[PATCH pve-storage v2 3/3] plugin: improve error handling when creating a content subdir fails

["Max R. Carrara" <m.carrara@proxmox.com>]

Replace the call to `mkpath()` with a helper inline subroutine that
uses `make_path()` instead. Follow the docs of `File::Path` [1] in
order to make our error handling here more finely-grained.

Note that the helper sub is mainly there to make the body of the loop
where `mkpath()` was originally called less convoluted / complex.

Add some additional context to the error message, namely that creating
the content directory for a given vtype failed. Also extract and
attach `make_path()`'s error message.

Handle "Permission denied" and "Read-only file system" errors
separately and, in addition to the context, tell the user to ensure
that the storage has read and write access when such errors occur.

Initially spotted this in the community forum [2].

[1]: https://perldoc.perl.org/File::Path#ERROR-HANDLING
[2]: https://forum.proxmox.com/threads/bug-creating-nfs-volume-storage.177354/

Signed-off-by: Max R. Carrara <m.carrara@proxmox.com>
---

Notes:
    NOTE: I ran into the second branch (the one for "Read-only file
    system") when testing things using my local NFS share—I figured I
    might as well handle that one too, since it's similar in nature.

 src/PVE/Storage/Plugin.pm | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/PVE/Storage/Plugin.pm b/src/PVE/Storage/Plugin.pm
index 04d87842..294a59e8 100644
--- a/src/PVE/Storage/Plugin.pm
+++ b/src/PVE/Storage/Plugin.pm
@@ -1903,6 +1903,33 @@ sub activate_storage {
         return;
     }

+    my $try_create_subdir = sub {
+        my ($vtype) = @_;
+
+        my $subdir = $class->get_subdir($scfg, $vtype);
+
+        File::Path::make_path($subdir, { error => \my $errors });
+        if (defined($errors) && scalar($errors->@*)) {
+            my $msg = "failed to create content directory '$subdir' for content '$vtype'";
+
+            for my $err_hash ($errors->@*) {
+                my ($file, $err_msg) = $err_hash->%*;
+
+                if (
+                    $err_msg =~ m/permission \s denied/ix
+                    || $err_msg =~ m/read -? only \s file \s? system/ix
+                ) {
+                    my $msg_prompt =
+                        "ensure that you have read and write access to your storage!";
+
+                    die "$msg - $err_msg - $msg_prompt\n";
+                }
+
+                die "$msg - $err_msg\n";
+            }
+        }
+    };
+
     # TODO: mkdir is basically deprecated since 8.0, but we don't warn here until 8.4 or 9.0, as we
     # only got the replacement in 8.0, so no real replacement window, and its really noisy.

@@ -1918,8 +1945,7 @@ sub activate_storage {
                 defined($scfg->{content}->{$vtype})
                 || ($vtype eq 'backup' && defined($scfg->{content}->{'rootdir'}))
             ) {
-                my $subdir = $class->get_subdir($scfg, $vtype);
-                mkpath $subdir;
+                $try_create_subdir->($vtype);
             }
         }
     }
--
2.47.3