Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches

# gpg: Signature made Thu 29 Sep 2016 14:11:30 BST
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  oslib-posix: add a configure switch to debug stack usage
  coroutine-sigaltstack: use helper for allocating stack memory
  coroutine-ucontext: use helper for allocating stack memory
  coroutine: add a macro for the coroutine stack size
  coroutine-sigaltstack: rename coroutine struct appropriately
  oslib-posix: add helpers for stack alloc and free
  block: Remove qemu_root_bds_opts
  block: Move 'discard' option to bdrv_open_common()
  block: Use 'detect-zeroes' option for 'blockdev-change-medium'
  block: Parse 'detect-zeroes' in bdrv_open_common()
  block/qapi: Move 'aio' option to file driver
  block/qapi: Use separate options type for curl driver
  block: Drop aio/cache consistency check from qmp_blockdev_add()
  block: Fix error path in qmp_blockdev_change_medium()
  block-backend: remove blk_flush_all
  qemu: use bdrv_flush_all for vm_stop et al
  block: reintroduce bdrv_flush_all

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

21 files changed, 342 insertions, 191 deletions

diff --git a/block.c b/block.c
index 493ecf3..bb1f1ec 100644
--- a/block.c
+++ b/block.c
@@ -42,6 +42,7 @@
 #include "qapi-event.h"
 #include "qemu/cutils.h"
 #include "qemu/id.h"
+#include "qapi/util.h"
 
 #ifdef CONFIG_BSD
 #include <sys/ioctl.h>
@@ -764,7 +765,7 @@ static void bdrv_inherited_options(int *child_flags, QDict *child_options,
     /* Our block drivers take care to send flushes and respect unmap policy,
      * so we can default to enable both on lower layers regardless of the
      * corresponding parent options. */
-    flags |= BDRV_O_UNMAP;
+    qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
 
     /* Clear flags that only apply to the top layer */
     flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ |
@@ -954,6 +955,16 @@ static QemuOptsList bdrv_runtime_opts = {
             .type = QEMU_OPT_BOOL,
             .help = "Node is opened in read-only mode",
         },
+        {
+            .name = "detect-zeroes",
+            .type = QEMU_OPT_STRING,
+            .help = "try to optimize zero writes (off, on, unmap)",
+        },
+        {
+            .name = "discard",
+            .type = QEMU_OPT_STRING,
+            .help = "discard operation (ignore/off, unmap/on)",
+        },
         { /* end of list */ }
     },
 };
@@ -970,6 +981,8 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
     const char *filename;
     const char *driver_name = NULL;
     const char *node_name = NULL;
+    const char *discard;
+    const char *detect_zeroes;
     QemuOpts *opts;
     BlockDriver *drv;
     Error *local_err = NULL;
@@ -1038,6 +1051,41 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file,
         }
     }
 
+    discard = qemu_opt_get(opts, "discard");
+    if (discard != NULL) {
+        if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
+            error_setg(errp, "Invalid discard option");
+            ret = -EINVAL;
+            goto fail_opts;
+        }
+    }
+
+    detect_zeroes = qemu_opt_get(opts, "detect-zeroes");
+    if (detect_zeroes) {
+        BlockdevDetectZeroesOptions value =
+            qapi_enum_parse(BlockdevDetectZeroesOptions_lookup,
+                            detect_zeroes,
+                            BLOCKDEV_DETECT_ZEROES_OPTIONS__MAX,
+                            BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
+                            &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            ret = -EINVAL;
+            goto fail_opts;
+        }
+
+        if (value == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
+            !(bs->open_flags & BDRV_O_UNMAP))
+        {
+            error_setg(errp, "setting detect-zeroes to unmap is not allowed "
+                             "without setting discard operation to unmap");
+            ret = -EINVAL;
+            goto fail_opts;
+        }
+
+        bs->detect_zeroes = value;
+    }
+
     if (filename != NULL) {
         pstrcpy(bs->filename, sizeof(bs->filename), filename);
     } else {
diff --git a/block/block-backend.c b/block/block-backend.c
index 0bd19ab..639294b 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1592,13 +1592,12 @@ void blk_update_root_state(BlockBackend *blk)
 }
 
 /*
- * Applies the information in the root state to the given BlockDriverState. This
- * does not include the flags which have to be specified for bdrv_open(), use
- * blk_get_open_flags_from_root_state() to inquire them.
+ * Returns the detect-zeroes setting to be used for bdrv_open() of a
+ * BlockDriverState which is supposed to inherit the root state.
  */
-void blk_apply_root_state(BlockBackend *blk, BlockDriverState *bs)
+bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk)
 {
-    bs->detect_zeroes = blk->root_state.detect_zeroes;
+    return blk->root_state.detect_zeroes;
 }
 
 /*
@@ -1640,28 +1639,6 @@ int blk_commit_all(void)
     return 0;
 }
 
-int blk_flush_all(void)
-{
-    BlockBackend *blk = NULL;
-    int result = 0;
-
-    while ((blk = blk_all_next(blk)) != NULL) {
-        AioContext *aio_context = blk_get_aio_context(blk);
-        int ret;
-
-        aio_context_acquire(aio_context);
-        if (blk_is_inserted(blk)) {
-            ret = blk_flush(blk);
-            if (ret < 0 && !result) {
-                result = ret;
-            }
-        }
-        aio_context_release(aio_context);
-    }
-
-    return result;
-}
-
 
 /* throttling disk I/O limits */
 void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg)
diff --git a/block/io.c b/block/io.c
index fdf7080..57a2eeb 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1619,6 +1619,31 @@ int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
                            BDRV_REQ_ZERO_WRITE | flags);
 }
 
