[PULL v2 12/20] block/io: support int64_t bytes in bdrv_aligned_pwritev()

[Eric Blake <eblake@redhat.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

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_aligned_pwritev() now and convert the dependencies:
bdrv_co_write_req_prepare() and bdrv_co_write_req_finish() to signed
type bytes.

Conversion of bdrv_co_write_req_prepare() and
bdrv_co_write_req_finish() is definitely safe, as all requests in
block/io must not overflow BDRV_MAX_LENGTH. Still add assertions.

For bdrv_aligned_pwritev() 'bytes' type is widened, so callers are
safe. Let's check usage of the parameter inside the function.

Passing to bdrv_co_write_req_prepare() and bdrv_co_write_req_finish()
is OK.

Passing to qemu_iovec_* is OK after new assertion. All other callees
are already updated to int64_t.

Checking alignment is not changed, offset + bytes and qiov_offset +
bytes calculations are safe (thanks to new assertions).

max_transfer is kept to be int for now. It has a default of INT_MAX
here, and some drivers may rely on it. It's to be refactored later.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201211183934.169161-12-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/io.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/block/io.c b/block/io.c
index 98d9f5bdf48a..59ae0a110da1 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1932,11 +1932,12 @@ fail:
 }

 static inline int coroutine_fn
-bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, uint64_t bytes,
+bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, int64_t bytes,
                           BdrvTrackedRequest *req, int flags)
 {
     BlockDriverState *bs = child->bs;
-    int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
+
+    bdrv_check_request(offset, bytes, &error_abort);

     if (bs->read_only) {
         return -EPERM;
@@ -1963,7 +1964,8 @@ bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, uint64_t bytes,

     assert(req->overlap_offset <= offset);
     assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
-    assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE);
+    assert(offset + bytes <= bs->total_sectors * BDRV_SECTOR_SIZE ||
+           child->perm & BLK_PERM_RESIZE);

     switch (req->type) {
     case BDRV_TRACKED_WRITE:
@@ -1984,12 +1986,14 @@ bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, uint64_t bytes,
 }

 static inline void coroutine_fn
-bdrv_co_write_req_finish(BdrvChild *child, int64_t offset, uint64_t bytes,
+bdrv_co_write_req_finish(BdrvChild *child, int64_t offset, int64_t bytes,
                          BdrvTrackedRequest *req, int ret)
 {
     int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
     BlockDriverState *bs = child->bs;

+    bdrv_check_request(offset, bytes, &error_abort);
+
     qatomic_inc(&bs->write_gen);

     /*
@@ -2026,16 +2030,18 @@ bdrv_co_write_req_finish(BdrvChild *child, int64_t offset, uint64_t bytes,
  * after possibly fragmenting it.
  */
 static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
-    BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
+    BdrvTrackedRequest *req, int64_t offset, int64_t bytes,
     int64_t align, QEMUIOVector *qiov, size_t qiov_offset, int flags)
 {
     BlockDriverState *bs = child->bs;
     BlockDriver *drv = bs->drv;
     int ret;

-    uint64_t bytes_remaining = bytes;
+    int64_t bytes_remaining = bytes;
     int max_transfer;

+    bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort);
+
     if (!drv) {
         return -ENOMEDIUM;
     }
@@ -2047,7 +2053,6 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
     assert(is_power_of_2(align));
     assert((offset & (align - 1)) == 0);
     assert((bytes & (align - 1)) == 0);
-    assert(!qiov || qiov_offset + bytes <= qiov->size);
     max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX),
                                    align);

@@ -2146,7 +2151,7 @@ static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child,
     assert(!bytes || (offset & (align - 1)) == 0);
     if (bytes >= align) {
         /* Write the aligned part in the middle. */
-        uint64_t aligned_bytes = bytes & ~(align - 1);
+        int64_t aligned_bytes = bytes & ~(align - 1);
         ret = bdrv_aligned_pwritev(child, req, offset, aligned_bytes, align,
                                    NULL, 0, flags);
         if (ret < 0) {
-- 
2.30.0