diff options
Diffstat (limited to 'wrapper.c')
| -rw-r--r-- | wrapper.c | 83 |
1 files changed, 83 insertions, 0 deletions
@@ -4,6 +4,16 @@ #include "cache.h" #include "config.h" +static intmax_t count_fsync_writeout_only; +static intmax_t count_fsync_hardware_flush; + +#ifdef HAVE_RTLGENRANDOM +/* This is required to get access to RtlGenRandom. */ +#define SystemFunction036 NTAPI SystemFunction036 +#include <NTSecAPI.h> +#undef SystemFunction036 +#endif + static int memory_limit_check(size_t size, int gentle) { static size_t limit = 0; @@ -539,6 +549,79 @@ int xmkstemp_mode(char *filename_template, int mode) return fd; } +/* + * Some platforms return EINTR from fsync. Since fsync is invoked in some + * cases by a wrapper that dies on failure, do not expose EINTR to callers. + */ +static int fsync_loop(int fd) +{ + int err; + + do { + err = fsync(fd); + } while (err < 0 && errno == EINTR); + return err; +} + +int git_fsync(int fd, enum fsync_action action) +{ + switch (action) { + case FSYNC_WRITEOUT_ONLY: + count_fsync_writeout_only += 1; + +#ifdef __APPLE__ + /* + * On macOS, fsync just causes filesystem cache writeback but + * does not flush hardware caches. + */ + return fsync_loop(fd); +#endif + +#ifdef HAVE_SYNC_FILE_RANGE + /* + * On linux 2.6.17 and above, sync_file_range is the way to + * issue a writeback without a hardware flush. An offset of + * 0 and size of 0 indicates writeout of the entire file and the + * wait flags ensure that all dirty data is written to the disk + * (potentially in a disk-side cache) before we continue. + */ + + return sync_file_range(fd, 0, 0, SYNC_FILE_RANGE_WAIT_BEFORE | + SYNC_FILE_RANGE_WRITE | + SYNC_FILE_RANGE_WAIT_AFTER); +#endif + +#ifdef fsync_no_flush + return fsync_no_flush(fd); +#endif + + errno = ENOSYS; + return -1; + + case FSYNC_HARDWARE_FLUSH: + count_fsync_hardware_flush += 1; + + /* + * On macOS, a special fcntl is required to really flush the + * caches within the storage controller. As of this writing, + * this is a very expensive operation on Apple SSDs. + */ +#ifdef __APPLE__ + return fcntl(fd, F_FULLFSYNC); +#else + return fsync_loop(fd); +#endif + default: + BUG("unexpected git_fsync(%d) call", action); + } +} + +void trace_git_fsync_stats(void) +{ + trace2_data_intmax("fsync", the_repository, "fsync/writeout-only", count_fsync_writeout_only); + trace2_data_intmax("fsync", the_repository, "fsync/hardware-flush", count_fsync_hardware_flush); +} + static int warn_if_unremovable(const char *op, const char *file, int rc) { int err; |