+++ /dev/null
-/*
- * Copyright (C) 2018-2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *
- * SPDX-License-Identifier: GPL-2.0-only
- *
- */
-
-#include <urcu.h>
-#include <urcu/list.h>
-#include <urcu/rculfhash.h>
-
-#include <fcntl.h>
-#include <inttypes.h>
-#include <pthread.h>
-#include <stdbool.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-
-#include <common/defaults.h>
-#include <common/error.h>
-#include <common/fs-handle-internal.h>
-#include <common/hashtable/hashtable.h>
-#include <common/hashtable/utils.h>
-#include <common/macros.h>
-#include <common/optional.h>
-
-#include "fd-tracker.h"
-#include "inode.h"
-
-/* Tracker lock must be taken by the user. */
-#define TRACKED_COUNT(tracker) \
- (tracker->count.suspendable.active + \
- tracker->count.suspendable.suspended + \
- tracker->count.unsuspendable)
-
-/* Tracker lock must be taken by the user. */
-#define ACTIVE_COUNT(tracker) \
- (tracker->count.suspendable.active + tracker->count.unsuspendable)
-
-/* Tracker lock must be taken by the user. */
-#define SUSPENDED_COUNT(tracker) (tracker->count.suspendable.suspended)
-
-/* Tracker lock must be taken by the user. */
-#define SUSPENDABLE_COUNT(tracker) \
- (tracker->count.suspendable.active + \
- tracker->count.suspendable.suspended)
-
-/* Tracker lock must be taken by the user. */
-#define UNSUSPENDABLE_COUNT(tracker) (tracker->count.unsuspendable)
-
-struct fd_tracker {
- pthread_mutex_t lock;
- struct {
- struct {
- unsigned int active;
- unsigned int suspended;
- } suspendable;
- unsigned int unsuspendable;
- } count;
- unsigned int capacity;
- struct {
- uint64_t uses;
- uint64_t misses;
- /* Failures to suspend or restore fs handles. */
- uint64_t errors;
- } stats;
- /*
- * The head of the active_handles list is always the least recently
- * used active handle. When an handle is used, it is removed from the
- * list and added to the end. When a file has to be suspended, the
- * first element in the list is "popped", suspended, and added to the
- * list of suspended handles.
- */
- struct cds_list_head active_handles;
- struct cds_list_head suspended_handles;
- struct cds_lfht *unsuspendable_fds;
- struct lttng_inode_registry *inode_registry;
- /* Unlinked files are moved in this directory under a unique name. */
- struct lttng_directory_handle *unlink_directory_handle;
- struct lttng_unlinked_file_pool *unlinked_file_pool;
-};
-
-struct open_properties {
- int flags;
- LTTNG_OPTIONAL(mode_t) mode;
-};
-
-/*
- * A fs_handle_tracked is not ref-counted. Therefore, it is assumed that a
- * handle is never in-use while it is being reclaimed. It can be
- * shared by multiple threads, but external synchronization is required
- * to ensure it is not still being used when it is reclaimed (close method).
- * In this respect, it is not different from a regular file descriptor.
- *
- * The fs_handle lock always nests _within_ the tracker's lock.
- */
-struct fs_handle_tracked {
- struct fs_handle parent;
- pthread_mutex_t lock;
- /*
- * Weak reference to the tracker. All fs_handles are assumed to have
- * been closed at the moment of the destruction of the fd_tracker.
- */
- struct fd_tracker *tracker;
- struct open_properties properties;
- struct lttng_inode *inode;
- int fd;
- /* inode number of the file at the time of the handle's creation. */
- uint64_t ino;
- bool in_use;
- /* Offset to which the file should be restored. */
- off_t offset;
- struct cds_list_head handles_list_node;
-};
-
-struct unsuspendable_fd {
- /*
- * Accesses are only performed through the tracker, which is protected
- * by its own lock.
