block: Use bdrv_refresh_filename() to pull

Before this patch, bdrv_refresh_filename() is used in a pushing manner:
Whenever the BDS graph is modified, the parents of the modified edges
are supposed to be updated (recursively upwards).  However, that is
nonviable, considering that we want child changes not to concern
parents.

Also, in the long run we want a pull model anyway: Here, we would have a
bdrv_filename() function which returns a BDS's filename, freshly
constructed.

This patch is an intermediate step.  It adds bdrv_refresh_filename()
calls before every place a BDS.filename value is used.  The only
exceptions are protocol drivers that use their own filename, which
clearly would not profit from refreshing that filename before.

Also, bdrv_get_encrypted_filename() is removed along the way (as a user
of BDS.filename), since it is completely unused.

In turn, all of the calls to bdrv_refresh_filename() before this patch
are removed, because we no longer have to call this function on graph
changes.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-2-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 15 insertions, 16 deletions

diff --git a/block.c b/block.c
index 16d59e0..88aa687 100644
--- a/block.c
+++ b/block.c
@@ -323,8 +323,11 @@ void bdrv_get_full_backing_filename_from_filename(const char *backed,
 void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz,
                                     Error **errp)
 {
-    char *backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
+    char *backed;
 
+    bdrv_refresh_filename(bs);
+
+    backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
     bdrv_get_full_backing_filename_from_filename(backed, bs->backing_file,
                                                  dest, sz, errp);
 }
@@ -1004,6 +1007,8 @@ static void bdrv_backing_attach(BdrvChild *c)
                "node is used as backing hd of '%s'",
                bdrv_get_device_or_node_name(parent));
 
+    bdrv_refresh_filename(backing_hd);
+
     parent->open_flags &= ~BDRV_O_NO_BACKING;
     pstrcpy(parent->backing_file, sizeof(parent->backing_file),
             backing_hd->filename);
@@ -1413,6 +1418,7 @@ static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
     }
 
     if (file != NULL) {
+        bdrv_refresh_filename(blk_bs(file));
         filename = blk_bs(file)->filename;
     } else {
         /*
@@ -2334,8 +2340,6 @@ void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
         bdrv_unref(backing_hd);
     }
 
-    bdrv_refresh_filename(bs);
-
 out:
     bdrv_refresh_limits(bs, NULL);
 }
@@ -2864,8 +2868,6 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
         g_free(child_key_dot);
     }
 
-    bdrv_refresh_filename(bs);
-
     /* Check if any unknown options were used */
     if (qdict_size(options) != 0) {
         const QDictEntry *entry = qdict_first(options);
@@ -3310,6 +3312,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
             if (local_err != NULL) {
                 error_propagate(errp, local_err);
             } else {
+                bdrv_refresh_filename(reopen_state->bs);
                 error_setg(errp, "failed while preparing to reopen image '%s'",
                            reopen_state->bs->filename);
             }
@@ -3937,7 +3940,10 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
     /* success - we can delete the intermediate states, and link top->base */
     /* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once
      * we've figured out how they should work. */
-    backing_file_str = backing_file_str ? backing_file_str : base->filename;
+    if (!backing_file_str) {
+        bdrv_refresh_filename(base);
+        backing_file_str = base->filename;
+    }
 
     QLIST_FOREACH_SAFE(c, &top->parents, next_parent, next) {
         /* Check whether we are allowed to switch c from top to base */
@@ -4485,16 +4491,6 @@ bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
     return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
 }
 
-const char *bdrv_get_encrypted_filename(BlockDriverState *bs)
-{
-    if (bs->backing && bs->backing->bs->encrypted)
-        return bs->backing_file;
-    else if (bs->encrypted)
-        return bs->filename;
-    else
-        return NULL;
-}
-
 void bdrv_get_backing_filename(BlockDriverState *bs,
                                char *filename, int filename_size)
 {
@@ -4615,6 +4611,9 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
 
     is_protocol = path_has_protocol(backing_file);
 
+    /* This will recursively refresh everything in the backing chain */
+    bdrv_refresh_filename(bs);
+
     for (curr_bs = bs; curr_bs->backing; curr_bs = curr_bs->backing->bs) {
 
         /* If either of the filename paths is actually a protocol, then