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-rw-r--r--src/journal/journal-file.c213
1 files changed, 192 insertions, 21 deletions
diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 52110aa498..96be339d5b 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -20,6 +20,7 @@
#include <errno.h>
#include <fcntl.h>
#include <linux/fs.h>
+#include <pthread.h>
#include <stddef.h>
#include <sys/mman.h>
#include <sys/statvfs.h>
@@ -86,33 +87,127 @@
/* The mmap context to use for the header we pick as one above the last defined typed */
#define CONTEXT_HEADER _OBJECT_TYPE_MAX
-static int journal_file_set_online(JournalFile *f) {
+/* This may be called from a separate thread to prevent blocking the caller for the duration of fsync().
+ * As a result we use atomic operations on f->offline_state for inter-thread communications with
+ * journal_file_set_offline() and journal_file_set_online(). */
+static void journal_file_set_offline_internal(JournalFile *f) {
assert(f);
+ assert(f->fd >= 0);
+ assert(f->header);
- if (!f->writable)
- return -EPERM;
+ for (;;) {
+ switch (f->offline_state) {
+ case OFFLINE_CANCEL:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_CANCEL, OFFLINE_DONE))
+ continue;
+ return;
- if (!(f->fd >= 0 && f->header))
- return -EINVAL;
+ case OFFLINE_AGAIN_FROM_SYNCING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_AGAIN_FROM_SYNCING, OFFLINE_SYNCING))
+ continue;
+ break;
+
+ case OFFLINE_AGAIN_FROM_OFFLINING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_AGAIN_FROM_OFFLINING, OFFLINE_SYNCING))
+ continue;
+ break;
+
+ case OFFLINE_SYNCING:
+ (void) fsync(f->fd);
+
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_SYNCING, OFFLINE_OFFLINING))
+ continue;
+
+ f->header->state = STATE_OFFLINE;
+ (void) fsync(f->fd);
+ break;
+
+ case OFFLINE_OFFLINING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_OFFLINING, OFFLINE_DONE))
+ continue;
+ /* fall through */
+
+ case OFFLINE_DONE:
+ return;
+
+ case OFFLINE_JOINED:
+ log_debug("OFFLINE_JOINED unexpected offline state for journal_file_set_offline_internal()");
+ return;
+ }
+ }
+}
+
+static void * journal_file_set_offline_thread(void *arg) {
+ JournalFile *f = arg;
+
+ journal_file_set_offline_internal(f);
+
+ return NULL;
+}
+
+static int journal_file_set_offline_thread_join(JournalFile *f) {
+ int r;
+
+ assert(f);
+
+ if (f->offline_state == OFFLINE_JOINED)
+ return 0;
+
+ r = pthread_join(f->offline_thread, NULL);
+ if (r)
+ return -r;
+
+ f->offline_state = OFFLINE_JOINED;
if (mmap_cache_got_sigbus(f->mmap, f->fd))
return -EIO;
- switch (f->header->state) {
- case STATE_ONLINE:
- return 0;
+ return 0;
+}
- case STATE_OFFLINE:
- f->header->state = STATE_ONLINE;
- (void) fsync(f->fd);
- return 0;
+/* Trigger a restart if the offline thread is mid-flight in a restartable state. */
+static bool journal_file_set_offline_try_restart(JournalFile *f) {
+ for (;;) {
+ switch (f->offline_state) {
+ case OFFLINE_AGAIN_FROM_SYNCING:
+ case OFFLINE_AGAIN_FROM_OFFLINING:
+ return true;
+
+ case OFFLINE_CANCEL:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_CANCEL, OFFLINE_AGAIN_FROM_SYNCING))
+ continue;
+ return true;
+
+ case OFFLINE_SYNCING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_SYNCING, OFFLINE_AGAIN_FROM_SYNCING))
+ continue;
+ return true;
+
+ case OFFLINE_OFFLINING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_OFFLINING, OFFLINE_AGAIN_FROM_OFFLINING))
+ continue;
+ return true;
default:
- return -EINVAL;
+ return false;
+ }
}
}
-int journal_file_set_offline(JournalFile *f) {
+/* Sets a journal offline.