- */
- int fd;
- char *name;
- struct cds_lfht_node tracker_node;
- struct rcu_head rcu_head;
-};
-
-static struct {
- pthread_mutex_t lock;
- bool initialized;
- unsigned long value;
-} seed = {
- .lock = PTHREAD_MUTEX_INITIALIZER,
-};
-
-static int match_fd(struct cds_lfht_node *node, const void *key);
-static void unsuspendable_fd_destroy(struct unsuspendable_fd *entry);
-static struct unsuspendable_fd *unsuspendable_fd_create(
- const char *name, int fd);
-static int open_from_properties(const struct lttng_directory_handle *dir_handle,
- const char *path, struct open_properties *properties);
-
-static void fs_handle_tracked_log(struct fs_handle_tracked *handle);
-static int fs_handle_tracked_suspend(struct fs_handle_tracked *handle);
-static int fs_handle_tracked_restore(struct fs_handle_tracked *handle);
-static int fs_handle_tracked_get_fd(struct fs_handle *_handle);
-static void fs_handle_tracked_put_fd(struct fs_handle *_handle);
-static int fs_handle_tracked_unlink(struct fs_handle *_handle);
-static int fs_handle_tracked_close(struct fs_handle *_handle);
-
-static void fd_tracker_track(
- struct fd_tracker *tracker, struct fs_handle_tracked *handle);
-static void fd_tracker_untrack(
- struct fd_tracker *tracker, struct fs_handle_tracked *handle);
-static int fd_tracker_suspend_handles(
- struct fd_tracker *tracker, unsigned int count);
-static int fd_tracker_restore_handle(
- struct fd_tracker *tracker, struct fs_handle_tracked *handle);
-
-/* Match function of the tracker's unsuspendable_fds hash table. */
-static int match_fd(struct cds_lfht_node *node, const void *key)
-{
- struct unsuspendable_fd *entry = caa_container_of(
- node, struct unsuspendable_fd, tracker_node);
-
- return hash_match_key_ulong(
- (void *) (unsigned long) entry->fd, (void *) key);
-}
-
-static void delete_unsuspendable_fd(struct rcu_head *head)
-{
- struct unsuspendable_fd *fd = caa_container_of(
- head, struct unsuspendable_fd, rcu_head);
-
- free(fd->name);
- free(fd);
-}
-
-static void unsuspendable_fd_destroy(struct unsuspendable_fd *entry)
-{
- if (!entry) {
- return;
- }
- call_rcu(&entry->rcu_head, delete_unsuspendable_fd);
-}
-
-static struct unsuspendable_fd *unsuspendable_fd_create(
- const char *name, int fd)
-{
- struct unsuspendable_fd *entry = zmalloc(sizeof(*entry));
-
- if (!entry) {
- goto error;
- }
- if (name) {
- entry->name = strdup(name);
- if (!entry->name) {
- goto error;
- }
- }
- cds_lfht_node_init(&entry->tracker_node);
- entry->fd = fd;
- return entry;
-error:
- unsuspendable_fd_destroy(entry);
- return NULL;
-}
-
-static void fs_handle_tracked_log(struct fs_handle_tracked *handle)
-{
- const char *path;
-
- pthread_mutex_lock(&handle->lock);
- lttng_inode_borrow_location(handle->inode, NULL, &path);
-
- if (handle->fd >= 0) {
- DBG_NO_LOC(" %s [active, fd %d%s]", path, handle->fd,
- handle->in_use ? ", in use" : "");
- } else {
- DBG_NO_LOC(" %s [suspended]", path);
- }
- pthread_mutex_unlock(&handle->lock);
-}
-
-/* Tracker lock must be held by the caller. */
-static int fs_handle_tracked_suspend(struct fs_handle_tracked *handle)
-{
- int ret = 0;
- struct stat fs_stat;
- const char *path;
- const struct lttng_directory_handle *node_directory_handle;
-
- pthread_mutex_lock(&handle->lock);
- lttng_inode_borrow_location(
