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pnfs/flexfiles: protect ktime manipulation with mirror lock 

It looks as if xchg() and cmpxchg() are not available for 64-bit integers on sparc32:

> New breakage seen in linux-next today:
>
> ERROR: "__xchg_called_with_bad_pointer" [fs/nfs/flexfilelayout/nfs_layout_flexfiles.ko] undefined!
> ERROR: "__cmpxchg_called_with_bad_pointer" [fs/nfs/flexfilelayout/nfs_layout_flexfiles.ko] undefined!
> make[2]: *** [__modpost] Error 1
> make[1]: *** [modules] Error 2

Given that mirror ktime manipulation is already under mirror->lock, let's make use of the fact.

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Peng Tao 2015-06-26 09:45:49 +08:00 committed by Trond Myklebust
parent 865a7ecb21
commit 9bbd9bb40c
1 changed files with 12 additions and 19 deletions
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31
fs/nfs/flexfilelayout/flexfilelayout.c
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@ -417,21 +417,9 @@ ff_layout_get_lseg_count(struct nfs4_ff_layout_segment *fls)
static void
nfs4_ff_start_busy_timer(struct nfs4_ff_busy_timer *timer)
{
ktime_t old, new;
/*
* Note: careful here!
* If the counter is zero, then we must not increment it until after
* we've set the start_time.
* If we were instead to use atomic_inc_return(), then another
* request might come in, bump, and then call end_busy_timer()
* before we've set the timer->start_time.
*/
old = timer->start_time;
if (atomic_inc_not_zero(&timer->n_ops) == 0) {
new = ktime_get();
cmpxchg(&timer->start_time.tv64, old.tv64, new.tv64);
atomic_inc(&timer->n_ops);
/* first IO request? */
if (atomic_inc_return(&timer->n_ops) == 1) {
timer->start_time = ktime_get();
}
}
@ -440,9 +428,12 @@ nfs4_ff_end_busy_timer(struct nfs4_ff_busy_timer *timer)
{
ktime_t start, now;
if (atomic_dec_return(&timer->n_ops) < 0)
WARN_ON_ONCE(1);
now = ktime_get();
start.tv64 = xchg(&timer->start_time.tv64, now.tv64);
atomic_dec(&timer->n_ops);
start = timer->start_time;
timer->start_time = now;
return ktime_sub(now, start);
}
@ -460,8 +451,10 @@ nfs4_ff_layoutstat_start_io(struct nfs4_ff_layout_mirror *mirror,
ktime_t now = ktime_get();
nfs4_ff_start_busy_timer(&layoutstat->busy_timer);
cmpxchg(&mirror->start_time.tv64, notime.tv64, now.tv64);
cmpxchg(&mirror->last_report_time.tv64, notime.tv64, now.tv64);
if (ktime_equal(mirror->start_time, notime))
mirror->start_time = now;
if (ktime_equal(mirror->last_report_time, notime))
mirror->last_report_time = now;
if (ktime_to_ms(ktime_sub(now, mirror->last_report_time)) >=
FF_LAYOUTSTATS_REPORT_INTERVAL) {
mirror->last_report_time = now;