[PATCH 03/11] rbd: kill incore snap_names_len

[Alex Elder <elder@inktank.com>]

The only thing the on-disk snap_names_len field is used for is to
size the buffer allocated to hold a copy of the snapshot names for
an rbd image.

Don't bother saving it in the in-core rbd_image_header structure.
Just use a local variable to hold the required buffer size while
it's needed.

Move the code that actually copies the snapshot names up closer
to where the required length is saved.

Signed-off-by: Alex Elder <elder@inktank.com>
---
 drivers/block/rbd.c |   19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index a8a4cba..7b3d861 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -81,7 +81,6 @@ struct rbd_image_header {
 	__u8 crypt_type;
 	__u8 comp_type;
 	struct ceph_snap_context *snapc;
-	u64 snap_names_len;
 	u32 total_snaps;

 	char *snap_names;
@@ -534,12 +533,14 @@ static int rbd_header_from_disk(struct
rbd_image_header *header,
 	header->object_prefix[len] = '\0';

 	if (snap_count) {
-		header->snap_names_len = le64_to_cpu(ondisk->snap_names_len);
-		BUG_ON(header->snap_names_len > (u64) SIZE_MAX);
-		header->snap_names = kmalloc(header->snap_names_len,
-					     GFP_KERNEL);
+		u64 snap_names_len = le64_to_cpu(ondisk->snap_names_len);
+
+		BUG_ON(snap_names_len > (u64) SIZE_MAX);
+		header->snap_names = kmalloc(snap_names_len, GFP_KERNEL);
 		if (!header->snap_names)
 			goto out_err;
+		memcpy(header->snap_names, &ondisk->snaps[snap_count],
+			snap_names_len);

 		size = snap_count * sizeof (*header->snap_sizes);
 		header->snap_sizes = kmalloc(size, GFP_KERNEL);
@@ -547,7 +548,6 @@ static int rbd_header_from_disk(struct
rbd_image_header *header,
 			goto out_err;
 	} else {
 		WARN_ON(ondisk->snap_names_len);
-		header->snap_names_len = 0;
 		header->snap_names = NULL;
 		header->snap_sizes = NULL;
 	}
@@ -579,10 +579,6 @@ static int rbd_header_from_disk(struct
rbd_image_header *header,
 			header->snap_sizes[i] =
 				le64_to_cpu(ondisk->snaps[i].image_size);
 		}
-
-		/* copy snapshot names */
-		memcpy(header->snap_names, &ondisk->snaps[snap_count],
-			header->snap_names_len);
 	}

 	return 0;
@@ -592,7 +588,6 @@ out_err:
 	header->snap_sizes = NULL;
 	kfree(header->snap_names);
 	header->snap_names = NULL;
-	header->snap_names_len = 0;
 	kfree(header->object_prefix);
 	header->object_prefix = NULL;

@@ -660,7 +655,6 @@ static void rbd_header_free(struct rbd_image_header
*header)
 	header->snap_sizes = NULL;
 	kfree(header->snap_names);
 	header->snap_names = NULL;
-	header->snap_names_len = 0;
 	ceph_put_snap_context(header->snapc);
 	header->snapc = NULL;
 }
@@ -1800,7 +1794,6 @@ static int __rbd_refresh_header(struct rbd_device
*rbd_dev, u64 *hver)
 	rbd_dev->header.total_snaps = h.total_snaps;
 	rbd_dev->header.snapc = h.snapc;
 	rbd_dev->header.snap_names = h.snap_names;
-	rbd_dev->header.snap_names_len = h.snap_names_len;
 	rbd_dev->header.snap_sizes = h.snap_sizes;
 	/* Free the extra copy of the object prefix */
 	WARN_ON(strcmp(rbd_dev->header.object_prefix, h.object_prefix));
-- 
1.7.9.5