference_acquired;

	DBG("Performing rename of inode from %s to %s with %s directory handles",
	    old_path,
	    new_path,
	    lttng_directory_handle_equals(old_directory_handle, new_directory_handle) ?
		    "identical" :
		    "different");

	if (!new_path_copy) {
		ret = -ENOMEM;
		goto end;
	}

	if (inode->unlink_pending) {
		WARN("An attempt to rename an unlinked file from %s to %s has been performed",
		     old_path,
		     new_path);
		ret = -ENOENT;
		goto end;
	}

	if (!overwrite) {
		/* Verify that file doesn't exist. */
		struct stat statbuf;

		ret = lttng_directory_handle_stat(new_directory_handle, new_path, &statbuf);
		if (ret == 0) {
			ERR("Refusing to rename %s as the destination already exists", old_path);
			ret = -EEXIST;
			goto end;
		} else if (ret < 0 && errno != ENOENT) {
			PERROR("Failed to stat() %s", new_path);
			ret = -errno;
			goto end;
		}
	}

	ret = lttng_directory_handle_rename(
		old_directory_handle, old_path, new_directory_handle, new_path);
	if (ret) {
		PERROR("Failed to rename file %s to %s", old_path, new_path);
		ret = -errno;
		goto end;
	}

	reference_acquired = lttng_directory_handle_get(new_directory_handle);
	LTTNG_ASSERT(reference_acquired);
	lttng_directory_handle_put(inode->location.directory_handle);
	free(inode->location.path);
	inode->location.directory_handle = new_directory_handle;
	/* Ownership transferred. */
	inode->location.path = new_path_copy;
	new_path_copy = nullptr;
end:
	free(new_path_copy);
	return ret;
}

int lttng_inode_unlink(struct lttng_inode *inode)
{
	int ret = 0;

	DBG("Attempting unlink of inode %s", inode->location.path);

	if (inode->unlink_pending) {
		WARN("An attempt to re-unlink %s has been performed, ignoring.",
		     inode->location.path);
		ret = -ENOENT;
		goto end;
	}

	/*
	 * Move to the temporary "deleted" directory until all
	 * references are released.
	 */
	ret = lttng_unlinked_file_pool_add_inode(inode->unlinked_file_pool, inode);
	if (ret) {
		PERROR("Failed to add inode \"%s\" to the unlinked file pool",
		       inode->location.path);
		goto end;
	}
	inode->unlink_pending = true;
end:
	return ret;
}

static struct lttng_inode *lttng_inode_create(const struct inode_id *id,
					      struct cds_lfht *ht,
					      struct lttng_unlinked_file_pool *unlinked_file_pool,
					      struct lttng_directory_handle *directory_handle,
					      const char *path)
{
	struct lttng_inode *inode = nullptr;
	char *path_copy;
	bool reference_acquired;

	path_copy = strdup(path);
	if (!path_copy) {
		goto end;
	}

	reference_acquired = lttng_directory_handle_get(directory_handle);
	LTTNG_ASSERT(reference_acquired);

	inode = zmalloc<lttng_inode>();
	if (!inode) {
		goto end;
	}

	urcu_ref_init(&inode->ref);
	cds_lfht_node_init(&inode->registry_node);
	inode->id = *id;
	inode->registry_ht = ht;
	inode->unlinked_file_pool = unlinked_file_pool;
	/* Ownership of path copy is transferred to inode. */
	inode->location.path = path_copy;
	path_copy = nullptr;
	inode->location.directory_handle = directory_handle;
end:
	free(path_copy);
	return inode;
}

struct lttng_inode_registry *lttng_inode_registry_create()
{
	struct lttng_inode_registry *registry = zmalloc<lttng_inode_registry>();

	if (!registry) {
		goto end;
	}

	pthread_mutex_lock(&seed.lock);
	if (!seed.initialized) {
		seed.value = (unsigned long) time(nullptr);
		seed.initialized = true;
	}
	pthread_mutex_unlock(&seed.lock);

	registry->inodes = cds_lfht_new(
		DEFAULT_HT_SIZE, 1, 0, CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, nullptr);
	if (!registry->inodes) {
		goto error;
	}
end:
	return registry;
error:
	lttng_inode_registry_destroy(registry);
	return nullptr;
}

void lttng_inode_registry_destroy(struct lttng_inode_registry *registry)
{
	if (!registry) {
		return;
	}
	if (registry->inodes) {
		int ret = cds_lfht_destroy(registry->inodes, nullptr);