- handle->inode, &node_directory_handle, &path);
- LTTNG_ASSERT(handle->fd >= 0);
- if (handle->in_use) {
- /* This handle can't be suspended as it is currently in use. */
- ret = -EAGAIN;
- goto end;
- }
-
- ret = lttng_directory_handle_stat(
- node_directory_handle, path, &fs_stat);
- if (ret) {
- PERROR("Filesystem handle to %s cannot be suspended as stat() failed",
- path);
- ret = -errno;
- goto end;
- }
-
- if (fs_stat.st_ino != handle->ino) {
- /* Don't suspend as the handle would not be restorable. */
- WARN("Filesystem handle to %s cannot be suspended as its inode changed",
- path);
- ret = -ENOENT;
- goto end;
- }
-
- handle->offset = lseek(handle->fd, 0, SEEK_CUR);
- if (handle->offset == -1) {
- WARN("Filesystem handle to %s cannot be suspended as lseek() failed to sample its current position",
- path);
- ret = -errno;
- goto end;
- }
-
- ret = close(handle->fd);
- if (ret) {
- PERROR("Filesystem handle to %s cannot be suspended as close() failed",
- path);
- ret = -errno;
- goto end;
- }
- DBG("Suspended filesystem handle to %s (fd %i) at position %" PRId64,
- path, handle->fd, handle->offset);
- handle->fd = -1;
-end:
- if (ret) {
- handle->tracker->stats.errors++;
- }
- pthread_mutex_unlock(&handle->lock);
- return ret;
-}
-
-/* Caller must hold the tracker and handle's locks. */
-static int fs_handle_tracked_restore(struct fs_handle_tracked *handle)
-{
- int ret, fd = -1;
- const char *path;
- const struct lttng_directory_handle *node_directory_handle;
-
- lttng_inode_borrow_location(
- handle->inode, &node_directory_handle, &path);
-
- LTTNG_ASSERT(handle->fd == -1);
- LTTNG_ASSERT(path);
- ret = open_from_properties(
- node_directory_handle, path, &handle->properties);
- if (ret < 0) {
- PERROR("Failed to restore filesystem handle to %s, open() failed",
- path);
- ret = -errno;
- goto end;
- }
- fd = ret;
-
- ret = lseek(fd, handle->offset, SEEK_SET);
- if (ret < 0) {
- PERROR("Failed to restore filesystem handle to %s, lseek() failed",
- path);
- ret = -errno;
- goto end;
- }
- DBG("Restored filesystem handle to %s (fd %i) at position %" PRId64,
- path, fd, handle->offset);
- ret = 0;
- handle->fd = fd;
- fd = -1;
-end:
- if (fd >= 0) {
- (void) close(fd);
- }
- return ret;
-}
-
-static int open_from_properties(const struct lttng_directory_handle *dir_handle,
- const char *path, struct open_properties *properties)
-{
- int ret;
-
- /*
- * open() ignores the 'flags' parameter unless the O_CREAT or O_TMPFILE
- * flags are set. O_TMPFILE would not make sense in the context of a
- * suspendable fs_handle as it would not be restorable (see OPEN(2)),
- * thus it is ignored here.
- */
- if ((properties->flags & O_CREAT) && properties->mode.is_set) {
- ret = lttng_directory_handle_open_file(dir_handle, path,
- properties->flags, properties->mode.value);
- } else {
- ret = lttng_directory_handle_open_file(dir_handle, path,
- properties->flags, 0);
- }
- /*
- * Some flags should not be used beyond the initial open() of a
- * restorable file system handle. O_CREAT and O_TRUNC must
- * be cleared since it would be unexpected to re-use them
- * when the handle is retored:
- * - O_CREAT should not be needed as the file has been created
- * on the initial call to open(),
- * - O_TRUNC would destroy the file's contents by truncating it
- * to length 0.
