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authorZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2013-11-13 00:42:22 -0500
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2014-01-11 16:54:59 -0500
commit348ced909724a1331b85d57aede80a102a00e428 (patch)
tree1b58129221dcfee9d8e2679cf48f12882f565bc2 /src/journal/journal-file.h
parentb94801803417c23d099cb7e508754181ecd27f9c (diff)
journald: do not free space when disk space runs low
Before, journald would remove journal files until both MaxUse= and KeepFree= settings would be satisfied. The first one depends (if set automatically) on the size of the file system and is constant. But the second one depends on current use of the file system, and a spike in disk usage would cause journald to delete journal files, trying to reach usage which would leave 15% of the disk free. This behaviour is surprising for the user who doesn't expect his logs to be purged when disk usage goes above 85%, which on a large disk could be some gigabytes from being full. In addition attempting to keep 15% free provides an attack vector where filling the disk sufficiently disposes of almost all logs. Instead, obey KeepFree= only as a limit on adding additional files. When replacing old files with new, ignore KeepFree=. This means that if journal disk usage reached some high point that at some later point start to violate the KeepFree= constraint, journald will not add files to go above this point, but it will stay (slightly) below it. When journald is restarted, it forgets the previous maximum usage value, and sets the limit based on the current usage, so if disk remains to be filled, journald might use one journal-file-size less on each restart, if restarts happen just after rotation. This seems like a reasonable compromise between implementation complexity and robustness.
Diffstat (limited to 'src/journal/journal-file.h')
-rw-r--r--src/journal/journal-file.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/src/journal/journal-file.h b/src/journal/journal-file.h
index 885b3b1df4..50dbe29cc1 100644
--- a/src/journal/journal-file.h
+++ b/src/journal/journal-file.h
@@ -37,6 +37,7 @@
typedef struct JournalMetrics {
uint64_t max_use;
+ uint64_t use;
uint64_t max_size;
uint64_t min_size;
uint64_t keep_free;