[PATCH] quota: Generate warnings for DQUOT_SPACE_NOFAIL allocations

[PATCH] quota: Generate warnings for DQUOT_SPACE_NOFAIL allocations

[Jan Kara]

Eryu has reported that since commit 7b9ca4c61bc2 "quota: Reduce
contention on dq_data_lock" test generic/233 occasionally fails. This is
caused by the fact that since that commit we don't generate warning and
set grace time for quota allocations that have DQUOT_SPACE_NOFAIL set
(these are for example some metadata allocations in ext4). We need these
allocations to behave regularly wrt warning generation and grace time
setting so fix the code to return to the original behavior.

Reported-by: Eryu Guan <eguan@redhat.com>
CC: stable@vger.kernel.org
Fixes: 7b9ca4c61bc278b771fb57d6290a31ab1fc7fdac
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/quota/dquot.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

I plan to queue this patch into my tree and send it to Linus for -rc5.

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 50b0556a124f..52ad15192e72 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1297,21 +1297,18 @@ static int dquot_add_space(struct dquot *dquot, qsize_t space,
 	spin_lock(&dquot->dq_dqb_lock);
 	if (!sb_has_quota_limits_enabled(sb, dquot->dq_id.type) ||
 	    test_bit(DQ_FAKE_B, &dquot->dq_flags))
-		goto add;
+		goto finish;
 
 	tspace = dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace
 		+ space + rsv_space;
 
-	if (flags & DQUOT_SPACE_NOFAIL)
-		goto add;
-
 	if (dquot->dq_dqb.dqb_bhardlimit &&
 	    tspace > dquot->dq_dqb.dqb_bhardlimit &&
             !ignore_hardlimit(dquot)) {
 		if (flags & DQUOT_SPACE_WARN)
 			prepare_warning(warn, dquot, QUOTA_NL_BHARDWARN);
 		ret = -EDQUOT;
-		goto out;
+		goto finish;
 	}
 
 	if (dquot->dq_dqb.dqb_bsoftlimit &&
@@ -1322,7 +1319,7 @@ static int dquot_add_space(struct dquot *dquot, qsize_t space,
 		if (flags & DQUOT_SPACE_WARN)
 			prepare_warning(warn, dquot, QUOTA_NL_BSOFTLONGWARN);
 		ret = -EDQUOT;
-		goto out;
+		goto finish;
 	}
 
 	if (dquot->dq_dqb.dqb_bsoftlimit &&
@@ -1338,13 +1335,21 @@ static int dquot_add_space(struct dquot *dquot, qsize_t space,
 			 * be always printed
 			 */
 			ret = -EDQUOT;
-			goto out;
+			goto finish;
 		}
 	}
-add:
-	dquot->dq_dqb.dqb_rsvspace += rsv_space;
-	dquot->dq_dqb.dqb_curspace += space;
-out:
+finish:
+	/*
+	 * We have to be careful and go through warning generation & grace time
+	 * setting even if DQUOT_SPACE_NOFAIL is set. That's why we check it
+	 * only here...
+	 */
+	if (flags & DQUOT_SPACE_NOFAIL)
+		ret = 0;
+	if (!ret) {
+		dquot->dq_dqb.dqb_rsvspace += rsv_space;
+		dquot->dq_dqb.dqb_curspace += space;
+	}
 	spin_unlock(&dquot->dq_dqb_lock);
 	return ret;
 }
-- 
2.12.3

Re: [PATCH] quota: Generate warnings for DQUOT_SPACE_NOFAIL allocations

[Eryu Guan]

On Tue, Oct 10, 2017 at 02:57:24PM +0200, Jan Kara wrote:
> Eryu has reported that since commit 7b9ca4c61bc2 "quota: Reduce
> contention on dq_data_lock" test generic/233 occasionally fails. This is
> caused by the fact that since that commit we don't generate warning and
> set grace time for quota allocations that have DQUOT_SPACE_NOFAIL set
> (these are for example some metadata allocations in ext4). We need these
> allocations to behave regularly wrt warning generation and grace time
> setting so fix the code to return to the original behavior.
> 
> Reported-by: Eryu Guan <eguan@redhat.com>

With this patch applied, I ran generic/233 on ext4 for 150 iterations
without hitting a failure. Thanks!

Tested-by: Eryu Guan <eguan@redhat.com>

> CC: stable@vger.kernel.org
> Fixes: 7b9ca4c61bc278b771fb57d6290a31ab1fc7fdac
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/quota/dquot.c | 27 ++++++++++++++++-----------
>  1 file changed, 16 insertions(+), 11 deletions(-)
> 
> I plan to queue this patch into my tree and send it to Linus for -rc5.
> 
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index 50b0556a124f..52ad15192e72 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -1297,21 +1297,18 @@ static int dquot_add_space(struct dquot *dquot, qsize_t space,
>  	spin_lock(&dquot->dq_dqb_lock);
>  	if (!sb_has_quota_limits_enabled(sb, dquot->dq_id.type) ||
>  	    test_bit(DQ_FAKE_B, &dquot->dq_flags))
> -		goto add;
> +		goto finish;
>  
>  	tspace = dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace
>  		+ space + rsv_space;
>  
> -	if (flags & DQUOT_SPACE_NOFAIL)
> -		goto add;
> -
>  	if (dquot->dq_dqb.dqb_bhardlimit &&
>  	    tspace > dquot->dq_dqb.dqb_bhardlimit &&
>              !ignore_hardlimit(dquot)) {
>  		if (flags & DQUOT_SPACE_WARN)
>  			prepare_warning(warn, dquot, QUOTA_NL_BHARDWARN);
>  		ret = -EDQUOT;
> -		goto out;
> +		goto finish;
>  	}
>  
>  	if (dquot->dq_dqb.dqb_bsoftlimit &&
> @@ -1322,7 +1319,7 @@ static int dquot_add_space(struct dquot *dquot, qsize_t space,
>  		if (flags & DQUOT_SPACE_WARN)
>  			prepare_warning(warn, dquot, QUOTA_NL_BSOFTLONGWARN);
>  		ret = -EDQUOT;
> -		goto out;
> +		goto finish;
>  	}
>  
>  	if (dquot->dq_dqb.dqb_bsoftlimit &&
> @@ -1338,13 +1335,21 @@ static int dquot_add_space(struct dquot *dquot, qsize_t space,
>  			 * be always printed
>  			 */
>  			ret = -EDQUOT;
> -			goto out;
> +			goto finish;
>  		}
>  	}
> -add:
> -	dquot->dq_dqb.dqb_rsvspace += rsv_space;
> -	dquot->dq_dqb.dqb_curspace += space;
> -out:
> +finish:
> +	/*
> +	 * We have to be careful and go through warning generation & grace time
> +	 * setting even if DQUOT_SPACE_NOFAIL is set. That's why we check it
> +	 * only here...
> +	 */
> +	if (flags & DQUOT_SPACE_NOFAIL)
> +		ret = 0;
> +	if (!ret) {
> +		dquot->dq_dqb.dqb_rsvspace += rsv_space;
> +		dquot->dq_dqb.dqb_curspace += space;
> +	}
>  	spin_unlock(&dquot->dq_dqb_lock);
>  	return ret;
>  }
> -- 
> 2.12.3
>