Re: [Qemu-devel] [PATCH v3 5/5] BlockConf: Call backend functions to detect geometry and blocksizes

Mon, 15 Dec 2014 06:42:33 -0800 

On 12/15/2014 04:50 PM, Markus Armbruster wrote:

Ekaterina Tumanova <tuman...@linux.vnet.ibm.com> writes:


geometry: hd_geometry_guess function autodetects the drive geometry.
This patch adds a block backend call, that probes the backing device
geometry. If the inner driver method is implemented and succeeds
(currently only for DASDs), the blkconf_geometry will pass-through
the backing device geometry. Otherwise will fallback to old logic.

blocksize: This patch initializes blocksize properties to 0.
In order to set the properly a blkconf_blocksizes was introduced.
If user didn't set physical or logical blocksize, it will
retrieve it's value from a driver (which will return a default 512 for
any backend but DASD).

The blkconf_blocksizes call was added to all users of BlkConf.

Signed-off-by: Ekaterina Tumanova <tuman...@linux.vnet.ibm.com>
---
  hw/block/block.c          | 18 ++++++++++++++++++
  hw/block/hd-geometry.c    | 12 ++++++++++++
  hw/block/nvme.c           |  1 +
  hw/block/virtio-blk.c     |  1 +
  hw/core/qdev-properties.c |  3 ++-
  hw/ide/qdev.c             |  1 +
  hw/scsi/scsi-disk.c       |  1 +
  hw/usb/dev-storage.c      |  1 +
  include/hw/block/block.h  |  5 +++--
  9 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/hw/block/block.c b/hw/block/block.c
index a625773..9c07516 100644
--- a/hw/block/block.c
+++ b/hw/block/block.c
@@ -25,6 +25,24 @@ void blkconf_serial(BlockConf *conf, char **serial)
      }
  }

+void blkconf_blocksizes(BlockConf *conf)
+{
+    BlockBackend *blk = conf->blk;
+    BlockSizes blocksizes;
+
+    if (conf->physical_block_size && conf->logical_block_size) {
+        return;
+    }


This conditional isn't necessary for correctness.  Feel free to drop it.



But this allows to avoid the ioctl call when user has specified both
values. Remove anyway?


+    blk_probe_blocksizes(blk, &blocksizes);
+
+    if (!conf->physical_block_size) {
+        conf->physical_block_size = blocksizes.phys;
+    }
+    if (!conf->logical_block_size) {
+        conf->logical_block_size = blocksizes.log;
+    }




I'll add a comment to make it apparent.


This works because you change the default block size to 0 (second to
last hunk).


+}
+
  void blkconf_geometry(BlockConf *conf, int *ptrans,
                        unsigned cyls_max, unsigned heads_max, unsigned 
secs_max,
                        Error **errp)
diff --git a/hw/block/hd-geometry.c b/hw/block/hd-geometry.c
index 6fcf74d..fbd602d 100644
--- a/hw/block/hd-geometry.c
+++ b/hw/block/hd-geometry.c
@@ -121,7 +121,17 @@ void hd_geometry_guess(BlockBackend *blk,
                         int *ptrans)
  {
      int cylinders, heads, secs, translation;
+    hdGeometry geo;

+    /* Try to probe the backing device geometry, otherwise fallback
+       to the old logic. (as of 12/2014 probing only succeeds on DASDs) */
+    if (blk_probe_geometry(blk, &geo) == 0) {
+        *pcyls = geo.cylinders;
+        *psecs = geo.sectors;
+        *pheads = geo.heads;
+        translation = BIOS_ATA_TRANSLATION_NONE;
+        goto done;
+    }


"else if" instead of goto, please.


      if (guess_disk_lchs(blk, &cylinders, &heads, &secs) < 0) {
          /* no LCHS guess: use a standard physical disk geometry  */
          guess_chs_for_size(blk, pcyls, pheads, psecs);
@@ -142,7 +152,9 @@ void hd_geometry_guess(BlockBackend *blk,
          /* disable any translation to be in sync with
             the logical geometry */
          translation = BIOS_ATA_TRANSLATION_NONE;
+
      }


Humor me: put the empty line behind the brace instead of before.


