int mail_transaction_log_lock_head(struct mail_transaction_log *log)
{
struct mail_transaction_log_file *file;
int ret = 0;
if (!log->log_2_unlink_checked) {
/* we need to check once in a while if .log.2 should be deleted
to avoid wasting space on such old files. but we also don't
want to waste time on checking it when the same mailbox
gets opened over and over again rapidly (e.g. pop3). so
do this only when there have actually been some changes
to mailbox (i.e. when it's being locked here) */
log->log_2_unlink_checked = TRUE;
mail_transaction_log_2_unlink_old(log);
}
/* we want to get the head file locked. this is a bit racy,
since by the time we have it locked a new log file may have been
created.
creating new log file requires locking the head file, so if we
can lock it and don't see another file, we can be sure no-one is
creating a new log at the moment */
for (;;) {
file = log->head;
if (mail_transaction_log_file_lock(file) < 0)
return -1;
file->refcount++;
ret = mail_transaction_log_refresh(log, TRUE);
if (--file->refcount == 0) {
mail_transaction_logs_clean(log);
file = NULL;
}
if (ret == 0 && log->head == file) {
/* success */
break;
}
if (file != NULL)
mail_transaction_log_file_unlock(file);
if (ret < 0)
break;
/* try again */
}
return ret;
}
int mail_transaction_log_lock_head(struct mail_transaction_log *log,
const char *lock_reason)
{
struct mail_transaction_log_file *file;
time_t lock_wait_started, lock_secs = 0;
const char *reason;
int ret = 0;
if (!log->log_2_unlink_checked) {
/* we need to check once in a while if .log.2 should be deleted
to avoid wasting space on such old files. but we also don't
want to waste time on checking it when the same mailbox
gets opened over and over again rapidly (e.g. pop3). so
do this only when there have actually been some changes
to mailbox (i.e. when it's being locked here) */
log->log_2_unlink_checked = TRUE;
mail_transaction_log_2_unlink_old(log);
}
/* we want to get the head file locked. this is a bit racy,
since by the time we have it locked a new log file may have been
created.
creating new log file requires locking the head file, so if we
can lock it and don't see another file, we can be sure no-one is
creating a new log at the moment */
lock_wait_started = time(NULL);
for (;;) {
file = log->head;
if (mail_transaction_log_file_lock(file) < 0)
return -1;
file->refcount++;
ret = mail_transaction_log_refresh(log, TRUE, &reason);
if (--file->refcount == 0) {
mail_transaction_log_file_unlock(file, t_strdup_printf(
"trying to lock head for %s", lock_reason));
mail_transaction_logs_clean(log);
file = NULL;
}
if (ret == 0 && log->head == file) {
/* success */
i_assert(file != NULL);
lock_secs = file->lock_created - lock_wait_started;
break;
}
if (file != NULL) {
mail_transaction_log_file_unlock(file, t_strdup_printf(
"trying to lock head for %s", lock_reason));
}
if (ret < 0)
break;
/* try again */
}
if (lock_secs > MAIL_TRANSACTION_LOG_LOCK_WARN_SECS) {
i_warning("Locking transaction log file %s took %ld seconds (%s)",
log->head->filepath, (long)lock_secs, lock_reason);
}
i_assert(ret < 0 || log->head != NULL);
return ret;
}
static int
mail_transaction_log_file_create2(struct mail_transaction_log_file *file,
int new_fd, bool reset,
struct dotlock **dotlock)
{
struct mail_index *index = file->log->index;
struct stat st;
const char *path2;
buffer_t *writebuf;
int fd, ret;
bool rename_existing, need_lock;
need_lock = file->log->head != NULL && file->log->head->locked;
if (fcntl(new_fd, F_SETFL, O_APPEND) < 0) {
log_file_set_syscall_error(file, "fcntl(O_APPEND)");
return -1;
}
if (file->log->nfs_flush) {
/* although we check also mtime and file size below, it's done
only to fix broken log files. we don't bother flushing
attribute cache just for that. */
nfs_flush_file_handle_cache(file->filepath);
}
/* log creation is locked now - see if someone already created it.
