[Qemu-block] [PATCH V5] block/nfs: add support for setting debug level

[Peter Lieven]

recent libnfs versions support logging debug messages. Add
support for it in qemu through an URL parameter.

Example:
 qemu -cdrom nfs://127.0.0.1/iso/my.iso?debug=2

Signed-off-by: Peter Lieven <address@hidden>
---
v4->v5: add a comment in the code why we limit the debug level [Stefan]
v3->v4: revert to the initial version, but limit max debug level
v2->v3: use a per-drive option instead of a global one. [Stefan]
v1->v2: reworked patch to accept the debug level as a cmdline
        parameter instead of an URI parameter [Stefan]

 block/nfs.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/block/nfs.c b/block/nfs.c
index fd79f89..ab1e267 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -36,6 +36,7 @@
 #include <nfsc/libnfs.h>
 
 #define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
+#define QEMU_NFS_MAX_DEBUG_LEVEL 2
 
 typedef struct NFSClient {
     struct nfs_context *context;
@@ -334,6 +335,17 @@ static int64_t nfs_client_open(NFSClient *client, const 
char *filename,
             }
             nfs_set_readahead(client->context, val);
 #endif
+#ifdef LIBNFS_FEATURE_DEBUG
+        } else if (!strcmp(qp->p[i].name, "debug")) {
+            /* limit the maximum debug level to avoid potential flooding
+             * of our log files. */
+            if (val > QEMU_NFS_MAX_DEBUG_LEVEL) {
+                error_report("NFS Warning: Limiting NFS debug level"
+                             " to %d", QEMU_NFS_MAX_DEBUG_LEVEL);
+                val = QEMU_NFS_MAX_DEBUG_LEVEL;
+            }
+            nfs_set_debug(client->context, val);
+#endif
         } else {
             error_setg(errp, "Unknown NFS parameter name: %s",
                        qp->p[i].name);
-- 
1.9.1