block: Mark bdrv_co_truncate() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_co_truncate() need to hold a reader lock for the graph.

For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230203152202.49054-4-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

11 files changed, 44 insertions, 28 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index ef512f7..f25f3ba 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2372,6 +2372,7 @@ int coroutine_fn blk_co_truncate(BlockBackend *blk, int64_t offset, bool exact,
                                  Error **errp)
 {
     IO_OR_GS_CODE();
+    GRAPH_RDLOCK_GUARD();
     if (!blk_is_available(blk)) {
         error_setg(errp, "No medium inserted");
         return -ENOMEDIUM;
diff --git a/block/crypto.c b/block/crypto.c
index 72ac305..a15f775 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -359,7 +359,7 @@ block_crypto_co_create_generic(BlockDriverState *bs, int64_t size,
     return ret;
 }
 
-static int coroutine_fn
+static int coroutine_fn GRAPH_RDLOCK
 block_crypto_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
                          PreallocMode prealloc, BdrvRequestFlags flags,
                          Error **errp)
diff --git a/block/io.c b/block/io.c
index d2be37b..35025fc 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3380,6 +3380,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
     int64_t old_size, new_bytes;
     int ret;
     IO_CODE();
+    assert_bdrv_graph_readable();
 
     /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
     if (!drv) {
diff --git a/block/parallels.c b/block/parallels.c
index d4378e0..36c9de8 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -165,9 +165,9 @@ static int64_t block_status(BDRVParallelsState *s, int64_t sector_num,
     return start_off;
 }
 
-static coroutine_fn int64_t allocate_clusters(BlockDriverState *bs,
-                                              int64_t sector_num,
-                                              int nb_sectors, int *pnum)
+static int64_t coroutine_fn GRAPH_RDLOCK
+allocate_clusters(BlockDriverState *bs, int64_t sector_num,
+                  int nb_sectors, int *pnum)
 {
     int ret = 0;
     BDRVParallelsState *s = bs->opaque;
@@ -329,6 +329,8 @@ static coroutine_fn int parallels_co_writev(BlockDriverState *bs,
     QEMUIOVector hd_qiov;
     int ret = 0;
 
+    assume_graph_lock(); /* FIXME */
+
     qemu_iovec_init(&hd_qiov, qiov->niov);
 
     while (nb_sectors > 0) {
@@ -414,9 +416,9 @@ static coroutine_fn int parallels_co_readv(BlockDriverState *bs,
 }
 
 
-static int coroutine_fn parallels_co_check(BlockDriverState *bs,
-                                           BdrvCheckResult *res,
-                                           BdrvCheckMode fix)
+static int coroutine_fn GRAPH_RDLOCK
+parallels_co_check(BlockDriverState *bs, BdrvCheckResult *res,
+                   BdrvCheckMode fix)
 {
     BDRVParallelsState *s = bs->opaque;
     int64_t size, prev_off, high_off;
diff --git a/block/preallocate.c b/block/preallocate.c
index c0dcf8c..42da9cb 100644
--- a/block/preallocate.c
+++ b/block/preallocate.c
@@ -370,7 +370,7 @@ static coroutine_fn int preallocate_co_pwritev_part(BlockDriverState *bs,
                                 flags);
 }
 
-static int coroutine_fn
+static int coroutine_fn GRAPH_RDLOCK
 preallocate_co_truncate(BlockDriverState *bs, int64_t offset,
                         bool exact, PreallocMode prealloc,
                         BdrvRequestFlags flags, Error **errp)
diff --git a/block/qcow.c b/block/qcow.c
index 20c53b4..5eb1ab5 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -350,11 +350,10 @@ static int qcow_reopen_prepare(BDRVReopenState *state,
  * return 0 if not allocated, 1 if *result is assigned, and negative
  * errno on failure.
  */
-static int coroutine_fn get_cluster_offset(BlockDriverState *bs,
-                                           uint64_t offset, int allocate,
-                                           int compressed_size,
-                                           int n_start, int n_end,
-                                           uint64_t *result)
+static int coroutine_fn GRAPH_RDLOCK
+get_cluster_offset(BlockDriverState *bs, uint64_t offset, int allocate,
+                   int compressed_size, int n_start, int n_end,
+                   uint64_t *result)
 {
     BDRVQcowState *s = bs->opaque;
     int min_index, i, j, l1_index, l2_index, ret;
@@ -536,6 +535,8 @@ static int coroutine_fn qcow_co_block_status(BlockDriverState *bs,
     int64_t n;
     uint64_t cluster_offset;
 
+    assume_graph_lock(); /* FIXME */
+
     qemu_co_mutex_lock(&s->lock);
     ret = get_cluster_offset(bs, offset, 0, 0, 0, 0, &cluster_offset);
     qemu_co_mutex_unlock(&s->lock);
@@ -630,6 +631,8 @@ static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, int64_t offset,
     uint8_t *buf;
     void *orig_buf;
 