+ *
+ * If wait is false then an offline is dispatched in a separate thread for a
+ * subsequent journal_file_set_offline() or journal_file_set_online() of the
+ * same journal to synchronize with.
+ *
+ * If wait is true, then either an existing offline thread will be restarted
+ * and joined, or if none exists the offline is simply performed in this
+ * context without involving another thread.
+ */
+int journal_file_set_offline(JournalFile *f, bool wait) {
+ bool restarted;
+ int r;
+
assert(f);
if (!f->writable)
@@ -124,19 +219,95 @@ int journal_file_set_offline(JournalFile *f) {
if (f->header->state != STATE_ONLINE)
return 0;
- (void) fsync(f->fd);
+ /* Restart an in-flight offline thread and wait if needed, or join a lingering done one. */
+ restarted = journal_file_set_offline_try_restart(f);
+ if ((restarted && wait) || !restarted) {
+ r = journal_file_set_offline_thread_join(f);
+ if (r < 0)
+ return r;
+ }
- if (mmap_cache_got_sigbus(f->mmap, f->fd))
- return -EIO;
+ if (restarted)
+ return 0;
+
+ /* Initiate a new offline. */
+ f->offline_state = OFFLINE_SYNCING;
+
+ if (wait) /* Without using a thread if waiting. */
+ journal_file_set_offline_internal(f);
+ else {
+ r = pthread_create(&f->offline_thread, NULL, journal_file_set_offline_thread, f);
+ if (r > 0)
+ return -r;
+ }
+
+ return 0;
+}
+
+static int journal_file_set_online(JournalFile *f) {
+ bool joined = false;
+
+ assert(f);
+
+ if (!f->writable)
+ return -EPERM;
+
+ if (!(f->fd >= 0 && f->header))
+ return -EINVAL;
- f->header->state = STATE_OFFLINE;
+ while (!joined) {
+ switch (f->offline_state) {
+ case OFFLINE_JOINED:
+ /* No offline thread, no need to wait. */
+ joined = true;
+ break;
+
+ case OFFLINE_SYNCING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_SYNCING, OFFLINE_CANCEL))
+ continue;
+ /* Canceled syncing prior to offlining, no need to wait. */
+ break;
+
+ case OFFLINE_AGAIN_FROM_SYNCING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_AGAIN_FROM_SYNCING, OFFLINE_CANCEL))
+ continue;
+ /* Canceled restart from syncing, no need to wait. */
+ break;
+
+ case OFFLINE_AGAIN_FROM_OFFLINING:
+ if (!__sync_bool_compare_and_swap(&f->offline_state, OFFLINE_AGAIN_FROM_OFFLINING, OFFLINE_CANCEL))
+ continue;
+ /* Canceled restart from offlining, must wait for offlining to complete however. */
+
+ /* fall through to wait */
+ default: {
+ int r;
+
+ r = journal_file_set_offline_thread_join(f);
+ if (r < 0)
+ return r;
+
+ joined = true;
+ break;
+ }
+ }
+ }
if (mmap_cache_got_sigbus(f->mmap, f->fd))
return -EIO;
- (void) fsync(f->fd);
+ switch (f->header->state) {
+ case STATE_ONLINE:
+ return 0;
- return 0;
+ case STATE_OFFLINE:
+ f->header->state = STATE_ONLINE;
+ (void) fsync(f->fd);
+ return 0;
+
+ default:
+ return -EINVAL;
+ }
}
JournalFile* journal_file_close(JournalFile *f) {
@@ -159,7 +330,7 @@ JournalFile* journal_file_close(JournalFile *f) {
sd_event_source_unref(f->post_change_timer);
}
- journal_file_set_offline(f);
+ journal_file_set_offline(f, true);
if (f->mmap && f->fd >= 0)
mmap_cache_close_fd(f->mmap, f->fd);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-07-04 14:39:29 +0000