journal: rework vacuuming logic

Implement a maximum limit on number of journal files to keep around.
Enforcing a limit is useful on this since our performance when viewing
pays a heavy penalty for each journal file to interleve. This setting is
turned on now by default, and set to 100.

Also, actully implement what 348ced909724a1331b85d57aede80a102a00e428
promised: use whatever we find on disk at startup as lower bound on how
much disk space we can use. That commit introduced some provisions to
implement this, but actually never did.

This also adds "journalctl --vacuum-files=" to vacuum files on disk by
their number explicitly.

1 files changed, 8 insertions, 5 deletions

diff --git a/src/journal/journal-file.h b/src/journal/journal-file.h
index 52e6b7a261..f2c07356c8 100644
--- a/src/journal/journal-file.h
+++ b/src/journal/journal-file.h
@@ -36,11 +36,13 @@
 #include "hashmap.h"
 
 typedef struct JournalMetrics {
-        uint64_t max_use;
-        uint64_t use;
-        uint64_t max_size;
-        uint64_t min_size;
-        uint64_t keep_free;
+        /* For all these: -1 means "pick automatically", and 0 means "no limit enforced" */
+        uint64_t max_size;     /* how large journal files grow at max */
+        uint64_t min_size;     /* how large journal files grow at least */
+        uint64_t max_use;      /* how much disk space to use in total at max, keep_free permitting */
+        uint64_t min_use;      /* how much disk space to use in total at least, even if keep_free says not to */
+        uint64_t keep_free;    /* how much to keep free on disk */
+        uint64_t n_max_files;  /* how many files to keep around at max */
 } JournalMetrics;
 
 typedef enum direction {
@@ -223,6 +225,7 @@ int journal_file_rotate(JournalFile **f, bool compress, bool seal);
 
 void journal_file_post_change(JournalFile *f);
 
+void journal_reset_metrics(JournalMetrics *m);
 void journal_default_metrics(JournalMetrics *m, int fd);
 
 int journal_file_get_cutoff_realtime_usec(JournalFile *f, usec_t *from, usec_t *to);