On 04/22/2013 03:05 AM, Josh Durgin wrote: > On 04/19/2013 03:50 PM, Alex Elder wrote: >> Define a new function zero_pages() that zeroes a range of memory >> defined by a page array, along the lines of zero_bio_chain(). It >> saves and the irq flags like bvec_kmap_irq() does, though I'm not >> sure at this point that it's necessary. > > It doesn't seem necessary to me. I don't see anything else doing > an irq save+restore around a k(un)map_atomic. I'm going to leave it in for now. I also wonder whether I need I need a flush_dcache_page() in there before the unmap. For x86 CPUs it's moot but for portability I'd like to do it right while the code is fresh in mind. http://tracker.ceph.com/issues/4777 -Alex > Other than that, looks good. > Reviewed-by: Josh Durgin <josh.durgin@xxxxxxxxxxx> > >> Update rbd_img_obj_request_read_callback() to use the new function >> if the object request contains page rather than bio data. >> >> For the moment, only bio data is used for osd READ ops. >> >> Signed-off-by: Alex Elder <elder@xxxxxxxxxxx> >> --- >> drivers/block/rbd.c | 55 >> +++++++++++++++++++++++++++++++++++++++++++-------- >> 1 file changed, 47 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c >> index 894af4f..ac9abab 100644 >> --- a/drivers/block/rbd.c >> +++ b/drivers/block/rbd.c >> @@ -971,6 +971,37 @@ static void zero_bio_chain(struct bio *chain, int >> start_ofs) >> } >> >> /* >> + * similar to zero_bio_chain(), zeros data defined by a page array, >> + * starting at the given byte offset from the start of the array and >> + * continuing up to the given end offset. The pages array is >> + * assumed to be big enough to hold all bytes up to the end. >> + */ >> +static void zero_pages(struct page **pages, u64 offset, u64 end) >> +{ >> + struct page **page = &pages[offset >> PAGE_SHIFT]; >> + >> + rbd_assert(end > offset); >> + rbd_assert(end - offset <= (u64)SIZE_MAX); >> + while (offset < end) { >> + size_t page_offset; >> + size_t length; >> + unsigned long flags; >> + void *kaddr; >> + >> + page_offset = (size_t)(offset & ~PAGE_MASK); >> + length = min(PAGE_SIZE - page_offset, (size_t)(end - offset)); >> + local_irq_save(flags); >> + kaddr = kmap_atomic(*page); >> + memset(kaddr + page_offset, 0, length); >> + kunmap_atomic(kaddr); >> + local_irq_restore(flags); >> + >> + offset += length; >> + page++; >> + } >> +} >> + >> +/* >> * Clone a portion of a bio, starting at the given byte offset >> * and continuing for the number of bytes indicated. >> */ >> @@ -1352,9 +1383,12 @@ static bool img_request_layered_test(struct >> rbd_img_request *img_request) >> static void >> rbd_img_obj_request_read_callback(struct rbd_obj_request *obj_request) >> { >> + u64 xferred = obj_request->xferred; >> + u64 length = obj_request->length; >> + >> dout("%s: obj %p img %p result %d %llu/%llu\n", __func__, >> obj_request, obj_request->img_request, obj_request->result, >> - obj_request->xferred, obj_request->length); >> + xferred, length); >> /* >> * ENOENT means a hole in the image. We zero-fill the >> * entire length of the request. A short read also implies >> @@ -1362,15 +1396,20 @@ rbd_img_obj_request_read_callback(struct >> rbd_obj_request *obj_request) >> * update the xferred count to indicate the whole request >> * was satisfied. >> */ >> - BUG_ON(obj_request->type != OBJ_REQUEST_BIO); >> + rbd_assert(obj_request->type != OBJ_REQUEST_NODATA); >> if (obj_request->result == -ENOENT) { >> - zero_bio_chain(obj_request->bio_list, 0); >> + if (obj_request->type == OBJ_REQUEST_BIO) >> + zero_bio_chain(obj_request->bio_list, 0); >> + else >> + zero_pages(obj_request->pages, 0, length); >> obj_request->result = 0; >> - obj_request->xferred = obj_request->length; >> - } else if (obj_request->xferred < obj_request->length && >> - !obj_request->result) { >> - zero_bio_chain(obj_request->bio_list, obj_request->xferred); >> - obj_request->xferred = obj_request->length; >> + obj_request->xferred = length; >> + } else if (xferred < length && !obj_request->result) { >> + if (obj_request->type == OBJ_REQUEST_BIO) >> + zero_bio_chain(obj_request->bio_list, xferred); >> + else >> + zero_pages(obj_request->pages, xferred, length); >> + obj_request->xferred = length; >> } >> obj_request_done_set(obj_request); >> } >> > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
