block: Add BDRV_O_RESIZE for blk_new_open()

blk_new_open() is a convenience function that processes flags rather
than QDict options as a simple way to just open an image file.

In order to keep it convenient in the future, it must automatically
request the necessary permissions. This can easily be inferred from the
flags for read and write, but we need another flag that tells us whether
to get the resize permission.

We can't just always request it because that means that no block jobs
can run on the resulting BlockBackend (which is something that e.g.
qemu-img commit wants to do), but we also can't request it never because
most of the .bdrv_create() implementations call blk_truncate().

The solution is to introduce another flag that is passed by all users
that want to resize the image.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

11 files changed, 23 insertions, 12 deletions

diff --git a/block/parallels.c b/block/parallels.c
index 6b0c0a917c..19935e29a9 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -488,7 +488,8 @@ static int parallels_create(const char *filename, QemuOpts *opts, Error **errp)
     }
 
     file = blk_new_open(filename, NULL, NULL,
-                        BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                        BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                        &local_err);
     if (file == NULL) {
         error_propagate(errp, local_err);
         return -EIO;
diff --git a/block/qcow.c b/block/qcow.c
index eb5d54c65a..9d6ac83959 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -823,7 +823,8 @@ static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
     }
 
     qcow_blk = blk_new_open(filename, NULL, NULL,
-                            BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                            BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                            &local_err);
     if (qcow_blk == NULL) {
         error_propagate(errp, local_err);
         ret = -EIO;
diff --git a/block/qcow2.c b/block/qcow2.c
index 6f79df8517..6a92d2ef3f 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2202,7 +2202,8 @@ static int qcow2_create2(const char *filename, int64_t total_size,
     }
 
     blk = blk_new_open(filename, NULL, NULL,
-                       BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                       &local_err);
     if (blk == NULL) {
         error_propagate(errp, local_err);
         return -EIO;
@@ -2266,7 +2267,8 @@ static int qcow2_create2(const char *filename, int64_t total_size,
     options = qdict_new();
     qdict_put(options, "driver", qstring_from_str("qcow2"));
     blk = blk_new_open(filename, NULL, options,
-                       BDRV_O_RDWR | BDRV_O_NO_FLUSH, &local_err);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_NO_FLUSH,
+                       &local_err);
     if (blk == NULL) {
         error_propagate(errp, local_err);
         ret = -EIO;
diff --git a/block/qed.c b/block/qed.c
index d8f947aaa3..5ec7fd83f2 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -625,7 +625,8 @@ static int qed_create(const char *filename, uint32_t cluster_size,
     }
 
     blk = blk_new_open(filename, NULL, NULL,
-                       BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                       &local_err);
     if (blk == NULL) {
         error_propagate(errp, local_err);
         return -EIO;
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 860ba61502..743471043e 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -1609,7 +1609,7 @@ static int sd_prealloc(const char *filename, Error **errp)
     int ret;
 
     blk = blk_new_open(filename, NULL, NULL,
-                       BDRV_O_RDWR | BDRV_O_PROTOCOL, errp);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
     if (blk == NULL) {
         ret = -EIO;
         goto out_with_err_set;
diff --git a/block/vdi.c b/block/vdi.c
index fd6e26dfed..9b4f70e977 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -763,7 +763,8 @@ static int vdi_create(const char *filename, QemuOpts *opts, Error **errp)
     }
 
     blk = blk_new_open(filename, NULL, NULL,
-                       BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                       &local_err);
     if (blk == NULL) {
         error_propagate(errp, local_err);
         ret = -EIO;
diff --git a/block/vhdx.c b/block/vhdx.c
index ab747f6393..052a753159 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1859,7 +1859,8 @@ static int vhdx_create(const char *filename, QemuOpts *opts, Error **errp)
     }
 
     blk = blk_new_open(filename, NULL, NULL,
-                       BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                       &local_err);
     if (blk == NULL) {
         error_propagate(errp, local_err);
         ret = -EIO;
diff --git a/block/vmdk.c b/block/vmdk.c
index f5e2fb5cf0..a9bd22bf93 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1703,7 +1703,8 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
     }
 
     blk = blk_new_open(filename, NULL, NULL,
-                       BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                       &local_err);
     if (blk == NULL) {
         error_propagate(errp, local_err);
         ret = -EIO;
@@ -2071,7 +2072,8 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp)
     }
 
     new_blk = blk_new_open(filename, NULL, NULL,
-                           BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                           BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                           &local_err);
     if (new_blk == NULL) {
         error_propagate(errp, local_err);
         ret = -EIO;
diff --git a/block/vpc.c b/block/vpc.c
index b9c9832637..f591d4be38 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -915,7 +915,8 @@ static int vpc_create(const char *filename, QemuOpts *opts, Error **errp)
     }
 
     blk = blk_new_open(filename, NULL, NULL,
-                       BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
+                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
+                       &local_err);
     if (blk == NULL) {
         error_propagate(errp, local_err);
         ret = -EIO;
diff --git a/include/block/block.h b/include/block/block.h
index ff951ea772..07f7561886 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -82,6 +82,7 @@ typedef struct HDGeometry {
 } HDGeometry;
 
 #define BDRV_O_RDWR        0x0002
+#define BDRV_O_RESIZE      0x0004 /* request permission for resizing the node */
 #define BDRV_O_SNAPSHOT    0x0008 /* open the file read only and save writes in a snapshot */
 #define BDRV_O_TEMPORARY   0x0010 /* delete the file after use */
 #define BDRV_O_NOCACHE     0x0020 /* do not use the host page cache */
diff --git a/qemu-img.c b/qemu-img.c
index caa76a7400..a48a471042 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3419,7 +3419,7 @@ static int img_resize(int argc, char **argv)
     qemu_opts_del(param);
 
     blk = img_open(image_opts, filename, fmt,
-                   BDRV_O_RDWR, false, quiet);
+                   BDRV_O_RDWR | BDRV_O_RESIZE, false, quiet);
     if (!blk) {
         ret = -1;
         goto out;