X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Ffd-tracker%2Ffd-tracker.c;h=772bf04bc5994efa5fc351a2ed933514506de36c;hp=65cbba99c0579378a2f89192f2cf2096c267f7b8;hb=ea05fafd4088958df7f994fcf903627bc609808d;hpb=5c1f54d1d586f61a92704753411bd82c5c928218 diff --git a/src/common/fd-tracker/fd-tracker.c b/src/common/fd-tracker/fd-tracker.c index 65cbba99c..772bf04bc 100644 --- a/src/common/fd-tracker/fd-tracker.c +++ b/src/common/fd-tracker/fd-tracker.c @@ -1,18 +1,8 @@ /* - * Copyright (C) 2018 - Jérémie Galarneau + * Copyright (C) 2018-2020 Jérémie Galarneau * - * This program is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License, version 2 only, as - * published by the Free Software Foundation. + * SPDX-License-Identifier: GPL-2.0-only * - * This program is distributed in the hope that it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for - * more details. - * - * You should have received a copy of the GNU General Public License along with - * this program; if not, write to the Free Software Foundation, Inc., 51 - * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include @@ -26,11 +16,13 @@ #include #include -#include "common/defaults.h" -#include "common/error.h" -#include "common/hashtable/hashtable.h" -#include "common/hashtable/utils.h" -#include "common/macros.h" +#include +#include +#include +#include +#include +#include +#include #include "fd-tracker.h" #include "inode.h" @@ -83,18 +75,18 @@ struct fd_tracker { 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; - struct { - bool is_set; - mode_t value; - } mode; + LTTNG_OPTIONAL(mode_t) mode; }; /* - * A fs_handle is not ref-counted. Therefore, it is assumed that a + * 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). @@ -102,7 +94,8 @@ struct open_properties { * * The fs_handle lock always nests _within_ the tracker's lock. */ -struct fs_handle { +struct fs_handle_tracked { + struct fs_handle parent; pthread_mutex_t lock; /* * Weak reference to the tracker. All fs_handles are assumed to have @@ -143,21 +136,25 @@ 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( +static int open_from_properties(const struct lttng_directory_handle *dir_handle, const char *path, struct open_properties *properties); -static void fs_handle_log(struct fs_handle *handle); -static int fs_handle_suspend(struct fs_handle *handle); -static int fs_handle_restore(struct fs_handle *handle); +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 *handle); + struct fd_tracker *tracker, struct fs_handle_tracked *handle); static void fd_tracker_untrack( - struct fd_tracker *tracker, struct fs_handle *handle); + 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 *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) @@ -208,12 +205,12 @@ error: return NULL; } -static void fs_handle_log(struct fs_handle *handle) +static void fs_handle_tracked_log(struct fs_handle_tracked *handle) { const char *path; pthread_mutex_lock(&handle->lock); - path = lttng_inode_get_path(handle->inode); + lttng_inode_borrow_location(handle->inode, NULL, &path); if (handle->fd >= 0) { DBG_NO_LOC(" %s [active, fd %d%s]", path, handle->fd, @@ -225,14 +222,16 @@ static void fs_handle_log(struct fs_handle *handle) } /* Tracker lock must be held by the caller. */ -static int fs_handle_suspend(struct fs_handle *handle) +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); - path = lttng_inode_get_path(handle->inode); + lttng_inode_borrow_location( + handle->inode, &node_directory_handle, &path); assert(handle->fd >= 0); if (handle->in_use) { /* This handle can't be suspended as it is currently in use. */ @@ -240,7 +239,8 @@ static int fs_handle_suspend(struct fs_handle *handle) goto end; } - ret = stat(path, &fs_stat); + 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); @@ -283,14 +283,19 @@ end: } /* Caller must hold the tracker and handle's locks. */ -static int fs_handle_restore(struct fs_handle *handle) +static int fs_handle_tracked_restore(struct fs_handle_tracked *handle) { int ret, fd = -1; - const char *path = lttng_inode_get_path(handle->inode); + const char *path; + const struct lttng_directory_handle *node_directory_handle; + + lttng_inode_borrow_location( + handle->inode, &node_directory_handle, &path); assert(handle->fd == -1); assert(path); - ret = open_from_properties(path, &handle->properties); + ret = open_from_properties( + node_directory_handle, path, &handle->properties); if (ret < 0) { PERROR("Failed to restore filesystem handle to %s, open() failed", path); @@ -318,7 +323,7 @@ end: return ret; } -static int open_from_properties( +static