- */
- properties->flags &= ~(O_CREAT | O_TRUNC);
- if (ret < 0) {
- ret = -errno;
- goto end;
- }
-end:
- return ret;
-}
-
-struct fd_tracker *fd_tracker_create(const char *unlinked_file_path,
- unsigned int capacity)
-{
- struct fd_tracker *tracker = zmalloc(sizeof(struct fd_tracker));
-
- if (!tracker) {
- goto end;
- }
-
- pthread_mutex_lock(&seed.lock);
- if (!seed.initialized) {
- seed.value = (unsigned long) time(NULL);
- seed.initialized = true;
- }
- pthread_mutex_unlock(&seed.lock);
-
- CDS_INIT_LIST_HEAD(&tracker->active_handles);
- CDS_INIT_LIST_HEAD(&tracker->suspended_handles);
- tracker->capacity = capacity;
- tracker->unsuspendable_fds = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0,
- CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL);
- if (!tracker->unsuspendable_fds) {
- ERR("Failed to create fd-tracker's unsuspendable_fds hash table");
- goto error;
- }
- tracker->inode_registry = lttng_inode_registry_create();
- if (!tracker->inode_registry) {
- ERR("Failed to create fd-tracker's inode registry");
- goto error;
- }
-
- tracker->unlinked_file_pool =
- lttng_unlinked_file_pool_create(unlinked_file_path);
- if (!tracker->unlinked_file_pool) {
- goto error;
- }
- DBG("File descriptor tracker created with a limit of %u simultaneously-opened FDs",
- capacity);
-end:
- return tracker;
-error:
- fd_tracker_destroy(tracker);
- return NULL;
-}
-
-void fd_tracker_log(struct fd_tracker *tracker)
-{
- struct fs_handle_tracked *handle;
- struct unsuspendable_fd *unsuspendable_fd;
- struct cds_lfht_iter iter;
-
- pthread_mutex_lock(&tracker->lock);
- DBG_NO_LOC("File descriptor tracker");
- DBG_NO_LOC(" Stats:");
- DBG_NO_LOC(" uses: %" PRIu64, tracker->stats.uses);
- DBG_NO_LOC(" misses: %" PRIu64, tracker->stats.misses);
- DBG_NO_LOC(" errors: %" PRIu64, tracker->stats.errors);
- DBG_NO_LOC(" Tracked: %u", TRACKED_COUNT(tracker));
- DBG_NO_LOC(" active: %u", ACTIVE_COUNT(tracker));
- DBG_NO_LOC(" suspendable: %u", SUSPENDABLE_COUNT(tracker));
- DBG_NO_LOC(" unsuspendable: %u", UNSUSPENDABLE_COUNT(tracker));
- DBG_NO_LOC(" suspended: %u", SUSPENDED_COUNT(tracker));
- DBG_NO_LOC(" capacity: %u", tracker->capacity);
-
- DBG_NO_LOC(" Tracked suspendable file descriptors");
- cds_list_for_each_entry(
- handle, &tracker->active_handles, handles_list_node) {
- fs_handle_tracked_log(handle);
- }
- cds_list_for_each_entry(handle, &tracker->suspended_handles,
- handles_list_node) {
- fs_handle_tracked_log(handle);
- }
- if (!SUSPENDABLE_COUNT(tracker)) {
- DBG_NO_LOC(" None");
- }
-
- DBG_NO_LOC(" Tracked unsuspendable file descriptors");
- rcu_read_lock();
- cds_lfht_for_each_entry(tracker->unsuspendable_fds, &iter,
- unsuspendable_fd, tracker_node) {
- DBG_NO_LOC(" %s [active, fd %d]",
- unsuspendable_fd->name ?: "Unnamed",
- unsuspendable_fd->fd);
- }
- rcu_read_unlock();
- if (!UNSUSPENDABLE_COUNT(tracker)) {
- DBG_NO_LOC(" None");
- }
-
- pthread_mutex_unlock(&tracker->lock);
-}
-
-int fd_tracker_destroy(struct fd_tracker *tracker)
-{
- int ret = 0;
-
- if (!tracker) {
- goto end;
- }
- /*
- * Refuse to destroy the tracker as fs_handles may still old
- * weak references to the tracker.
