From: Dmitry Monakhov Date: Thu, 31 Oct 2019 10:39:20 +0000 (+0000) Subject: quota: Check that quota is not dirty before release X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=072d24ef6cb1f309f6c45c71e5b0f04a2e9d48a6;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git quota: Check that quota is not dirty before release commit df4bb5d128e2c44848aeb36b7ceceba3ac85080d upstream. There is a race window where quota was redirted once we drop dq_list_lock inside dqput(), but before we grab dquot->dq_lock inside dquot_release() TASK1 TASK2 (chowner) ->dqput() we_slept: spin_lock(&dq_list_lock) if (dquot_dirty(dquot)) { spin_unlock(&dq_list_lock); dquot->dq_sb->dq_op->write_dquot(dquot); goto we_slept if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) { spin_unlock(&dq_list_lock); dquot->dq_sb->dq_op->release_dquot(dquot); dqget() mark_dquot_dirty() dqput() goto we_slept; } So dquot dirty quota will be released by TASK1, but on next we_sleept loop we detect this and call ->write_dquot() for it. XFSTEST: https://github.com/dmonakhov/xfstests/commit/440a80d4cbb39e9234df4d7240aee1d551c36107 Link: https://lore.kernel.org/r/20191031103920.3919-2-dmonakhov@openvz.org CC: stable@vger.kernel.org Signed-off-by: Dmitry Monakhov Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c index 87e577a49b0d..542fa21aeaa9 100644 --- a/fs/ocfs2/quota_global.c +++ b/fs/ocfs2/quota_global.c @@ -714,7 +714,7 @@ static int ocfs2_release_dquot(struct dquot *dquot) mutex_lock(&dquot->dq_lock); /* Check whether we are not racing with some other dqget() */ - if (atomic_read(&dquot->dq_count) > 1) + if (dquot_is_busy(dquot)) goto out; /* Running from downconvert thread? Postpone quota processing to wq */ if (current == osb->dc_task) { diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index f9246ac4eef8..1c575861bac4 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -479,7 +479,7 @@ int dquot_release(struct dquot *dquot) mutex_lock(&dquot->dq_lock); /* Check whether we are not racing with some other dqget() */ - if (atomic_read(&dquot->dq_count) > 1) + if (dquot_is_busy(dquot)) goto out_dqlock; mutex_lock(&dqopt->dqio_mutex); if (dqopt->ops[dquot->dq_id.type]->release_dqblk) { diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h index 87733344768c..0a60fe354bc5 100644 --- a/include/linux/quotaops.h +++ b/include/linux/quotaops.h @@ -54,6 +54,16 @@ static inline struct dquot *dqgrab(struct dquot *dquot) atomic_inc(&dquot->dq_count); return dquot; } + +static inline bool dquot_is_busy(struct dquot *dquot) +{ + if (test_bit(DQ_MOD_B, &dquot->dq_flags)) + return true; + if (atomic_read(&dquot->dq_count) > 1) + return true; + return false; +} + void dqput(struct dquot *dquot); int dquot_scan_active(struct super_block *sb, int (*fn)(struct dquot *dquot, unsigned long priv),