4.1-stable review patch. If anyone has any objections, please let me know.
------------------ From: Mike Snitzer <snit...@redhat.com> commit bd4aaf8f9b85d6b2df3231fd62b219ebb75d3568 upstream. A DM regression on 32 bit systems was reported against v4.2-rc3 here: https://lkml.org/lkml/2015/7/29/401 Fix this by reverting both commit 1c220c69 ("dm: fix casting bug in dm_merge_bvec()") and 148e51ba ("dm: improve documentation and code clarity in dm_merge_bvec"). This combined revert is done to eliminate the possibility of a partial revert in stable@ kernels. In hindsight the correct fix, at the time 1c220c69 was applied to fix the regression that 148e51ba introduced, should've been to simply revert 148e51ba. Reported-by: Josh Boyer <jwbo...@fedoraproject.org> Tested-by: Adam Williamson <awill...@redhat.com> Acked-by: Joe Thornber <e...@redhat.com> Signed-off-by: Mike Snitzer <snit...@redhat.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/md/dm.c | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1719,7 +1719,8 @@ static int dm_merge_bvec(struct request_ struct mapped_device *md = q->queuedata; struct dm_table *map = dm_get_live_table_fast(md); struct dm_target *ti; - sector_t max_sectors, max_size = 0; + sector_t max_sectors; + int max_size = 0; if (unlikely(!map)) goto out; @@ -1732,18 +1733,10 @@ static int dm_merge_bvec(struct request_ * Find maximum amount of I/O that won't need splitting */ max_sectors = min(max_io_len(bvm->bi_sector, ti), - (sector_t) queue_max_sectors(q)); + (sector_t) BIO_MAX_SECTORS); max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size; - - /* - * FIXME: this stop-gap fix _must_ be cleaned up (by passing a sector_t - * to the targets' merge function since it holds sectors not bytes). - * Just doing this as an interim fix for stable@ because the more - * comprehensive cleanup of switching to sector_t will impact every - * DM target that implements a ->merge hook. - */ - if (max_size > INT_MAX) - max_size = INT_MAX; + if (max_size < 0) + max_size = 0; /* * merge_bvec_fn() returns number of bytes @@ -1751,13 +1744,13 @@ static int dm_merge_bvec(struct request_ * max is precomputed maximal io size */ if (max_size && ti->type->merge) - max_size = ti->type->merge(ti, bvm, biovec, (int) max_size); + max_size = ti->type->merge(ti, bvm, biovec, max_size); /* * If the target doesn't support merge method and some of the devices - * provided their merge_bvec method (we know this by looking for the - * max_hw_sectors that dm_set_device_limits may set), then we can't - * allow bios with multiple vector entries. So always set max_size - * to 0, and the code below allows just one page. + * provided their merge_bvec method (we know this by looking at + * queue_max_hw_sectors), then we can't allow bios with multiple vector + * entries. So always set max_size to 0, and the code below allows + * just one page. */ else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9) max_size = 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
