motr_sal: [CORTX-32689] Fix multipart download issue

DPG17 · Sachin Punadikar · commit db760651bf7b · 2022-08-20T08:53:00.000+05:30
Problem:
After DI changes, the unit size is limited to 1MB for objects &gt;= 1MB.
In SNS 3+2 config, the first part object for a 10MB object is partially
uploaded, causing EIO (-5) error during Get obj API call.

Solution:
Use part object size to calculate optimal block size.

Signed-off-by: Dattaprasad Govekar &lt;dattaprasad.govekar@seagate.com&gt;
diff --git a/src/rgw/rgw_sal_motr.cc b/src/rgw/rgw_sal_motr.cc
@@ -2890,7 +2890,7 @@ int MotrObject::write_mobj(const DoutPrefixProvider *dpp, bufferlist&& in_buffer
     available_data = io_ctxt.total_bufer_sz;
   }
 
-  bs = this->get_optimal_bs(left);
+  bs = this->get_optimal_bs(expected_obj_size);
   ldpp_dout(dpp, 20) <<__func__<< ": left=" << left << " bs=" << bs << dendl;
   if ((left + available_data) < bs) {
     // Determine if there are any further chunks/bytes from socket to be processed

Original file line number	Diff line number	Diff line change
`@@ -2890,7 +2890,7 @@ int MotrObject::write_mobj(const DoutPrefixProvider *dpp, bufferlist&& in_buffer`
`2890`	`2890`	`available_data = io_ctxt.total_bufer_sz;`
`2891`	`2891`	`}`
`2892`	`2892`
`2893`		`- bs = this->get_optimal_bs(left);`
	`2893`	`+ bs = this->get_optimal_bs(expected_obj_size);`
`2894`	`2894`	`ldpp_dout(dpp, 20) <<__func__<< ": left=" << left << " bs=" << bs << dendl;`
`2895`	`2895`	`if ((left + available_data) < bs) {`
`2896`	`2896`	`// Determine if there are any further chunks/bytes from socket to be processed`