- */
- pthread_mutex_lock(&tracker->lock);
- if (TRACKED_COUNT(tracker)) {
- ERR("A file descriptor leak has been detected: %u tracked file descriptors are still being tracked",
- TRACKED_COUNT(tracker));
- pthread_mutex_unlock(&tracker->lock);
- fd_tracker_log(tracker);
- ret = -1;
- goto end;
- }
- pthread_mutex_unlock(&tracker->lock);
-
- if (tracker->unsuspendable_fds) {
- ret = cds_lfht_destroy(tracker->unsuspendable_fds, NULL);
- LTTNG_ASSERT(!ret);
- }
-
- lttng_inode_registry_destroy(tracker->inode_registry);
- lttng_unlinked_file_pool_destroy(tracker->unlinked_file_pool);
- pthread_mutex_destroy(&tracker->lock);
- free(tracker);
-end:
- return ret;
-}
-
-struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker,
- struct lttng_directory_handle *directory,
- const char *path,
- int flags,
- mode_t *mode)
-{
- int ret;
- struct fs_handle_tracked *handle = NULL;
- struct stat fd_stat;
- struct open_properties properties = {
- .flags = flags,
- .mode.is_set = !!mode,
- .mode.value = mode ? *mode : 0,
- };
-
- pthread_mutex_lock(&tracker->lock);
- if (ACTIVE_COUNT(tracker) == tracker->capacity) {
- if (tracker->count.suspendable.active > 0) {
- ret = fd_tracker_suspend_handles(tracker, 1);
- if (ret) {
- goto end;
- }
- } else {
- /*
- * There are not enough active suspendable file
- * descriptors to open a new fd and still accommodate
- * the tracker's capacity.
- */
- WARN("Cannot open file system handle, too many unsuspendable file descriptors are opened (%u)",
- tracker->count.unsuspendable);
- goto end;
- }
- }
-
- handle = zmalloc(sizeof(*handle));
- if (!handle) {
- goto end;
- }
- handle->parent = (typeof(handle->parent)) {
- .get_fd = fs_handle_tracked_get_fd,
- .put_fd = fs_handle_tracked_put_fd,
- .unlink = fs_handle_tracked_unlink,
- .close = fs_handle_tracked_close,
- };
-
- handle->tracker = tracker;
-
- ret = pthread_mutex_init(&handle->lock, NULL);
- if (ret) {
- PERROR("Failed to initialize handle mutex while creating fs handle");
- goto error_mutex_init;
- }
-
- handle->fd = open_from_properties(directory, path, &properties);
- if (handle->fd < 0) {
- PERROR("Failed to open fs handle to %s, open() returned", path);
- goto error;
- }
-
- handle->properties = properties;
-
- handle->inode = lttng_inode_registry_get_inode(tracker->inode_registry,
- directory, path, handle->fd,
- tracker->unlinked_file_pool);
- if (!handle->inode) {
- ERR("Failed to get lttng_inode corresponding to file %s", path);
- goto error;
- }
-
- if (fstat(handle->fd, &fd_stat)) {
- PERROR("Failed to retrieve file descriptor inode while creating fs handle, fstat() returned");
- goto error;
- }
- handle->ino = fd_stat.st_ino;
-
- fd_tracker_track(tracker, handle);
-end:
- pthread_mutex_unlock(&tracker->lock);
- return handle ? &handle->parent : NULL;
-error:
- if (handle->inode) {
- lttng_inode_put(handle->inode);
- }
- pthread_mutex_destroy(&handle->lock);
-error_mutex_init:
- free(handle);
- handle = NULL;
- goto end;
-}
-
-/* Caller must hold the tracker's lock. */
-static int fd_tracker_suspend_handles(
- struct fd_tracker *tracker, unsigned int count)
