On Wed, Nov 18, Alan Cox wrote: > > Using the BKL in llseek() does not protect the inode's i_size from > > modification since the i_size is protected by a seqlock nowadays. Since > > default_llseek() is already using the i_size_read() wrapper it is not the > > BKL which is serializing the access here. > > The access to file->f_pos is not protected by the BKL either since its > > access in vfs_write()/vfs_read() is not protected by any lock. If the BKL > > is not protecting anything here it can clearly get removed. > > No. Your logic is flawed > > The BKL is protected something here - it protects the change of offset > with respect to other BKL users within drivers. The question is what if > anything in any other driver code depends upon the BKL and uses it to > protect f_pos. Probably very little if anything but a grep for f_pos > through the drivers might not be a bad idea before assuming this. Very > few touch f_pos except in their own llseek method. As I said, f_pos is changed without holding BKL in the VFS already. Therefore even if the driver tries to protect f_pos by holding the BKL it is racing against concurrent read()/write() anyway on f_pos. Regards, Jan -- Jan Blunck <jblunck@xxxxxxx> -- 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
