Andrew, can you please send this on to Linus and -stable ASAP? It's causing massive problems for our users.
On Thu, Aug 12, 2010 at 04:50:59PM -0400, Jeff Moyer wrote: > Hi, > > commit c2c6ca4 (direct-io: do not merge logically non-contiguous > requests) introduced a bug whereby all O_DIRECT I/Os were submitted a > page at a time to the block layer. The problem is that the code > expected dio->block_in_file to correspond to the current page in the > dio. In fact, it corresponds to the previous page submitted via > submit_page_section. This was purely an oversight, as the > dio->cur_page_fs_offset field was introduced for just this purpose. > This patch simply uses the correct variable when calculating whether > there is a mismatch between contiguous logical blocks and contiguous > physical blocks (as described in the comments). > > I also switched the if conditional following this check to an else if, > to ensure that we never call dio_bio_submit twice for the same dio (in > theory, this should not happen, anyway). > > I've tested this by running blktrace and verifying that a 64KB I/O was > submitted as a single I/O. I also ran the patched kernel through > xfstests' aio tests using xfs, ext4 (with 1k and 4k block sizes) and > btrfs and verified that there were no regressions as compared to an > unpatched kernel. > > Comments, as always, are welcome. > > Cheers, > Jeff > > Signed-off-by: Jeff Moyer <[email protected]> > Acked-by: Josef Bacik <[email protected]> > > diff --git a/fs/direct-io.c b/fs/direct-io.c > index 7600aac..445901c 100644 > --- a/fs/direct-io.c > +++ b/fs/direct-io.c > @@ -632,7 +632,7 @@ static int dio_send_cur_page(struct dio *dio) > int ret = 0; > > if (dio->bio) { > - loff_t cur_offset = dio->block_in_file << dio->blkbits; > + loff_t cur_offset = dio->cur_page_fs_offset; > loff_t bio_next_offset = dio->logical_offset_in_bio + > dio->bio->bi_size; > > @@ -657,7 +657,7 @@ static int dio_send_cur_page(struct dio *dio) > * Submit now if the underlying fs is about to perform a > * metadata read > */ > - if (dio->boundary) > + else if (dio->boundary) > dio_bio_submit(dio); > } > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ ---end quoted text--- _______________________________________________ Btrfs-devel mailing list [email protected] http://oss.oracle.com/mailman/listinfo/btrfs-devel
