Linux 4.7 compat: Fix deadlock during lookup on case-insensitive

We must not use d_add_ci if the dentry already has the real name. Otherwise, d_add_ci()->d_alloc_parallel() will find itself on the lookup hash and wait on itself causing deadlock. Tested-by: satmandu Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Closes #5124 Closes #5141 Closes #5147 Closes #5148
openzfs · Feb 3, 2017 · c0716f1 · c0716f1
1 parent dbc95a6
commit c0716f1
Showing 1 changed file with 7 additions and 3 deletions.
diff --git a/module/zfs/zpl_inode.c b/module/zfs/zpl_inode.c
@@ -102,9 +102,13 @@ zpl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
 		struct dentry *new_dentry;
 		struct qstr ci_name;
 
-		ci_name.name = pn.pn_buf;
-		ci_name.len = strlen(pn.pn_buf);
-		new_dentry = d_add_ci(dentry, ip, &ci_name);
+		if (strcmp(dname(dentry), pn.pn_buf) == 0) {
+			new_dentry = d_splice_alias(ip,  dentry);
+		} else {
+			ci_name.name = pn.pn_buf;
+			ci_name.len = strlen(pn.pn_buf);
+			new_dentry = d_add_ci(dentry, ip, &ci_name);
+		}
 		kmem_free(pn.pn_buf, ZFS_MAXNAMELEN);
 		return (new_dentry);
 	} else {