On Thu, Sep 21, 2017 at 03:36:10PM +0200, Christoph Hellwig wrote: > On Wed, Sep 20, 2017 at 04:08:24PM -0700, Darrick J. Wong wrote: > > > I'm still wondering why we allocate a potentially large getbmapx buffer, > > > fill it out, and only then format the results to userspace? I think > > > getbmap (the ioctl) is now the only user of these functions, so can't > > > we just call the formatter directly from _getbmap_report_one and > > > _getbmap_report_hole, like what getfsmap does? > > > > > > (I also feel like I've asked this before, so apologies if I'm merely > > > forgetting the answer.) > > > > Oh right, it's because we have the inode locked, and copying things to > > userspace could incur a page fault, which we can't risk with the inode > > locked because some malicious person could create a fragmented file with > > a bmap request header at the start of the file, mmap the file, and call > > bmap on the fragmented file with the pointer being the mmap region. > > Yes. > > Can I get a Reviewed-by: tag now? :) Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
