IO operations like truncate inside preallocate_set_perm() looks like
insane complexity which should not seen in the reality.

Preallocate filter lifecycle is very close to the lifecycle of CBT.
This is well handled inside QCOW2 driver. The approach should be the
same inside preallocation filter. It should be enough to be handled
inside preallocate_reopen_prepare() and preallocate_inactivate().

There is no more need to have preallocate_set_perm() and
preallocate_child_perm() perms.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Hanna Reitz <hreitz@redhat.com>
---
 block/preallocate.c | 39 ---------------------------------------
 1 file changed, 39 deletions(-)

diff --git a/block/preallocate.c b/block/preallocate.c
index 65c1ff5d78..c448258c42 100644
--- a/block/preallocate.c
+++ b/block/preallocate.c
@@ -75,13 +75,9 @@ typedef struct BDRVPreallocateState {
      * be invalid (< 0) when we don't have both exclusive BLK_PERM_RESIZE and
      * BLK_PERM_WRITE permissions on file child.
      */
-
-    /* Gives up the resize permission on children when parents don't need it */
-    QEMUBH *drop_resize_bh;
 } BDRVPreallocateState;
 
 static int preallocate_drop_resize(BlockDriverState *bs, Error **errp);
-static void preallocate_drop_resize_bh(void *opaque);
 
 #define PREALLOCATE_OPT_PREALLOC_ALIGN "prealloc-align"
 #define PREALLOCATE_OPT_PREALLOC_SIZE "prealloc-size"
@@ -150,7 +146,6 @@ static int preallocate_open(BlockDriverState *bs, QDict *options, int flags,
      * For this to work, mark them invalid.
      */
     s->file_end = s->zero_start = s->data_end = -EINVAL;
-    s->drop_resize_bh = qemu_bh_new(preallocate_drop_resize_bh, bs);
 
     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
     if (ret < 0) {
@@ -200,14 +195,9 @@ preallocate_truncate_to_real_size(BlockDriverState *bs, Error **errp)
 
 static void preallocate_close(BlockDriverState *bs)
 {
-    BDRVPreallocateState *s = bs->opaque;
-
     GLOBAL_STATE_CODE();
     GRAPH_RDLOCK_GUARD_MAINLOOP();
 
-    qemu_bh_cancel(s->drop_resize_bh);
-    qemu_bh_delete(s->drop_resize_bh);
-
     preallocate_truncate_to_real_size(bs, NULL);
 }
 
@@ -528,34 +518,6 @@ preallocate_drop_resize(BlockDriverState *bs, Error **errp)
     return 0;
 }
 
-static void preallocate_drop_resize_bh(void *opaque)
-{
-    GLOBAL_STATE_CODE();
-    GRAPH_RDLOCK_GUARD_MAINLOOP();
-
-    /*
-     * In case of errors, we'll simply keep the exclusive lock on the image
-     * indefinitely.
-     */
-    preallocate_drop_resize(opaque, NULL);
-}
-
-static void GRAPH_RDLOCK
-preallocate_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared)
-{
-    BDRVPreallocateState *s = bs->opaque;
-
-    if (can_write_resize(perm)) {
-        qemu_bh_cancel(s->drop_resize_bh);
-        if (s->data_end < 0) {
-            s->data_end = s->file_end = s->zero_start =
-                bs->file->bs->total_sectors * BDRV_SECTOR_SIZE;
-        }
-    } else {
-        qemu_bh_schedule(s->drop_resize_bh);
-    }
-}
-
 static void preallocate_child_perm(BlockDriverState *bs, BdrvChild *c,
     BdrvChildRole role, BlockReopenQueue *reopen_queue,
     uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared)
@@ -604,7 +566,6 @@ static BlockDriver bdrv_preallocate_filter = {
     .bdrv_co_flush = preallocate_co_flush,
     .bdrv_co_truncate = preallocate_co_truncate,
 
-    .bdrv_set_perm = preallocate_set_perm,
     .bdrv_child_perm = preallocate_child_perm,
 
     .bdrv_inactivate = preallocate_inactivate,
-- 
2.45.2