On Mon, Mar 08, 2010 at 03:35:37AM -0500, Mikulas Patocka wrote: > Hi > > That patch with limits->max_segments = 1; is wrong. It fixes this bug > sometimes and sometimes not. > > The problem is, if someone attempts to create a bio with two vector > entries, the first maps the last sector contained in some page and the > second maps the first sector of the next physical page: it has one > segment, it has size <= PAGE_SIZE, but it still may cross raid stripe and > the raid driver will reject it. Now that you put it that way ;) You are right. My asumption that "single segment" was equalvalent in practice with "single bvec" does not hold true in that case. Then, what about adding seg_boundary_mask restrictions as well? max_sectors = PAGE_SIZE >> 9; max_segments = 1; seg_boundary_mask = PAGE_SIZE -1; or some such. > > > This is not the first time this has been patched, btw. > > > See https://bugzilla.redhat.com/show_bug.cgi?id=440093 > > > and the patch by Mikulas: > > > https://bugzilla.redhat.com/attachment.cgi?id=342638&action=diff > > Look at this patch, it is the proper way how to fix it: create a > merge_bvec_fn that reject more than one biovec entry. If adding seg_boundary_mask is still not sufficient, lets merge that patch instead? Why has it been dropped, respectively never been merged? It became obsolete for dm-linear by 7bc3447b, but in general the bug is still there, or am I missing something? Lars -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
