LittleFS free space

garfius · June 11, 2025, 1:14pm

I just ask wether littlefs on waveshare_rp2040_pizero shall be configured or else, because when i do:

FSInfo *info;
LittleFS.info(*info);

The value at info->totalBytes is always default value=537140992
So, i am afraid i will end up writing ouside real area.

My board definition:

[env:pico_nodebug_16MB]
platform = https://github.com/maxgerhardt/platform-raspberrypi.git 
board = waveshare_rp2040_pizero
framework = arduino
board_build.core = earlephilhower
board_build.filesystem_size = 5m
board_build.filesystem = littlefs
board_build.partitions = partitions.csv
build_flags = -O3

Thanks in advence, best regards.

sivar2311 · June 11, 2025, 1:27pm

LittleFS.info takes a reference to a FSInfo struct as parameter. See

github.com/earlephilhower/arduino-pico

libraries%2FLittleFS%2Fsrc%2FLittleFS.h

master


      
                  return false;
              }
              int rc = lfs_rename(&_lfs, pathFrom, pathTo);
              if (rc != 0) {
                  DEBUGV("lfs_rename: rc=%d, from=`%s`, to=`%s`\n", rc, pathFrom, pathTo);
                  return false;
              }
              return true;
          }
          
          bool info(FSInfo& info) override {
              if (!_mounted) {
                  return false;
              }
              info.blockSize = _blockSize;
              info.pageSize = _pageSize;
              info.maxOpenFiles = _maxOpenFds;
              info.maxPathLength = LFS_NAME_MAX;
              info.totalBytes = _size;
              info.usedBytes = _getUsedBlocks() * _blockSize;
              return true;

Therefore the code must be

FSInfo info;
LittleFS.info(info);

A wonder why no crash happened.

maxgerhardt · June 11, 2025, 8:14pm

If we want to be really pedantic we can also zero-init the struct first, use that as the FSInfo& (“reference”, aka just a variable name) and compute the free (approximate) space, or rather the size of the unused blocks as:

FSInfo info {};
LittleFS.info(info);
Serial.println("LittleFS free bytes: " + String(info.totalBytes - info.usedBytes));