note that if we're rotating, we need to keep the log locked until
the file has been rewritten. and because fcntl() locks are stupid,
if we go and open()+close() the file and we had it already opened,
its locks are lost. so we use stat() to check if the file has been
recreated, although it almost never is. */
if (reset)
rename_existing = FALSE;
else if (nfs_safe_stat(file->filepath, &st) < 0) {
if (errno != ENOENT) {
log_file_set_syscall_error(file, "stat()");
return -1;
}
rename_existing = FALSE;
} else if (st.st_ino == file->st_ino &&
CMP_DEV_T(st.st_dev, file->st_dev) &&
/* inode/dev checks are enough when we're rotating the file,
but not when we're replacing a broken log file */
st.st_mtime == file->last_mtime &&
(uoff_t)st.st_size == file->last_size) {
/* no-one else recreated the file */
rename_existing = TRUE;
} else {
/* recreated. use the file if its header is ok */
fd = nfs_safe_open(file->filepath, O_RDWR | O_APPEND);
if (fd == -1) {
if (errno != ENOENT) {
log_file_set_syscall_error(file, "open()");
return -1;
}
} else {
file->fd = fd;
file->last_size = 0;
if (mail_transaction_log_file_read_hdr(file,
FALSE) > 0 &&
mail_transaction_log_file_stat(file, FALSE) == 0) {
/* yes, it was ok */
file_dotlock_delete(dotlock);
mail_transaction_log_file_add_to_list(file);
return 0;
}
file->fd = -1;
if (close(fd) < 0)
log_file_set_syscall_error(file, "close()");
}
rename_existing = FALSE;
}
if (index->fd == -1 && !rename_existing) {
/* creating the initial index */
reset = TRUE;
}
if (mail_transaction_log_init_hdr(file->log, &file->hdr) < 0)
return -1;
if (reset) {
/* don't reset modseqs. if we're reseting due to rebuilding
indexes we'll probably want to keep uidvalidity and in such
cases we really don't want to shrink modseqs. */
file->hdr.prev_file_seq = 0;
file->hdr.prev_file_offset = 0;
}
writebuf = buffer_create_dynamic(pool_datastack_create(), 128);
buffer_append(writebuf, &file->hdr, sizeof(file->hdr));
if (index->ext_hdr_init_data != NULL && reset)
log_write_ext_hdr_init_data(index, writebuf);
if (write_full(new_fd, writebuf->data, writebuf->used) < 0) {
log_file_set_syscall_error(file, "write_full()");
return -1;
}
if (file->log->index->fsync_mode == FSYNC_MODE_ALWAYS) {
/* the header isn't important, so don't bother calling
fdatasync() unless it's required */
if (fdatasync(new_fd) < 0) {
log_file_set_syscall_error(file, "fdatasync()");
return -1;
}
}
file->fd = new_fd;
ret = mail_transaction_log_file_stat(file, FALSE);
if (need_lock) {
/* we'll need to preserve the lock */
if (mail_transaction_log_file_lock(file) < 0)
ret = -1;
}
/* if we return -1 the dotlock deletion code closes the fd */
file->fd = -1;
if (ret < 0)
return -1;
/* keep two log files */
if (rename_existing) {
/* rename() would be nice and easy way to do this, except then
there's a race condition between the rename and
file_dotlock_replace(). during that time the log file
doesn't exist, which could cause problems. */
path2 = t_strconcat(file->filepath, ".2", NULL);
if (i_unlink_if_exists(path2) < 0) {
/* try to link() anyway */
}
if (nfs_safe_link(file->filepath, path2, FALSE) < 0 &&
errno != ENOENT && errno != EEXIST) {
mail_index_set_error(index, "link(%s, %s) failed: %m",
file->filepath, path2);
/* ignore the error. we don't care that much about the
second log file and we're going to overwrite this
first one. */
}
/* NOTE: here's a race condition where both .log and .log.2
point to the same file. our reading code should ignore that
though by comparing the inodes. */
}
if (file_dotlock_replace(dotlock,
DOTLOCK_REPLACE_FLAG_DONT_CLOSE_FD) <= 0)
return -1;
/* success */
file->fd = new_fd;
mail_transaction_log_file_add_to_list(file);
i_assert(!need_lock || file->locked);
return 1;
}
