[Qemu-devel] [PATCH 13/20] iscsi: Support BDRV_REQ_FUA

[Kevin Wolf <kwolf@redhat.com>]

This replaces the existing hack in the iscsi driver that sent the FUA
bit in writethrough mode and ignored the following flush in order to
optimise the number of roundtrips (see commit 73b5394e).

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/iscsi.c | 24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/block/iscsi.c b/block/iscsi.c
index 3b54536..4f75204 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -70,7 +70,6 @@ typedef struct IscsiLun {
     bool lbprz;
     bool dpofua;
     bool has_write_same;
-    bool force_next_flush;
     bool request_timed_out;
 } IscsiLun;
 
@@ -84,7 +83,6 @@ typedef struct IscsiTask {
     QEMUBH *bh;
     IscsiLun *iscsilun;
     QEMUTimer retry_timer;
-    bool force_next_flush;
     int err_code;
 } IscsiTask;
 
@@ -282,8 +280,6 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
         }
         iTask->err_code = iscsi_translate_sense(&task->sense);
         error_report("iSCSI Failure: %s", iscsi_get_error(iscsi));
-    } else {
-        iTask->iscsilun->force_next_flush |= iTask->force_next_flush;
     }
 
 out:
@@ -452,15 +448,15 @@ static void iscsi_allocationmap_clear(IscsiLun *iscsilun, int64_t sector_num,
     }
 }
 
-static int coroutine_fn iscsi_co_writev(BlockDriverState *bs,
-                                        int64_t sector_num, int nb_sectors,
-                                        QEMUIOVector *iov)
+static int coroutine_fn
+iscsi_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
+                      QEMUIOVector *iov, int flags)
 {
     IscsiLun *iscsilun = bs->opaque;
     struct IscsiTask iTask;
     uint64_t lba;
     uint32_t num_sectors;
-    int fua;
+    bool fua;
 
     if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
         return -EINVAL;
@@ -476,8 +472,7 @@ static int coroutine_fn iscsi_co_writev(BlockDriverState *bs,
     num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
     iscsi_co_init_iscsitask(iscsilun, &iTask);
 retry:
-    fua = iscsilun->dpofua && !bdrv_enable_write_cache(bs);
-    iTask.force_next_flush = !fua;
+    fua = iscsilun->dpofua && (flags & BDRV_REQ_FUA);
     if (iscsilun->use_16_for_rw) {
         iTask.task = iscsi_write16_task(iscsilun->iscsi, iscsilun->lun, lba,
                                         NULL, num_sectors * iscsilun->block_size,
@@ -715,11 +710,6 @@ static int coroutine_fn iscsi_co_flush(BlockDriverState *bs)
     IscsiLun *iscsilun = bs->opaque;
     struct IscsiTask iTask;
 
-    if (!iscsilun->force_next_flush) {
-        return 0;
-    }
-    iscsilun->force_next_flush = false;
-
     iscsi_co_init_iscsitask(iscsilun, &iTask);
 retry:
     if (iscsi_synchronizecache10_task(iscsilun->iscsi, iscsilun->lun, 0, 0, 0,
@@ -1019,7 +1009,6 @@ coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
     }
 
     iscsi_co_init_iscsitask(iscsilun, &iTask);
-    iTask.force_next_flush = true;
 retry:
     if (use_16_for_ws) {
         iTask.task = iscsi_writesame16_task(iscsilun->iscsi, iscsilun->lun, lba,
@@ -1851,7 +1840,8 @@ static BlockDriver bdrv_iscsi = {
     .bdrv_co_discard      = iscsi_co_discard,
     .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
     .bdrv_co_readv         = iscsi_co_readv,
-    .bdrv_co_writev        = iscsi_co_writev,
+    .bdrv_co_writev_flags  = iscsi_co_writev_flags,
+    .supported_write_flags = BDRV_REQ_FUA,
     .bdrv_co_flush_to_disk = iscsi_co_flush,
 
 #ifdef __linux__
-- 
1.8.3.1