[PATCH v2 16/29] tools/xl: support new 9pfs backend xen-9pfsd

[Juergen Gross <jgross@xxxxxxxx>]

Add support for the new 9pfs backend "xen-9pfsd". For this backend type
the tag defaults to "Xen" and the host side path to
"/var/log/xen/guests/<dom-name>".

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- test max_files and max_open_files, too (Jason Andryuk)
---
 docs/man/xl.cfg.5.pod.in | 36 ++++++++++++++++++++++++++++++++++--
 tools/xl/xl_parse.c      | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index 2e234b450e..80011adbf3 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -772,10 +772,16 @@ settings, from the following list:
 
 =over 4
 
+=item B<type=TYPE>
+
+The backendtype for the PV device. Supported values are B<qemu> and
+B<xen-9pfsd>.  The default is B<qemu>.
+
 =item B<tag=STRING>
 
 9pfs tag to identify the filesystem share. The tag is needed on the
-guest side to mount it.
+guest side to mount it. For the backendtype of B<xen-9pfsd> the tag defaults to
+"Xen".
 
 =item B<security_model="none">
 
@@ -785,12 +791,38 @@ squash or remap).
 
 =item B<path=STRING>
 
-Filesystem path on the backend to export.
+Filesystem path on the backend to export. For the backendtype of B<xen-9pfsd>
+the path defaults to "@XEN_LOG_DIR@/guests/<guest-name>".
 
 =item B<backend=domain-id>
 
 Specify the backend domain name or id, defaults to dom0.
 
+=item B<max-files=NUMBER>
+
+Specify the maximum number of files below B<path>. A value of 0 (which
+is the default) doesn't limit the number of files. Only valid for
+B<type=xen-9pfsd>.
+
+=item B<max-open-files=NUMBER>
+
+Specify the maximum number of concurrently opened files below B<path>.
+Multiple opens of the same file are counted individually. Only valid for
+B<type=xen-9pfsd>, which has a default of B<max-open-files=5>.
+
+=item B<max-space=NUMBER>
+
+Specify the maximum used disk space in MiB below B<path>. A value of 0 (which
+is the default) doesn't limit the usable disk space. Only valid for
+B<type=xen-9pfsd>.
+
+=item B<auto-delete=BOOLEAN>
+
+When set the backend will delete the oldest file which is currently not
+opened by the guest in case the disk space limit set via B<max-space> or the
+file limit set via B<max-files> is being reached. Only valid for
+B<type=xen-9pfsd>.
+
 =back
 
 =item B<pvcalls=[ "backend=domain-id", ... ]>
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index ed983200c3..3ded557ebc 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -2232,6 +2232,20 @@ void parse_config_data(const char *config_source,
                     replace_string(&p9->tag, value);
                 } else if (!strcmp(key, "backend")) {
                     replace_string(&p9->backend_domname, value);
+                } else if (!strcmp(key, "type")) {
+                    if (libxl_p9_type_from_string(value, &p9->type)) {
+                        fprintf(stderr, "failed to parse 9pfs type: %s\n",
+                                value);
+                        exit(1);
+                    }
+                } else if (!strcmp(key, "max-files")) {
+                    p9->max_files = parse_ulong(value);
+                } else if (!strcmp(key, "max-open-files")) {
+                    p9->max_open_files = parse_ulong(value);
+                } else if (!strcmp(key, "max-space")) {
+                    p9->max_space = parse_ulong(value);
+                } else if (!strcmp(key, "auto-delete")) {
+                    p9->auto_delete = strtoul(value, NULL, 0);
                 } else {
                     fprintf(stderr, "Unknown 9pfs parameter '%s'\n", key);
                     exit(1);
@@ -2242,6 +2256,28 @@ void parse_config_data(const char *config_source,
 
             libxl_string_list_dispose(&pairs);
 
+            if (p9->type == LIBXL_P9_TYPE_UNKNOWN) {
+                p9->type = LIBXL_P9_TYPE_QEMU;
+            }
+            if (p9->type == LIBXL_P9_TYPE_QEMU &&
+                (p9->max_files || p9->max_open_files || p9->max_space ||
+                 p9->auto_delete)) {
+                fprintf(stderr, "Illegal 9pfs parameter combination\n");
+                exit(1);
+            }
+            if (p9->type == LIBXL_P9_TYPE_XEN_9PFSD) {
+                if (!p9->tag) {
+                    replace_string(&p9->tag, "Xen");
+                }
+                if (!p9->path) {
+                    char *path;
+
+                    xasprintf(&path, XEN_LOG_DIR "/guests/%s", c_info->name);
+                    replace_string(&p9->path, path);
+                    free(path);
+                }
+            }
+
             if (!p9->path || !p9->security_model || !p9->tag) {
                 fprintf(stderr, "9pfs spec missing required field!\n");
                 exit(1);
-- 
2.35.3