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rbd: define image request originator flag 

Define a flag indicating whether an image request originated from
the Linux block layer (from blk_fetch_request()) or whether it was
initiated in order to satisfy an object request for a child image
of a layered rbd device.  For image requests initiated by objects of
child images we'll save a pointer to the object request rather than
the Linux block request.

For now, only block requests are used.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2013-01-24 16:13:36 -06:00 committed by Sage Weil
parent 0c425248e0
commit 9849e98636
1 changed files with 26 additions and 5 deletions
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31
drivers/block/rbd.c
View File

@ -203,18 +203,22 @@ struct rbd_obj_request {
};
enum img_req_flags {
IMG_REQ_WRITE, /* read = 0, write = 1 */
IMG_REQ_WRITE, /* I/O direction: read = 0, write = 1 */
IMG_REQ_CHILD, /* initiator: block = 0, child image = 1 */
};
struct rbd_img_request {
struct request *rq;
struct rbd_device *rbd_dev;
u64 offset; /* starting image byte offset */
u64 length; /* byte count from offset */
unsigned long flags;
union {
u64 snap_id; /* for reads */
struct ceph_snap_context *snapc; /* for writes */
u64 snap_id; /* for reads */
};
union {
struct request *rq; /* block request */
struct rbd_obj_request *obj_request; /* obj req initiator */
};
spinlock_t completion_lock;/* protects next_completion */
u32 next_completion;
@ -1231,6 +1235,18 @@ static bool img_request_write_test(struct rbd_img_request *img_request)
return test_bit(IMG_REQ_WRITE, &img_request->flags) != 0;
}
static void img_request_child_set(struct rbd_img_request *img_request)
{
set_bit(IMG_REQ_CHILD, &img_request->flags);
smp_mb();
}
static bool img_request_child_test(struct rbd_img_request *img_request)
{
smp_mb();
return test_bit(IMG_REQ_CHILD, &img_request->flags) != 0;
}
static void
rbd_img_obj_request_read_callback(struct rbd_obj_request *obj_request)
{
@ -1499,7 +1515,8 @@ static void rbd_obj_request_destroy(struct kref *kref)
static struct rbd_img_request *rbd_img_request_create(
struct rbd_device *rbd_dev,
u64 offset, u64 length,
bool write_request)
bool write_request,
bool child_request)
{
struct rbd_img_request *img_request;
struct ceph_snap_context *snapc = NULL;
@ -1530,6 +1547,8 @@ static struct rbd_img_request *rbd_img_request_create(
} else {
img_request->snap_id = rbd_dev->spec->snap_id;
}
if (child_request)
img_request_child_set(img_request);
spin_lock_init(&img_request->completion_lock);
img_request->next_completion = 0;
img_request->callback = NULL;
@ -1578,7 +1597,9 @@ static void rbd_img_obj_callback(struct rbd_obj_request *obj_request)
dout("%s: img %p obj %p\n", __func__, img_request, obj_request);
rbd_assert(img_request != NULL);
rbd_assert(!img_request_child_test(img_request))
rbd_assert(img_request->rq != NULL);
rbd_assert(img_request->obj_request_count > 0);
rbd_assert(which != BAD_WHICH);
rbd_assert(which < img_request->obj_request_count);
@ -2012,7 +2033,7 @@ static void rbd_request_fn(struct request_queue *q)
result = -ENOMEM;
img_request = rbd_img_request_create(rbd_dev, offset, length,
write_request);
write_request, false);
if (!img_request)
goto end_request;