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Xen PV backend: Move call to bdrv_new from blk_init to blk_connect

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This commit delays the point at which bdrv_new (and hence blk_open
on the underlying device) is called from blk_init to blk_connect.
This ensures that in an inbound live migrate, the block device is
not opened until it has been closed at the other end. This is in
preparation for supporting devices with open/close consistency
without using O_DIRECT. This commit does NOT itself change O_DIRECT
semantics.

Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
This commit is contained in:
Alex Bligh 2013-04-05 15:45:10 +00:00 committed by Stefano Stabellini
parent d05ef16045
commit 86f425db3b
1 changed files with 54 additions and 46 deletions
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100
hw/xen_disk.c
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@ -700,7 +700,7 @@ static void blk_alloc(struct XenDevice *xendev)
static int blk_init(struct XenDevice *xendev) static int blk_init(struct XenDevice *xendev)
{ {
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev); struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
int index, qflags, info = 0; int info = 0;
/* read xenstore entries */ /* read xenstore entries */
if (blkdev->params == NULL) { if (blkdev->params == NULL) {
@ -743,10 +743,7 @@ static int blk_init(struct XenDevice *xendev)
} }
/* read-only ? */ /* read-only ? */
qflags = BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NATIVE_AIO; if (strcmp(blkdev->mode, "w")) {
if (strcmp(blkdev->mode, "w") == 0) {
qflags |= BDRV_O_RDWR;
} else {
info |= VDISK_READONLY; info |= VDISK_READONLY;
} }
@ -755,50 +752,14 @@ static int blk_init(struct XenDevice *xendev)
info |= VDISK_CDROM; info |= VDISK_CDROM;
} }
/* init qemu block driver */
index = (blkdev->xendev.dev - 202 * 256) / 16;
blkdev->dinfo = drive_get(IF_XEN, 0, index);
if (!blkdev->dinfo) {
/* setup via xenbus -> create new block driver instance */
xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
blkdev->bs = bdrv_new(blkdev->dev);
if (blkdev->bs) {
if (bdrv_open(blkdev->bs, blkdev->filename, NULL, qflags,
bdrv_find_whitelisted_format(blkdev->fileproto)) != 0) {
bdrv_delete(blkdev->bs);
blkdev->bs = NULL;
}
}
if (!blkdev->bs) {
goto out_error;
}
} else {
/* setup via qemu cmdline -> already setup for us */
xen_be_printf(&blkdev->xendev, 2, "get configured bdrv (cmdline setup)\n");
blkdev->bs = blkdev->dinfo->bdrv;
}
bdrv_attach_dev_nofail(blkdev->bs, blkdev);
blkdev->file_blk = BLOCK_SIZE; blkdev->file_blk = BLOCK_SIZE;
blkdev->file_size = bdrv_getlength(blkdev->bs);
if (blkdev->file_size < 0) {
xen_be_printf(&blkdev->xendev, 1, "bdrv_getlength: %d (%s) | drv %s\n",
(int)blkdev->file_size, strerror(-blkdev->file_size),
bdrv_get_format_name(blkdev->bs) ?: "-");
blkdev->file_size = 0;
}
xen_be_printf(xendev, 1, "type \"%s\", fileproto \"%s\", filename \"%s\"," /* fill info
" size %" PRId64 " (%" PRId64 " MB)\n", * blk_connect supplies sector-size and sectors
blkdev->type, blkdev->fileproto, blkdev->filename, */
blkdev->file_size, blkdev->file_size >> 20);
/* fill info */
xenstore_write_be_int(&blkdev->xendev, "feature-flush-cache", 1); xenstore_write_be_int(&blkdev->xendev, "feature-flush-cache", 1);
xenstore_write_be_int(&blkdev->xendev, "feature-persistent", 1); xenstore_write_be_int(&blkdev->xendev, "feature-persistent", 1);
xenstore_write_be_int(&blkdev->xendev, "info", info); xenstore_write_be_int(&blkdev->xendev, "info", info);
xenstore_write_be_int(&blkdev->xendev, "sector-size", blkdev->file_blk);
xenstore_write_be_int(&blkdev->xendev, "sectors",
blkdev->file_size / blkdev->file_blk);
return 0; return 0;
out_error: out_error:
@ -818,7 +779,54 @@ out_error:
static int blk_connect(struct XenDevice *xendev) static int blk_connect(struct XenDevice *xendev)
{ {
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev); struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
int pers; int pers, index, qflags;
/* read-only ? */
qflags = BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NATIVE_AIO;
if (strcmp(blkdev->mode, "w") == 0) {
qflags |= BDRV_O_RDWR;
}
/* init qemu block driver */
index = (blkdev->xendev.dev - 202 * 256) / 16;
blkdev->dinfo = drive_get(IF_XEN, 0, index);
if (!blkdev->dinfo) {
/* setup via xenbus -> create new block driver instance */
xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
blkdev->bs = bdrv_new(blkdev->dev);
if (blkdev->bs) {
if (bdrv_open(blkdev->bs, blkdev->filename, NULL, qflags,
bdrv_find_whitelisted_format(blkdev->fileproto)) != 0) {
bdrv_delete(blkdev->bs);
blkdev->bs = NULL;
}
}
if (!blkdev->bs) {
return -1;
}
} else {
/* setup via qemu cmdline -> already setup for us */
xen_be_printf(&blkdev->xendev, 2, "get configured bdrv (cmdline setup)\n");
blkdev->bs = blkdev->dinfo->bdrv;
}
bdrv_attach_dev_nofail(blkdev->bs, blkdev);
blkdev->file_size = bdrv_getlength(blkdev->bs);
if (blkdev->file_size < 0) {
xen_be_printf(&blkdev->xendev, 1, "bdrv_getlength: %d (%s) | drv %s\n",
(int)blkdev->file_size, strerror(-blkdev->file_size),
bdrv_get_format_name(blkdev->bs) ?: "-");
blkdev->file_size = 0;
}
xen_be_printf(xendev, 1, "type \"%s\", fileproto \"%s\", filename \"%s\","
" size %" PRId64 " (%" PRId64 " MB)\n",
blkdev->type, blkdev->fileproto, blkdev->filename,
blkdev->file_size, blkdev->file_size >> 20);
/* Fill in number of sector size and number of sectors */
xenstore_write_be_int(&blkdev->xendev, "sector-size", blkdev->file_blk);
xenstore_write_be_int(&blkdev->xendev, "sectors",
blkdev->file_size / blkdev->file_blk);
if (xenstore_read_fe_int(&blkdev->xendev, "ring-ref", &blkdev->ring_ref) == -1) { if (xenstore_read_fe_int(&blkdev->xendev, "ring-ref", &blkdev->ring_ref) == -1) {
return -1; return -1;