On Friday 03 September 2010, Ken'ichi Ohmichi wrote: > Thank you for investigating. > IIUC, this problem may happen if using "cp" command instead of > makedumpfile. > > Does the following method in generic_file_llseek_unlocked() fail ? > Is inode->i_sb->s_maxbytes too small ? > > 65 if (offset < 0 || offset > inode->i_sb->s_maxbytes) > 66 return -EINVAL; > Yes, that is the main difference between generic_file_llseek and default_llseek, besides the use of the BKL. We have discussed changing this before, but so far without a conclusive answer. If we can come up with a better test here, we might be able to just kill default_llseek in favor of generic_file_llseek. The problem is handling the special cases here. For a /proc file, s_maxbytes is probably always zero, but that could be changed, same for file systems using get_sb_single. For some reason, get_sb_pseudo sets does set s_maxbytes while get_sb_single/simple_fill_super does not. Character devices are also special, because the s_maxbytes for them AFAICT is the one from the file system holding the device, so using generic_file_llseek would definitely be incorrect for them. Arnd
