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, 51 insertions, 13 deletions

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 085d5f346d..1071c6d6d7 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -49,6 +49,9 @@
 #define DEFAULT_MAX_USE_LOWER (1ULL*1024ULL*1024ULL)           /* 1 MiB */
 #define DEFAULT_MAX_USE_UPPER (4ULL*1024ULL*1024ULL*1024ULL)   /* 4 GiB */
 
+/* This is the default minimal use limit, how much we'll use even if keep_free suggests otherwise. */
+#define DEFAULT_MIN_USE (1ULL*1024ULL*1024ULL)                 /* 1 MiB */
+
 /* This is the upper bound if we deduce max_size from max_use */
 #define DEFAULT_MAX_SIZE_UPPER (128ULL*1024ULL*1024ULL)        /* 128 MiB */
 
@@ -60,6 +63,9 @@
  * size */
 #define DEFAULT_KEEP_FREE (1024ULL*1024ULL)                    /* 1 MB */
 
+/* This is the default maximum number of journal files to keep around. */
+#define DEFAULT_N_MAX_FILES (100)
+
 /* n_data was the first entry we added after the initial file format design */
 #define HEADER_SIZE_MIN ALIGN64(offsetof(Header, n_data))
 
@@ -2957,16 +2963,35 @@ int journal_file_copy_entry(JournalFile *from, JournalFile *to, Object *o, uint6
         return r;
 }
 
+void journal_reset_metrics(JournalMetrics *m) {
+        assert(m);
+
+        /* Set everything to "pick automatic values". */
+
+        *m = (JournalMetrics) {
+                .min_use = (uint64_t) -1,
+                .max_use = (uint64_t) -1,
+                .min_size = (uint64_t) -1,
+                .max_size = (uint64_t) -1,
+                .keep_free = (uint64_t) -1,
+                .n_max_files = (uint64_t) -1,
+        };
+}
+
 void journal_default_metrics(JournalMetrics *m, int fd) {
-        uint64_t fs_size = 0;
+        char a[FORMAT_BYTES_MAX], b[FORMAT_BYTES_MAX], c[FORMAT_BYTES_MAX], d[FORMAT_BYTES_MAX], e[FORMAT_BYTES_MAX];
         struct statvfs ss;
-        char a[FORMAT_BYTES_MAX], b[FORMAT_BYTES_MAX], c[FORMAT_BYTES_MAX], d[FORMAT_BYTES_MAX];
+        uint64_t fs_size;
 
         assert(m);
         assert(fd >= 0);
 
         if (fstatvfs(fd, &ss) >= 0)
                 fs_size = ss.f_frsize * ss.f_blocks;
+        else {
+                log_debug_errno(errno, "Failed to detremine disk size: %m");
+                fs_size = 0;
+        }
 
         if (m->max_use == (uint64_t) -1) {
 
@@ -2983,10 +3008,16 @@ void journal_default_metrics(JournalMetrics *m, int fd) {
         } else {
                 m->max_use = PAGE_ALIGN(m->max_use);
 
-                if (m->max_use < JOURNAL_FILE_SIZE_MIN*2)
+                if (m->max_use != 0 && m->max_use < JOURNAL_FILE_SIZE_MIN*2)
                         m->max_use = JOURNAL_FILE_SIZE_MIN*2;
         }
 
+        if (m->min_use == (uint64_t) -1)
+                m->min_use = DEFAULT_MIN_USE;
+
+        if (m->min_use > m->max_use)
+                m->min_use = m->max_use;
+
         if (m->max_size == (uint64_t) -1) {
                 m->max_size = PAGE_ALIGN(m->max_use / 8); /* 8 chunks */
 
@@ -2995,11 +3026,13 @@ void journal_default_metrics(JournalMetrics *m, int fd) {
         } else
                 m->max_size = PAGE_ALIGN(m->max_size);
 
-        if (m->max_size < JOURNAL_FILE_SIZE_MIN)
-                m->max_size = JOURNAL_FILE_SIZE_MIN;
+        if (m->max_size != 0) {
+                if (m->max_size < JOURNAL_FILE_SIZE_MIN)
+                        m->max_size = JOURNAL_FILE_SIZE_MIN;
 
-        if (m->max_size*2 > m->max_use)
-                m->max_use = m->max_size*2;
+                if (m->max_use != 0 && m->max_size*2 > m->max_use)
+                        m->max_use = m->max_size*2;
+        }
 
         if (m->min_size == (uint64_t) -1)
                 m->min_size = JOURNAL_FILE_SIZE_MIN;
@@ -3009,7 +3042,7 @@ void journal_default_metrics(JournalMetrics *m, int fd) {
                 if (m->min_size < JOURNAL_FILE_SIZE_MIN)
                         m->min_size = JOURNAL_FILE_SIZE_MIN;
 
-                if (m->min_size > m->max_size)
+                if (m->max_size != 0 && m->min_size > m->max_size)
                         m->max_size = m->min_size;
         }
 
@@ -3025,11 +3058,16 @@ void journal_default_metrics(JournalMetrics *m, int fd) {
                         m->keep_free = DEFAULT_KEEP_FREE;
         }
 
-        log_debug("Fixed max_use=%s max_size=%s min_size=%s keep_free=%s",
-                  format_bytes(a, sizeof(a), m->max_use),
-                  format_bytes(b, sizeof(b), m->max_size),
-                  format_bytes(c, sizeof(c), m->min_size),
-                  format_bytes(d, sizeof(d), m->keep_free));
+        if (m->n_max_files == (uint64_t) -1)
+                m->n_max_files = DEFAULT_N_MAX_FILES;
+
+        log_debug("Fixed min_use=%s max_use=%s max_size=%s min_size=%s keep_free=%s n_max_files=%" PRIu64,
+                  format_bytes(a, sizeof(a), m->min_use),
+                  format_bytes(b, sizeof(b), m->max_use),
+                  format_bytes(c, sizeof(c), m->max_size),
+                  format_bytes(d, sizeof(d), m->min_size),
+                  format_bytes(e, sizeof(e), m->keep_free),
+                  m->n_max_files);
 }
 
 int journal_file_get_cutoff_realtime_usec(JournalFile *f, usec_t *from, usec_t *to) {