static int farm_read(uint64_t oid, struct siocb *iocb)
{
int i;
if (iocb->epoch < sys->epoch) {
void *buffer;
buffer = read_working_object(oid, iocb->length);
if (!buffer) {
/* Here if read the object from the targeted epoch failed,
* we need to read from the later epoch, because at some epoch
* we doesn't write the object to the snapshot, we assume
* it in the current local object directory, but maybe
* in the next epoch we removed it from the local directory.
* in this case, we should try to retrieve object upwards, since.
* when the object is to be removed, it will get written to the
* snapshot at later epoch. */
for (i = iocb->epoch; i < sys->epoch; i++) {
buffer = retrieve_object_from_snap(oid, i);
if (buffer)
break;
}
}
if (!buffer)
return SD_RES_NO_OBJ;
memcpy(iocb->buf, buffer, iocb->length);
free(buffer);
} else {
ssize_t size = xpread(iocb->fd, iocb->buf, iocb->length, iocb->offset);
if (size != iocb->length)
return SD_RES_EIO;
}
return SD_RES_SUCCESS;
}
static int farm_read(uint64_t oid, struct siocb *iocb)
{
int flags = def_open_flags, fd, ret = SD_RES_SUCCESS;
uint32_t epoch = sys_epoch();
char path[PATH_MAX];
ssize_t size;
int i;
void *buffer;
if (iocb->epoch < epoch) {
buffer = read_working_object(oid, iocb->offset, iocb->length);
if (!buffer) {
/* Here if read the object from the targeted epoch failed,
* we need to read from the later epoch, because at some epoch
* we doesn't write the object to the snapshot, we assume
* it in the current local object directory, but maybe
* in the next epoch we removed it from the local directory.
* in this case, we should try to retrieve object upwards, since.
* when the object is to be removed, it will get written to the
* snapshot at later epoch.
*/
for (i = iocb->epoch; i < epoch; i++) {
buffer = retrieve_object_from_snap(oid, i);
if (buffer)
break;
}
}
if (!buffer)
return SD_RES_NO_OBJ;
memcpy(iocb->buf, buffer, iocb->length);
free(buffer);
return SD_RES_SUCCESS;
}
if (!is_data_obj(oid))
flags &= ~O_DIRECT;
sprintf(path, "%s%016"PRIx64, obj_path, oid);
fd = open(path, flags);
if (fd < 0)
return err_to_sderr(oid, errno);
if (flock(fd, LOCK_SH) < 0) {
ret = SD_RES_EIO;
eprintf("%m\n");
goto out;
}
size = xpread(fd, iocb->buf, iocb->length, iocb->offset);
if (flock(fd, LOCK_UN) < 0) {
ret = SD_RES_EIO;
eprintf("%m\n");
goto out;
}
if (size != iocb->length) {
ret = SD_RES_EIO;
goto out;
}
out:
close(fd);
return ret;
}