From: werner@suse.de
Upstream: marked as openSUSE-specific fix originally, but may well
	worth be to be sent upstream.

Original description:
	(none)

Augmented description [jengelh@inai.de]:
Disable COW on journal files, as that is naturally leading to a lot
of unwanted fragmentation on btrfs.
No word on compression…
---
 src/journal/journald-server.c |   34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

Index: systemd-227/src/journal/journald-server.c
===================================================================
--- systemd-227.orig/src/journal/journald-server.c
+++ systemd-227/src/journal/journald-server.c
@@ -24,6 +24,7 @@
 #include <selinux/selinux.h>
 #endif
 #include <sys/ioctl.h>
+#include <linux/fs.h>
 #include <sys/mman.h>
 #include <sys/signalfd.h>
 #include <sys/statvfs.h>
@@ -861,6 +862,39 @@ void server_driver_message(Server *s, sd
         dispatch_message_real(s, iovec, n, ELEMENTSOF(iovec), &ucred, NULL, NULL, 0, NULL, LOG_INFO, 0);
 }
 
+/*
+ * On journaling and/or compressing file systems, avoid doubling the efforts
+ * for the system, that is, set NOCOW and NOCOMP inode flags. Check for every
+ * single flag, as otherwise, some of the file systems may return EOPNOTSUPP on
+ * a single unkown flag (like Btrfs does).
+ *
+ * …but src/journal/journal-file.c already sets NOCOW too…⸘
+ */
+static void disable_cow(const char *dir, const Server *serv)
+{
+        unsigned long flags;
+        int fd = open(dir, O_DIRECTORY);
+
+        if (fd < 0)
+                return;
+        if (ioctl(fd, FS_IOC_GETFLAGS, &flags) == 0) {
+                unsigned long old = flags;
+                if (!(flags & FS_NOATIME_FL) &&
+                    ioctl(fd, FS_IOC_SETFLAGS, flags | FS_NOATIME_FL) == 0)
+                        flags |= FS_NOATIME_FL;
+                if (!(flags & FS_NOCOW_FL) &&
+                    ioctl(fd, FS_IOC_SETFLAGS, flags | FS_NOCOW_FL) == 0)
+                        flags |= FS_NOCOW_FL;
+                if (!(flags & FS_NOCOMP_FL) && serv->compress) {
+                        flags &= ~FS_COMPR_FL;
+                        flags |= FS_NOCOMP_FL;
+                }
+                if (old != flags)
+                        ioctl(fd, FS_IOC_SETFLAGS, flags);
+        }
+        close(fd);
+}
+
 void server_dispatch_message(
                 Server *s,
                 struct iovec *iovec, unsigned n, unsigned m,
@@ -948,6 +982,7 @@ static int system_journal_open(Server *s
 
                 fn = strjoina("/var/log/journal/", SERVER_MACHINE_ID(s));
                 (void) mkdir(fn, 0755);
+                disable_cow(fn, s);
 
                 fn = strjoina(fn, "/system.journal");
                 r = journal_file_open_reliably(fn, O_RDWR|O_CREAT, 0640, s->compress, s->seal, &s->system_metrics, s->mmap, NULL, &s->system_journal);