linux-kernel - [PATCH -next 3/3] ubifs: read-only if LEB may always be taken in ubifs_garbage

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Date:   Mon, 15 Nov 2021 09:31:44 +0800
From:   Baokun Li <libaokun1@...wei.com>
To:     <richard@....at>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     <libaokun1@...wei.com>, <yukuai3@...wei.com>
Subject: [PATCH -next 3/3] ubifs: read-only if LEB may always be taken in ubifs_garbage_collect

If ubifs_garbage_collect_leb() returns -EAGAIN and ubifs_return_leb
returns error, a LEB will always has a "taken" flag. In this case,
set the ubifs to read-only to prevent a worse situation.

Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
 fs/ubifs/gc.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index 1f74a127fe3a..3134d070fcc0 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -756,8 +756,17 @@ int ubifs_garbage_collect(struct ubifs_info *c, int anyway)
 				 * caller instead of the original '-EAGAIN'.
 				 */
 				err = ubifs_return_leb(c, lp.lnum);
-				if (err)
+				if (err) {
 					ret = err;
+					/*
+					 * An LEB may always be "taken",
+					 * so setting ubifs to read-only,
+					 * and then executing sync wbuf will
+					 * return -EROFS and enter the "out"
+					 * error branch.
+					 */
+					ubifs_ro_mode(c, ret);
+				}
 				/*  Maybe double return LEB if goto out */
 				lp.lnum = -1;
 				break;
-- 
2.31.1