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-221/src/journal/journald-server.c
===================================================================
--- systemd-221.orig/src/journal/journald-server.c
+++ systemd-221/src/journal/journald-server.c
@@ -21,6 +21,7 @@
 
 #include <sys/signalfd.h>
 #include <sys/ioctl.h>
+#include <linux/fs.h>
 #include <linux/sockios.h>
 #include <sys/statvfs.h>
 #include <sys/mman.h>
@@ -918,6 +919,38 @@ finish:
         dispatch_message_real(s, iovec, n, m, ucred, tv, label, label_len, unit_id, priority, object_pid);
 }
 
+/*
+ * 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);
+}
 
 static int system_journal_open(Server *s, bool flush_requested) {
         int r;
@@ -947,6 +980,7 @@ static int system_journal_open(Server *s
 
                 fn = strjoina("/var/log/journal/", ids);
                 (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);