+/*
+ * Flush ALL BDSes regardless of if they are reachable via a BlkBackend or not.
+ */
+int bdrv_flush_all(void)
+{
+    BdrvNextIterator it;
+    BlockDriverState *bs = NULL;
+    int result = 0;
+
+    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
+        AioContext *aio_context = bdrv_get_aio_context(bs);
+        int ret;
+
+        aio_context_acquire(aio_context);
+        ret = bdrv_flush(bs);
+        if (ret < 0 && !result) {
+            result = ret;
+        }
+        aio_context_release(aio_context);
+    }
+
+    return result;
+}
+
+
 typedef struct BdrvCoGetBlockStatusData {
     BlockDriverState *bs;
     BlockDriverState *base;
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 6ed7547..166e9d1 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -143,6 +143,7 @@ typedef struct BDRVRawState {
     bool has_discard:1;
     bool has_write_zeroes:1;
     bool discard_zeroes:1;
+    bool use_linux_aio:1;
     bool has_fallocate;
     bool needs_alignment;
 } BDRVRawState;
@@ -367,18 +368,6 @@ static void raw_parse_flags(int bdrv_flags, int *open_flags)
     }
 }
 
-#ifdef CONFIG_LINUX_AIO
-static bool raw_use_aio(int bdrv_flags)
-{
-    /*
-     * Currently Linux do AIO only for files opened with O_DIRECT
-     * specified so check NOCACHE flag too
-     */
-    return (bdrv_flags & (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) ==
-                         (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO);
-}
-#endif
-
 static void raw_parse_filename(const char *filename, QDict *options,
                                Error **errp)
 {
@@ -399,6 +388,11 @@ static QemuOptsList raw_runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "File name of the image",
         },
+        {
+            .name = "aio",
+            .type = QEMU_OPT_STRING,
+            .help = "host AIO implementation (threads, native)",
+        },
         { /* end of list */ }
     },
 };
@@ -410,6 +404,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
     QemuOpts *opts;
     Error *local_err = NULL;
     const char *filename = NULL;
+    BlockdevAioOptions aio, aio_default;
     int fd, ret;
     struct stat st;
 
@@ -429,6 +424,18 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
         goto fail;
     }
 
+    aio_default = (bdrv_flags & BDRV_O_NATIVE_AIO)
+                  ? BLOCKDEV_AIO_OPTIONS_NATIVE
+                  : BLOCKDEV_AIO_OPTIONS_THREADS;
+    aio = qapi_enum_parse(BlockdevAioOptions_lookup, qemu_opt_get(opts, "aio"),
+                          BLOCKDEV_AIO_OPTIONS__MAX, aio_default, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto fail;
+    }
+    s->use_linux_aio = (aio == BLOCKDEV_AIO_OPTIONS_NATIVE);
+
     s->open_flags = open_flags;
     raw_parse_flags(bdrv_flags, &s->open_flags);
 
@@ -444,14 +451,15 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
     s->fd = fd;
 
 #ifdef CONFIG_LINUX_AIO
-    if (!raw_use_aio(bdrv_flags) && (bdrv_flags & BDRV_O_NATIVE_AIO)) {
+     /* Currently Linux does AIO only for files opened with O_DIRECT */
+    if (s->use_linux_aio && !(s->open_flags & O_DIRECT)) {
         error_setg(errp, "aio=native was specified, but it requires "
                          "cache.direct=on, which was not specified.");
         ret = -EINVAL;
         goto fail;
     }
 #else
-    if (bdrv_flags & BDRV_O_NATIVE_AIO) {
+    if (s->use_linux_aio) {
         error_setg(errp, "aio=native was specified, but is not supported "
                          "in this build.");
         ret = -EINVAL;
@@ -1256,7 +1264,7 @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, uint64_t offset,
         if (!bdrv_qiov_is_aligned(bs, qiov)) {
             type |= QEMU_AIO_MISALIGNED;
 #ifdef CONFIG_LINUX_AIO
-        } else if (bs->open_flags & BDRV_O_NATIVE_AIO) {
+        } else if (s->use_linux_aio) {
             LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs));
             assert(qiov->size == bytes);
             return laio_co_submit(bs, aio, s->fd, offset, qiov, type);
@@ -1285,7 +1293,8 @@ static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, uint64_t offset,
 static void raw_aio_plug(BlockDriverState *bs)
 {
 #ifdef CONFIG_LINUX_AIO
-    if (bs->open_flags & BDRV_O_NATIVE_AIO) {
+    BDRVRawState *s = bs->opaque;
+    if (s->use_linux_aio) {
         LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs));
         laio_io_plug(bs, aio);
     }
@@ -1295,7 +1304,8 @@ static void raw_aio_plug(BlockDriverState *bs)
 static void raw_aio_unplug(BlockDriverState *bs)
 {
 #ifdef CONFIG_LINUX_AIO
-    if (bs->open_flags & BDRV_O_NATIVE_AIO) {
+    BDRVRawState *s = bs->opaque;
+    if (s->use_linux_aio) {
         LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs));
         laio_io_unplug(bs, aio);
     }
diff --git a/block/raw-win32.c b/block/raw-win32.c
index 56f45fe..734bb10 100644
--- a/block/raw-win32.c
+++ b/block/raw-win32.c
@@ -32,6 +32,7 @@
 #include "block/thread-pool.h"
 #include "qemu/iov.h"
 #include "qapi/qmp/qstring.h"
+#include "qapi/util.h"
 #include <windows.h>
 #include <winioctl.h>
 
