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[Qemu-devel] [RFC PATCH 17/41] block: Request real permissions in blk_ne


From: Kevin Wolf
Subject: [Qemu-devel] [RFC PATCH 17/41] block: Request real permissions in blk_new_open()
Date: Mon, 13 Feb 2017 18:22:39 +0100

We can figure out the necessary permissions from the flags that the
caller passed.

Signed-off-by: Kevin Wolf <address@hidden>
---
 block/block-backend.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index 1f80854..e10a278 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -160,6 +160,7 @@ BlockBackend *blk_new_open(const char *filename, const char 
*reference,
 {
     BlockBackend *blk;
     BlockDriverState *bs;
+    uint64_t perm;
 
     blk = blk_new(0, BLK_PERM_ALL);
     bs = bdrv_open(filename, reference, options, flags, errp);
@@ -168,9 +169,20 @@ BlockBackend *blk_new_open(const char *filename, const 
char *reference,
         return NULL;
     }
 
-    /* FIXME Use real permissions */
+    /* blk_new_open() is mainly used in .bdrv_create implementations and the
+     * tools where sharing isn't a concern because the BDS stays private, so we
+     * just request permission according to the flags.
+     *
+     * The exceptions are xen_disk and blockdev_init(); in these cases, the
+     * caller of blk_new_open() doesn't make use of the permissions, but they
+     * shouldn't hurt either. We can still share everything here because the
+     * guest devices will add their own blockers if they can't share. */
+    perm = BLK_PERM_CONSISTENT_READ;
+    if (flags & BDRV_O_RDWR) {
+        perm |= BLK_PERM_WRITE;
+    }
     blk->root = bdrv_root_attach_child(bs, "root", &child_root,
-                                       0, BLK_PERM_ALL, blk, &error_abort);
+                                       perm, BLK_PERM_ALL, blk, &error_abort);
 
     return blk;
 }
-- 
1.8.3.1




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