exec: split qemu_ram_alloc_from_file()

Add qemu_ram_alloc_from_fd(), which can be use to allocate ramblock from
fd only.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170602141229.15326-4-marcandre.lureau@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

exec.c

@@ -1914,14 +1914,12 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
 }
 
 #ifdef __linux__
-RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
-                                   bool share, const char *mem_path,
-                                   Error **errp)
+RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
+                                 bool share, int fd,
+                                 Error **errp)
 {
     RAMBlock *new_block;
     Error *local_err = NULL;
-    int fd;
-    bool created;
     int64_t file_size;
 
     if (xen_enabled()) {
@@ -1946,18 +1944,12 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
         return NULL;
     }
 
-    fd = file_ram_open(mem_path, memory_region_name(mr), &created, errp);
-    if (fd < 0) {
-        return NULL;
-    }
-
     size = HOST_PAGE_ALIGN(size);
     file_size = get_file_size(fd);
     if (file_size > 0 && file_size < size) {
         error_setg(errp, "backing store %s size 0x%" PRIx64
                    " does not match 'size' option 0x" RAM_ADDR_FMT,
                    mem_path, file_size, size);
-        close(fd);
         return NULL;
     }
 
@@ -1968,10 +1960,6 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
     new_block->flags = share ? RAM_SHARED : 0;
     new_block->host = file_ram_alloc(new_block, size, fd, !file_size, errp);
     if (!new_block->host) {
-        if (created) {
-            unlink(mem_path);
-        }
-        close(fd);
         g_free(new_block);
         return NULL;
     }
@@ -1983,6 +1971,33 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
         return NULL;
     }
     return new_block;
+
+}
+
+
+RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
+                                   bool share, const char *mem_path,
+                                   Error **errp)
+{
+    int fd;
+    bool created;
+    RAMBlock *block;
+
+    fd = file_ram_open(mem_path, memory_region_name(mr), &created, errp);
+    if (fd < 0) {
+        return NULL;
+    }
+
+    block = qemu_ram_alloc_from_fd(size, mr, share, fd, errp);
+    if (!block) {
+        if (created) {
+            unlink(mem_path);
+        }
+        close(fd);
+        return NULL;
+    }
+
+    return block;
 }
 #endif
 

include/exec/ram_addr.h

@@ -65,6 +65,9 @@ unsigned long last_ram_page(void);
 RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
                                    bool share, const char *mem_path,
                                    Error **errp);
+RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
+                                 bool share, int fd,
+                                 Error **errp);
 RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
                                   MemoryRegion *mr, Error **errp);
 RAMBlock *qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr, Error **errp);