		LTTNG_ASSERT(!ret);
	}
	free(registry);
}

struct lttng_inode *
lttng_inode_registry_get_inode(struct lttng_inode_registry *registry,
			       struct lttng_directory_handle *handle,
			       const char *path,
			       int fd,
			       struct lttng_unlinked_file_pool *unlinked_file_pool)
{
	int ret;
	struct stat statbuf;
	struct inode_id id;
	struct cds_lfht_iter iter;
	struct cds_lfht_node *node;
	struct lttng_inode *inode = nullptr;

	ret = fstat(fd, &statbuf);
	if (ret < 0) {
		PERROR("stat() failed on fd %i", fd);
		goto end;
	}

	id.device = statbuf.st_dev;
	id.inode = statbuf.st_ino;

	rcu_read_lock();
	cds_lfht_lookup(registry->inodes, lttng_inode_id_hash(&id), lttng_inode_match, &id, &iter);
	node = cds_lfht_iter_get_node(&iter);
	if (node) {
		inode = lttng::utils::container_of(node, &lttng_inode::registry_node);
		lttng_inode_get(inode);
		goto end_unlock;
	}

	inode = lttng_inode_create(&id, registry->inodes, unlinked_file_pool, handle, path);
	if (!inode) {
		goto end_unlock;
	}

