Re: [syzbot] Re: kernel BUG in ocfs2_reserve_suballoc_bits()

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Subject: Re: kernel BUG in ocfs2_reserve_suballoc_bits()
Author: dmantipov@xxxxxxxxx

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git bf9aa14fc523d2763fc9a10672a709224e8fcaf4

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 60df52e4c1f8..d65326d36b1c 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -2440,6 +2440,13 @@ int ocfs2_inode_lock_full_nested(struct inode *inode,
 
 	status = 0;
 	acquired = 0;
+
+	/* Do not trust a filesystem which is known for containing errors. */
+	if (ocfs2_has_errors(osb)) {
+		status = -EINVAL;
+		goto bail;
+	}
+
 	/* We'll allow faking a readonly metadata lock for
 	 * rodevices. */
 	if (ocfs2_is_hard_readonly(osb)) {
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 51c52768132d..a48f79ca750a 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -665,6 +665,17 @@ static inline int ocfs2_is_soft_readonly(struct ocfs2_super *osb)
 	return ret;
 }
 
+static inline int ocfs2_has_errors(struct ocfs2_super *osb)
+{
+	int ret;
+
+	spin_lock(&osb->osb_lock);
+	ret = osb->osb_flags & OCFS2_OSB_ERROR_FS;
+	spin_unlock(&osb->osb_lock);
+
+	return ret;
+}
+
 static inline int ocfs2_clusterinfo_valid(struct ocfs2_super *osb)
 {
 	return (osb->s_feature_incompat &