@@ -252,7 +253,8 @@ static void raw_probe_alignment(BlockDriverState *bs, Error **errp)
     }
 }
 
-static void raw_parse_flags(int flags, int *access_flags, DWORD *overlapped)
+static void raw_parse_flags(int flags, bool use_aio, int *access_flags,
+                            DWORD *overlapped)
 {
     assert(access_flags != NULL);
     assert(overlapped != NULL);
@@ -264,7 +266,7 @@ static void raw_parse_flags(int flags, int *access_flags, DWORD *overlapped)
     }
 
     *overlapped = FILE_ATTRIBUTE_NORMAL;
-    if (flags & BDRV_O_NATIVE_AIO) {
+    if (use_aio) {
         *overlapped |= FILE_FLAG_OVERLAPPED;
     }
     if (flags & BDRV_O_NOCACHE) {
@@ -292,10 +294,35 @@ static QemuOptsList raw_runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "File name of the image",
         },
+        {
+            .name = "aio",
+            .type = QEMU_OPT_STRING,
+            .help = "host AIO implementation (threads, native)",
+        },
         { /* end of list */ }
     },
 };
 
+static bool get_aio_option(QemuOpts *opts, int flags, Error **errp)
+{
+    BlockdevAioOptions aio, aio_default;
+
+    aio_default = (flags & BDRV_O_NATIVE_AIO) ? BLOCKDEV_AIO_OPTIONS_NATIVE
+                                              : BLOCKDEV_AIO_OPTIONS_THREADS;
+    aio = qapi_enum_parse(BlockdevAioOptions_lookup, qemu_opt_get(opts, "aio"),
+                          BLOCKDEV_AIO_OPTIONS__MAX, aio_default, errp);
+
+    switch (aio) {
+    case BLOCKDEV_AIO_OPTIONS_NATIVE:
+        return true;
+    case BLOCKDEV_AIO_OPTIONS_THREADS:
+        return false;
+    default:
+        error_setg(errp, "Invalid AIO option");
+    }
+    return false;
+}
+
 static int raw_open(BlockDriverState *bs, QDict *options, int flags,
                     Error **errp)
 {
@@ -305,6 +332,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
     QemuOpts *opts;
     Error *local_err = NULL;
     const char *filename;
+    bool use_aio;
     int ret;
 
     s->type = FTYPE_FILE;
@@ -319,7 +347,14 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
 
     filename = qemu_opt_get(opts, "filename");
 
-    raw_parse_flags(flags, &access_flags, &overlapped);
+    use_aio = get_aio_option(opts, flags, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto fail;
+    }
+
+    raw_parse_flags(flags, use_aio, &access_flags, &overlapped);
 
     if (filename[0] && filename[1] == ':') {
         snprintf(s->drive_path, sizeof(s->drive_path), "%c:\\", filename[0]);
@@ -346,7 +381,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
         goto fail;
     }
 
-    if (flags & BDRV_O_NATIVE_AIO) {
+    if (use_aio) {
         s->aio = win32_aio_init();
         if (s->aio == NULL) {
             CloseHandle(s->hfile);
@@ -647,6 +682,7 @@ static int hdev_open(BlockDriverState *bs, QDict *options, int flags,
 
     Error *local_err = NULL;
     const char *filename;
+    bool use_aio;
 
     QemuOpts *opts = qemu_opts_create(&raw_runtime_opts, NULL, 0,
                                       &error_abort);
@@ -659,6 +695,16 @@ static int hdev_open(BlockDriverState *bs, QDict *options, int flags,
 
     filename = qemu_opt_get(opts, "filename");
 
+    use_aio = get_aio_option(opts, flags, &local_err);
+    if (!local_err && use_aio) {
+        error_setg(&local_err, "AIO is not supported on Windows host devices");
+    }
+    if (local_err) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto done;
+    }
+
     if (strstart(filename, "/dev/cdrom", NULL)) {
         if (find_cdrom(device_name, sizeof(device_name)) < 0) {
             error_setg(errp, "Could not open CD-ROM drive");
@@ -677,7 +723,7 @@ static int hdev_open(BlockDriverState *bs, QDict *options, int flags,
     }
     s->type = find_device_type(bs, filename);
 
-    raw_parse_flags(flags, &access_flags, &overlapped);
+    raw_parse_flags(flags, use_aio, &access_flags, &overlapped);
 
     create_flags = OPEN_EXISTING;
 
diff --git a/blockdev.c b/blockdev.c
index 29c6561..07ec733 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -356,7 +356,6 @@ static void extract_common_blockdev_options(QemuOpts *opts, int *bdrv_flags,
     const char **throttling_group, ThrottleConfig *throttle_cfg,
     BlockdevDetectZeroesOptions *detect_zeroes, Error **errp)
 {
-    const char *discard;
     Error *local_error = NULL;
     const char *aio;
 
@@ -365,13 +364,6 @@ static void extract_common_blockdev_options(QemuOpts *opts, int *bdrv_flags,
             *bdrv_flags |= BDRV_O_COPY_ON_READ;
         }
 
-        if ((discard = qemu_opt_get(opts, "discard")) != NULL) {
-            if (bdrv_parse_discard_flags(discard, bdrv_flags) != 0) {
-                error_setg(errp, "Invalid discard option");
-                return;
-            }
-        }
-
         if ((aio = qemu_opt_get(opts, "aio")) != NULL) {
             if (!strcmp(aio, "native")) {
                 *bdrv_flags |= BDRV_O_NATIVE_AIO;
@@ -449,15 +441,6 @@ static void extract_common_blockdev_options(QemuOpts *opts, int *bdrv_flags,
             error_propagate(errp, local_error);
             return;
         }
-
-        if (bdrv_flags &&
-            *detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
-            !(*bdrv_flags & BDRV_O_UNMAP))
-        {
-            error_setg(errp, "setting detect-zeroes to unmap is not allowed "
-                             "without setting discard operation to unmap");
-            return;
-        }
     }
 }
 
