journal: Add compact mode

This adds a new flag in preparation for incompatible journal changes
which will be gated behind this flag. The max file size of journal
files in compact mode is limited to 4 GiB.

3 files changed, 19 insertions, 6 deletions

diff --git a/src/libsystemd/sd-journal/journal-def.h b/src/libsystemd/sd-journal/journal-def.h
index ffd1af005f..e0919a7faa 100644
--- a/src/libsystemd/sd-journal/journal-def.h
+++ b/src/libsystemd/sd-journal/journal-def.h
@@ -152,19 +152,22 @@ enum {
         HEADER_INCOMPATIBLE_COMPRESSED_LZ4  = 1 << 1,
         HEADER_INCOMPATIBLE_KEYED_HASH      = 1 << 2,
         HEADER_INCOMPATIBLE_COMPRESSED_ZSTD = 1 << 3,
+        HEADER_INCOMPATIBLE_COMPACT         = 1 << 4,
 };
 
 #define HEADER_INCOMPATIBLE_ANY               \
         (HEADER_INCOMPATIBLE_COMPRESSED_XZ |  \
          HEADER_INCOMPATIBLE_COMPRESSED_LZ4 | \
          HEADER_INCOMPATIBLE_KEYED_HASH |     \
-         HEADER_INCOMPATIBLE_COMPRESSED_ZSTD)
+         HEADER_INCOMPATIBLE_COMPRESSED_ZSTD | \
+         HEADER_INCOMPATIBLE_COMPACT)
 
 #define HEADER_INCOMPATIBLE_SUPPORTED                            \
         ((HAVE_XZ ? HEADER_INCOMPATIBLE_COMPRESSED_XZ : 0) |     \
          (HAVE_LZ4 ? HEADER_INCOMPATIBLE_COMPRESSED_LZ4 : 0) |   \
          (HAVE_ZSTD ? HEADER_INCOMPATIBLE_COMPRESSED_ZSTD : 0) | \
-         HEADER_INCOMPATIBLE_KEYED_HASH)
+         HEADER_INCOMPATIBLE_KEYED_HASH |                        \
+         HEADER_INCOMPATIBLE_COMPACT)
 
 enum {
         HEADER_COMPATIBLE_SEALED = 1 << 0,
diff --git a/src/libsystemd/sd-journal/journal-file.c b/src/libsystemd/sd-journal/journal-file.c
index 1fad2a8146..8a8b92a36c 100644
--- a/src/libsystemd/sd-journal/journal-file.c
+++ b/src/libsystemd/sd-journal/journal-file.c
@@ -44,6 +44,7 @@
 
 /* This is the minimum journal file size */
 #define JOURNAL_FILE_SIZE_MIN (512 * 1024ULL)             /* 512 KiB */
+#define JOURNAL_COMPACT_SIZE_MAX UINT32_MAX               /* 4 GiB */
 
 /* These are the lower and upper bounds if we deduce the max_use value
  * from the file system size */
@@ -387,7 +388,7 @@ static bool warn_wrong_flags(const JournalFile *f, bool compatible) {
                                   f->path, type, flags & ~any);
                 flags = (flags & any) & ~supported;
                 if (flags) {
-                        const char* strv[5];
+                        const char* strv[6];
                         size_t n = 0;
                         _cleanup_free_ char *t = NULL;
 
@@ -403,6 +404,8 @@ static bool warn_wrong_flags(const JournalFile *f, bool compatible) {
                                         strv[n++] = "zstd-compressed";
                                 if (flags & HEADER_INCOMPATIBLE_KEYED_HASH)
                                         strv[n++] = "keyed-hash";
+                                if (flags & HEADER_INCOMPATIBLE_COMPACT)
+                                        strv[n++] = "compact";
                         }
                         strv[n] = NULL;
                         assert(n < ELEMENTSOF(strv));
@@ -3229,7 +3232,7 @@ void journal_file_print_header(JournalFile *f) {
                "Sequential number ID: %s\n"
                "State: %s\n"
                "Compatible flags:%s%s\n"
-               "Incompatible flags:%s%s%s%s%s\n"
+               "Incompatible flags:%s%s%s%s%s%s\n"
                "Header size: %"PRIu64"\n"
                "Arena size: %"PRIu64"\n"
                "Data hash table size: %"PRIu64"\n"
@@ -3256,6 +3259,7 @@ void journal_file_print_header(JournalFile *f) {
                JOURNAL_HEADER_COMPRESSED_LZ4(f->header) ? " COMPRESSED-LZ4" : "",
                JOURNAL_HEADER_COMPRESSED_ZSTD(f->header) ? " COMPRESSED-ZSTD" : "",
                JOURNAL_HEADER_KEYED_HASH(f->header) ? " KEYED-HASH" : "",
+               JOURNAL_HEADER_COMPACT(f->header) ? " COMPACT" : "",
                (le32toh(f->header->incompatible_flags) & ~HEADER_INCOMPATIBLE_ANY) ? " ???" : "",
                le64toh(f->header->header_size),
                le64toh(f->header->arena_size),
@@ -3336,7 +3340,7 @@ static int journal_file_warn_btrfs(JournalFile *f) {
         return 1;
 }
 
-static void journal_default_metrics(JournalMetrics *m, int fd) {
+static void journal_default_metrics(JournalMetrics *m, int fd, bool compact) {
         struct statvfs ss;
         uint64_t fs_size = 0;
 
@@ -3379,6 +3383,9 @@ static void journal_default_metrics(JournalMetrics *m, int fd) {
         else
                 m->max_size = PAGE_ALIGN(m->max_size);
 
+        if (compact && m->max_size > JOURNAL_COMPACT_SIZE_MAX)
+                m->max_size = JOURNAL_COMPACT_SIZE_MAX;
+
         if (m->max_size != 0) {
                 if (m->max_size < JOURNAL_FILE_SIZE_MIN)
                         m->max_size = JOURNAL_FILE_SIZE_MIN;
@@ -3570,7 +3577,7 @@ int journal_file_open(
 
         if (journal_file_writable(f)) {
                 if (metrics) {
-                        journal_default_metrics(metrics, f->fd);
+                        journal_default_metrics(metrics, f->fd, JOURNAL_HEADER_COMPACT(f->header));
                         f->metrics = *metrics;
                 } else if (template)
                         f->metrics = template->metrics;
diff --git a/src/libsystemd/sd-journal/journal-file.h b/src/libsystemd/sd-journal/journal-file.h
index be02b2624f..01942ec72b 100644
--- a/src/libsystemd/sd-journal/journal-file.h
+++ b/src/libsystemd/sd-journal/journal-file.h
@@ -184,6 +184,9 @@ static inline bool VALID_EPOCH(uint64_t u) {
 #define JOURNAL_HEADER_KEYED_HASH(h) \
         FLAGS_SET(le32toh((h)->incompatible_flags), HEADER_INCOMPATIBLE_KEYED_HASH)
 
+#define JOURNAL_HEADER_COMPACT(h) \
+        FLAGS_SET(le32toh((h)->incompatible_flags), HEADER_INCOMPATIBLE_COMPACT)
+
 int journal_file_move_to_object(JournalFile *f, ObjectType type, uint64_t offset, Object **ret);
 int journal_file_read_object_header(JournalFile *f, ObjectType type, uint64_t offset, Object *ret);