[Qemu-devel] [PATCH RFC 1/3] xen_disk: handle disk files on ramfs/tmpfs

[Roger Pau Monne <roger.pau@citrix.com>]

Files that reside on ramfs or tmpfs cannot be opened with O_DIRECT,
if first call to bdrv_open fails with errno = EINVAL, try a second
call without BDRV_O_NOCACHE.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: xen-devel@lists.xen.org
Cc: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com>
Cc: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/xen_disk.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/hw/xen_disk.c b/hw/xen_disk.c
index e6bb2f2..a159ee5 100644
--- a/hw/xen_disk.c
+++ b/hw/xen_disk.c
@@ -562,7 +562,7 @@ static void blk_alloc(struct XenDevice *xendev)
 static int blk_init(struct XenDevice *xendev)
 {
     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
-    int index, qflags, info = 0;
+    int index, qflags, info = 0, rc;
 
     /* read xenstore entries */
     if (blkdev->params == NULL) {
@@ -625,8 +625,18 @@ static int blk_init(struct XenDevice *xendev)
         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, qflags,
-                        bdrv_find_whitelisted_format(blkdev->fileproto)) != 0) {
+            rc = bdrv_open(blkdev->bs, blkdev->filename, qflags,
+                        bdrv_find_whitelisted_format(blkdev->fileproto));
+            if (rc != 0 && errno == EINVAL) {
+                /* Files on ramfs or tmpfs cannot be opened with O_DIRECT,
+                 * remove the BDRV_O_NOCACHE flag, and try to open
+                 * the file again.
+                 */
+                qflags &= ~BDRV_O_NOCACHE;
+                rc = bdrv_open(blkdev->bs, blkdev->filename, qflags,
+                        bdrv_find_whitelisted_format(blkdev->fileproto));
+            }
+            if (rc != 0) {
                 bdrv_delete(blkdev->bs);
                 blkdev->bs = NULL;
             }
-- 
1.7.7.5 (Apple Git-26)