@@ -650,35 +633,11 @@ err_no_opts:
     return NULL;
 }
 
-static QemuOptsList qemu_root_bds_opts;
-
 /* Takes the ownership of bs_opts */
 static BlockDriverState *bds_tree_init(QDict *bs_opts, Error **errp)
 {
-    BlockDriverState *bs;
-    QemuOpts *opts;
-    Error *local_error = NULL;
-    BlockdevDetectZeroesOptions detect_zeroes;
     int bdrv_flags = 0;
 
-    opts = qemu_opts_create(&qemu_root_bds_opts, NULL, 1, errp);
-    if (!opts) {
-        goto fail;
-    }
-
-    qemu_opts_absorb_qdict(opts, bs_opts, &local_error);
-    if (local_error) {
-        error_propagate(errp, local_error);
-        goto fail;
-    }
-
-    extract_common_blockdev_options(opts, &bdrv_flags, NULL, NULL,
-                                    &detect_zeroes, &local_error);
-    if (local_error) {
-        error_propagate(errp, local_error);
-        goto fail;
-    }
-
     /* bdrv_open() defaults to the values in bdrv_flags (for compatibility
      * with other callers) rather than what we want as the real defaults.
      * Apply the defaults here instead. */
@@ -690,21 +649,7 @@ static BlockDriverState *bds_tree_init(QDict *bs_opts, Error **errp)
         bdrv_flags |= BDRV_O_INACTIVE;
     }
 
-    bs = bdrv_open(NULL, NULL, bs_opts, bdrv_flags, errp);
-    if (!bs) {
-        goto fail_no_bs_opts;
-    }
-
-    bs->detect_zeroes = detect_zeroes;
-
-fail_no_bs_opts:
-    qemu_opts_del(opts);
-    return bs;
-
-fail:
-    qemu_opts_del(opts);
-    QDECREF(bs_opts);
-    return NULL;
+    return bdrv_open(NULL, NULL, bs_opts, bdrv_flags, errp);
 }
 
 void blockdev_close_all_bdrv_states(void)
@@ -2549,6 +2494,7 @@ void qmp_blockdev_change_medium(bool has_device, const char *device,
     BlockBackend *blk;
     BlockDriverState *medium_bs = NULL;
     int bdrv_flags;
+    bool detect_zeroes;
     int rc;
     QDict *options = NULL;
     Error *err = NULL;
@@ -2588,8 +2534,12 @@ void qmp_blockdev_change_medium(bool has_device, const char *device,
         abort();
     }
 
+    options = qdict_new();
+    detect_zeroes = blk_get_detect_zeroes_from_root_state(blk);
+    qdict_put(options, "detect-zeroes",
+              qstring_from_str(detect_zeroes ? "on" : "off"));
+
     if (has_format) {
-        options = qdict_new();
         qdict_put(options, "driver", qstring_from_str(format));
     }
 
@@ -2614,7 +2564,7 @@ void qmp_blockdev_change_medium(bool has_device, const char *device,
     error_free(err);
     err = NULL;
 
-    qmp_x_blockdev_remove_medium(has_device, device, has_id, id, errp);
+    qmp_x_blockdev_remove_medium(has_device, device, has_id, id, &err);
     if (err) {
         error_propagate(errp, err);
         goto fail;
@@ -2626,8 +2576,6 @@ void qmp_blockdev_change_medium(bool has_device, const char *device,
         goto fail;
     }
 
-    blk_apply_root_state(blk, medium_bs);
-
     qmp_blockdev_close_tray(has_device, device, has_id, id, errp);
 
 fail:
@@ -3832,21 +3780,6 @@ void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
     QDict *qdict;
     Error *local_err = NULL;
 
-    /* TODO Sort it out in raw-posix and drive_new(): Reject aio=native with
-     * cache.direct=false instead of silently switching to aio=threads, except
-     * when called from drive_new().
-     *
-     * For now, simply forbidding the combination for all drivers will do. */
-    if (options->has_aio && options->aio == BLOCKDEV_AIO_OPTIONS_NATIVE) {
-        bool direct = options->has_cache &&
-                      options->cache->has_direct &&
-                      options->cache->direct;
-        if (!direct) {
-            error_setg(errp, "aio=native requires cache.direct=true");
-            goto fail;
-        }
-    }
-
     visit_type_BlockdevOptions(v, NULL, &options, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
@@ -4005,10 +3938,6 @@ QemuOptsList qemu_common_drive_opts = {
             .type = QEMU_OPT_BOOL,
             .help = "enable/disable snapshot mode",
         },{
-            .name = "discard",
-            .type = QEMU_OPT_STRING,
-            .help = "discard operation (ignore/off, unmap/on)",
-        },{
             .name = "aio",
             .type = QEMU_OPT_STRING,
             .help = "host AIO implementation (threads, native)",
@@ -4135,31 +4064,6 @@ QemuOptsList qemu_common_drive_opts = {
     },
 };
 
