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authorLennart Poettering <lennart@poettering.net>2015-01-08 01:22:29 +0100
committerLennart Poettering <lennart@poettering.net>2015-01-08 01:22:29 +0100
commit11689d2a021d95a8447d938180e0962cd9439763 (patch)
tree83e4e1a10a219bd6344e995f445b4fe95ed54acb /src/journal
parent3c4230a5afb27faec2176d4642c0e2e145971b5c (diff)
journald: turn off COW for journal files on btrfs
btrfs' COW logic results in heavily fragment journal files, which is detrimental for perfomance. Hence, turn off COW for journal files as we create them. Turning off COW comes at the cost of data integrity guarantees, but this should be acceptable, given that we do our own checksumming, and generally have a pretty conservative write pattern. Also see discussion on linux-btrfs: http://www.spinics.net/lists/linux-btrfs/msg41001.html
Diffstat (limited to 'src/journal')
-rw-r--r--src/journal/journal-file.c28
-rw-r--r--src/journal/journalctl.c12
2 files changed, 30 insertions, 10 deletions
diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index c9030c56ad..c20af5d9bf 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -26,6 +26,7 @@
#include <sys/statvfs.h>
#include <fcntl.h>
#include <stddef.h>
+#include <linux/fs.h>
#include "btrfs-util.h"
#include "journal-def.h"
@@ -141,8 +142,17 @@ 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)
- btrfs_defrag_fd(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);
+ }
safe_close(f->fd);
free(f->path);
@@ -2591,6 +2601,18 @@ 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
@@ -2808,6 +2830,8 @@ 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 386e3505c0..62931f14c9 100644
--- a/src/journal/journalctl.c
+++ b/src/journal/journalctl.c
@@ -1294,7 +1294,7 @@ 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, attr = 0;
+ int fd = -1, r;
sd_id128_t machine, boot;
char *p = NULL, *k = NULL;
struct FSSHeader h;
@@ -1389,13 +1389,9 @@ static int setup_keys(void) {
/* Enable secure remove, exclusion from dump, synchronous
* writing and in-place updating */
- 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");
+ 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");
zero(h);
memcpy(h.signature, "KSHHRHLP", 8);