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rbd: define zero_pages()

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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.

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@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2013-04-19 15:34:50 -05:00 committed by Sage Weil
parent b454e36d26
commit b9434c5b43
1 changed files with 47 additions and 8 deletions
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55
drivers/block/rbd.c
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@ -970,6 +970,37 @@ 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);
}