block/io: support int64_t bytes in bdrv_co_p{read,write}v_part()

We are generally moving to int64_t for both offset and bytes parameters
on all io paths.

Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.

We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).

So, prepare bdrv_co_preadv_part() and bdrv_co_pwritev_part() and their
remaining dependencies now.

bdrv_pad_request() is updated simultaneously, as pointer to bytes passed
to it both from bdrv_co_pwritev_part() and bdrv_co_preadv_part().

So, all callers of bdrv_pad_request() are updated to pass 64bit bytes.
bdrv_pad_request() is already good for 64bit requests, add
corresponding assertion.

Look at bdrv_co_preadv_part() and bdrv_co_pwritev_part().
Type is widening, so callers are safe. Let's look inside the functions.

In bdrv_co_preadv_part() and bdrv_aligned_pwritev() we only pass bytes
to other already int64_t interfaces (and some obviously safe
calculations), it's OK.

In bdrv_co_do_zero_pwritev() aligned_bytes may become large now, still
it's passed to bdrv_aligned_pwritev which supports int64_t bytes.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201211183934.169161-15-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

block/io.c

@@ -1725,11 +1725,13 @@ static void bdrv_padding_destroy(BdrvRequestPadding *pad)
  */
 static int bdrv_pad_request(BlockDriverState *bs,
                             QEMUIOVector **qiov, size_t *qiov_offset,
-                            int64_t *offset, unsigned int *bytes,
+                            int64_t *offset, int64_t *bytes,
                             BdrvRequestPadding *pad, bool *padded)
 {
     int ret;
 
+    bdrv_check_qiov_request(*offset, *bytes, *qiov, *qiov_offset, &error_abort);
+
     if (!bdrv_init_padding(bs, *offset, *bytes, pad)) {
         if (padded) {
             *padded = false;
@@ -1764,7 +1766,7 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child,
 }
 
 int coroutine_fn bdrv_co_preadv_part(BdrvChild *child,
-    int64_t offset, unsigned int bytes,
+    int64_t offset, int64_t bytes,
     QEMUIOVector *qiov, size_t qiov_offset,
     BdrvRequestFlags flags)
 {
@@ -1773,7 +1775,7 @@ int coroutine_fn bdrv_co_preadv_part(BdrvChild *child,
     BdrvRequestPadding pad;
     int ret;
 
-    trace_bdrv_co_preadv(bs, offset, bytes, flags);
+    trace_bdrv_co_preadv_part(bs, offset, bytes, flags);
 
     if (!bdrv_is_inserted(bs)) {
         return -ENOMEDIUM;
@@ -2117,7 +2119,7 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
 
 static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child,
                                                 int64_t offset,
-                                                unsigned int bytes,
+                                                int64_t bytes,
                                                 BdrvRequestFlags flags,
                                                 BdrvTrackedRequest *req)
 {
@@ -2191,7 +2193,7 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
 }
 
 int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov, size_t qiov_offset,
+    int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset,
     BdrvRequestFlags flags)
 {
     BlockDriverState *bs = child->bs;
@@ -2201,7 +2203,7 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
     int ret;
     bool padded = false;
 
-    trace_bdrv_co_pwritev(child->bs, offset, bytes, flags);
+    trace_bdrv_co_pwritev_part(child->bs, offset, bytes, flags);
 
     if (!bdrv_is_inserted(bs)) {
         return -ENOMEDIUM;

block/trace-events

@@ -11,8 +11,8 @@ blk_root_attach(void *child, void *blk, void *bs) "child %p blk %p bs %p"
 blk_root_detach(void *child, void *blk, void *bs) "child %p blk %p bs %p"
 
 # io.c
-bdrv_co_preadv(void *bs, int64_t offset, int64_t nbytes, unsigned int flags) "bs %p offset %"PRId64" nbytes %"PRId64" flags 0x%x"
-bdrv_co_pwritev(void *bs, int64_t offset, int64_t nbytes, unsigned int flags) "bs %p offset %"PRId64" nbytes %"PRId64" flags 0x%x"
+bdrv_co_preadv_part(void *bs, int64_t offset, int64_t bytes, unsigned int flags) "bs %p offset %" PRId64 " bytes %" PRId64 " flags 0x%x"
+bdrv_co_pwritev_part(void *bs, int64_t offset, int64_t bytes, unsigned int flags) "bs %p offset %" PRId64 " bytes %" PRId64 " flags 0x%x"
 bdrv_co_pwrite_zeroes(void *bs, int64_t offset, int count, int flags) "bs %p offset %"PRId64" count %d flags 0x%x"
 bdrv_co_do_copy_on_readv(void *bs, int64_t offset, int64_t bytes, int64_t cluster_offset, int64_t cluster_bytes) "bs %p offset %" PRId64 " bytes %" PRId64 " cluster_offset %" PRId64 " cluster_bytes %" PRId64
 bdrv_co_copy_range_from(void *src, uint64_t src_offset, void *dst, uint64_t dst_offset, uint64_t bytes, int read_flags, int write_flags) "src %p offset %"PRIu64" dst %p offset %"PRIu64" bytes %"PRIu64" rw flags 0x%x 0x%x"

include/block/block_int.h

@@ -1035,13 +1035,13 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child,
     int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
     BdrvRequestFlags flags);
 int coroutine_fn bdrv_co_preadv_part(BdrvChild *child,
-    int64_t offset, unsigned int bytes,
+    int64_t offset, int64_t bytes,
     QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags);
 int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
     int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
     BdrvRequestFlags flags);
 int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
-    int64_t offset, unsigned int bytes,
+    int64_t offset, int64_t bytes,
     QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags);
 
 static inline int coroutine_fn bdrv_co_pread(BdrvChild *child,