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authorDmitry Monakhov <dmtrmonakhov@yandex-team.ru>2019-10-31 13:39:20 +0300
committerJan Kara <jack@suse.cz>2019-10-31 21:07:42 +0300
commitdf4bb5d128e2c44848aeb36b7ceceba3ac85080d (patch)
treea45954c3bb978dbf2aa7de092b3e5c53adc95dfd
parent6ff33d99fc5c96797103b48b7b0902c296f09c05 (diff)
downloadlinux-df4bb5d128e2c44848aeb36b7ceceba3ac85080d.tar.xz
quota: Check that quota is not dirty before release
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 <dmtrmonakhov@yandex-team.ru> Signed-off-by: Jan Kara <jack@suse.cz>
-rw-r--r--fs/ocfs2/quota_global.c2
-rw-r--r--fs/quota/dquot.c2
-rw-r--r--include/linux/quotaops.h10
3 files changed, 12 insertions, 2 deletions
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 7a922190a8c7..eda83487c9ec 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -728,7 +728,7 @@ 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 b492b9ea829a..72d24a5451bb 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -497,7 +497,7 @@ 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;
if (dqopt->ops[dquot->dq_id.type]->release_dqblk) {
ret = dqopt->ops[dquot->dq_id.type]->release_dqblk(dquot);
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 185d94829701..91e0b7624053 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),