crypto: distinguish between main loop and I/O in block_crypto_amend_options_generic_luks

block_crypto_amend_options_generic_luks uses the block layer
permission API, therefore it should be called with the BQL held.

However, the same function is being called by two BlockDriver
callbacks: bdrv_amend_options (under BQL) and bdrv_co_amend (I/O).

The latter is I/O because it is invoked by block/amend.c's
blockdev_amend_run(), a .run callback of the amend JobDriver.

Therefore we want to change this function to still perform
the permission check, but making sure it is done under BQL regardless
of the caller context.

Remove the permission check in block_crypto_amend_options_generic_luks()
and:
- in block_crypto_amend_options_luks() (BQL case, called by
  .bdrv_amend_options()), reuse helper functions
  block_crypto_amend_{prepare/cleanup} that take care of checking
  permissions.

- for block_crypto_co_amend_luks() (I/O case, called by
  .bdrv_co_amend()), don't check for permissions but delegate
  .bdrv_amend_pre_run() and .bdrv_amend_clean() to do it,
  performing these checks before and after the job runs in its aiocontext.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220209105452.1694545-3-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/crypto.c b/block/crypto.c
index 70b2f0735141cf93c1d913f4e7c9a36a75a12958..9d5fecbef86b16f3001e5ee6999927a7b55d1d02 100644 (file)
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -815,30 +815,17 @@ block_crypto_amend_options_generic_luks(BlockDriverState *bs,
                                         Error **errp)
 {
     BlockCrypto *crypto = bs->opaque;
-    int ret;
 
     assert(crypto);
     assert(crypto->block);
 
-    /* apply for exclusive read/write permissions to the underlying file*/
-    crypto->updating_keys = true;
-    ret = bdrv_child_refresh_perms(bs, bs->file, errp);
-    if (ret) {
-        goto cleanup;
-    }
-
-    ret = qcrypto_block_amend_options(crypto->block,
-                                      block_crypto_read_func,
-                                      block_crypto_write_func,
-                                      bs,
-                                      amend_options,
-                                      force,
-                                      errp);
-cleanup:
-    /* release exclusive read/write permissions to the underlying file*/
-    crypto->updating_keys = false;
-    bdrv_child_refresh_perms(bs, bs->file, errp);
-    return ret;
+    return qcrypto_block_amend_options(crypto->block,
+                                       block_crypto_read_func,
+                                       block_crypto_write_func,
+                                       bs,
+                                       amend_options,
+                                       force,
+                                       errp);
 }
 
 static int
@@ -864,8 +851,16 @@ block_crypto_amend_options_luks(BlockDriverState *bs,
     if (!amend_options) {
         goto cleanup;
     }
+
+    ret = block_crypto_amend_prepare(bs, errp);
+    if (ret) {
+        goto perm_cleanup;
+    }
     ret = block_crypto_amend_options_generic_luks(bs, amend_options,
                                                   force, errp);
+
+perm_cleanup:
+    block_crypto_amend_cleanup(bs);
 cleanup:
     qapi_free_QCryptoBlockAmendOptions(amend_options);
     return ret;