+done:
      if (ptrans) {
          *ptrans = translation;
      }


Much easier to gauge than v2.  Geometry change is a compatibility
problem.  You change it only when blk_probe_geometry() succeeds.  It
succeeds only for DASD.  Mission accomplished.

Recommend to add a hint to the function contract of the
bdrv_probe_geometry() callback in block_int.h:

     /**
      * Try to get @bs's geometry (cyls, heads, sectos)
      * On success, store them in @geo and return 0.
      * On failure return -errno.
      * Only drivers that want to override guest geometry implement this
      * callback; see hd_geometry_guess().
      */
     int (*bdrv_probe_geometry)(BlockDriverState *bs, hdGeometry *geo);


diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 1327658..244e382 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -763,6 +763,7 @@ static int nvme_init(PCIDevice *pci_dev)
      if (!n->serial) {
          return -1;
      }
+    blkconf_blocksizes(&n->conf);

      pci_conf = pci_dev->config;
      pci_conf[PCI_INTERRUPT_PIN] = 1;
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index b19b102..6f01565 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -745,6 +745,7 @@ static void virtio_blk_device_realize(DeviceState *dev, 
Error **errp)
          error_propagate(errp, err);
          return;
      }
+    blkconf_blocksizes(&conf->conf);

      virtio_init(vdev, "virtio-blk", VIRTIO_ID_BLOCK,
                  sizeof(struct virtio_blk_config));
diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index 2e47f70..ba81709 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -580,7 +580,8 @@ static void set_blocksize(Object *obj, Visitor *v, void 
*opaque,
          error_propagate(errp, local_err);
          return;
      }
-    if (value < min || value > max) {
+    /* value of 0 means "unset" */
+    if (value && (value < min || value > max)) {
          error_set(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
                    dev->id?:"", name, (int64_t)value, min, max);
          return;
diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
index b4f096e..e71ff7f 100644
--- a/hw/ide/qdev.c
+++ b/hw/ide/qdev.c
@@ -164,6 +164,7 @@ static int ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind)
      }

      blkconf_serial(&dev->conf, &dev->serial);
+    blkconf_blocksizes(&dev->conf);
      if (kind != IDE_CD) {
          blkconf_geometry(&dev->conf, &dev->chs_trans, 65536, 16, 255, &err);
          if (err) {
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index 2f75d7d..5288129 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -2230,6 +2230,7 @@ static void scsi_realize(SCSIDevice *dev, Error **errp)
      }

      blkconf_serial(&s->qdev.conf, &s->serial);
+    blkconf_blocksizes(&s->qdev.conf);
      if (dev->type == TYPE_DISK) {
          blkconf_geometry(&dev->conf, NULL, 65535, 255, 255, &err);
          if (err) {
diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index 4539733..cc02dfd 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -611,6 +611,7 @@ static void usb_msd_realize_storage(USBDevice *dev, Error 
**errp)
      }

      blkconf_serial(&s->conf, &dev->serial);
+    blkconf_blocksizes(&s->conf);

      /*
       * Hack alert: this pretends to be a block device, but it's really
diff --git a/include/hw/block/block.h b/include/hw/block/block.h
index 0d0ce9a..3e502a8 100644
--- a/include/hw/block/block.h
+++ b/include/hw/block/block.h
@@ -44,9 +44,9 @@ static inline unsigned int get_physical_block_exp(BlockConf 
*conf)
  #define DEFINE_BLOCK_PROPERTIES(_state, _conf)                          \
      DEFINE_PROP_DRIVE("drive", _state, _conf.blk),                      \
      DEFINE_PROP_BLOCKSIZE("logical_block_size", _state,                 \
-                          _conf.logical_block_size, 512),               \
+                          _conf.logical_block_size, 0),               \
      DEFINE_PROP_BLOCKSIZE("physical_block_size", _state,                \
-                          _conf.physical_block_size, 512),              \
+                          _conf.physical_block_size, 0),              \
      DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 0),  \
      DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 0),    \
      DEFINE_PROP_UINT32("discard_granularity", _state, \
@@ -63,6 +63,7 @@ void blkconf_serial(BlockConf *conf, char **serial);
  void blkconf_geometry(BlockConf *conf, int *trans,
                        unsigned cyls_max, unsigned heads_max, unsigned 
secs_max,
                        Error **errp);
+void blkconf_blocksizes(BlockConf *conf);

  /* Hard disk geometry */

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