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.
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);
}
--
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