-static QemuOptsList qemu_root_bds_opts = {
-    .name = "root-bds",
-    .head = QTAILQ_HEAD_INITIALIZER(qemu_root_bds_opts.head),
-    .desc = {
-        {
-            .name = "discard",
-            .type = QEMU_OPT_STRING,
-            .help = "discard operation (ignore/off, unmap/on)",
-        },{
-            .name = "aio",
-            .type = QEMU_OPT_STRING,
-            .help = "host AIO implementation (threads, native)",
-        },{
-            .name = "copy-on-read",
-            .type = QEMU_OPT_BOOL,
-            .help = "copy read data from backing file into image file",
-        },{
-            .name = "detect-zeroes",
-            .type = QEMU_OPT_STRING,
-            .help = "try to optimize zero writes (off, on, unmap)",
-        },
-        { /* end of list */ }
-    },
-};
-
 QemuOptsList qemu_drive_opts = {
     .name = "drive",
     .head = QTAILQ_HEAD_INITIALIZER(qemu_drive_opts.head),
diff --git a/configure b/configure
index df4a247..5751d8e 100755
--- a/configure
+++ b/configure
@@ -296,6 +296,7 @@ libiscsi=""
 libnfs=""
 coroutine=""
 coroutine_pool=""
+debug_stack_usage="no"
 seccomp=""
 glusterfs=""
 glusterfs_xlator_opt="no"
@@ -1004,6 +1005,8 @@ for opt do
   ;;
   --enable-coroutine-pool) coroutine_pool="yes"
   ;;
+  --enable-debug-stack-usage) debug_stack_usage="yes"
+  ;;
   --disable-docs) docs="no"
   ;;
   --enable-docs) docs="yes"
@@ -4331,6 +4334,17 @@ if test "$coroutine" = "gthread" -a "$coroutine_pool" = "yes"; then
   error_exit "'gthread' coroutine backend does not support pool (use --disable-coroutine-pool)"
 fi
 
+if test "$debug_stack_usage" = "yes"; then
+  if test "$cpu" = "ia64" -o "$cpu" = "hppa"; then
+    error_exit "stack usage debugging is not supported for $cpu"
+  fi
+  if test "$coroutine_pool" = "yes"; then
+    echo "WARN: disabling coroutine pool for stack usage debugging"
+    coroutine_pool=no
+  fi
+fi
+
+
 ##########################################
 # check if we have open_by_handle_at
 
@@ -4916,6 +4930,7 @@ echo "QGA MSI support   $guest_agent_msi"
 echo "seccomp support   $seccomp"
 echo "coroutine backend $coroutine"
 echo "coroutine pool    $coroutine_pool"
+echo "debug stack usage $debug_stack_usage"
 echo "GlusterFS support $glusterfs"
 echo "Archipelago support $archipelago"
 echo "gcov              $gcov_tool"
@@ -5384,6 +5399,10 @@ else
   echo "CONFIG_COROUTINE_POOL=0" >> $config_host_mak
 fi
 
+if test "$debug_stack_usage" = "yes" ; then
+  echo "CONFIG_DEBUG_STACK_USAGE=y" >> $config_host_mak
+fi
+
 if test "$open_by_handle_at" = "yes" ; then
   echo "CONFIG_OPEN_BY_HANDLE=y" >> $config_host_mak
 fi
diff --git a/cpus.c b/cpus.c
index b2fbe33..31204bb 100644
--- a/cpus.c
+++ b/cpus.c
@@ -751,7 +751,7 @@ static int do_vm_stop(RunState state)
 
     bdrv_drain_all();
     replay_disable_events();
-    ret = blk_flush_all();
+    ret = bdrv_flush_all();
 
     return ret;
 }
@@ -1408,7 +1408,7 @@ int vm_stop_force_state(RunState state)
         bdrv_drain_all();
         /* Make sure to return an error if the flush in a previous vm_stop()
          * failed. */
-        return blk_flush_all();
+        return bdrv_flush_all();
     }
 }
 
diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
index aa78393..f85635c 100644
--- a/hw/i386/xen/xen_platform.c
+++ b/hw/i386/xen/xen_platform.c
@@ -134,8 +134,6 @@ static void platform_fixed_ioport_writew(void *opaque, uint32_t addr, uint32_t v
            devices, and bit 2 the non-primary-master IDE devices. */
         if (val & UNPLUG_ALL_IDE_DISKS) {
             DPRINTF("unplug disks\n");
-            blk_drain_all();
-            blk_flush_all();
             pci_unplug_disks(pci_dev->bus);
         }
         if (val & UNPLUG_ALL_NICS) {
diff --git a/hw/ide/piix.c b/hw/ide/piix.c
index c190fca..d5777fd 100644
--- a/hw/ide/piix.c
+++ b/hw/ide/piix.c
@@ -179,6 +179,10 @@ int pci_piix3_xen_ide_unplug(DeviceState *dev)
         if (di != NULL && !di->media_cd) {
             BlockBackend *blk = blk_by_legacy_dinfo(di);
             DeviceState *ds = blk_get_attached_dev(blk);
+
+            blk_drain(blk);
+            blk_flush(blk);
+
             if (ds) {
                 blk_detach_dev(blk, ds);
             }
diff --git a/include/block/block.h b/include/block/block.h
index e18233a..107c603 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -108,6 +108,7 @@ typedef struct HDGeometry {
 #define BDRV_OPT_CACHE_DIRECT   "cache.direct"
 #define BDRV_OPT_CACHE_NO_FLUSH "cache.no-flush"
 #define BDRV_OPT_READ_ONLY      "read-only"
+#define BDRV_OPT_DISCARD        "discard"
 
