[Qemu-devel] [PATCH]: block: get rid of the BDRV_O_FILE flag

[Christoph Hellwig <hch@lst.de>]

BDRV_O_FILE is only used to communicate between bdrv_file_open and bdrv_open.
It affects two things:  first bdrv_open only searches for protocols using
find_protocol instead of all image formats and host drivers.  We can easily
move that to the caller and pass the found driver to bdrv_open.  Second
it is used to not force a read-write open of a snapshot file.  But we never
use bdrv_file_open to open snapshots and this behaviour doesn't make sense
to start with.

qemu-io abused the BDRV_O_FILE for it's growable option, switch it to
using bdrv_file_open to make sure we only open files as growable were
we can actually support that.

This patch requires Kevin's "[PATCH] Replace calls of old bdrv_open" to
be applied first.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: qemu/block.c
===================================================================
--- qemu.orig/block.c	2010-04-05 16:30:39.370254354 +0200
+++ qemu/block.c	2010-04-05 16:32:40.992005645 +0200
@@ -335,10 +335,16 @@ static BlockDriver *find_image_format(co
 int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags)
 {
     BlockDriverState *bs;
+    BlockDriver *drv;
     int ret;
 
+    drv = find_protocol(filename);
+    if (!drv) {
+        return -ENOENT;
+    }
+
     bs = bdrv_new("");
-    ret = bdrv_open(bs, filename, flags | BDRV_O_FILE, NULL);
+    ret = bdrv_open(bs, filename, flags, drv);
     if (ret < 0) {
         bdrv_delete(bs);
         return ret;
@@ -416,9 +422,8 @@ int bdrv_open(BlockDriverState *bs, cons
     }
 
     pstrcpy(bs->filename, sizeof(bs->filename), filename);
-    if (flags & BDRV_O_FILE) {
-        drv = find_protocol(filename);
-    } else if (!drv) {
+
+    if (!drv) {
         drv = find_hdev_driver(filename);
         if (!drv) {
             drv = find_image_format(filename);
@@ -450,14 +455,12 @@ int bdrv_open(BlockDriverState *bs, cons
      * Clear flags that are internal to the block layer before opening the
      * image.
      */
-    open_flags = flags & ~(BDRV_O_FILE | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
+    open_flags = flags & ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
 
     /*
      * Snapshots should be writeable.
-     *
-     * XXX(hch): and what is the point of a snapshot during a read-only open?
      */
-    if (!(flags & BDRV_O_FILE) && bs->is_temporary) {
+    if (bs->is_temporary) {
         open_flags |= BDRV_O_RDWR;
     }
 
Index: qemu/block.h
===================================================================
--- qemu.orig/block.h	2010-04-05 16:30:39.371254214 +0200
+++ qemu/block.h	2010-04-05 16:31:29.944004249 +0200
@@ -29,10 +29,6 @@ typedef struct QEMUSnapshotInfo {
 
 #define BDRV_O_RDWR        0x0002
 #define BDRV_O_SNAPSHOT    0x0008 /* open the file read only and save writes in a snapshot */
-#define BDRV_O_FILE        0x0010 /* open as a raw file (do not try to
-                                     use a disk image format on top of
-                                     it (default for
-                                     bdrv_file_open()) */
 #define BDRV_O_NOCACHE     0x0020 /* do not use the host page cache */
 #define BDRV_O_CACHE_WB    0x0040 /* use write-back caching */
 #define BDRV_O_NATIVE_AIO  0x0080 /* use native AIO instead of the thread pool */
Index: qemu/qemu-io.c
===================================================================
--- qemu.orig/qemu-io.c	2010-04-05 16:30:39.381254145 +0200
+++ qemu/qemu-io.c	2010-04-05 16:31:29.946004598 +0200
@@ -1276,23 +1276,23 @@ static int openfile(char *name, int flag
 		return 1;
 	}
 
-	bs = bdrv_new("hda");
-	if (!bs)
-		return 1;
-
 	if (growable) {
-		flags |= BDRV_O_FILE;
-	}
+		if (bdrv_file_open(&bs, name, flags)) {
+			fprintf(stderr, "%s: can't open device %s\n", progname, name);
+			return 1;
+		}
+	} else {
+		bs = bdrv_new("hda");
+		if (!bs)
+			return 1;
 
-	if (bdrv_open(bs, name, flags, NULL) < 0) {
-		fprintf(stderr, "%s: can't open device %s\n", progname, name);
-		bs = NULL;
-		return 1;
+		if (bdrv_open(bs, name, flags, NULL) < 0) {
+			fprintf(stderr, "%s: can't open device %s\n", progname, name);
+			bs = NULL;
+			return 1;
+		}
 	}
 
-	if (growable) {
-		bs->growable = 1;
-	}
 	return 0;
 }