	node = cds_lfht_add_unique(registry->inodes,
				   lttng_inode_id_hash(&inode->id),
				   lttng_inode_match,
				   &inode->id,
				   &inode->registry_node);
	LTTNG_ASSERT(node == &inode->registry_node);
end_unlock:
	rcu_read_unlock();
end:
	return inode;
}
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
	3	*
	4	* SPDX-License-Identifier: GPL-2.0-only
	5	*
	6	*/
	7
	8	#include "inode.hpp"
	9
	10	#include <common/defaults.hpp>
	11	#include <common/error.hpp>
	12	#include <common/hashtable/utils.hpp>
	13	#include <common/macros.hpp>
	14	#include <common/optional.hpp>
	15	#include <common/string-utils/format.hpp>
	16	#include <common/utils.hpp>
	17
	18	#include <lttng/constant.h>
	19
	20	#include <inttypes.h>
	21	#include <sys/stat.h>
	22	#include <sys/types.h>
	23	#include <unistd.h>
	24	#include <urcu.h>
	25	#include <urcu/rculfhash.h>
	26	#include <urcu/ref.h>
	27
	28	namespace {
	29	struct inode_id {
	30	dev_t device;
	31	ino_t inode;
	32	};
	33	} /* namespace */
	34
	35	struct lttng_inode_registry {
	36	/* Hashtable of inode_id to lttng_inode. */
	37	struct cds_lfht *inodes;
	38	};
	39
	40	struct lttng_inode {
	41	struct inode_id id;
	42	/* Node in the lttng_inode_registry's ht. */
	43	struct cds_lfht_node registry_node;
	44	/* Weak reference to ht containing the node. */
	45	struct cds_lfht *registry_ht;
	46	struct urcu_ref ref;
	47	struct rcu_head rcu_head;
	48	/* Location from which this file can be opened. */
	49	struct {
	50	struct lttng_directory_handle *directory_handle;
	51	char *path;
	52	} location;
	53	/* Unlink the underlying file at the release of the inode. */
	54	bool unlink_pending;
	55	LTTNG_OPTIONAL(unsigned int) unlinked_id;
	56	/* Weak reference. */
	57	struct lttng_unlinked_file_pool *unlinked_file_pool;
	58	};
	59
	60	struct lttng_unlinked_file_pool {
	61	struct lttng_directory_handle *unlink_directory_handle;
	62	char *unlink_directory_path;
	63	unsigned int file_count;
	64	unsigned int next_id;
	65	};
	66
	67	namespace {
	68	struct {
	69	pthread_mutex_t lock;
	70	bool initialized;
	71	unsigned long value;
	72	} seed = {
	73	.lock = PTHREAD_MUTEX_INITIALIZER,
	74	.initialized = false,
	75	.value = 0,
	76	};
	77	} /* namespace */
	78
	79	static unsigned long lttng_inode_id_hash(const struct inode_id *id)
	80	{
	81	uint64_t device = id->device, inode_no = id->inode;
	82
	83	return hash_key_u64(&device, seed.value) ^ hash_key_u64(&inode_no, seed.value);
	84	}
	85
	86	static int lttng_inode_match(struct cds_lfht_node node, const void key)
	87	{
	88	const struct inode_id id = (inode_id ) key;
	89	const struct lttng_inode *inode =
	90	lttng::utils::container_of(node, &lttng_inode::registry_node);
	91
	92	return inode->id.device == id->device && inode->id.inode == id->inode;
	93	}
	94
	95	static void lttng_inode_free(struct rcu_head *head)
	96	{
	97	struct lttng_inode *inode = lttng::utils::container_of(head, &lttng_inode::rcu_head);
	98
	99	free(inode);
	100	}
	101
	102	static int lttng_unlinked_file_pool_add_inode(struct lttng_unlinked_file_pool *pool,
	103	struct lttng_inode *inode)
	104	{
	105	int ret;
	106	const unsigned int unlinked_id = pool->next_id++;
	107	char *inode_unlinked_name;
	108	bool reference_acquired;
	109
	110	DBG("Adding inode of %s to unlinked file pool as id %u", inode->location.path, unlinked_id);
	111	ret = asprintf(&inode_unlinked_name, "%u", unlinked_id);
	112	if (ret < 0) {
	113	ERR("Failed to format unlinked inode name");
	114	ret = -1;
	115	goto end;
	116	}
	117
	118	if (pool->file_count == 0) {
	119	DBG("Creating unlinked files directory at %s", pool->unlink_directory_path);
	120	LTTNG_ASSERT(!pool->unlink_directory_handle);
	121	ret = utils_mkdir(pool->unlink_directory_path, S_IRWXU \| S_IRWXG, -1, -1);
	122	if (ret) {
	123	if (errno == EEXIST) {
	124	/*
	125	* Unexpected (previous crash?), but not an
	126	* error.
	127	*/
	128	DBG("Unlinked file directory \"%s\" already exists",
