[Qemu-devel] [PATCH v4 4/6] qed: replace is_write with flags field

[Stefan Hajnoczi]

Per-request attributes like read/write are currently implemented as bool
fields in the QEDAIOCB struct.  This becomes unwiedly as the number of
attributes grows.  For example, the qed_aio_setup() function would have
to take multiple bool arguments and at call sites it would be hard to
distinguish the meaning of each bool.

Instead use a flags field with bitmask constants.  This will be used
when zero write support is added.

Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 block/qed.c  |   15 ++++++++-------
 block/qed.h  |    6 +++++-
 trace-events |    2 +-
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/block/qed.c b/block/qed.c
index 8da3ebe..b66dd17 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1233,8 +1233,8 @@ static void qed_aio_next_io(void *opaque, int ret)
 {
     QEDAIOCB *acb = opaque;
     BDRVQEDState *s = acb_to_s(acb);
-    QEDFindClusterFunc *io_fn =
-        acb->is_write ? qed_aio_write_data : qed_aio_read_data;
+    QEDFindClusterFunc *io_fn = (acb->flags & QED_AIOCB_WRITE) ?
+                                qed_aio_write_data : qed_aio_read_data;
 
     trace_qed_aio_next_io(s, acb, ret, acb->cur_pos + acb->cur_qiov.size);
 
@@ -1264,14 +1264,14 @@ static BlockDriverAIOCB *qed_aio_setup(BlockDriverState 
*bs,
                                        int64_t sector_num,
                                        QEMUIOVector *qiov, int nb_sectors,
                                        BlockDriverCompletionFunc *cb,
-                                       void *opaque, bool is_write)
+                                       void *opaque, int flags)
 {
     QEDAIOCB *acb = qemu_aio_get(&qed_aio_pool, bs, cb, opaque);
 
     trace_qed_aio_setup(bs->opaque, acb, sector_num, nb_sectors,
-                         opaque, is_write);
+                        opaque, flags);
 
-    acb->is_write = is_write;
+    acb->flags = flags;
     acb->finished = NULL;
     acb->qiov = qiov;
     acb->qiov_offset = 0;
@@ -1291,7 +1291,7 @@ static BlockDriverAIOCB 
*bdrv_qed_aio_readv(BlockDriverState *bs,
                                             BlockDriverCompletionFunc *cb,
                                             void *opaque)
 {
-    return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, false);
+    return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
 }
 
 static BlockDriverAIOCB *bdrv_qed_aio_writev(BlockDriverState *bs,
@@ -1300,7 +1300,8 @@ static BlockDriverAIOCB 
*bdrv_qed_aio_writev(BlockDriverState *bs,
                                              BlockDriverCompletionFunc *cb,
                                              void *opaque)
 {
-    return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, true);
+    return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb,
+                         opaque, QED_AIOCB_WRITE);
 }
 
 static BlockDriverAIOCB *bdrv_qed_aio_flush(BlockDriverState *bs,
diff --git a/block/qed.h b/block/qed.h
index 62cbd3b..abed147 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -123,12 +123,16 @@ typedef struct QEDRequest {
     CachedL2Table *l2_table;
 } QEDRequest;
 
+enum {
+    QED_AIOCB_WRITE = 0x0001,       /* read or write? */
+};
+
 typedef struct QEDAIOCB {
     BlockDriverAIOCB common;
     QEMUBH *bh;
     int bh_ret;                     /* final return status for completion bh */
     QSIMPLEQ_ENTRY(QEDAIOCB) next;  /* next request */
-    bool is_write;                  /* false - read, true - write */
+    int flags;                      /* QED_AIOCB_* bits ORed together */
     bool *finished;                 /* signal for cancel completion */
     uint64_t end_pos;               /* request end on block device, in bytes */
 
diff --git a/trace-events b/trace-events
index faab38c..2e68c2c 100644
--- a/trace-events
+++ b/trace-events
@@ -319,7 +319,7 @@ qed_need_check_timer_cb(void *s) "s %p"
 qed_start_need_check_timer(void *s) "s %p"
 qed_cancel_need_check_timer(void *s) "s %p"
 qed_aio_complete(void *s, void *acb, int ret) "s %p acb %p ret %d"
-qed_aio_setup(void *s, void *acb, int64_t sector_num, int nb_sectors, void 
*opaque, int is_write) "s %p acb %p sector_num %"PRId64" nb_sectors %d opaque 
%p is_write %d"
+qed_aio_setup(void *s, void *acb, int64_t sector_num, int nb_sectors, void 
*opaque, int flags) "s %p acb %p sector_num %"PRId64" nb_sectors %d opaque %p 
flags %#x"
 qed_aio_next_io(void *s, void *acb, int ret, uint64_t cur_pos) "s %p acb %p 
ret %d cur_pos %"PRIu64
 qed_aio_read_data(void *s, void *acb, int ret, uint64_t offset, size_t len) "s 
%p acb %p ret %d offset %"PRIu64" len %zu"
 qed_aio_write_data(void *s, void *acb, int ret, uint64_t offset, size_t len) 
"s %p acb %p ret %d offset %"PRIu64" len %zu"
-- 
1.7.8.3