index 70d8aa649d5cfb956c42b7260418ac4a6dd96813..4f3b97c7cf795b1ba9e1f386fe1a8ac1d1ee3c06 100755 (executable)
LIBS_including_readline="$LIBS"
LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
-for ac_func in cbrt clock_gettime dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll pstat pthread_is_threaded_np readlink setproctitle setsid shm_open symlink sync_file_range utime utimes wcstombs_l
+for ac_func in cbrt clock_gettime dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate pstat pthread_is_threaded_np readlink setproctitle setsid shm_open symlink sync_file_range utime utimes wcstombs_l
do :
as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
index c63780139eb7adbc0555dd417a2cb64386561325..a5879060d0715785db3712da3ce7b02b7052a6f0 100644 (file)
static bool dsm_impl_posix(dsm_op op, dsm_handle handle, Size request_size,
void **impl_private, void **mapped_address,
Size *mapped_size, int elevel);
+static int dsm_impl_posix_resize(int fd, off_t size);
#endif
#ifdef USE_DSM_SYSV
static bool dsm_impl_sysv(dsm_op op, dsm_handle handle, Size request_size,
@@ -319,7 +320,8 @@ dsm_impl_posix(dsm_op op, dsm_handle handle, Size request_size,
}
request_size = st.st_size;
}
- else if (*mapped_size != request_size && ftruncate(fd, request_size))
+ else if (*mapped_size != request_size &&
+ dsm_impl_posix_resize(fd, request_size) != 0)
{
int save_errno;
@@ -392,7 +394,55 @@ dsm_impl_posix(dsm_op op, dsm_handle handle, Size request_size,
return true;
}
-#endif
+
+/*
+ * Set the size of a virtual memory region associated with a file descriptor.
+ * If necessary, also ensure that virtual memory is actually allocated by the
+ * operating system, to avoid nasty surprises later.
+ *
+ * Returns non-zero if either truncation or allocation fails, and sets errno.
+ */
+static int
+dsm_impl_posix_resize(int fd, off_t size)
+{
+ int rc;
+
+ /* Truncate (or extend) the file to the requested size. */
+ rc = ftruncate(fd, size);
+
+ /*
+ * On Linux, a shm_open fd is backed by a tmpfs file. After resizing with
+ * ftruncate, the file may contain a hole. Accessing memory backed by a
+ * hole causes tmpfs to allocate pages, which fails with SIGBUS if there
+ * is no more tmpfs space available. So we ask tmpfs to allocate pages
+ * here, so we can fail gracefully with ENOSPC now rather than risking
+ * SIGBUS later.
+ */
+#if defined(HAVE_POSIX_FALLOCATE) && defined(__linux__)
+ if (rc == 0)
+ {
+ /* We may get interrupted, if so just retry. */
+ do
+ {
+ rc = posix_fallocate(fd, 0, size);
+ } while (rc == -1 && errno == EINTR);
+
+ if (rc != 0 && errno == ENOSYS)
+ {
+ /*
+ * Kernel too old (< 2.6.23). Rather than fail, just trust that
+ * we won't hit the problem (it typically doesn't show up without
+ * many-GB-sized requests, anyway).
+ */
+ rc = 0;
+ }
+ }
+#endif /* HAVE_POSIX_FALLOCATE && __linux__ */
+
+ return rc;
+}
+
+#endif /* USE_DSM_POSIX */
#ifdef USE_DSM_SYSV
/*