From: Wang Shilong <wshilong@ddn.com>
Date: Tue, 26 Feb 2019 14:38:29 +0000 (+0800)
Subject: LU-12020 llite: make sure name pack atomic
X-Git-Tag: 2.12.52~10
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=f575b6551b2b8690894baeab95d6fe35e57e9418

LU-12020 llite: make sure name pack atomic

We are trying to access dentry name directly and pass it
down without holding @d_lock, this is racy and possibly
make us trigger assertions:

(mdc_lib.c:137:mdc_pack_name()) ASSERTION( lu_name_is_valid_2(buf, cpy_len) ) failed:

Fix the problem by allocting memory and copy name with @d_lock
held.

Change-Id: Iae0066661f42e8fca9358cbedd9cb21828779bbb
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-on: https://review.whamcloud.com/34330
Tested-by: Jenkins
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---

diff --git a/lustre/llite/file.c b/lustre/llite/file.c
index fe8c450..155236c 100644
--- a/lustre/llite/file.c
+++ b/lustre/llite/file.c
@@ -498,7 +498,7 @@ static int ll_intent_file_open(struct dentry *de, void *lmm, int lmmsize,
 {
 	struct ll_sb_info *sbi = ll_i2sbi(de->d_inode);
 	struct dentry *parent = de->d_parent;
-	const char *name = NULL;
+	char *name = NULL;
 	int len = 0;
 	struct md_op_data *op_data;
 	struct ptlrpc_request *req = NULL;
@@ -510,21 +510,41 @@ static int ll_intent_file_open(struct dentry *de, void *lmm, int lmmsize,
 
 	/* if server supports open-by-fid, or file name is invalid, don't pack
 	 * name in open request */
-	if (!(exp_connect_flags(sbi->ll_md_exp) & OBD_CONNECT_OPEN_BY_FID) &&
-	    lu_name_is_valid_2(de->d_name.name, de->d_name.len)) {
-		name = de->d_name.name;
+	if (!(exp_connect_flags(sbi->ll_md_exp) & OBD_CONNECT_OPEN_BY_FID)) {
+retry:
 		len = de->d_name.len;
+		name = kmalloc(len, GFP_NOFS);
+		if (!name)
+			RETURN(-ENOMEM);
+		/* race here */
+		spin_lock(&de->d_lock);
+		if (len != de->d_name.len) {
+			spin_unlock(&de->d_lock);
+			kfree(name);
+			goto retry;
+		}
+		memcpy(name, de->d_name.name, len);
+		spin_unlock(&de->d_lock);
+
+		if (!lu_name_is_valid_2(name, len)) {
+			kfree(name);
+			name = NULL;
+			len = 0;
+		}
 	}
 
 	op_data = ll_prep_md_op_data(NULL, parent->d_inode, de->d_inode,
 				     name, len, 0, LUSTRE_OPC_ANY, NULL);
-	if (IS_ERR(op_data))
+	if (IS_ERR(op_data)) {
+		kfree(name);
 		RETURN(PTR_ERR(op_data));
+	}
 	op_data->op_data = lmm;
 	op_data->op_data_size = lmmsize;
 
 	rc = md_intent_lock(sbi->ll_md_exp, op_data, itp, &req,
 			    &ll_md_blocking_ast, 0);
+	kfree(name);
 	ll_finish_md_op_data(op_data);
 	if (rc == -ESTALE) {
 		/* reason for keep own exit path - don`t flood log