	129	pool->unlink_directory_path);
	130	} else {
	131	PERROR("Failed to create unlinked files directory at %s",
	132	pool->unlink_directory_path);
	133	goto end;
	134	}
	135	}
	136	pool->unlink_directory_handle =
	137	lttng_directory_handle_create(pool->unlink_directory_path);
	138	if (!pool->unlink_directory_handle) {
	139	ERR("Failed to create directory handle to unlinked file pool at %s",
	140	pool->unlink_directory_path);
	141	ret = -1;
	142	goto end;
	143	}
	144	}
	145
	146	ret = lttng_directory_handle_rename(inode->location.directory_handle,
	147	inode->location.path,
	148	pool->unlink_directory_handle,
	149	inode_unlinked_name);
	150	if (ret) {
	151	goto end;
	152	}
	153
	154	lttng_directory_handle_put(inode->location.directory_handle);
	155	inode->location.directory_handle = nullptr;
	156	reference_acquired = lttng_directory_handle_get(pool->unlink_directory_handle);
	157	LTTNG_ASSERT(reference_acquired);
	158	inode->location.directory_handle = pool->unlink_directory_handle;
	159
	160	free(inode->location.path);
	161	inode->location.path = inode_unlinked_name;
	162	inode_unlinked_name = nullptr;
	163	LTTNG_OPTIONAL_SET(&inode->unlinked_id, unlinked_id);
	164	pool->file_count++;
	165	end:
	166	free(inode_unlinked_name);
	167	return ret;
	168	}
	169
	170	static int lttng_unlinked_file_pool_remove_inode(struct lttng_unlinked_file_pool *pool,
	171	struct lttng_inode *inode)
	172	{
	173	int ret;
	174
	175	DBG("Removing inode with unlinked id %u from unlinked file pool",
	176	LTTNG_OPTIONAL_GET(inode->unlinked_id));
	177
	178	ret = lttng_directory_handle_unlink_file(inode->location.directory_handle,
	179	inode->location.path);
	180	if (ret) {
	181	PERROR("Failed to unlink file %s from unlinked file directory",
	182	inode->location.path);
	183	goto end;
	184	}
	185	free(inode->location.path);
	186	inode->location.path = nullptr;
	187	lttng_directory_handle_put(inode->location.directory_handle);
	188	inode->location.directory_handle = nullptr;
	189
	190	pool->file_count--;
	191	if (pool->file_count == 0) {
	192	ret = utils_recursive_rmdir(pool->unlink_directory_path);
	193	if (ret) {
	194	/*
	195	* There is nothing the caller can do, don't report an
	196	* error except through logging.
	197	*/
	198	PERROR("Failed to remove unlinked files directory at %s",
	199	pool->unlink_directory_path);
	200	}
	201	lttng_directory_handle_put(pool->unlink_directory_handle);
	202	pool->unlink_directory_handle = nullptr;
	203	}
	204	end:
	205	return ret;
	206	}
	207
	208	static void lttng_inode_destroy(struct lttng_inode *inode)
	209	{
	210	if (!inode) {
	211	return;
	212	}
	213
	214	rcu_read_lock();
	215	cds_lfht_del(inode->registry_ht, &inode->registry_node);
	216	rcu_read_unlock();
	217
	218	if (inode->unlink_pending) {
	219	int ret;
	220
	221	LTTNG_ASSERT(inode->location.directory_handle);
	222	LTTNG_ASSERT(inode->location.path);
	223	DBG("Removing %s from unlinked file pool", inode->location.path);
	224	ret = lttng_unlinked_file_pool_remove_inode(inode->unlinked_file_pool, inode);
	225	if (ret) {
	226	PERROR("Failed to unlink %s", inode->location.path);
	227	}
	228	}
	229
	230	lttng_directory_handle_put(inode->location.directory_handle);
	231	inode->location.directory_handle = nullptr;
	232	free(inode->location.path);
	233	inode->location.path = nullptr;
	234	call_rcu(&inode->rcu_head, lttng_inode_free);
	235	}
	236
	237	static void lttng_inode_release(struct urcu_ref *ref)
	238	{
	239	lttng_inode_destroy(lttng::utils::container_of(ref, &lttng_inode::ref));
	240	}
	241
	242	static void lttng_inode_get(struct lttng_inode *inode)
	243	{
	244	urcu_ref_get(&inode->ref);
	245	}
	246
	247	struct lttng_unlinked_file_pool lttng_unlinked_file_pool_create(const char path)
	248	{
	249	struct lttng_unlinked_file_pool *pool = zmalloc<lttng_unlinked_file_pool>();
	250
	251	if (!pool) {
	252	goto error;
	253	}
	254