int open_from_properties(const struct lttng_directory_handle *dir_handle, const char *path, struct open_properties *properties) { int ret; @@ -330,9 +335,11 @@ static int open_from_properties( * thus it is ignored here. */ if ((properties->flags & O_CREAT) && properties->mode.is_set) { - ret = open(path, properties->flags, properties->mode.value); + ret = lttng_directory_handle_open_file(dir_handle, path, + properties->flags, properties->mode.value); } else { - ret = open(path, properties->flags); + ret = lttng_directory_handle_open_file(dir_handle, path, + properties->flags, 0); } /* * Some flags should not be used beyond the initial open() of a @@ -353,7 +360,9 @@ end: return ret; } -struct fd_tracker *fd_tracker_create(unsigned int capacity) +LTTNG_HIDDEN +struct fd_tracker *fd_tracker_create(const char *unlinked_file_path, + unsigned int capacity) { struct fd_tracker *tracker = zmalloc(sizeof(struct fd_tracker)); @@ -382,6 +391,12 @@ struct fd_tracker *fd_tracker_create(unsigned int capacity) 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: @@ -391,9 +406,10 @@ error: return NULL; } +LTTNG_HIDDEN void fd_tracker_log(struct fd_tracker *tracker) { - struct fs_handle *handle; + struct fs_handle_tracked *handle; struct unsuspendable_fd *unsuspendable_fd; struct cds_lfht_iter iter; @@ -411,13 +427,13 @@ void fd_tracker_log(struct fd_tracker *tracker) DBG_NO_LOC(" capacity: %u", tracker->capacity); DBG_NO_LOC(" Tracked suspendable file descriptors"); - cds_list_for_each_entry ( + cds_list_for_each_entry( handle, &tracker->active_handles, handles_list_node) { - fs_handle_log(handle); + fs_handle_tracked_log(handle); } - cds_list_for_each_entry (handle, &tracker->suspended_handles, + cds_list_for_each_entry(handle, &tracker->suspended_handles, handles_list_node) { - fs_handle_log(handle); + fs_handle_tracked_log(handle); } if (!SUSPENDABLE_COUNT(tracker)) { DBG_NO_LOC(" None"); @@ -425,7 +441,7 @@ void fd_tracker_log(struct fd_tracker *tracker) DBG_NO_LOC(" Tracked unsuspendable file descriptors"); rcu_read_lock(); - cds_lfht_for_each_entry (tracker->unsuspendable_fds, &iter, + cds_lfht_for_each_entry(tracker->unsuspendable_fds, &iter, unsuspendable_fd, tracker_node) { DBG_NO_LOC(" %s [active, fd %d]", unsuspendable_fd->name ?: "Unnamed", @@ -439,10 +455,14 @@ void fd_tracker_log(struct fd_tracker *tracker) pthread_mutex_unlock(&tracker->lock); } +LTTNG_HIDDEN 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. @@ -464,19 +484,22 @@ int fd_tracker_destroy(struct fd_tracker *tracker) } 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; } +LTTNG_HIDDEN 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 *handle = NULL; + struct fs_handle_tracked *handle = NULL; struct stat fd_stat; struct open_properties properties = { .flags = flags, @@ -507,6 +530,13 @@ struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker, 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); @@ -515,7 +545,7 @@ struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker, goto error_mutex_init; } - handle->fd = open_from_properties(path, &properties); + 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; @@ -523,8 +553,9 @@ struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker, handle->properties = properties; - handle->inode = lttng_inode_registry_get_inode( - tracker->inode_registry, handle->fd, path); + 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; @@ -539,7 +570,7 @@ struct fs_handle *fd_tracker_open_fs_handle(struct fd_tracker *tracker, fd_tracker_track(tracker, handle); end: pthread_mutex_unlock(&tracker->lock); - return handle; + return handle ? &handle->parent : NULL; error: if (handle->inode) { lttng_inode_put(handle->inode); @@ -556,26 +587,29 @@ static int fd_tracker_suspend_handles( struct fd_tracker *tracker, unsigned int count) { unsigned int left_to_close = count; - struct fs_handle *handle, *tmp; + 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, + cds_list_for_each_entry_safe(handle, tmp, &tracker->active_handles, handles_list_node) { int ret; fd_tracker_untrack(tracker, handle); - ret = fs_handle_suspend(handle); + ret = fs_handle_tracked_suspend(handle); fd_tracker_track(tracker, handle); if (!ret) { left_to_close--; } + attempts_left--; - if (!left_to_close) { + if (left_to_close == 0 || attempts_left == 0) { break; } } return left_to_close ? -EMFILE : 0; } +LTTNG_HIDDEN int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker, int *out_fds, const char **names, @@ -585,9 +619,13 @@ int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker, { int