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author | Peng Tao <tao.peng@primarydata.com> | 2015-06-26 01:45:49 (GMT) |
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committer | Trond Myklebust <trond.myklebust@primarydata.com> | 2015-06-26 18:01:37 (GMT) |
commit | 9bbd9bb40cfae5ff35710e88866fcadb0e8f91ed (patch) | |
tree | 432e168ff7408d6d5386688f79459f083f9dcfc0 /fs/nfs/flexfilelayout/flexfilelayout.c | |
parent | 865a7ecb2131a3ba26cc1d49daf18275375109f0 (diff) | |
download | linux-9bbd9bb40cfae5ff35710e88866fcadb0e8f91ed.tar.xz |
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>
Diffstat (limited to 'fs/nfs/flexfilelayout/flexfilelayout.c')
-rw-r--r-- | fs/nfs/flexfilelayout/flexfilelayout.c | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c index d3b3b62..85b4234 100644 --- a/fs/nfs/flexfilelayout/flexfilelayout.c +++ b/fs/nfs/flexfilelayout/flexfilelayout.c @@ -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; |