ssh: use BlockDriverState's AioContext

Drop the assumption that we're using the main AioContext.  Use
bdrv_get_aio_context() to register fd handlers in the right AioContext
for this BlockDriverState.

The .bdrv_detach_aio_context() and .bdrv_attach_aio_context() interfaces
are not needed since no fd handlers, timers, or BHs stay registered when
requests have been drained.

For now this doesn't make much difference but will allow ssh to work in
IOThread instances in the future.

Acked-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/ssh.c

@@ -773,7 +773,7 @@ static void restart_coroutine(void *opaque)
     qemu_coroutine_enter(co, NULL);
 }
 
-static coroutine_fn void set_fd_handler(BDRVSSHState *s)
+static coroutine_fn void set_fd_handler(BDRVSSHState *s, BlockDriverState *bs)
 {
     int r;
     IOHandler *rd_handler = NULL, *wr_handler = NULL;
@@ -791,24 +791,26 @@ static coroutine_fn void set_fd_handler(BDRVSSHState *s)
     DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock,
             rd_handler, wr_handler);
 
-    qemu_aio_set_fd_handler(s->sock, rd_handler, wr_handler, co);
+    aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock,
+                       rd_handler, wr_handler, co);
 }
 
-static coroutine_fn void clear_fd_handler(BDRVSSHState *s)
+static coroutine_fn void clear_fd_handler(BDRVSSHState *s,
+                                          BlockDriverState *bs)
 {
     DPRINTF("s->sock=%d", s->sock);
-    qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL);
+    aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, NULL, NULL, NULL);
 }
 
 /* A non-blocking call returned EAGAIN, so yield, ensuring the
  * handlers are set up so that we'll be rescheduled when there is an
  * interesting event on the socket.
  */
-static coroutine_fn void co_yield(BDRVSSHState *s)
+static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
 {
-    set_fd_handler(s);
+    set_fd_handler(s, bs);
     qemu_coroutine_yield();
-    clear_fd_handler(s);
+    clear_fd_handler(s, bs);
 }
 
 /* SFTP has a function `libssh2_sftp_seek64' which seeks to a position
@@ -838,7 +840,7 @@ static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags)
     }
 }
 
-static coroutine_fn int ssh_read(BDRVSSHState *s,
+static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs,
                                  int64_t offset, size_t size,
                                  QEMUIOVector *qiov)
 {
@@ -871,7 +873,7 @@ static coroutine_fn int ssh_read(BDRVSSHState *s,
         DPRINTF("sftp_read returned %zd", r);
 
         if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
-            co_yield(s);
+            co_yield(s, bs);
             goto again;
         }
         if (r < 0) {
@@ -906,14 +908,14 @@ static coroutine_fn int ssh_co_readv(BlockDriverState *bs,
     int ret;
 
     qemu_co_mutex_lock(&s->lock);
-    ret = ssh_read(s, sector_num * BDRV_SECTOR_SIZE,
+    ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE,
                    nb_sectors * BDRV_SECTOR_SIZE, qiov);
     qemu_co_mutex_unlock(&s->lock);
 
     return ret;
 }
 
-static int ssh_write(BDRVSSHState *s,
+static int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
                      int64_t offset, size_t size,
                      QEMUIOVector *qiov)
 {
@@ -941,7 +943,7 @@ static int ssh_write(BDRVSSHState *s,
         DPRINTF("sftp_write returned %zd", r);
 
         if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
-            co_yield(s);
+            co_yield(s, bs);
             goto again;
         }
         if (r < 0) {
@@ -960,7 +962,7 @@ static int ssh_write(BDRVSSHState *s,
          */
         if (r == 0) {
             ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE);
-            co_yield(s);
+            co_yield(s, bs);
             goto again;
         }
 
@@ -988,7 +990,7 @@ static coroutine_fn int ssh_co_writev(BlockDriverState *bs,
     int ret;
 
     qemu_co_mutex_lock(&s->lock);
-    ret = ssh_write(s, sector_num * BDRV_SECTOR_SIZE,
+    ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE,
                     nb_sectors * BDRV_SECTOR_SIZE, qiov);
     qemu_co_mutex_unlock(&s->lock);
 
@@ -1009,15 +1011,15 @@ static void unsafe_flush_warning(BDRVSSHState *s, const char *what)
 
 #ifdef HAS_LIBSSH2_SFTP_FSYNC
 
-static coroutine_fn int ssh_flush(BDRVSSHState *s)
+static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs)
 {
     int r;
 
     DPRINTF("fsync");
  again:
     r = libssh2_sftp_fsync(s->sftp_handle);
     if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
-        co_yield(s);
+        co_yield(s, bs);
         goto again;
     }
     if (r == LIBSSH2_ERROR_SFTP_PROTOCOL &&
@@ -1039,7 +1041,7 @@ static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
     int ret;
 
     qemu_co_mutex_lock(&s->lock);
-    ret = ssh_flush(s);
+    ret = ssh_flush(s, bs);
     qemu_co_mutex_unlock(&s->lock);
 
     return ret;