[PATCH v2 07/11] file-posix: remove the zone append write granularity check

[Niklas Cassel <cassel@kernel.org>]

The check rejects a zone append whose individual iovec lengths are not
multiples of the zone write granularity. That is stricter than the
constraint it is meant to enforce, which applies to the size of the
request as a whole. A request whose total is properly aligned but which
is split across, say, a 512 byte and a 3584 byte iovec is refused here,
even though the iovec boundaries do not survive into the scatter gather
list that reaches the device.

Nor is the driver the right place to enforce it. The kernel and the
device validate writes to a sequential zone themselves, which is why the
same function already passes the request length down without comparing it
against BlockLimits.max_append_sectors. The sector granularity that holds
for every backend is now checked once in bdrv_co_zone_append(), and a
frontend enforces the granularity it advertises to its guest.

Drop the check. BlockLimits.write_granularity is now set in one place, by
this driver from the zone_write_granularity queue attribute, and read in
one place, by the frontend that reports it.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 block/file-posix.c | 16 +---------------
 1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index c0d6ee30e4..f267513a4e 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -3593,8 +3593,6 @@ raw_co_zone_append(BlockDriverState *bs,
                    BdrvRequestFlags flags) {
     assert(flags == 0);
     int64_t zone_size_mask = bs->bl.zone_size - 1;
-    int64_t iov_len = 0;
-    int64_t len = 0;
 
     if (*offset & zone_size_mask) {
         error_report("sector offset %" PRId64 " is not aligned to zone size "
@@ -3602,20 +3600,8 @@ raw_co_zone_append(BlockDriverState *bs,
         return -EINVAL;
     }
 
-    int64_t wg = bs->bl.write_granularity;
-    int64_t wg_mask = wg - 1;
-    for (int i = 0; i < qiov->niov; i++) {
-        iov_len = qiov->iov[i].iov_len;
-        if (iov_len & wg_mask) {
-            error_report("len of IOVector[%d] %" PRId64 " is not aligned to "
-                         "block size %" PRId64 "", i, iov_len, wg);
-            return -EINVAL;
-        }
-        len += iov_len;
-    }
-
     trace_zbd_zone_append(bs, *offset >> BDRV_SECTOR_BITS);
-    return raw_co_prw(bs, offset, len, qiov, QEMU_AIO_ZONE_APPEND, 0);
+    return raw_co_prw(bs, offset, qiov->size, qiov, QEMU_AIO_ZONE_APPEND, 0);
 }
 #endif
 
-- 
2.55.0