It works well for me too. ---------------------------------------- > From: chris.mason@xxxxxxxxxx > To: chris.mason@xxxxxxxxxx > CC: xin.zhong@xxxxxxxxx; mitch.harder@xxxxxxxxxxxxxxxx; thierryzhong@xxxxxxxxxxx; linux-btrfs@xxxxxxxxxxxxxxx > Subject: RE: [PATCH] btrfs file write debugging patch > Date: Fri, 4 Mar 2011 07:19:39 -0500 > > Excerpts from Chris Mason's message of 2011-03-03 20:51:55 -0500: > > Excerpts from Zhong, Xin's message of 2011-03-02 05:58:49 -0500: > > > It seems that if we give an unaligned address to btrfs write and the buffer reside on more than 2 pages. It will trigger this bug. > > > If we give an aligned address to btrfs write, it works well no matter how many pages are given. > > > > > > I use ftrace to observe it. It seems iov_iter_fault_in_readable do not trigger pagefault handling when the address is not aligned. I do not quite understand the reason behind it. But the solution should be to process the page one by one. And that's also what generic file write routine does. > > > > > > Any suggestion are welcomed. Thanks! > > > > Great job guys. I'm using this on top of my debugging patch. It passes > > the unaligned test but I'll give it a real run tonight and look for > > other problems. > > > > (This is almost entirely untested, please don't use it quite yet) > > > > > -chris > > > > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c > > index 89a6a26..6a44add 100644 > > --- a/fs/btrfs/file.c > > +++ b/fs/btrfs/file.c > > @@ -1039,6 +1038,14 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, > > > > copied = btrfs_copy_from_user(pos, num_pages, > > write_bytes, pages, &i); > > + > > + /* > > + * if we have trouble faulting in the pages, fall > > + * back to one page at a time > > + */ > > + if (copied < write_bytes) > > + nrptrs = 1; > > + > > if (copied == 0) > > dirty_pages = 0; > > else > > Ok, this is working well for me. Anyone see any problems with it? > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" 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-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
