Storvsc driver needs to ensure there are no 'holes' in the presented sg list (all segments in the middle of the list need to be of PAGE_SIZE). When a hole is detected storvsc driver creates a 'bounce sgl' without holes and copies data over with its own copy_{to,from}_bounce_buffer() functions. Scsi layer already has scsi_sg_copy_{to,from}_buffer() functions to linearize a list, the only difference is that already existent functions create a flat buffer instead of a new list but we can cope.
Reported-by: Radim Krčmář <rkrc...@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com> --- drivers/scsi/storvsc_drv.c | 281 ++++++--------------------------------------- 1 file changed, 36 insertions(+), 245 deletions(-) diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 40c43ae..31e8c67 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -393,8 +393,8 @@ static void storvsc_on_channel_callback(void *context); struct storvsc_cmd_request { struct scsi_cmnd *cmd; - unsigned int bounce_sgl_count; - struct scatterlist *bounce_sgl; + unsigned int bounce_len; + void *bounce_buf; struct hv_device *device; @@ -586,21 +586,6 @@ get_in_err: } -static void destroy_bounce_buffer(struct scatterlist *sgl, - unsigned int sg_count) -{ - int i; - struct page *page_buf; - - for (i = 0; i < sg_count; i++) { - page_buf = sg_page((&sgl[i])); - if (page_buf != NULL) - __free_page(page_buf); - } - - kfree(sgl); -} - static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count) { int i; @@ -628,199 +613,6 @@ static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count) return -1; } -static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl, - unsigned int sg_count, - unsigned int len, - int write) -{ - int i; - int num_pages; - struct scatterlist *bounce_sgl; - struct page *page_buf; - unsigned int buf_len = ((write == WRITE_TYPE) ? 0 : PAGE_SIZE); - - num_pages = ALIGN(len, PAGE_SIZE) >> PAGE_SHIFT; - - bounce_sgl = kcalloc(num_pages, sizeof(struct scatterlist), GFP_ATOMIC); - if (!bounce_sgl) - return NULL; - - sg_init_table(bounce_sgl, num_pages); - for (i = 0; i < num_pages; i++) { - page_buf = alloc_page(GFP_ATOMIC); - if (!page_buf) - goto cleanup; - sg_set_page(&bounce_sgl[i], page_buf, buf_len, 0); - } - - return bounce_sgl; - -cleanup: - destroy_bounce_buffer(bounce_sgl, num_pages); - return NULL; -} - -/* Assume the original sgl has enough room */ -static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl, - struct scatterlist *bounce_sgl, - unsigned int orig_sgl_count, - unsigned int bounce_sgl_count) -{ - int i; - int j = 0; - unsigned long src, dest; - unsigned int srclen, destlen, copylen; - unsigned int total_copied = 0; - unsigned long bounce_addr = 0; - unsigned long dest_addr = 0; - unsigned long flags; - struct scatterlist *cur_dest_sgl; - struct scatterlist *cur_src_sgl; - - local_irq_save(flags); - cur_dest_sgl = orig_sgl; - cur_src_sgl = bounce_sgl; - for (i = 0; i < orig_sgl_count; i++) { - dest_addr = (unsigned long) - kmap_atomic(sg_page(cur_dest_sgl)) + - cur_dest_sgl->offset; - dest = dest_addr; - destlen = cur_dest_sgl->length; - - if (bounce_addr == 0) - bounce_addr = (unsigned long)kmap_atomic( - sg_page(cur_src_sgl)); - - while (destlen) { - src = bounce_addr + cur_src_sgl->offset; - srclen = cur_src_sgl->length - cur_src_sgl->offset; - - copylen = min(srclen, destlen); - memcpy((void *)dest, (void *)src, copylen); - - total_copied += copylen; - cur_src_sgl->offset += copylen; - destlen -= copylen; - dest += copylen; - - if (cur_src_sgl->offset == cur_src_sgl->length) { - /* full */ - kunmap_atomic((void *)bounce_addr); - j++; - - /* - * It is possible that the number of elements - * in the bounce buffer may not be equal to - * the number of elements in the original - * scatter list. Handle this correctly. - */ - - if (j == bounce_sgl_count) { - /* - * We are done; cleanup and return. - */ - kunmap_atomic((void *)(dest_addr - - cur_dest_sgl->offset)); - local_irq_restore(flags); - return total_copied; - } - - /* if we need to use another bounce buffer */ - if (destlen || i != orig_sgl_count - 1) { - cur_src_sgl = sg_next(cur_src_sgl); - bounce_addr = (unsigned long) - kmap_atomic( - sg_page(cur_src_sgl)); - } - } else if (destlen == 0 && i == orig_sgl_count - 1) { - /* unmap the last bounce that is < PAGE_SIZE */ - kunmap_atomic((void *)bounce_addr); - } - } - - kunmap_atomic((void *)(dest_addr - cur_dest_sgl->offset)); - cur_dest_sgl = sg_next(cur_dest_sgl); - } - - local_irq_restore(flags); - - return total_copied; -} - -/* Assume the bounce_sgl has enough room ie using the create_bounce_buffer() */ -static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl, - struct scatterlist *bounce_sgl, - unsigned int orig_sgl_count) -{ - int i; - int