[Qemu-devel] [PATCH v4 05/21] block: make bdrv_co_is_allocated static

[Paolo Bonzini <pbonzini@redhat.com>]

bdrv_is_allocated can detect coroutine context and go through a fast
path, similar to other block layer functions.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block.c               | 24 +++++++++++++++---------
 block/backup.c        |  4 ++--
 block/raw.c           |  2 +-
 block/stream.c        |  4 ++--
 include/block/block.h |  2 --
 5 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/block.c b/block.c
index b11254a..fc5ea56 100644
--- a/block.c
+++ b/block.c
@@ -2533,7 +2533,7 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
     if (flags & BDRV_REQ_COPY_ON_READ) {
         int pnum;
 
-        ret = bdrv_co_is_allocated(bs, sector_num, nb_sectors, &pnum);
+        ret = bdrv_is_allocated(bs, sector_num, nb_sectors, &pnum);
         if (ret < 0) {
             goto out;
         }
@@ -2987,8 +2987,9 @@ typedef struct BdrvCoIsAllocatedData {
  * 'nb_sectors' is the max value 'pnum' should be set to.  If nb_sectors goes
  * beyond the end of the disk image it will be clamped.
  */
-int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t sector_num,
-                                      int nb_sectors, int *pnum)
+static int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs,
+                                             int64_t sector_num,
+                                             int nb_sectors, int *pnum)
 {
     int64_t n;
 
@@ -3038,10 +3039,15 @@ int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
         .done = false,
     };
 
-    co = qemu_coroutine_create(bdrv_is_allocated_co_entry);
-    qemu_coroutine_enter(co, &data);
-    while (!data.done) {
-        qemu_aio_wait();
+    if (qemu_in_coroutine()) {
+        /* Fast-path if already in coroutine context */
+        bdrv_is_allocated_co_entry(&data);
+    } else {
+        co = qemu_coroutine_create(bdrv_is_allocated_co_entry);
+        qemu_coroutine_enter(co, &data);
+        while (!data.done) {
+            qemu_aio_wait();
+        }
     }
     return data.ret;
 }
@@ -3069,8 +3075,8 @@ int coroutine_fn bdrv_co_is_allocated_above(BlockDriverState *top,
     intermediate = top;
     while (intermediate && intermediate != base) {
         int pnum_inter;
-        ret = bdrv_co_is_allocated(intermediate, sector_num, nb_sectors,
-                                   &pnum_inter);
+        ret = bdrv_is_allocated(intermediate, sector_num, nb_sectors,
+                                &pnum_inter);
         if (ret < 0) {
             return ret;
         } else if (ret) {
diff --git a/block/backup.c b/block/backup.c
index 6ae8a05..9931bb9 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -289,14 +289,14 @@ static void coroutine_fn backup_run(void *opaque)
                  * backing file. */
 
                 for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
-                    /* bdrv_co_is_allocated() only returns true/false based
+                    /* bdrv_is_allocated() only returns true/false based
                      * on the first set of sectors it comes accross that
                      * are are all in the same state.
                      * For that reason we must verify each sector in the
                      * backup cluster length.  We end up copying more than
                      * needed but at some point that is always the case. */
                     alloced =
-                        bdrv_co_is_allocated(bs,
+                        bdrv_is_allocated(bs,
                                 start * BACKUP_SECTORS_PER_CLUSTER + i,
                                 BACKUP_SECTORS_PER_CLUSTER - i, &n);
                     i += n;
diff --git a/block/raw.c b/block/raw.c
index 4751825..1467d75 100644
--- a/block/raw.c
+++ b/block/raw.c
@@ -62,7 +62,7 @@ static int coroutine_fn raw_co_is_allocated(BlockDriverState *bs,
                                             int64_t sector_num,
                                             int nb_sectors, int *pnum)
 {
-    return bdrv_co_is_allocated(bs->file, sector_num, nb_sectors, pnum);
+    return bdrv_is_allocated(bs->file, sector_num, nb_sectors, pnum);
 }
 
 static int coroutine_fn raw_co_write_zeroes(BlockDriverState *bs,
diff --git a/block/stream.c b/block/stream.c
index 7fe9e48..fb1f9c3 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -115,8 +115,8 @@ wait:
             break;
         }
 
-        ret = bdrv_co_is_allocated(bs, sector_num,
-                                   STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n);
+        ret = bdrv_is_allocated(bs, sector_num,
+                                STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n);
         if (ret == 1) {
             /* Allocated in the top, no need to copy.  */
             copy = false;
diff --git a/include/block/block.h b/include/block/block.h
index 742fce5..dde745f 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -181,8 +181,6 @@ int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,
  */
 int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
     int nb_sectors);
-int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t sector_num,
-    int nb_sectors, int *pnum);
 int coroutine_fn bdrv_co_is_allocated_above(BlockDriverState *top,
                                             BlockDriverState *base,
                                             int64_t sector_num,
-- 
1.8.3.1