 
 #define BDRV_SECTOR_BITS   9
@@ -333,6 +334,7 @@ int bdrv_inactivate_all(void);
 /* Ensure contents are flushed to disk.  */
 int bdrv_flush(BlockDriverState *bs);
 int coroutine_fn bdrv_co_flush(BlockDriverState *bs);
+int bdrv_flush_all(void);
 void bdrv_close_all(void);
 void bdrv_drain(BlockDriverState *bs);
 void coroutine_fn bdrv_co_drain(BlockDriverState *bs);
diff --git a/include/qemu/coroutine_int.h b/include/qemu/coroutine_int.h
index 6df9d33..14d4f1d 100644
--- a/include/qemu/coroutine_int.h
+++ b/include/qemu/coroutine_int.h
@@ -28,6 +28,8 @@
 #include "qemu/queue.h"
 #include "qemu/coroutine.h"
 
+#define COROUTINE_STACK_SIZE (1 << 20)
+
 typedef enum {
     COROUTINE_YIELD = 1,
     COROUTINE_TERMINATE = 2,
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 3b29317..a7993af 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -152,7 +152,6 @@ BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
 int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int count);
 int blk_co_flush(BlockBackend *blk);
 int blk_flush(BlockBackend *blk);
-int blk_flush_all(void);
 int blk_commit_all(void);
 void blk_drain(BlockBackend *blk);
 void blk_drain_all(void);
@@ -199,7 +198,7 @@ void blk_io_unplug(BlockBackend *blk);
 BlockAcctStats *blk_get_stats(BlockBackend *blk);
 BlockBackendRootState *blk_get_root_state(BlockBackend *blk);
 void blk_update_root_state(BlockBackend *blk);
-void blk_apply_root_state(BlockBackend *blk, BlockDriverState *bs);
+bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk);
 int blk_get_open_flags_from_root_state(BlockBackend *blk);
 
 void *blk_aio_get(const AIOCBInfo *aiocb_info, BlockBackend *blk,
diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h
index 9c7dfdf..3cfedbc 100644
--- a/include/sysemu/os-posix.h
+++ b/include/sysemu/os-posix.h
@@ -60,4 +60,31 @@ int qemu_utimens(const char *path, const qemu_timespec *times);
 
 bool is_daemonized(void);
 
+/**
+ * qemu_alloc_stack:
+ * @sz: pointer to a size_t holding the requested usable stack size
+ *
+ * Allocate memory that can be used as a stack, for instance for
+ * coroutines. If the memory cannot be allocated, this function
+ * will abort (like g_malloc()). This function also inserts an
+ * additional guard page to catch a potential stack overflow.
+ * Note that the memory required for the guard page and alignment
+ * and minimal stack size restrictions will increase the value of sz.
+ *
+ * The allocated stack must be freed with qemu_free_stack().
+ *
+ * Returns: pointer to (the lowest address of) the stack memory.
+ */
+void *qemu_alloc_stack(size_t *sz);
+
+/**
+ * qemu_free_stack:
+ * @stack: stack to free
+ * @sz: size of stack in bytes
+ *
+ * Free a stack allocated via qemu_alloc_stack(). Note that sz must
+ * be exactly the adjusted stack size returned by qemu_alloc_stack.
+ */
+void qemu_free_stack(void *stack, size_t sz);
+
 #endif
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 92193ab..9d797b8 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1721,15 +1721,16 @@
 ##
 # @BlockdevOptionsFile
 #
-# Driver specific block device options for the file backend and similar
-# protocols.
+# Driver specific block device options for the file backend.
 #
 # @filename:    path to the image file
+# @aio:         #optional AIO backend (default: threads) (since: 2.8)
 #
 # Since: 1.7
 ##
 { 'struct': 'BlockdevOptionsFile',
-  'data': { 'filename': 'str' } }
+  'data': { 'filename': 'str',
+            '*aio': 'BlockdevAioOptions' } }
 