	255	if (!path \|\| *path != '/') {
	256	ERR("Unlinked file pool must be created with an absolute path, path = \"%s\"",
	257	path ? path : "NULL");
	258	goto error;
	259	}
	260
	261	pool->unlink_directory_path = strdup(path);
	262	if (!pool->unlink_directory_path) {
	263	PERROR("Failed to allocation unlinked file pool path");
	264	goto error;
	265	}
	266	DBG("Unlinked file pool created at: %s", path);
	267	return pool;
	268	error:
	269	lttng_unlinked_file_pool_destroy(pool);
	270	return nullptr;
	271	}
	272
	273	void lttng_unlinked_file_pool_destroy(struct lttng_unlinked_file_pool *pool)
	274	{
	275	if (!pool) {
	276	return;
	277	}
	278
	279	LTTNG_ASSERT(pool->file_count == 0);
	280	lttng_directory_handle_put(pool->unlink_directory_handle);
	281	free(pool->unlink_directory_path);
	282	free(pool);
	283	}
	284
	285	void lttng_inode_put(struct lttng_inode *inode)
	286	{
	287	urcu_ref_put(&inode->ref, lttng_inode_release);
	288	}
	289
	290	struct lttng_directory_handle lttng_inode_get_location_directory_handle(struct lttng_inode inode)
	291	{
	292	if (inode->location.directory_handle) {
	293	const bool reference_acquired =
	294	lttng_directory_handle_get(inode->location.directory_handle);
	295
	296	LTTNG_ASSERT(reference_acquired);
	297	}
	298	return inode->location.directory_handle;
	299	}
	300
	301	void lttng_inode_borrow_location(struct lttng_inode *inode,
	302	const struct lttng_directory_handle **out_directory_handle,
	303	const char **out_path)
	304	{
	305	if (out_directory_handle) {
	306	*out_directory_handle = inode->location.directory_handle;
	307	}
	308	if (out_path) {
	309	*out_path = inode->location.path;
	310	}
	311	}
	312
	313	int lttng_inode_rename(struct lttng_inode *inode,
	314	struct lttng_directory_handle *old_directory_handle,
	315	const char *old_path,
	316	struct lttng_directory_handle *new_directory_handle,
	317	const char *new_path,
	318	bool overwrite)
	319	{
	320	int ret = 0;
	321	char *new_path_copy = strdup(new_path);
	322	bool reference_acquired;
	323
	324	DBG("Performing rename of inode from %s to %s with %s directory handles",
	325	old_path,
	326	new_path,
	327	lttng_directory_handle_equals(old_directory_handle, new_directory_handle) ?
	328	"identical" :
	329	"different");
	330
	331	if (!new_path_copy) {
	332	ret = -ENOMEM;
	333	goto end;
	334	}
	335
	336	if (inode->unlink_pending) {
	337	WARN("An attempt to rename an unlinked file from %s to %s has been performed",
	338	old_path,
	339	new_path);
	340	ret = -ENOENT;
	341	goto end;
	342	}
	343
	344	if (!overwrite) {
	345	/* Verify that file doesn't exist. */
	346	struct stat statbuf;
	347
	348	ret = lttng_directory_handle_stat(new_directory_handle, new_path, &statbuf);
	349	if (ret == 0) {
	350	ERR("Refusing to rename %s as the destination already exists", old_path);
	351	ret = -EEXIST;
	352	goto end;
	353	} else if (ret < 0 && errno != ENOENT) {
	354	PERROR("Failed to stat() %s", new_path);
	355	ret = -errno;
	356	goto end;
	357	}
	358	}
	359
	360	ret = lttng_directory_handle_rename(
	361	old_directory_handle, old_path, new_directory_handle, new_path);
	362	if (ret) {
	363	PERROR("Failed to rename file %s to %s", old_path, new_path);
	364	ret = -errno;
	365	goto end;
	366	}
	367
	368	reference_acquired = lttng_directory_handle_get(new_directory_handle);
	369	LTTNG_ASSERT(reference_acquired);
	370	lttng_directory_handle_put(inode->location.directory_handle);
	371	free(inode->location.path);
	372	inode->location.directory_handle = new_directory_handle;
	373	/* Ownership transferred. */
	374	inode->location.path = new_path_copy;
	375	new_path_copy = nullptr;
	376	end:
	377	free(new_path_copy);
	378	return ret;
	379	}
	380
	381	int lttng_inode_unlink(struct lttng_inode *inode)
	382	{
	383	int ret = 0;
	384
	385	DBG("Attempting unlink of inode %s", inode->location.path);
	386
	387	if (inode->unlink_pending) {
	388	WARN("An attempt to re-unlink %s has been performed, ignoring.",