-{
- unsigned int left_to_close = count;
- unsigned int attempts_left = tracker->count.suspendable.active;
- struct fs_handle_tracked *handle, *tmp;
-
- cds_list_for_each_entry_safe(handle, tmp, &tracker->active_handles,
- handles_list_node) {
- int ret;
-
- fd_tracker_untrack(tracker, handle);
- ret = fs_handle_tracked_suspend(handle);
- fd_tracker_track(tracker, handle);
- if (!ret) {
- left_to_close--;
- }
- attempts_left--;
-
- if (left_to_close == 0 || attempts_left == 0) {
- break;
- }
- }
- return left_to_close ? -EMFILE : 0;
-}
-
-int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker,
- int *out_fds,
- const char **names,
- unsigned int fd_count,
- fd_open_cb open,
- void *user_data)
-{
- int ret, user_ret, i, fds_to_suspend;
- unsigned int active_fds;
- struct unsuspendable_fd **entries;
-
- entries = zmalloc(fd_count * sizeof(*entries));
- if (!entries) {
- ret = -1;
- goto end;
- }
-
- pthread_mutex_lock(&tracker->lock);
-
- active_fds = ACTIVE_COUNT(tracker);
- fds_to_suspend = (int) active_fds + (int) fd_count -
- (int) tracker->capacity;
- if (fds_to_suspend > 0) {
- if (fds_to_suspend <= tracker->count.suspendable.active) {
- ret = fd_tracker_suspend_handles(
- tracker, fds_to_suspend);
- if (ret) {
- goto end_unlock;
- }
- } else {
- /*
- * There are not enough active suspendable file
- * descriptors to open a new fd and still accommodates the
- * tracker's capacity.
- */
- WARN("Cannot open unsuspendable fd, too many unsuspendable file descriptors are opened (%u)",
- tracker->count.unsuspendable);
- ret = -EMFILE;
- goto end_unlock;
- }
- }
-
- user_ret = open(user_data, out_fds);
- if (user_ret) {
- ret = user_ret;
- goto end_unlock;
- }
-
- /*
- * Add the fds returned by the user's callback to the hashtable
- * of unsuspendable fds.
- */
- for (i = 0; i < fd_count; i++) {
- struct unsuspendable_fd *entry = unsuspendable_fd_create(
- names ? names[i] : NULL, out_fds[i]);
-
- if (!entry) {
- ret = -1;
- goto end_free_entries;
- }
- entries[i] = entry;
- }
-
- rcu_read_lock();
- for (i = 0; i < fd_count; i++) {
- struct cds_lfht_node *node;
- struct unsuspendable_fd *entry = entries[i];
-
- node = cds_lfht_add_unique(tracker->unsuspendable_fds,
- hash_key_ulong((void *) (unsigned long)
- out_fds[i],
- seed.value),
- match_fd, (void *) (unsigned long) out_fds[i],
- &entry->tracker_node);
-
- if (node != &entry->tracker_node) {
- ret = -EEXIST;
- rcu_read_unlock();
- goto end_free_entries;
- }
- entries[i] = NULL;
- }
- tracker->count.unsuspendable += fd_count;
- rcu_read_unlock();
- ret = user_ret;
-end_unlock:
- pthread_mutex_unlock(&tracker->lock);
-end:
- free(entries);
- return ret;
-end_free_entries:
- for (i = 0; i < fd_count; i++) {
- unsuspendable_fd_destroy(entries[i]);
- }
- goto end_unlock;
-}
-
-int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker,
- int *fds_in,
- unsigned int fd_count,
- fd_close_cb close,
- void *user_data)
-{
- int i, ret, user_ret;
- int *fds = NULL;
-
- /*
- * Maintain a local copy of fds_in as the user's callback may modify its
- * contents (e.g. setting the fd(s) to -1 after close).
