[PATCH pve-storage 2/2] fix #3936: api: add zfs-blocksize format

[David Riley <d.riley@proxmox.com>]

Add a new JSONSchema format pve-storage-zfs-blocksize to validate
the ZFS blocksize parameter.

Validation [0][1]:
* Range: 512 bytes to 16 MiB
* Format: Allow positive integers with optional 'k' or 'm' suffix.
* Constraint: Must be a power of two.

Link: https://bugzilla.proxmox.com/show_bug.cgi?id=3936

[0] https://openzfs.github.io/openzfs-docs/man/v2.4/7/zfsprops.7.html#volblocksize
[1] https://openzfs.github.io/openzfs-docs/man/v2.4/7/zfsprops.7.html#recordsize

Signed-off-by: David Riley <d.riley@proxmox.com>
---
 src/PVE/Storage/Plugin.pm        | 34 ++++++++++++++++++++++++++++++++
 src/PVE/Storage/ZFSPoolPlugin.pm |  1 +
 2 files changed, 35 insertions(+)

diff --git a/src/PVE/Storage/Plugin.pm b/src/PVE/Storage/Plugin.pm
index afd3141..486fab9 100644
--- a/src/PVE/Storage/Plugin.pm
+++ b/src/PVE/Storage/Plugin.pm
@@ -449,6 +449,40 @@ sub verify_dir_override {
     die "invalid override '$value'\n";
 }
 
+PVE::JSONSchema::register_format('pve-storage-zfs-blocksize', \&verify_zfs_blocksize);
+
+sub verify_zfs_blocksize {
+    my ($value, $noerr) = @_;
+
+    return $value if !defined($value) || $value eq '';
+
+    if ($value =~ m/^([1-9][0-9]*)([km])?$/i) {
+        my ($num, $unit) = ($1, lc($2 // ''));
+
+        if ($unit eq 'k') {
+            $num *= 1024;
+        } elsif ($unit eq 'm') {
+            $num *= 1024 * 1024;
+        }
+
+        if (
+            $num >= 512
+            && $num <= 16 * 1024 * 1024
+            && ($num & ($num - 1)) == 0
+        ) {
+            return $value;
+        }
+
+        return undef if $noerr;
+        die "value '$value' is not a valid ZFS blocksize. Must be a power of 2 "
+            . "between 512B and 16MiB (e.g., 4k, 8k, 16k, 64k, 1m).\n";
+    }
+
+    return undef if $noerr;
+    die "invalid ZFS blocksize format '$value'. Use a positive number "
+        . "(no leading zeros) with an optional 'k' or 'm' suffix.\n";
+}
+
 sub private {
     return $defaultData;
 }
diff --git a/src/PVE/Storage/ZFSPoolPlugin.pm b/src/PVE/Storage/ZFSPoolPlugin.pm
index fcd7804..6a64401 100644
--- a/src/PVE/Storage/ZFSPoolPlugin.pm
+++ b/src/PVE/Storage/ZFSPoolPlugin.pm
@@ -31,6 +31,7 @@ sub properties {
         blocksize => {
             description => "block size",
             type => 'string',
+            format => 'pve-storage-zfs-blocksize',
         },
         sparse => {
             description => "use sparse volumes",
-- 
2.47.3