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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