- */
- fds = malloc(sizeof(*fds) * fd_count);
- if (!fds) {
- ret = -1;
- goto end;
- }
- memcpy(fds, fds_in, sizeof(*fds) * fd_count);
-
- pthread_mutex_lock(&tracker->lock);
- rcu_read_lock();
-
- /* Let the user close the file descriptors. */
- user_ret = close(user_data, fds_in);
- if (user_ret) {
- ret = user_ret;
- goto end_unlock;
- }
-
- /* Untrack the fds that were just closed by the user's callback. */
- for (i = 0; i < fd_count; i++) {
- struct cds_lfht_node *node;
- struct cds_lfht_iter iter;
- struct unsuspendable_fd *entry;
-
- cds_lfht_lookup(tracker->unsuspendable_fds,
- hash_key_ulong((void *) (unsigned long) fds[i],
- seed.value),
- match_fd, (void *) (unsigned long) fds[i],
- &iter);
- node = cds_lfht_iter_get_node(&iter);
- if (!node) {
- /* Unknown file descriptor. */
- WARN("Untracked file descriptor %d passed to fd_tracker_close_unsuspendable_fd()",
- fds[i]);
- ret = -EINVAL;
- goto end_unlock;
- }
- entry = caa_container_of(
- node, struct unsuspendable_fd, tracker_node);
-
- cds_lfht_del(tracker->unsuspendable_fds, node);
- unsuspendable_fd_destroy(entry);
- fds[i] = -1;
- }
-
- tracker->count.unsuspendable -= fd_count;
- ret = 0;
-end_unlock:
- rcu_read_unlock();
- pthread_mutex_unlock(&tracker->lock);
- free(fds);
-end:
- return ret;
-}
-
-/* Caller must have taken the tracker's and handle's locks. */
-static void fd_tracker_track(
- struct fd_tracker *tracker, struct fs_handle_tracked *handle)
-{
- if (handle->fd >= 0) {
- tracker->count.suspendable.active++;
- cds_list_add_tail(&handle->handles_list_node,
- &tracker->active_handles);
- } else {
- tracker->count.suspendable.suspended++;
- cds_list_add_tail(&handle->handles_list_node,
- &tracker->suspended_handles);
- }
-}
-
-/* Caller must have taken the tracker's and handle's locks. */
-static void fd_tracker_untrack(
- struct fd_tracker *tracker, struct fs_handle_tracked *handle)
-{
- if (handle->fd >= 0) {
- tracker->count.suspendable.active--;
- } else {
- tracker->count.suspendable.suspended--;
- }
- cds_list_del(&handle->handles_list_node);
-}
-
-/* Caller must have taken the tracker's and handle's locks. */
-static int fd_tracker_restore_handle(
- struct fd_tracker *tracker, struct fs_handle_tracked *handle)
-{
- int ret;
-
- fd_tracker_untrack(tracker, handle);
- if (ACTIVE_COUNT(tracker) >= tracker->capacity) {
- ret = fd_tracker_suspend_handles(tracker, 1);
- if (ret) {
- goto end;
- }
- }
- ret = fs_handle_tracked_restore(handle);
-end:
- fd_tracker_track(tracker, handle);
- return ret ? ret : handle->fd;
-}
-
-static int fs_handle_tracked_get_fd(struct fs_handle *_handle)
-{
- int ret;
- struct fs_handle_tracked *handle =
- container_of(_handle, struct fs_handle_tracked, parent);
-
- /*
- * TODO This should be optimized as it is a fairly hot path.
- * The fd-tracker's lock should only be taken when a fs_handle is
- * restored (slow path). On the fast path (fs_handle is active),
- * the only effect on the fd_tracker is marking the handle as the
- * most recently used. Currently, it is done by a call to the
- * track/untrack helpers, but it should be done atomically.
- *
- * Note that the lock's nesting order must still be respected here.
- * The handle's lock nests inside the tracker's lock.