 ##
 # @BlockdevOptionsNull
@@ -2211,6 +2212,18 @@
             '*top-id': 'str' } }
 
 ##
+# @BlockdevOptionsCurl
+#
+# Driver specific block device options for the curl backend.
+#
+# @filename:    path to the image file
+#
+# Since: 1.7
+##
+{ 'struct': 'BlockdevOptionsCurl',
+  'data': { 'filename': 'str' } }
+
+##
 # @BlockdevOptions
 #
 # Options for creating a block device.  Many options are available for all
@@ -2221,7 +2234,6 @@
 #                 This option is required on the top level of blockdev-add.
 # @discard:       #optional discard-related options (default: ignore)
 # @cache:         #optional cache-related options
-# @aio:           #optional AIO backend (default: threads)
 # @read-only:     #optional whether the block device should be read-only
 #                 (default: false)
 # @detect-zeroes: #optional detect and optimize zero writes (Since 2.1)
@@ -2236,7 +2248,6 @@
             '*node-name': 'str',
             '*discard': 'BlockdevDiscardOptions',
             '*cache': 'BlockdevCacheOptions',
-            '*aio': 'BlockdevAioOptions',
             '*read-only': 'bool',
             '*detect-zeroes': 'BlockdevDetectZeroesOptions' },
   'discriminator': 'driver',
@@ -2248,13 +2259,13 @@
       'cloop':      'BlockdevOptionsGenericFormat',
       'dmg':        'BlockdevOptionsGenericFormat',
       'file':       'BlockdevOptionsFile',
-      'ftp':        'BlockdevOptionsFile',
-      'ftps':       'BlockdevOptionsFile',
+      'ftp':        'BlockdevOptionsCurl',
+      'ftps':       'BlockdevOptionsCurl',
       'gluster':    'BlockdevOptionsGluster',
       'host_cdrom': 'BlockdevOptionsFile',
       'host_device':'BlockdevOptionsFile',
-      'http':       'BlockdevOptionsFile',
-      'https':      'BlockdevOptionsFile',
+      'http':       'BlockdevOptionsCurl',
+      'https':      'BlockdevOptionsCurl',
 # TODO iscsi: Wait for structured options
       'luks':       'BlockdevOptionsLUKS',
 # TODO nbd: Should take InetSocketAddress for 'host'?
@@ -2271,7 +2282,7 @@
       'replication':'BlockdevOptionsReplication',
 # TODO sheepdog: Wait for structured options
 # TODO ssh: Should take InetSocketAddress for 'host'?
-      'tftp':       'BlockdevOptionsFile',
+      'tftp':       'BlockdevOptionsCurl',
       'vdi':        'BlockdevOptionsGenericFormat',
       'vhdx':       'BlockdevOptionsGenericFormat',
       'vmdk':       'BlockdevOptionsGenericCOWFormat',
diff --git a/tests/qemu-iotests/087 b/tests/qemu-iotests/087
index 5c04577..b1ac71f 100755
--- a/tests/qemu-iotests/087
+++ b/tests/qemu-iotests/087
@@ -117,10 +117,10 @@ run_qemu <<EOF
       "options": {
         "driver": "$IMGFMT",
         "node-name": "disk",
-        "aio": "native",
         "file": {
             "driver": "file",
-            "filename": "$TEST_IMG"
+            "filename": "$TEST_IMG",
+            "aio": "native"
         }
       }
     }
diff --git a/tests/qemu-iotests/087.out b/tests/qemu-iotests/087.out
index bef6862..cd02eae 100644
--- a/tests/qemu-iotests/087.out
+++ b/tests/qemu-iotests/087.out
@@ -27,7 +27,7 @@ QMP_VERSION
 Testing:
 QMP_VERSION
 {"return": {}}
-{"error": {"class": "GenericError", "desc": "aio=native requires cache.direct=true"}}
+{"error": {"class": "GenericError", "desc": "aio=native was specified, but it requires cache.direct=on, which was not specified."}}
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN"}
 
diff --git a/util/coroutine-sigaltstack.c b/util/coroutine-sigaltstack.c
index a7c3366..f6fc49a 100644
--- a/util/coroutine-sigaltstack.c
+++ b/util/coroutine-sigaltstack.c
@@ -33,8 +33,9 @@
 typedef struct {
     Coroutine base;
     void *stack;
+    size_t stack_size;
     sigjmp_buf env;
-} CoroutineUContext;
+} CoroutineSigAltStack;
 
 /**
  * Per-thread coroutine bookkeeping
@@ -44,7 +45,7 @@ typedef struct {
     Coroutine *current;
 
     /** The default coroutine */
-    CoroutineUContext leader;
+    CoroutineSigAltStack leader;
 
     /** Information for the signal handler (trampoline) */
     sigjmp_buf tr_reenter;
@@ -89,7 +90,7 @@ static void __attribute__((constructor)) coroutine_init(void)
  * (from the signal handler when it is not signal handling, read ahead
  * for more information).
  */
-static void coroutine_bootstrap(CoroutineUContext *self, Coroutine *co)
+static void coroutine_bootstrap(CoroutineSigAltStack *self, Coroutine *co)
 {
     /* Initialize longjmp environment and switch back the caller */
     if (!sigsetjmp(self->env, 0)) {
@@ -109,7 +110,7 @@ static void coroutine_bootstrap(CoroutineUContext *self, Coroutine *co)
  */
 static void coroutine_trampoline(int signal)
 {
-    CoroutineUContext *self;
+    CoroutineSigAltStack *self;
     Coroutine *co;
     CoroutineThreadState *coTS;
 
@@ -143,8 +144,7 @@ static void coroutine_trampoline(int signal)
 
 Coroutine *qemu_coroutine_new(void)
 {
-    const size_t stack_size = 1 << 20;
-    CoroutineUContext *co;
+    CoroutineSigAltStack *co;
     CoroutineThreadState *coTS;
     struct sigaction sa;
     struct sigaction osa;
@@ -164,7 +164,8 @@ Coroutine *qemu_coroutine_new(void)
      */
 
     co = g_malloc0(sizeof(*co));
-    co->stack = g_malloc(stack_size);
+    co->stack_size = COROUTINE_STACK_SIZE;
+    co->stack = qemu_alloc_stack(&co->stack_size);
     co->base.entry_arg = &old_env; /* stash away our jmp_buf */
 
     coTS = coroutine_get_thread_state();
@@ -189,7 +190,7 @@ Coroutine *qemu_coroutine_new(void)
      * Set the new stack.
      */
     ss.ss_sp = co->stack;
-    ss.ss_size = stack_size;
+    ss.ss_size = co->stack_size;
     ss.ss_flags = 0;
     if (sigaltstack(&ss, &oss) < 0) {
         abort();
@@ -251,17 +252,17 @@ Coroutine *qemu_coroutine_new(void)
 
 void qemu_coroutine_delete(Coroutine *co_)
 {
-    CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
+    CoroutineSigAltStack *co = DO_UPCAST(CoroutineSigAltStack, base, co_);
 
-    g_free(co->stack);
+    qemu_free_stack(co->stack, co->stack_size);
     g_free(co);
 }
 
 CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
                                       CoroutineAction action)
 {
-    CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
-    CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);
+    CoroutineSigAltStack *from = DO_UPCAST(CoroutineSigAltStack, base, from_);
+    CoroutineSigAltStack *to = DO_UPCAST(CoroutineSigAltStack, base, to_);
     CoroutineThreadState *s = coroutine_get_thread_state();
     int ret;
 
diff --git a/util/coroutine-ucontext.c b/util/coroutine-ucontext.c
index 2bb7e10..6621f3f 100644
--- a/util/coroutine-ucontext.c
+++ b/util/coroutine-ucontext.c
@@ -34,6 +34,7 @@
 typedef struct {
     Coroutine base;
     void *stack;
+    size_t stack_size;
     sigjmp_buf env;
 
 #ifdef CONFIG_VALGRIND_H
@@ -82,7 +83,6 @@ static void coroutine_trampoline(int i0, int i1)
 
 Coroutine *qemu_coroutine_new(void)
 {
-    const size_t stack_size = 1 << 20;
     CoroutineUContext *co;
     ucontext_t old_uc, uc;
     sigjmp_buf old_env;
@@ -101,17 +101,18 @@ Coroutine *qemu_coroutine_new(void)
     }
 
     co = g_malloc0(sizeof(*co));
-    co->stack = g_malloc(stack_size);
+    co->stack_size = COROUTINE_STACK_SIZE;
+    co->stack = qemu_alloc_stack(&co->stack_size);
     co->base.entry_arg = &old_env; /* stash away our jmp_buf */
 
     uc.uc_link = &old_uc;
     uc.uc_stack.ss_sp = co->stack;
-    uc.uc_stack.ss_size = stack_size;
+    uc.uc_stack.ss_size = co->stack_size;
     uc.uc_stack.ss_flags = 0;
 
 #ifdef CONFIG_VALGRIND_H
     co->valgrind_stack_id =
-        VALGRIND_STACK_REGISTER(co->stack, co->stack + stack_size);
+        VALGRIND_STACK_REGISTER(co->stack, co->stack + co->stack_size);
 #endif
 
     arg.p = co;
@@ -149,7 +150,7 @@ void qemu_coroutine_delete(Coroutine *co_)
     valgrind_stack_deregister(co);
 #endif
 
-    g_free(co->stack);
+    qemu_free_stack(co->stack, co->stack_size);
     g_free(co);
 }
 
diff --git a/util/coroutine-win32.c b/util/coroutine-win32.c
index 02e28e8..de6bd4f 100644
--- a/util/coroutine-win32.c
+++ b/util/coroutine-win32.c
@@ -71,7 +71,7 @@ static void CALLBACK coroutine_trampoline(void *co_)
 
 Coroutine *qemu_coroutine_new(void)
 {
-    const size_t stack_size = 1 << 20;
+    const size_t stack_size = COROUTINE_STACK_SIZE;
     CoroutineWin32 *co;
 
     co = g_malloc0(sizeof(*co));
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index f2d4e9e..aaec189 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -50,6 +50,10 @@
 
 #include "qemu/mmap-alloc.h"
 
+#ifdef CONFIG_DEBUG_STACK_USAGE
+#include "qemu/error-report.h"
+#endif
+
 int qemu_get_thread_id(void)
 {
 #if defined(__linux__)
@@ -499,3 +503,76 @@ pid_t qemu_fork(Error **errp)
     }
     return pid;
 }
+
+void *qemu_alloc_stack(size_t *sz)
+{
+    void *ptr, *guardpage;
+#ifdef CONFIG_DEBUG_STACK_USAGE
+    void *ptr2;
+#endif
+    size_t pagesz = getpagesize();
+#ifdef _SC_THREAD_STACK_MIN
+    /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
+    long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN);
+    *sz = MAX(MAX(min_stack_sz, 0), *sz);
+#endif
+    /* adjust stack size to a multiple of the page size */
+    *sz = ROUND_UP(*sz, pagesz);
+    /* allocate one extra page for the guard page */
+    *sz += pagesz;
+
+    ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE,
+               MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if (ptr == MAP_FAILED) {
+        abort();
+    }
+
+#if defined(HOST_IA64)
+    /* separate register stack */
+    guardpage = ptr + (((*sz - pagesz) / 2) & ~pagesz);
+#elif defined(HOST_HPPA)
+    /* stack grows up */
+    guardpage = ptr + *sz - pagesz;
+#else
+    /* stack grows down */
+    guardpage = ptr;
+#endif
+    if (mprotect(guardpage, pagesz, PROT_NONE) != 0) {
+        abort();
+    }
+
+#ifdef CONFIG_DEBUG_STACK_USAGE
+    for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) {
+        *(uint32_t *)ptr2 = 0xdeadbeaf;
+    }
+#endif
+
+    return ptr;
+}
+
+#ifdef CONFIG_DEBUG_STACK_USAGE
+static __thread unsigned int max_stack_usage;
+#endif
+
+void qemu_free_stack(void *stack, size_t sz)
+{
+#ifdef CONFIG_DEBUG_STACK_USAGE
+    unsigned int usage;
+    void *ptr;
+
+    for (ptr = stack + getpagesize(); ptr < stack + sz;
+         ptr += sizeof(uint32_t)) {
+        if (*(uint32_t *)ptr != 0xdeadbeaf) {
+            break;
+        }
+    }
+    usage = sz - (uintptr_t) (ptr - stack);
+    if (usage > max_stack_usage) {
+        error_report("thread %d max stack usage increased from %u to %u",
+                     qemu_get_thread_id(), max_stack_usage, usage);
+        max_stack_usage = usage;
+    }
+#endif
+
+    munmap(stack, sz);
+}