[Gluster-devel] [PATCH] block/gluster: add support to choose libgfapi logfile

[Prasanna Kumar Kalever]

currently all the libgfapi logs defaults to '/dev/stderr' as it was hardcoded
in a call to glfs logging api, in case if debug level is chosen to DEBUG/TRACE
gfapi logs will be huge and fill/overflow the console view.

this patch provides a commandline option to mention log file path which helps
in logging to the specified file and also help in persisting the gfapi logs.

Usage: -drive file=gluster://hostname/volname/image.qcow2,file.debug=9,\
                 file.logfile=/var/log/qemu/qemu-gfapi.log

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever at redhat.com>
---
 block/gluster.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/block/gluster.c b/block/gluster.c
index 16f7778..6875429 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -24,6 +24,7 @@ typedef struct GlusterAIOCB {
 typedef struct BDRVGlusterState {
     struct glfs *glfs;
     struct glfs_fd *fd;
+    const char *logfile;
     bool supports_seek_data;
     int debug_level;
 } BDRVGlusterState;
@@ -34,6 +35,7 @@ typedef struct GlusterConf {
     char *volname;
     char *image;
     char *transport;
+    const char *logfile;
     int debug_level;
 } GlusterConf;
 
@@ -181,7 +183,8 @@ static struct glfs *qemu_gluster_init(GlusterConf *gconf, const char *filename,
     ret = qemu_gluster_parseuri(gconf, filename);
     if (ret < 0) {
         error_setg(errp, "Usage: file=gluster[+transport]://[server[:port]]/"
-                   "volname/image[?socket=...]");
+                   "volname/image[?socket=...][,file.debug=N]"
+                   "[,file.logfile=/path/filename.log]");
         errno = -ret;
         goto out;
     }
@@ -197,7 +200,7 @@ static struct glfs *qemu_gluster_init(GlusterConf *gconf, const char *filename,
         goto out;
     }
 
-    ret = glfs_set_logging(glfs, "-", gconf->debug_level);
+    ret = glfs_set_logging(glfs, gconf->logfile, gconf->debug_level);
     if (ret < 0) {
         goto out;
     }
@@ -256,6 +259,8 @@ static void gluster_finish_aiocb(struct glfs_fd *fd, ssize_t ret, void *arg)
 }
 
 #define GLUSTER_OPT_FILENAME "filename"
+#define GLUSTER_OPT_LOGFILE "logfile"
+#define GLUSTER_LOGFILE_DEFAULT "-" /* '-' handled in libgfapi as /dev/stderr */
 #define GLUSTER_OPT_DEBUG "debug"
 #define GLUSTER_DEBUG_DEFAULT 4
 #define GLUSTER_DEBUG_MAX 9
@@ -271,6 +276,11 @@ static QemuOptsList runtime_opts = {
             .help = "URL to the gluster image",
         },
         {
+            .name = GLUSTER_OPT_LOGFILE,
+            .type = QEMU_OPT_STRING,
+            .help = "Logfile path of libgfapi",
+        },
+        {
             .name = GLUSTER_OPT_DEBUG,
             .type = QEMU_OPT_NUMBER,
             .help = "Gluster log level, valid range is 0-9",
@@ -339,6 +349,12 @@ static int qemu_gluster_open(BlockDriverState *bs,  QDict *options,
 
     filename = qemu_opt_get(opts, GLUSTER_OPT_FILENAME);
 
+    s->logfile = qemu_opt_get(opts, GLUSTER_OPT_LOGFILE);
+    if (!s->logfile) {
+            s->logfile = GLUSTER_LOGFILE_DEFAULT;
+    }
+    gconf->logfile = s->logfile;
+
     s->debug_level = qemu_opt_get_number(opts, GLUSTER_OPT_DEBUG,
                                          GLUSTER_DEBUG_DEFAULT);
     if (s->debug_level < 0) {
@@ -422,6 +438,7 @@ static int qemu_gluster_reopen_prepare(BDRVReopenState *state,
 
     gconf = g_new0(GlusterConf, 1);
 
+    gconf->logfile = s->logfile;
     gconf->debug_level = s->debug_level;
     reop_s->glfs = qemu_gluster_init(gconf, state->bs->filename, errp);
     if (reop_s->glfs == NULL) {
@@ -556,6 +573,11 @@ static int qemu_gluster_create(const char *filename,
     char *tmp = NULL;
     GlusterConf *gconf = g_new0(GlusterConf, 1);
 
+    gconf->logfile = qemu_opt_get_del(opts, GLUSTER_OPT_LOGFILE);
+    if (!gconf->logfile) {
+            gconf->logfile = GLUSTER_LOGFILE_DEFAULT;
+    }
+
     gconf->debug_level = qemu_opt_get_number_del(opts, GLUSTER_OPT_DEBUG,
                                                  GLUSTER_DEBUG_DEFAULT);
     if (gconf->debug_level < 0) {
@@ -949,6 +971,11 @@ static QemuOptsList qemu_gluster_create_opts = {
             .help = "Preallocation mode (allowed values: off, full)"
         },
         {
+            .name = GLUSTER_OPT_LOGFILE,
+            .type = QEMU_OPT_STRING,
+            .help = "Logfile path of libgfapi",
+        },
+        {
             .name = GLUSTER_OPT_DEBUG,
             .type = QEMU_OPT_NUMBER,
             .help = "Gluster log level, valid range is 0-9",
-- 
2.7.4