+    assume_graph_lock(); /* FIXME */
+
     if (qiov->niov > 1) {
         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
         if (buf == NULL) {
@@ -726,6 +729,8 @@ static coroutine_fn int qcow_co_pwritev(BlockDriverState *bs, int64_t offset,
     uint8_t *buf;
     void *orig_buf;
 
+    assume_graph_lock(); /* FIXME */
+
     s->cluster_cache_offset = -1; /* disable compressed cache */
 
     /* We must always copy the iov when encrypting, so we
@@ -1056,6 +1061,8 @@ qcow_co_pwritev_compressed(BlockDriverState *bs, int64_t offset, int64_t bytes,
     uint8_t *buf, *out_buf;
     uint64_t cluster_offset;
 
+    assume_graph_lock(); /* FIXME */
+
     buf = qemu_blockalign(bs, s->cluster_size);
     if (bytes != s->cluster_size) {
         if (bytes > s->cluster_size ||
diff --git a/block/qcow2.c b/block/qcow2.c
index ee0e5b4..e06ea7b 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3183,9 +3183,9 @@ static int qcow2_set_up_encryption(BlockDriverState *bs,
  *
  * Returns: 0 on success, -errno on failure.
  */
-static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
-                                       uint64_t new_length, PreallocMode mode,
-                                       Error **errp)
+static int coroutine_fn GRAPH_RDLOCK
+preallocate_co(BlockDriverState *bs, uint64_t offset, uint64_t new_length,
+               PreallocMode mode, Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t bytes;
@@ -4209,9 +4209,9 @@ fail:
     return ret;
 }
 
-static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
-                                          bool exact, PreallocMode prealloc,
-                                          BdrvRequestFlags flags, Error **errp)
+static int coroutine_fn GRAPH_RDLOCK
+qcow2_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
+                  PreallocMode prealloc, BdrvRequestFlags flags, Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t old_length;
@@ -4672,6 +4672,8 @@ qcow2_co_pwritev_compressed_part(BlockDriverState *bs,
     AioTaskPool *aio = NULL;
     int ret = 0;
 
+    assume_graph_lock(); /* FIXME */
+
     if (has_data_file(bs)) {
         return -ENOTSUP;
     }
diff --git a/block/raw-format.c b/block/raw-format.c
index 0dc469b..f39e1f5 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -384,9 +384,9 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
     }
 }
 
-static int coroutine_fn raw_co_truncate(BlockDriverState *bs, int64_t offset,
-                                        bool exact, PreallocMode prealloc,
-                                        BdrvRequestFlags flags, Error **errp)
+static int coroutine_fn GRAPH_RDLOCK
+raw_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
+                PreallocMode prealloc, BdrvRequestFlags flags, Error **errp)
 {
     BDRVRawState *s = bs->opaque;
 
diff --git a/block/vmdk.c b/block/vmdk.c
index 171c927..3fcb753 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -2130,6 +2130,8 @@ static int coroutine_fn
 vmdk_co_pwritev_compressed(BlockDriverState *bs, int64_t offset, int64_t bytes,
                            QEMUIOVector *qiov)
 {
+    assume_graph_lock(); /* FIXME */
+
     if (bytes == 0) {
         /* The caller will write bytes 0 to signal EOF.
          * When receive it, we align EOF to a sector boundary. */
diff --git a/include/block/block-io.h b/include/block/block-io.h
index f9fa882..9a09ec2 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -72,9 +72,9 @@ int coroutine_fn bdrv_co_pwrite_sync(BdrvChild *child, int64_t offset,
 int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
                                        int64_t bytes, BdrvRequestFlags flags);
 
-int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
-                                  PreallocMode prealloc, BdrvRequestFlags flags,
-                                  Error **errp);
+int coroutine_fn GRAPH_RDLOCK
+bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
+                 PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
 
 int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs);
 int64_t co_wrapper_mixed bdrv_nb_sectors(BlockDriverState *bs);
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index ba2e0fc..eaf62be 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -677,9 +677,10 @@ struct BlockDriver {
      * If @exact is true and this function fails but would succeed
      * with @exact = false, it should return -ENOTSUP.
      */
-    int coroutine_fn (*bdrv_co_truncate)(BlockDriverState *bs, int64_t offset,
-                                         bool exact, PreallocMode prealloc,
-                                         BdrvRequestFlags flags, Error **errp);
+    int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_truncate)(
+        BlockDriverState *bs, int64_t offset, bool exact,
+        PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
+
     int64_t coroutine_fn (*bdrv_co_getlength)(BlockDriverState *bs);
     int64_t coroutine_fn (*bdrv_co_get_allocated_file_size)(
         BlockDriverState *bs);