[PATCH] storvsc: get rid of homegrown copy_{to,from}_bounce_buffer()
Vitaly Kuznetsov
vkuznets at redhat.com
Tue Sep 22 16:27:50 UTC 2015
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 <rkrcmar at redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets at 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
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