ret, user_ret, i, fds_to_suspend; unsigned int active_fds; - struct unsuspendable_fd *entries[fd_count]; + struct unsuspendable_fd **entries; - memset(entries, 0, sizeof(entries)); + entries = zmalloc(fd_count * sizeof(*entries)); + if (!entries) { + ret = -1; + goto end; + } pthread_mutex_lock(&tracker->lock); @@ -599,25 +637,25 @@ int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker, ret = fd_tracker_suspend_handles( tracker, fds_to_suspend); if (ret) { - goto end; + goto end_unlock; } } else { /* * There are not enough active suspendable file - * descriptors to open a new fd and still accomodate the + * 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; + goto end_unlock; } } user_ret = open(user_data, out_fds); if (user_ret) { ret = user_ret; - goto end; + goto end_unlock; } /* @@ -657,16 +695,19 @@ int fd_tracker_open_unsuspendable_fd(struct fd_tracker *tracker, tracker->count.unsuspendable += fd_count; rcu_read_unlock(); ret = user_ret; -end: +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; + goto end_unlock; } +LTTNG_HIDDEN int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker, int *fds_in, unsigned int fd_count, @@ -674,12 +715,17 @@ int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker, void *user_data) { int i, ret, user_ret; - int fds[fd_count]; + 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); @@ -689,7 +735,7 @@ int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker, user_ret = close(user_data, fds_in); if (user_ret) { ret = user_ret; - goto end; + goto end_unlock; } /* Untrack the fds that were just closed by the user's callback. */ @@ -709,7 +755,7 @@ int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker, WARN("Untracked file descriptor %d passed to fd_tracker_close_unsuspendable_fd()", fds[i]); ret = -EINVAL; - goto end; + goto end_unlock; } entry = caa_container_of( node, struct unsuspendable_fd, tracker_node); @@ -721,15 +767,17 @@ int fd_tracker_close_unsuspendable_fd(struct fd_tracker *tracker, tracker->count.unsuspendable -= fd_count; ret = 0; -end: +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 *handle) + struct fd_tracker *tracker, struct fs_handle_tracked *handle) { if (handle->fd >= 0) { tracker->count.suspendable.active++; @@ -744,7 +792,7 @@ static void fd_tracker_track( /* Caller must have taken the tracker's and handle's locks. */ static void fd_tracker_untrack( - struct fd_tracker *tracker, struct fs_handle *handle) + struct fd_tracker *tracker, struct fs_handle_tracked *handle) { if (handle->fd >= 0) { tracker->count.suspendable.active--; @@ -756,7 +804,7 @@ static void fd_tracker_untrack( /* Caller must have taken the tracker's and handle's locks. */ static int fd_tracker_restore_handle( - struct fd_tracker *tracker, struct fs_handle *handle) + struct fd_tracker *tracker, struct fs_handle_tracked *handle) { int ret; @@ -767,15 +815,17 @@ static int fd_tracker_restore_handle( goto end; } } - ret = fs_handle_restore(handle); + ret = fs_handle_tracked_restore(handle); end: fd_tracker_track(tracker, handle); return ret ? ret : handle->fd; } -int fs_handle_get_fd(struct fs_handle *handle) +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. @@ -813,29 +863,37 @@ end: return ret; } -void fs_handle_put_fd(struct fs_handle *handle) +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); } -int fs_handle_unlink(struct fs_handle *handle) +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_defer_unlink(handle->inode); + ret = lttng_inode_unlink(handle->inode); pthread_mutex_unlock(&handle->lock); pthread_mutex_unlock(&handle->tracker->lock); return ret; } -int fs_handle_close(struct fs_handle *handle) +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; @@ -845,7 +903,29 @@ int fs_handle_close(struct fs_handle *handle) pthread_mutex_lock(&handle->tracker->lock); pthread_mutex_lock(&handle->lock); if (handle->inode) { - path = lttng_inode_get_path(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) { @@ -854,7 +934,7 @@ int fs_handle_close(struct fs_handle *handle) * isn't much the user can do about it. */ if (close(handle->fd)) { - PERROR("Failed to close the file descritptor (%d) of fs handle to %s, close() returned", + PERROR("Failed to close the file descriptor (%d) of fs handle to %s, close() returned", handle->fd, path ? path : "Unknown"); } handle->fd = -1; @@ -866,6 +946,7 @@ int fs_handle_close(struct fs_handle *handle) pthread_mutex_destroy(&handle->lock); pthread_mutex_unlock(&handle->tracker->lock); free(handle); + lttng_directory_handle_put(inode_directory_handle); end: return ret; }