repart: Rework Minimize= option settings

Instead of having Minimize= take a boolean let's allow for two
different ways to enable it. "best" means we want the most minimal
image possible, which currently is only possible for read-only
filesystems but can be extended in the future with bisection
to find the most minimal possible size.

We also add "guess", which is the current behavior, where we
populate once and use the sparse size to make a reasonable guess
on a size that fits all the sources without needing to O(log(n))
tries to find the most minimal size.

diff --git a/man/repart.d.xml b/man/repart.d.xml
index d5ce3f8587a06d2e43da47f840be2e80476ffcd3..1da38a4e91b7d52648462037894ac6e1f749b9ac 100644 (file)
--- a/man/repart.d.xml
+++ b/man/repart.d.xml
@@ -590,11 +590,16 @@
       <varlistentry>
         <term><varname>Minimize=</varname></term>
 
-        <listitem><para>Takes a boolean. Disabled by default. If enabled, the partition is created at least
-        as big as required for the minimal file system of the type specified by <varname>Format=</varname>,
-        taking into account the sources configured with  <varname>CopyFiles=</varname>. Note that unless the
-        filesystem is a read-only filesystem, <command>systemd-repart</command> will have to populate the
-        filesystem twice, so enabling this option might slow down repart when populating large partitions.
+        <listitem><para>Takes one of <literal>off</literal>, <literal>best</literal>, and
+        <literal>guess</literal> (alternatively, also accepts a boolean value, which is mapped to
+        <literal>off</literal> when false, and <literal>best</literal> when true). Defaults to
+        <literal>off</literal>. If set to <literal>best</literal>, the partition will have the minimal size
+        required to store the sources configured with <varname>CopyFiles=</varname>. <literal>best</literal>
+        is currently only supported for read-only filesystems. If set to <literal>guess</literal>, the
+        partition is created at least as big as required to store the sources configured with
+        <varname>CopyFiles=</varname>. Note that unless the filesystem is a read-only filesystem,
+        <command>systemd-repart</command> will have to populate the filesystem twice to guess the minimal
+        required size, so enabling this option might slow down repart when populating large partitions.
         </para></listitem>
       </varlistentry>
     </variablelist>

diff --git a/src/partition/repart.c b/src/partition/repart.c
index b70c54e531f431c49a76cbe57a33e639d4c9f38b..80cd7daba321db5d34394c3d7576123c826ce60b 100644 (file)
--- a/src/partition/repart.c
+++ b/src/partition/repart.c
@@ -178,6 +178,14 @@ typedef enum VerityMode {
         _VERITY_MODE_INVALID = -EINVAL,
 } VerityMode;
 
+typedef enum MinimizeMode {
+        MINIMIZE_OFF,
+        MINIMIZE_BEST,
+        MINIMIZE_GUESS,
+        _MINIMIZE_MODE_MAX,
+        _MINIMIZE_MODE_INVALID = -EINVAL,
+} MinimizeMode;
+
 typedef struct Partition {
         char *definition_path;
         char **drop_in_files;
@@ -221,7 +229,7 @@ typedef struct Partition {
         EncryptMode encrypt;
         VerityMode verity;
         char *verity_match_key;
-        bool minimize;
+        MinimizeMode minimize;
 
         uint64_t gpt_flags;
         int no_auto;
@@ -284,8 +292,15 @@ static const char *verity_mode_table[_VERITY_MODE_MAX] = {
         [VERITY_SIG]  = "signature",
 };
 
+static const char *minimize_mode_table[_MINIMIZE_MODE_MAX] = {
+        [MINIMIZE_OFF]   = "off",
+        [MINIMIZE_BEST]  = "best",
+        [MINIMIZE_GUESS] = "guess",
+};
+
 DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING_WITH_BOOLEAN(encrypt_mode, EncryptMode, ENCRYPT_KEY_FILE);
 DEFINE_PRIVATE_STRING_TABLE_LOOKUP(verity_mode, VerityMode);
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING_WITH_BOOLEAN(minimize_mode, MinimizeMode, MINIMIZE_BEST);
 
 static uint64_t round_down_size(uint64_t v, uint64_t p) {
         return (v / p) * p;
@@ -1532,6 +1547,7 @@ static int config_parse_uuid(
 }
 
 static DEFINE_CONFIG_PARSE_ENUM_WITH_DEFAULT(config_parse_verity, verity_mode, VerityMode, VERITY_OFF, "Invalid verity mode");
+static DEFINE_CONFIG_PARSE_ENUM_WITH_DEFAULT(config_parse_minimize, minimize_mode, MinimizeMode, MINIMIZE_OFF, "Invalid minimize mode");
 
 static int partition_read_definition(Partition *p, const char *path, const char *const *conf_file_dirs) {
 
@@ -1559,7 +1575,7 @@ static int partition_read_definition(Partition *p, const char *path, const char
                 { "Partition", "NoAuto",          config_parse_tristate,    0, &p->no_auto           },
                 { "Partition", "GrowFileSystem",  config_parse_tristate,    0, &p->growfs            },
                 { "Partition", "SplitName",       config_parse_string,      0, &p->split_name_format },
-                { "Partition", "Minimize",        config_parse_bool,        0, &p->minimize          },
+                { "Partition", "Minimize",        config_parse_minimize,    0, &p->minimize          },
                 {}
         };
         int r;
@@ -1616,10 +1632,14 @@ static int partition_read_definition(Partition *p, const char *path, const char
                         return log_oom();
         }
 
-        if (p->minimize && !p->format)
+        if (p->minimize != MINIMIZE_OFF && !p->format)
                 return log_syntax(NULL, LOG_ERR, path, 1, SYNTHETIC_ERRNO(EINVAL),
                                   "Minimize= can only be enabled if Format= is set");
 
+        if (p->minimize == MINIMIZE_BEST && !fstype_is_ro(p->format))
+                return log_syntax(NULL, LOG_ERR, path, 1, SYNTHETIC_ERRNO(EINVAL),
+                                  "Minimize=best can only be used with read-only filesystems");
+
         if ((!strv_isempty(p->copy_files) || !strv_isempty(p->make_directories)) && !mkfs_supports_root_option(p->format) && geteuid() != 0)
                 return log_syntax(NULL, LOG_ERR, path, 1, SYNTHETIC_ERRNO(EPERM),
                                   "Need to be root to populate %s filesystems with CopyFiles=/MakeDirectories=",
@@ -5282,7 +5302,7 @@ static int context_minimize(Context *context) {
                 if (!p->format)
                         continue;
 
-                if (!p->minimize)
+                if (p->minimize == MINIMIZE_OFF)
                         continue;
 
                 if (!partition_needs_populate(p))