Commit 662518b1 authored by Alex Elder's avatar Alex Elder
Browse files

rbd: update in-core header directly 



Now that rbd_header_from_disk() only fills in one-time fields once,
we can extend it slightly so it releases the other fields before
replacing their values.  This way there's no need to pass a
temporary buffer and then copy all the results in.  Just use the rbd
device header structure in rbd_header_from_disk() so its values get
updated directly.

Note that this means we need to take the header semaphore at the
point we update things.  So pass the rbd_dev rather than the address
of its header as its first argument to rbd_header_from_disk(), and
have it return an error code.

As a result, rbd_dev_v1_header_read() does all the work,
rbd_read_header() becomes unnecessary, and rbd_dev_v1_refresh()
becomes a very simple wrapper.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent bb23e37a

drivers/block/rbd.c

+27 −71
Original line number Diff line number Diff line
@@ -730,9 +730,10 @@ static bool rbd_dev_ondisk_valid(struct rbd_image_header_ondisk *ondisk) 
 * Fill an rbd image header with information from the given format 1

 * on-disk header.

 */

static int rbd_header_from_disk(struct rbd_image_header *header,

static int rbd_header_from_disk(struct rbd_device *rbd_dev,

				 struct rbd_image_header_ondisk *ondisk)

{

	struct rbd_image_header *header = &rbd_dev->header;

	bool first_time = header->object_prefix == NULL;

	struct ceph_snap_context *snapc;

	char *object_prefix = NULL;
@@ -802,6 +803,7 @@ static int rbd_header_from_disk(struct rbd_image_header *header, 


	/* We won't fail any more, fill in the header */



	down_write(&rbd_dev->header_rwsem);

	if (first_time) {

		header->object_prefix = object_prefix;

		header->obj_order = ondisk->options.order;
@@ -811,6 +813,10 @@ static int rbd_header_from_disk(struct rbd_image_header *header, 
		header->stripe_unit = 0;

		header->stripe_count = 0;

		header->features = 0;

	} else {

		ceph_put_snap_context(header->snapc);

		kfree(header->snap_names);

		kfree(header->snap_sizes);

	}



	/* The remaining fields always get updated (when we refresh) */
@@ -820,6 +826,14 @@ static int rbd_header_from_disk(struct rbd_image_header *header, 
	header->snap_names = snap_names;

	header->snap_sizes = snap_sizes;



	/* Make sure mapping size is consistent with header info */



	if (rbd_dev->spec->snap_id == CEPH_NOSNAP || first_time)

		if (rbd_dev->mapping.size != header->image_size)

			rbd_dev->mapping.size = header->image_size;



	up_write(&rbd_dev->header_rwsem);



	return 0;

out_2big:

	ret = -EIO;
@@ -3032,17 +3046,11 @@ out: 
}



/*

 * Read the complete header for the given rbd device.

 *

 * Returns a pointer to a dynamically-allocated buffer containing

 * the complete and validated header.  Caller can pass the address

 * of a variable that will be filled in with the version of the

 * header object at the time it was read.

 *

 * Returns a pointer-coded errno if a failure occurs.

 * Read the complete header for the given rbd device.  On successful

 * return, the rbd_dev->header field will contain up-to-date

 * information about the image.

 */

static struct rbd_image_header_ondisk *

rbd_dev_v1_header_read(struct rbd_device *rbd_dev)

static int rbd_dev_v1_header_read(struct rbd_device *rbd_dev)

{

	struct rbd_image_header_ondisk *ondisk = NULL;

	u32 snap_count = 0;
@@ -3067,22 +3075,22 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev) 
		size += names_size;

		ondisk = kmalloc(size, GFP_KERNEL);

		if (!ondisk)

			return ERR_PTR(-ENOMEM);

			return -ENOMEM;



		ret = rbd_obj_read_sync(rbd_dev, rbd_dev->header_name,

				       0, size, ondisk);

		if (ret < 0)

			goto out_err;

			goto out;

		if ((size_t)ret < size) {

			ret = -ENXIO;

			rbd_warn(rbd_dev, "short header read (want %zd got %d)",

				size, ret);

			goto out_err;

			goto out;

		}

		if (!rbd_dev_ondisk_valid(ondisk)) {

			ret = -ENXIO;

			rbd_warn(rbd_dev, "invalid header");

			goto out_err;

			goto out;

		}



		names_size = le64_to_cpu(ondisk->snap_names_len);
@@ -3090,27 +3098,8 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev) 
		snap_count = le32_to_cpu(ondisk->snap_count);

	} while (snap_count != want_count);



	return ondisk;



out_err:

	kfree(ondisk);



	return ERR_PTR(ret);

}



/*

 * reload the ondisk the header

 */

static int rbd_read_header(struct rbd_device *rbd_dev,

			   struct rbd_image_header *header)

{

	struct rbd_image_header_ondisk *ondisk;

	int ret;



	ondisk = rbd_dev_v1_header_read(rbd_dev);

	if (IS_ERR(ondisk))

		return PTR_ERR(ondisk);

	ret = rbd_header_from_disk(header, ondisk);

	ret = rbd_header_from_disk(rbd_dev, ondisk);

out:

	kfree(ondisk);



	return ret;
@@ -3121,40 +3110,7 @@ static int rbd_read_header(struct rbd_device *rbd_dev, 
 */

static int rbd_dev_v1_refresh(struct rbd_device *rbd_dev)

{

	int ret;

	struct rbd_image_header h;



	memset(&h, 0, sizeof (h));

	ret = rbd_read_header(rbd_dev, &h);

	if (ret < 0)

		return ret;



	down_write(&rbd_dev->header_rwsem);



	/* Update image size, and check for resize of mapped image */

	rbd_dev->header.image_size = h.image_size;

	if (rbd_dev->spec->snap_id == CEPH_NOSNAP)

		if (rbd_dev->mapping.size != rbd_dev->header.image_size)

			rbd_dev->mapping.size = rbd_dev->header.image_size;



	/* rbd_dev->header.object_prefix shouldn't change */

	kfree(rbd_dev->header.snap_sizes);

	kfree(rbd_dev->header.snap_names);

	/* osd requests may still refer to snapc */

	ceph_put_snap_context(rbd_dev->header.snapc);



	rbd_dev->header.image_size = h.image_size;

	rbd_dev->header.snapc = h.snapc;

	rbd_dev->header.snap_names = h.snap_names;

	rbd_dev->header.snap_sizes = h.snap_sizes;

	/* Free the extra copy of the object prefix */

	if (strcmp(rbd_dev->header.object_prefix, h.object_prefix))

		rbd_warn(rbd_dev, "object prefix changed (ignoring)");

	kfree(h.object_prefix);



	up_write(&rbd_dev->header_rwsem);



	return ret;

	return rbd_dev_v1_header_read(rbd_dev);

}



/*
@@ -4517,7 +4473,7 @@ static int rbd_dev_v1_probe(struct rbd_device *rbd_dev) 


	/* Populate rbd image metadata */



	ret = rbd_read_header(rbd_dev, &rbd_dev->header);

	ret = rbd_dev_v1_header_read(rbd_dev);

	if (ret < 0)

		goto out_err;

CRA Git | Maintained and supported by SUSTech CRA and CCSE