	389	inode->location.path);
	390	ret = -ENOENT;
	391	goto end;
	392	}
	393
	394	/*
	395	* Move to the temporary "deleted" directory until all
	396	* references are released.
	397	*/
	398	ret = lttng_unlinked_file_pool_add_inode(inode->unlinked_file_pool, inode);
	399	if (ret) {
	400	PERROR("Failed to add inode \"%s\" to the unlinked file pool",
	401	inode->location.path);
	402	goto end;
	403	}
	404	inode->unlink_pending = true;
	405	end:
	406	return ret;
	407	}
	408
	409	static struct lttng_inode lttng_inode_create(const struct inode_id id,
	410	struct cds_lfht *ht,
	411	struct lttng_unlinked_file_pool *unlinked_file_pool,
	412	struct lttng_directory_handle *directory_handle,
	413	const char *path)
	414	{
	415	struct lttng_inode *inode = nullptr;
	416	char *path_copy;
	417	bool reference_acquired;
	418
	419	path_copy = strdup(path);
	420	if (!path_copy) {
	421	goto end;
	422	}
	423
	424	reference_acquired = lttng_directory_handle_get(directory_handle);
	425	LTTNG_ASSERT(reference_acquired);
	426
	427	inode = zmalloc<lttng_inode>();
	428	if (!inode) {
	429	goto end;
	430	}
	431
	432	urcu_ref_init(&inode->ref);
	433	cds_lfht_node_init(&inode->registry_node);
	434	inode->id = *id;
	435	inode->registry_ht = ht;
	436	inode->unlinked_file_pool = unlinked_file_pool;
	437	/* Ownership of path copy is transferred to inode. */
	438	inode->location.path = path_copy;
	439	path_copy = nullptr;
	440	inode->location.directory_handle = directory_handle;
	441	end:
	442	free(path_copy);
	443	return inode;
	444	}
	445
	446	struct lttng_inode_registry *lttng_inode_registry_create()
	447	{
	448	struct lttng_inode_registry *registry = zmalloc<lttng_inode_registry>();
	449
	450	if (!registry) {
	451	goto end;
	452	}
	453
	454	pthread_mutex_lock(&seed.lock);
	455	if (!seed.initialized) {
	456	seed.value = (unsigned long) time(nullptr);
	457	seed.initialized = true;
	458	}
	459	pthread_mutex_unlock(&seed.lock);
	460
	461	registry->inodes = cds_lfht_new(
	462	DEFAULT_HT_SIZE, 1, 0, CDS_LFHT_AUTO_RESIZE \| CDS_LFHT_ACCOUNTING, nullptr);
	463	if (!registry->inodes) {
	464	goto error;
	465	}
	466	end:
	467	return registry;
	468	error:
	469	lttng_inode_registry_destroy(registry);
	470	return nullptr;
	471	}
	472
	473	void lttng_inode_registry_destroy(struct lttng_inode_registry *registry)
	474	{
	475	if (!registry) {
	476	return;
	477	}
	478	if (registry->inodes) {
	479	int ret = cds_lfht_destroy(registry->inodes, nullptr);
	480
	481	LTTNG_ASSERT(!ret);
	482	}
	483	free(registry);
	484	}
	485
	486	struct lttng_inode *
	487	lttng_inode_registry_get_inode(struct lttng_inode_registry *registry,
	488	struct lttng_directory_handle *handle,
	489	const char *path,
	490	int fd,
	491	struct lttng_unlinked_file_pool *unlinked_file_pool)
	492	{
	493	int ret;
	494	struct stat statbuf;
	495	struct inode_id id;
	496	struct cds_lfht_iter iter;
	497	struct cds_lfht_node *node;
	498	struct lttng_inode *inode = nullptr;
	499
	500	ret = fstat(fd, &statbuf);
	501	if (ret < 0) {
	502	PERROR("stat() failed on fd %i", fd);
	503	goto end;
	504	}
	505
	506	id.device = statbuf.st_dev;
	507	id.inode = statbuf.st_ino;
	508
	509	rcu_read_lock();
	510	cds_lfht_lookup(registry->inodes, lttng_inode_id_hash(&id), lttng_inode_match, &id, &iter);
	511	node = cds_lfht_iter_get_node(&iter);
	512	if (node) {
	513	inode = lttng::utils::container_of(node, &lttng_inode::registry_node);
	514	lttng_inode_get(inode);
	515	goto end_unlock;
	516	}
	517
	518	inode = lttng_inode_create(&id, registry->inodes, unlinked_file_pool, handle, path);
	519	if (!inode) {
	520	goto end_unlock;
	521	}
	522
	523	node = cds_lfht_add_unique(registry->inodes,
	524	lttng_inode_id_hash(&inode->id),
	525	lttng_inode_match,
	526	&inode->id,
	527	&inode->registry_node);
	528	LTTNG_ASSERT(node == &inode->registry_node);
	529	end_unlock:
	530	rcu_read_unlock();
	531	end:
	532	return inode;
	533	}