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AP_Logger: File: take advantage of new optimal fsync API

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Now FATFS will always sync on 4K boundaries even if it gets misaligned
due to a short or forced write.

LittleFS behavior is verified identical.
This commit is contained in:
Thomas Watson 2025-02-16 12:33:00 -06:00 committed by Peter Barker
parent ed2c42ede2
commit ca3c2c7c72
1 changed files with 6 additions and 21 deletions
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27
libraries/AP_Logger/AP_Logger_File.cpp
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@ -987,9 +987,10 @@ void AP_Logger_File::io_timer(void)
return;
}
#if AP_FILESYSTEM_LITTLEFS_ENABLED && CONFIG_HAL_BOARD != HAL_BOARD_SITL
bool sync_block = AP::littlefs().sync_block(_write_fd, _write_offset, nbytes);
#endif // AP_FILESYSTEM_LITTLEFS_ENABLED
uint32_t bytes_until_fsync = AP::FS().bytes_until_fsync(_write_fd);
if (bytes_until_fsync > 0 && nbytes > bytes_until_fsync) {
nbytes = bytes_until_fsync; // write exactly enough to sync
}
ssize_t nwritten = AP::FS().write(_write_fd, head, nbytes);
last_io_operation = "";
@ -1016,28 +1017,12 @@ void AP_Logger_File::io_timer(void)
_write_offset += nwritten;
_writebuf.advance(nwritten);
/*
fsync on littlefs is extremely expensive (20% CPU on an H7) particularly because the
COW architecture can mean you end up copying a load of blocks. instead try and only sync
at the end of a block to avoid copying and minimise CPU. fsync is needed for the file
metadata (including size) to be updated
*/
#if CONFIG_HAL_BOARD != HAL_BOARD_SITL && CONFIG_HAL_BOARD_SUBTYPE != HAL_BOARD_SUBTYPE_LINUX_NONE
#if AP_FILESYSTEM_LITTLEFS_ENABLED
if (sync_block)
#endif // AP_FILESYSTEM_LITTLEFS_ENABLED
{
/*
the best strategy for minimizing corruption on microSD cards
seems to be to write in 4k chunks and fsync the file on each
chunk, ensuring the directory entry is updated after each
write.
*/
// we know nwritten > 0 so we won't sync if bytes_until_fsync == 0
if ((uint32_t)nwritten == bytes_until_fsync) {
last_io_operation = "fsync";
AP::FS().fsync(_write_fd);
last_io_operation = "";
}
#endif
#if AP_RTC_ENABLED && CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS
// ChibiOS does not update mtime on writes, so if we opened