From: Rafał Miłecki rafal@milecki.pl
Right now wbuf timer has hardcoded timeouts and there is no place for manual adjustments. Some projects / cases many need that though. Few file systems allow doing that by respecting dirty_writeback_interval that can be set using sysctl (dirty_writeback_centisecs).
Lowering dirty_writeback_interval could be some way of dealing with user space apps lacking proper fsyncs. This is definitely *not* a perfect solution but we don't have ideal (user space) world. There were already advanced discussions on this matter, mostly when ext4 was introduced and it wasn't behaving as ext3. Anyway, the final decision was to add some hacks to the ext4, as trying to fix whole user space or adding new API was pointless.
We can't (and shouldn't?) just follow ext4. We can't e.g. sync on close as this would cause too many commits and flash wearing. On the other hand we still should allow some trade-off between -o sync and default wbuf timeout. Respecting dirty_writeback_interval should allow some sane cutomizations if used warily.
Signed-off-by: Rafał Miłecki rafal@milecki.pl Reviewed-by: Boris Brezillon boris.brezillon@free-electrons.com Signed-off-by: Richard Weinberger richard@nod.at --- fs/ubifs/io.c | 8 ++++---- fs/ubifs/ubifs.h | 4 ---- 2 files changed, 4 insertions(+), 8 deletions(-)
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c index 4d6ce4a2a4b6..3be28900bf37 100644 --- a/fs/ubifs/io.c +++ b/fs/ubifs/io.c @@ -452,11 +452,11 @@ static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer) */ static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf) { - ktime_t softlimit = ktime_set(WBUF_TIMEOUT_SOFTLIMIT, 0); - unsigned long long delta; + ktime_t softlimit = ms_to_ktime(dirty_writeback_interval * 10); + unsigned long long delta = dirty_writeback_interval;
- delta = WBUF_TIMEOUT_HARDLIMIT - WBUF_TIMEOUT_SOFTLIMIT; - delta *= 1000000000ULL; + /* centi to milli, milli to nano, then 10% */ + delta *= 10ULL * NSEC_PER_MSEC / 10ULL;
ubifs_assert(!hrtimer_active(&wbuf->timer)); ubifs_assert(delta <= ULONG_MAX); diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h index ade4b3137a1d..b8b18d446a49 100644 --- a/fs/ubifs/ubifs.h +++ b/fs/ubifs/ubifs.h @@ -83,10 +83,6 @@ */ #define BGT_NAME_PATTERN "ubifs_bgt%d_%d"
-/* Write-buffer synchronization timeout interval in seconds */ -#define WBUF_TIMEOUT_SOFTLIMIT 3 -#define WBUF_TIMEOUT_HARDLIMIT 5 - /* Maximum possible inode number (only 32-bit inodes are supported now) */ #define MAX_INUM 0xFFFFFFFF