Namjae Jeon <linkinjeon@xxxxxxxxx> writes: >>> /* fat_get_cluster() assumes the requested blocknr isn't truncated. */ >>> down_read(&MSDOS_I(mapping->host)->truncate_lock); >>> + /* To get block number beyond file size in fallocated region */ >>> + atomic_set(&MSDOS_I(mapping->host)->beyond_isize, 1); >>> blocknr = generic_block_bmap(mapping, block, fat_get_block); >>> + atomic_set(&MSDOS_I(mapping->host)->beyond_isize, 0); >>> up_read(&MSDOS_I(mapping->host)->truncate_lock); >> >> This is racy. While user is using bmap, kernel can allocate new blocks. >> We should use another function for this. > I understand that fat can map fallocated blocks in read case while > user is using bmap. > But I can not find the case allocate new blocks. > If I am missing something, Could you please elaborate more ? > Is it a case of _bmap request returning the block number for block > allocated in parallel write path ? ->beyond_size is global for inode. So, write(2) path on same inode with bmap() also can see 1 set by bmap() while another process is using bmap(). -- OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
