linux-kernel - [PATCH AUTOSEL 5.17 146/149] ceph: fix memory leak in ceph_readdir when note_last

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Date:   Fri,  1 Apr 2022 10:25:33 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Xiubo Li <xiubli@...hat.com>, Jeff Layton <jlayton@...nel.org>,
        Ilya Dryomov <idryomov@...il.com>,
        Sasha Levin <sashal@...nel.org>, ceph-devel@...r.kernel.org
Subject: [PATCH AUTOSEL 5.17 146/149] ceph: fix memory leak in ceph_readdir when note_last_dentry returns error

From: Xiubo Li <xiubli@...hat.com>

[ Upstream commit f639d9867eea647005dc824e0e24f39ffc50d4e4 ]

Reset the last_readdir at the same time, and add a comment explaining
why we don't free last_readdir when dir_emit returns false.

Signed-off-by: Xiubo Li <xiubli@...hat.com>
Reviewed-by: Jeff Layton <jlayton@...nel.org>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ceph/dir.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 133dbd9338e7..d91fa53e12b3 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -478,8 +478,11 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 					2 : (fpos_off(rde->offset) + 1);
 			err = note_last_dentry(dfi, rde->name, rde->name_len,
 					       next_offset);
-			if (err)
+			if (err) {
+				ceph_mdsc_put_request(dfi->last_readdir);
+				dfi->last_readdir = NULL;
 				return err;
+			}
 		} else if (req->r_reply_info.dir_end) {
 			dfi->next_offset = 2;
 			/* keep last name */
@@ -520,6 +523,12 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 		if (!dir_emit(ctx, rde->name, rde->name_len,
 			      ceph_present_ino(inode->i_sb, le64_to_cpu(rde->inode.in->ino)),
 			      le32_to_cpu(rde->inode.in->mode) >> 12)) {
+			/*
+			 * NOTE: Here no need to put the 'dfi->last_readdir',
+			 * because when dir_emit stops us it's most likely
+			 * doesn't have enough memory, etc. So for next readdir
+			 * it will continue.
+			 */
 			dout("filldir stopping us...\n");
 			return 0;
 		}
-- 
2.34.1