--- zzzz-none-000/linux-3.10.107/fs/ocfs2/quota_global.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/ocfs2/quota_global.c	2021-02-04 17:41:59.000000000 +0000
@@ -10,6 +10,7 @@
 #include <linux/jiffies.h>
 #include <linux/writeback.h>
 #include <linux/workqueue.h>
+#include <linux/llist.h>
 
 #include <cluster/masklog.h>
 
@@ -234,7 +235,7 @@
 		len = sb->s_blocksize - OCFS2_QBLK_RESERVED_SPACE - offset;
 	}
 
-	if (gqinode->i_size < off + len) {
+	if (i_size_read(gqinode) < off + len) {
 		loff_t rounded_end =
 				ocfs2_align_bytes_to_blocks(sb, off + len);
 
@@ -335,8 +336,8 @@
 int ocfs2_global_read_info(struct super_block *sb, int type)
 {
 	struct inode *gqinode = NULL;
-	unsigned int ino[MAXQUOTAS] = { USER_QUOTA_SYSTEM_INODE,
-					GROUP_QUOTA_SYSTEM_INODE };
+	unsigned int ino[OCFS2_MAXQUOTAS] = { USER_QUOTA_SYSTEM_INODE,
+					      GROUP_QUOTA_SYSTEM_INODE };
 	struct ocfs2_global_disk_dqinfo dinfo;
 	struct mem_dqinfo *info = sb_dqinfo(sb, type);
 	struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
@@ -679,6 +680,27 @@
 	       OCFS2_INODE_UPDATE_CREDITS;
 }
 
+void ocfs2_drop_dquot_refs(struct work_struct *work)
+{
+	struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
+					       dquot_drop_work);
+	struct llist_node *list;
+	struct ocfs2_dquot *odquot, *next_odquot;
+
+	list = llist_del_all(&osb->dquot_drop_list);
+	llist_for_each_entry_safe(odquot, next_odquot, list, list) {
+		/* Drop the reference we acquired in ocfs2_dquot_release() */
+		dqput(&odquot->dq_dquot);
+	}
+}
+
+/*
+ * Called when the last reference to dquot is dropped. If we are called from
+ * downconvert thread, we cannot do all the handling here because grabbing
+ * quota lock could deadlock (the node holding the quota lock could need some
+ * other cluster lock to proceed but with blocked downconvert thread we cannot
+ * release any lock).
+ */
 static int ocfs2_release_dquot(struct dquot *dquot)
 {
 	handle_t *handle;
@@ -694,6 +716,19 @@
 	/* Check whether we are not racing with some other dqget() */
 	if (atomic_read(&dquot->dq_count) > 1)
 		goto out;
+	/* Running from downconvert thread? Postpone quota processing to wq */
+	if (current == osb->dc_task) {
+		/*
+		 * Grab our own reference to dquot and queue it for delayed
+		 * dropping.  Quota code rechecks after calling
+		 * ->release_dquot() and won't free dquot structure.
+		 */
+		dqgrab(dquot);
+		/* First entry on list -> queue work */
+		if (llist_add(&OCFS2_DQUOT(dquot)->list, &osb->dquot_drop_list))
+			queue_work(ocfs2_wq, &osb->dquot_drop_work);
+		goto out;
+	}
 	status = ocfs2_lock_global_qf(oinfo, 1);
 	if (status < 0)
 		goto out;
@@ -785,8 +820,8 @@
 		 */
 		WARN_ON(journal_current_handle());
 		status = ocfs2_extend_no_holes(gqinode, NULL,
-			gqinode->i_size + (need_alloc << sb->s_blocksize_bits),
-			gqinode->i_size);
+			i_size_read(gqinode) + (need_alloc << sb->s_blocksize_bits),
+			i_size_read(gqinode));
 		if (status < 0)
 			goto out_dq;
 	}