- */
- pthread_mutex_lock(&handle->tracker->lock);
- pthread_mutex_lock(&handle->lock);
- LTTNG_ASSERT(!handle->in_use);
-
- handle->tracker->stats.uses++;
- if (handle->fd >= 0) {
- ret = handle->fd;
- /* Mark as most recently used. */
- fd_tracker_untrack(handle->tracker, handle);
- fd_tracker_track(handle->tracker, handle);
- } else {
- handle->tracker->stats.misses++;
- ret = fd_tracker_restore_handle(handle->tracker, handle);
- if (ret < 0) {
- handle->tracker->stats.errors++;
- goto end;
- }
- }
- handle->in_use = true;
-end:
- pthread_mutex_unlock(&handle->lock);
- pthread_mutex_unlock(&handle->tracker->lock);
- return ret;
-}
-
-static void fs_handle_tracked_put_fd(struct fs_handle *_handle)
-{
- struct fs_handle_tracked *handle =
- container_of(_handle, struct fs_handle_tracked, parent);
-
- pthread_mutex_lock(&handle->lock);
- handle->in_use = false;
- pthread_mutex_unlock(&handle->lock);
-}
-
-static int fs_handle_tracked_unlink(struct fs_handle *_handle)
-{
- int ret;
- struct fs_handle_tracked *handle =
- container_of(_handle, struct fs_handle_tracked, parent);
-
- pthread_mutex_lock(&handle->tracker->lock);
- pthread_mutex_lock(&handle->lock);
- ret = lttng_inode_unlink(handle->inode);
- pthread_mutex_unlock(&handle->lock);
- pthread_mutex_unlock(&handle->tracker->lock);
- return ret;
-}
-
-static int fs_handle_tracked_close(struct fs_handle *_handle)
-{
- int ret = 0;
- const char *path = NULL;
- struct fs_handle_tracked *handle =
- container_of(_handle, struct fs_handle_tracked, parent);
- struct lttng_directory_handle *inode_directory_handle = NULL;
-
- if (!handle) {
- ret = -EINVAL;
- goto end;
- }
-
- pthread_mutex_lock(&handle->tracker->lock);
- pthread_mutex_lock(&handle->lock);
- if (handle->inode) {
- lttng_inode_borrow_location(handle->inode, NULL, &path);
- /*
- * Here a reference to the inode's directory handle is acquired
- * to prevent the last reference to it from being released while
- * the tracker's lock is taken.
- *
- * If this wasn't done, the directory handle could attempt to
- * close its underlying directory file descriptor, which would
- * attempt to lock the tracker's lock, resulting in a deadlock.
- *
- * Since a new reference to the directory handle is taken within
- * the scope of this function, it is not possible for the last
- * reference to the inode's location directory handle to be
- * released during the call to lttng_inode_put().
- *
- * We wait until the tracker's lock is released to release the
- * reference. Hence, the call to the tracker is delayed just
- * enough to not attempt to recursively acquire the tracker's
- * lock twice.
- */
- inode_directory_handle =
- lttng_inode_get_location_directory_handle(
- handle->inode);
- }
- fd_tracker_untrack(handle->tracker, handle);
- if (handle->fd >= 0) {
- /*
- * The return value of close() is not propagated as there
- * isn't much the user can do about it.
- */
- if (close(handle->fd)) {
- PERROR("Failed to close the file descriptor (%d) of fs handle to %s, close() returned",
- handle->fd, path ? path : "Unknown");
- }
- handle->fd = -1;
- }
- if (handle->inode) {
- lttng_inode_put(handle->inode);
- }
- pthread_mutex_unlock(&handle->lock);
- pthread_mutex_destroy(&handle->lock);
- pthread_mutex_unlock(&handle->tracker->lock);
- free(handle);
- lttng_directory_handle_put(inode_directory_handle);
-end:
- return ret;
-}
projects / lttng-tools.git / blobdiff