[systemd-devel] [PATCH 1/2] Revert patch 11689d2a which force the NOCOW attribute

[Goffredo Baroncelli]

From: Goffredo Baroncelli <kreijack at inwind.it>

Revert patch 11689d2a, which force the NOCOW attribute for the journal files.
This patch was introduced to allievate the perfomances problem that
journald shows on the BTRFS filesystem.

Because the NOCOW attribute is forced the user can't revert to
the old behavior. However NOCOW attribute disables the btrfs checksums, which
prevent BTRFS to rebuild a currupted file in an RAIDx filesystem.

To continue to set the NOCOW attribute, use the h|H command of systemd-tmpfile.
---
 src/journal/journal-file.c | 28 ++--------------------------
 src/journal/journalctl.c   | 12 ++++++++----
 2 files changed, 10 insertions(+), 30 deletions(-)

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 2845e05..9d56069 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -26,7 +26,6 @@
 #include <sys/statvfs.h>
 #include <fcntl.h>
 #include <stddef.h>
-#include <linux/fs.h>
 
 #include "btrfs-util.h"
 #include "journal-def.h"
@@ -142,17 +141,8 @@ void journal_file_close(JournalFile *f) {
         if (f->mmap && f->fd >= 0)
                 mmap_cache_close_fd(f->mmap, f->fd);
 
-        if (f->fd >= 0 && f->defrag_on_close) {
-
-                /* Be friendly to btrfs: turn COW back on again now,
-                 * and defragment the file. We won't write to the file
-                 * ever again, hence remove all fragmentation, and
-                 * reenable all the good bits COW usually provides
-                 * (such as data checksumming). */
-
-                (void) chattr_fd(f->fd, false, FS_NOCOW_FL);
-                (void) btrfs_defrag_fd(f->fd);
-        }
+        if (f->fd >= 0 && f->defrag_on_close)
+                btrfs_defrag_fd(f->fd);
 
         safe_close(f->fd);
         free(f->path);
@@ -2602,18 +2592,6 @@ int journal_file_open(
                 goto fail;
 
         if (f->last_stat.st_size == 0 && f->writable) {
-
-                /* Before we write anything, turn off COW logic. Given
-                 * our write pattern that is quite unfriendly to COW
-                 * file systems this should greatly improve
-                 * performance on COW file systems, such as btrfs, at
-                 * the expense of data integrity features (which
-                 * shouldn't be too bad, given that we do our own
-                 * checksumming). */
-                r = chattr_fd(f->fd, true, FS_NOCOW_FL);
-                if (r < 0)
-                        log_warning_errno(errno, "Failed to set file attributes: %m");
-
                 /* Let's attach the creation time to the journal file,
                  * so that the vacuuming code knows the age of this
                  * file even if the file might end up corrupted one
@@ -2831,8 +2809,6 @@ int journal_file_open_reliably(
 
         /* btrfs doesn't cope well with our write pattern and
          * fragments heavily. Let's defrag all files we rotate */
-
-        (void) chattr_path(p, false, FS_NOCOW_FL);
         (void) btrfs_defrag(p);
 
         log_warning("File %s corrupted or uncleanly shut down, renaming and replacing.", fname);
diff --git a/src/journal/journalctl.c b/src/journal/journalctl.c
index 55c7786..abb9d0c 100644
--- a/src/journal/journalctl.c
+++ b/src/journal/journalctl.c
@@ -1290,7 +1290,7 @@ static int setup_keys(void) {
         size_t mpk_size, seed_size, state_size, i;
         uint8_t *mpk, *seed, *state;
         ssize_t l;
-        int fd = -1, r;
+        int fd = -1, r, attr = 0;
         sd_id128_t machine, boot;
         char *p = NULL, *k = NULL;
         struct FSSHeader h;
@@ -1385,9 +1385,13 @@ static int setup_keys(void) {
 
         /* Enable secure remove, exclusion from dump, synchronous
          * writing and in-place updating */
-        r = chattr_fd(fd, true, FS_SECRM_FL|FS_NODUMP_FL|FS_SYNC_FL|FS_NOCOW_FL);
-        if (r < 0)
-                log_warning_errno(errno, "Failed to set file attributes: %m");
+        if (ioctl(fd, FS_IOC_GETFLAGS, &attr) < 0)
+                log_warning_errno(errno, "FS_IOC_GETFLAGS failed: %m");
+
+        attr |= FS_SECRM_FL|FS_NODUMP_FL|FS_SYNC_FL|FS_NOCOW_FL;
+
+        if (ioctl(fd, FS_IOC_SETFLAGS, &attr) < 0)
+                log_warning_errno(errno, "FS_IOC_SETFLAGS failed: %m");
 
         zero(h);
         memcpy(h.signature, "KSHHRHLP", 8);
-- 
2.1.4