Failure on writing large files

[emillindq]

Hi and thank you for an amazing project!

I've noticed that master is broken when performance testing by writing to a large file. The following problem is also existing in v1.0.0 but happens after a much longer time.

My scenario is the following:

• 16GB SD-card
• MBR with one partition 1GB
• Formatted on Ubuntu using fdisk and mkfs.ext4
• Insert card into board running an ST MCU using SDIO interface.
• calling ext4_mbr_scan, ext4_mkfs_read_info, ext4_device_register, ext4_mount, ext4_recover, ext4_journal_start to mount it
• calling ext4_fopen2 and continuously ext4_fwrite with a buffer of 32768 bytes.

It works fine for a while but after about 20MB written, the block device write function gets called with an address outside of the SRAM of the MCU. After a little digging, size wraps around here because block_size * fblock_count becomes larger than size.

lwext4/src/ext4.c

Line 1952 in 58bcf89

size -= block_size * fblock_count;

I've tried with the provided ext4_mbr_write and ext4_mkfs but it's the same problem.