{"record":{"id":"69d4771fe05cc276","repo":"juicedata/juicefs","slug":"open-control-file-for-s-s","errorCode":null,"errorMessage":"open control file for %s: %s","messagePattern":"open control file for (.+?): (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"cmd/warmup.go","lineNumber":254,"sourceCode":"\t\t\t\tlogger.Warnf(\"Skipped path %q because it fails to get absolute path: %s\", pathStr, e)\n\t\t\t\tcontinue\n\t\t\t}\n\t\t\tpaths = append(paths, vfs.JoinTarget(abs, spec))\n\t\t}\n\t\tif err = scanner.Err(); err != nil {\n\t\t\tlogger.Fatalf(\"Reading file %q failed with error: %s\", fname, err)\n\t\t}\n\t}\n\tif len(paths) == 0 {\n\t\tlogger.Infof(\"no path\")\n\t\treturn nil\n\t}\n\n\t// find mount point\n\tfirst, _, _, _ := vfs.SplitTarget(paths[0])\n\tcontroller, err := openController(first)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"open control file for %s: %s\", first, err)\n\t}\n\tdefer controller.Close()\n\n\tmp := first\n\tfor ; mp != \"/\"; mp = filepath.Dir(mp) {\n\t\tinode, err := utils.GetFileInode(mp)\n\t\tif err != nil {\n\t\t\tlogger.Fatalf(\"lookup inode for %q: %s\", mp, err)\n\t\t}\n\t\tif inode == uint64(meta.RootInode) {\n\t\t\tbreak\n\t\t}\n\t}\n\n\tthreads := ctx.Uint(\"threads\")\n\tif threads == 0 {\n\t\tlogger.Warnf(\"threads should be larger than 0, reset it to 1\")\n\t\tthreads = 1","sourceCodeStart":236,"sourceCodeEnd":272,"githubUrl":"https://github.com/juicedata/juicefs/blob/c9a67b23e8e08ec23ec331aa6f1675e2319e921c/cmd/warmup.go#L236-L272","documentation":"warmup opens the mount's control file (via openController on the first resolved target path) to talk to the FUSE daemon for cache warming. If opening the control file fails — the mount point has no JuiceFS control interface, the daemon is unresponsive, or permission is denied — the error is wrapped as 'open control file for %s: %s'.","triggerScenarios":"`juicefs warmup <path>` where openController fails: path not on a JuiceFS FUSE mount, .control file missing or not accessible, or the FUSE daemon hung so the open times out.","commonSituations":"Warming caches on a subpath that is a different (non-JuiceFS) filesystem; mount in a crashed/zombie state; running without permission to open the control file; warmup invoked inside a container lacking the FUSE device.","solutions":["Check the inner error after the colon (ENOENT vs EPERM vs timeout) to distinguish missing mount from permission issues.","Confirm the path is inside a live JuiceFS mount (`juicefs status <meta-url>` or check <mp>/.stats).","Ensure the FUSE device is available (/dev/fuse) and the mount is healthy; remount if the daemon is hung.","Run with sufficient permissions (the control file may be root-owned)."],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":"if _, err := os.Stat(filepath.Join(mp, \".control\")); err != nil {\n    return fmt.Errorf(\"no JuiceFS control file at %s: %w\", mp, err)\n}","typeGuard":null,"tryCatchPattern":"controller, err := openController(first)\nif err != nil {\n    if os.IsPermission(err) { /* run with elevated perms or fix ownership */ }\n    if errors.Is(err, os.ErrNotExist) { /* not a JuiceFS mount */ }\n    return err\n}\ndefer controller.Close()","preventionTips":["Warm up paths only under an active JuiceFS FUSE mount","Ensure /dev/fuse is available and the daemon is responsive (check <mp>/.stats)","Run warmup with permissions to open the control file (often root-owned)"],"tags":["warmup","cache","control-file","cli"],"backgroundTag":"file-open-failed","analyzedSha":"c9a67b23e8e08ec23ec331aa6f1675e2319e921c","analyzedAt":"2026-09-06T17:55:48.476Z","contentChangedAt":"2026-09-06T17:55:48.476Z","schemaVersion":2},"datasetVersion":"2026-09-14T00:17:10.932Z"}