j = 0; - unsigned long src, dest; - unsigned int srclen, destlen, copylen; - unsigned int total_copied = 0; - unsigned long bounce_addr = 0; - unsigned long src_addr = 0; - unsigned long flags; - struct scatterlist *cur_src_sgl; - struct scatterlist *cur_dest_sgl; - - local_irq_save(flags); - - cur_src_sgl = orig_sgl; - cur_dest_sgl = bounce_sgl; - - for (i = 0; i < orig_sgl_count; i++) { - src_addr = (unsigned long) - kmap_atomic(sg_page(cur_src_sgl)) + - cur_src_sgl->offset; - src = src_addr; - srclen = cur_src_sgl->length; - - if (bounce_addr == 0) - bounce_addr = (unsigned long) - kmap_atomic(sg_page(cur_dest_sgl)); - - while (srclen) { - /* assume bounce offset always == 0 */ - dest = bounce_addr + cur_dest_sgl->length; - destlen = PAGE_SIZE - cur_dest_sgl->length; - - copylen = min(srclen, destlen); - memcpy((void *)dest, (void *)src, copylen); - - total_copied += copylen; - cur_dest_sgl->length += copylen; - srclen -= copylen; - src += copylen; - - if (cur_dest_sgl->length == PAGE_SIZE) { - /* full..move to next entry */ - kunmap_atomic((void *)bounce_addr); - bounce_addr = 0; - j++; - } - - /* if we need to use another bounce buffer */ - if (srclen && bounce_addr == 0) { - cur_dest_sgl = sg_next(cur_dest_sgl); - bounce_addr = (unsigned long) - kmap_atomic( - sg_page(cur_dest_sgl)); - } - - } - - kunmap_atomic((void *)(src_addr - cur_src_sgl->offset)); - cur_src_sgl = sg_next(cur_src_sgl); - } - - if (bounce_addr) - kunmap_atomic((void *)bounce_addr); - - local_irq_restore(flags); - - return total_copied; -} - static void handle_sc_creation(struct vmbus_channel *new_sc) { struct hv_device *device = new_sc->primary_channel->device_obj; @@ -1171,14 +963,11 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request) host = stor_dev->host; vm_srb = &cmd_request->vstor_packet.vm_srb; - if (cmd_request->bounce_sgl_count) { + if (cmd_request->bounce_len) { if (vm_srb->data_in == READ_TYPE) - copy_from_bounce_buffer(scsi_sglist(scmnd), - cmd_request->bounce_sgl, - scsi_sg_count(scmnd), - cmd_request->bounce_sgl_count); - destroy_bounce_buffer(cmd_request->bounce_sgl, - cmd_request->bounce_sgl_count); + scsi_sg_copy_from_buffer(scmnd, cmd_request->bounce_buf, + cmd_request->bounce_len); + kfree(cmd_request->bounce_buf); } scmnd->result = vm_srb->scsi_status; @@ -1694,48 +1483,51 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd) if (sg_count) { /* check if we need to bounce the sgl */ if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1) { - cmd_request->bounce_sgl = - create_bounce_buffer(sgl, sg_count, - length, - vm_srb->data_in); - if (!cmd_request->bounce_sgl) + cmd_request->bounce_buf = kmalloc(length, GFP_ATOMIC); + if (!cmd_request->bounce_buf) return SCSI_MLQUEUE_HOST_BUSY; - cmd_request->bounce_sgl_count = - ALIGN(length, PAGE_SIZE) >> PAGE_SHIFT; + cmd_request->bounce_len = length; if (vm_srb->data_in == WRITE_TYPE) - copy_to_bounce_buffer(sgl, - cmd_request->bounce_sgl, sg_count); + scsi_sg_copy_to_buffer(scmnd, + cmd_request->bounce_buf, + cmd_request->bounce_len); - sgl = cmd_request->bounce_sgl; - sg_count = cmd_request->bounce_sgl_count; + sg_count = ALIGN(length, PAGE_SIZE) >> PAGE_SHIFT; } - if (sg_count > MAX_PAGE_BUFFER_COUNT) { - payload_sz = (sg_count * sizeof(void *) + sizeof(struct vmbus_packet_mpb_array)); payload = kmalloc(payload_sz, GFP_ATOMIC); if (!payload) { - if (cmd_request->bounce_sgl_count) - destroy_bounce_buffer( - cmd_request->bounce_sgl, - cmd_request->bounce_sgl_count); - - return SCSI_MLQUEUE_DEVICE_BUSY; + if (cmd_request->bounce_len) + kfree(cmd_request->bounce_buf); + return SCSI_MLQUEUE_DEVICE_BUSY; } } payload->range.len = length; - payload->range.offset = sgl[0].offset; - cur_sgl = sgl; - for (i = 0; i < sg_count; i++) { - payload->range.pfn_array[i] = - page_to_pfn(sg_page((cur_sgl))); - cur_sgl = sg_next(cur_sgl); + if (!cmd_request->bounce_len) { + payload->range.offset = sgl[0].offset; + + cur_sgl = sgl; + for (i = 0; i < sg_count; i++) { + payload->range.pfn_array[i] = + page_to_pfn(sg_page((cur_sgl))); + cur_sgl = sg_next(cur_sgl); + } + } else { + payload->range.offset = (unsigned long) + cmd_request->bounce_buf & ~PAGE_MASK; + + for (i = 0; i < sg_count; i++) + payload->range.pfn_array[i] = + virt_to_phys(cmd_request->bounce_buf + + i * PAGE_SIZE) + >> PAGE_SHIFT; } } else if (scsi_sglist(scmnd)) { @@ -1755,9 +1547,8 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd) if (ret == -EAGAIN) { /* no more space */ - if (cmd_request->bounce_sgl_count) - destroy_bounce_buffer(cmd_request->bounce_sgl, - cmd_request->bounce_sgl_count); + if (cmd_request->bounce_len) + kfree(cmd_request->bounce_buf); return SCSI_MLQUEUE_DEVICE_BUSY; } -- 2.4.3 -- 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/