[Qemu-devel] [PATCH 02/10] qga/qmp_guest_fstrim: Return per path fstrim result

[Michael Roth <mdroth@linux.vnet.ibm.com>]

From: Justin Ossevoort <justin@quarantainenet.nl>

The current guest-fstrim support only returns an error if some
mountpoint was unable to be trimmed, skipping any possible additional
mountpoints. The result of the TRIM operation itself is also discarded.

This change returns a per mountpoint result of the TRIM operation. If an
error occurs on some mountpoints that error is returned and the
guest-fstrim continue with any additional mountpoints.

The returned values for errors, minimum and trimmed are dependant on the
filesystem, storage stacks and kernel version.

Signed-off-by: Justin Ossevoort <justin@quarantainenet.nl>
* s/type/struct/ in schema type definitions
* moved version annotation for new guest-fstrim return field to
  the field itself rather than applying to the entire command
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 qga/commands-posix.c | 54 ++++++++++++++++++++++++++++++++++++++--------------
 qga/commands-win32.c |  4 +++-
 qga/qapi-schema.json | 30 +++++++++++++++++++++++++++--
 3 files changed, 71 insertions(+), 17 deletions(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 9ff33ec..c349d4b 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -1325,8 +1325,12 @@ static void guest_fsfreeze_cleanup(void)
 /*
  * Walk list of mounted file systems in the guest, and trim them.
  */
-void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
+GuestFilesystemTrimResponse *
+qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
 {
+    GuestFilesystemTrimResponse *response;
+    GuestFilesystemTrimResultList *list;
+    GuestFilesystemTrimResult *result;
     int ret = 0;
     FsMountList mounts;
     struct FsMount *mount;
@@ -1340,39 +1344,59 @@ void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
     build_fs_mount_list(&mounts, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
-        return;
+        return NULL;
     }
 
+    response = g_malloc0(sizeof(*response));
+
     QTAILQ_FOREACH(mount, &mounts, next) {
+        result = g_malloc0(sizeof(*result));
+        result->path = g_strdup(mount->dirname);
+
+        list = g_malloc0(sizeof(*list));
+        list->value = result;
+        list->next = response->paths;
+        response->paths = list;
+
         fd = qemu_open(mount->dirname, O_RDONLY);
         if (fd == -1) {
-            error_setg_errno(errp, errno, "failed to open %s", mount->dirname);
-            goto error;
+            result->error = g_strdup_printf("failed to open: %s",
+                                            strerror(errno));
+            result->has_error = true;
+            continue;
         }
 
         /* We try to cull filesytems we know won't work in advance, but other
          * filesytems may not implement fstrim for less obvious reasons.  These
-         * will report EOPNOTSUPP; we simply ignore these errors.  Any other
-         * error means an unexpected error, so return it in those cases.  In
-         * some other cases ENOTTY will be reported (e.g. CD-ROMs).
+         * will report EOPNOTSUPP; while in some other cases ENOTTY will be
+         * reported (e.g. CD-ROMs).
+         * Any other error means an unexpected error.
          */
         r.start = 0;
         r.len = -1;
         r.minlen = has_minimum ? minimum : 0;
         ret = ioctl(fd, FITRIM, &r);
         if (ret == -1) {
-            if (errno != ENOTTY && errno != EOPNOTSUPP) {
-                error_setg_errno(errp, errno, "failed to trim %s",
-                                 mount->dirname);
-                close(fd);
-                goto error;
+            result->has_error = true;
+            if (errno == ENOTTY || errno == EOPNOTSUPP) {
+                result->error = g_strdup("trim not supported");
+            } else {
+                result->error = g_strdup_printf("failed to trim: %s",
+                                                strerror(errno));
             }
+            close(fd);
+            continue;
         }
+
+        result->has_minimum = true;
+        result->minimum = r.minlen;
+        result->has_trimmed = true;
+        result->trimmed = r.len;
         close(fd);
     }
 
-error:
     free_fs_mount_list(&mounts);
+    return response;
 }
 #endif /* CONFIG_FSTRIM */
 
@@ -2401,9 +2425,11 @@ int64_t qmp_guest_fsfreeze_thaw(Error **errp)
 #endif /* CONFIG_FSFREEZE */
 
 #if !defined(CONFIG_FSTRIM)
-void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
+GuestFilesystemTrimResponse *
+qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
 {
     error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
 }
 #endif
 
diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index fbddc8b..13679a1 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -493,9 +493,11 @@ static void guest_fsfreeze_cleanup(void)
  * Walk list of mounted file systems in the guest, and discard unused
  * areas.
  */
-void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
+GuestFilesystemTrimResponse *
+qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
 {
     error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
 }
 
 typedef enum {
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index b446dc7..58cbf66 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -425,6 +425,30 @@
   'returns': 'int' }
 
 ##
+# @GuestFilesystemTrimResult
+#
+# @path: path that was trimmed
+# @error: an error message when trim failed
+# @trimmed: bytes trimmed for this path
+# @minimum: reported effective minimum for this path
+#
+# Since: 2.4
+##
+{ 'struct': 'GuestFilesystemTrimResult',
+  'data': {'path': 'str',
+           '*trimmed': 'int', '*minimum': 'int', '*error': 'str'} }
+
+##
+# @GuestFilesystemTrimResponse
+#
+# @paths: list of @GuestFilesystemTrimResult per path that was trimmed
+#
+# Since: 2.4
+##
+{ 'struct': 'GuestFilesystemTrimResponse',
+  'data': {'paths': ['GuestFilesystemTrimResult']} }
+
+##
 # @guest-fstrim:
 #
 # Discard (or "trim") blocks which are not in use by the filesystem.
@@ -437,12 +461,14 @@
 #       fragmented free space, although not all blocks will be discarded.
 #       The default value is zero, meaning "discard every free block".
 #
-# Returns: Nothing.
+# Returns: A @GuestFilesystemTrimResponse which contains the
+#          status of all trimmed paths. (since 2.4)
 #
 # Since: 1.2
 ##
 { 'command': 'guest-fstrim',
-  'data': { '*minimum': 'int' } }
+  'data': { '*minimum': 'int' },
+  'returns': 'GuestFilesystemTrimResponse' }
 
 ##
 # @guest-suspend-disk
-- 
1.9.1