rbd: more cleanup in rbd_header_from_disk()

This just rearranges things a bit more in rbd_header_from_disk()
so that the snapshot sizes are initialized right after the buffer
to hold them is allocated and doing a little further consolidation
that follows from that.  Also adds a few simple comments.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 163fd85..145fbf6 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -520,6 +520,7 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
        u32 snap_count;
        size_t len;
        size_t size;
+       u32 i;
 
        memset(header, 0, sizeof (*header));
 
@@ -535,6 +536,8 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
        if (snap_count) {
                u64 snap_names_len = le64_to_cpu(ondisk->snap_names_len);
 
+               /* Save a copy of the snapshot names */
+
                if (snap_names_len > (u64) SIZE_MAX)
                        return -EIO;
                header->snap_names = kmalloc(snap_names_len, GFP_KERNEL);
@@ -549,10 +552,15 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
                memcpy(header->snap_names, &ondisk->snaps[snap_count],
                        snap_names_len);
 
+               /* Record each snapshot's size */
+
                size = snap_count * sizeof (*header->snap_sizes);
                header->snap_sizes = kmalloc(size, GFP_KERNEL);
                if (!header->snap_sizes)
                        goto out_err;
+               for (i = 0; i < snap_count; i++)
+                       header->snap_sizes[i] =
+                               le64_to_cpu(ondisk->snaps[i].image_size);
        } else {
                WARN_ON(ondisk->snap_names_len);
                header->snap_names = NULL;
@@ -565,6 +573,8 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
        header->comp_type = ondisk->options.comp_type;
        header->total_snaps = snap_count;
 
+       /* Allocate and fill in the snapshot context */
+
        size = sizeof (struct ceph_snap_context);
        size += snap_count * sizeof (header->snapc->snaps[0]);
        header->snapc = kzalloc(size, GFP_KERNEL);
@@ -574,19 +584,9 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
        atomic_set(&header->snapc->nref, 1);
        header->snapc->seq = le64_to_cpu(ondisk->snap_seq);
        header->snapc->num_snaps = snap_count;
-
-       /* Fill in the snapshot information */
-
-       if (snap_count) {
-               u32 i;
-
-               for (i = 0; i < snap_count; i++) {
-                       header->snapc->snaps[i] =
-                               le64_to_cpu(ondisk->snaps[i].id);
-                       header->snap_sizes[i] =
-                               le64_to_cpu(ondisk->snaps[i].image_size);
-               }
-       }
+       for (i = 0; i < snap_count; i++)
+               header->snapc->snaps[i] =
+                       le64_to_cpu(ondisk->snaps[i].id);
 
        return 0;