linux-kernel - [PATCH 5.4 269/314] afs: afs_write_end() should change i

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Message-Id: <20200623195351.817322134@linuxfoundation.org>
Date:   Tue, 23 Jun 2020 21:57:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Howells <dhowells@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 269/314] afs: afs_write_end() should change i_size under the right lock

From: David Howells <dhowells@...hat.com>

[ Upstream commit 1f32ef79897052ef7d3d154610d8d6af95abde83 ]

Fix afs_write_end() to change i_size under vnode->cb_lock rather than
->wb_lock so that it doesn't race with afs_vnode_commit_status() and
afs_getattr().

The ->wb_lock is only meant to guard access to ->wb_keys which isn't
accessed by that piece of code.

Fixes: 4343d00872e1 ("afs: Get rid of the afs_writeback record")
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/afs/write.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/afs/write.c b/fs/afs/write.c
index 371db86c6c5ec..96b042af62485 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -194,11 +194,11 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 
 	i_size = i_size_read(&vnode->vfs_inode);
 	if (maybe_i_size > i_size) {
-		spin_lock(&vnode->wb_lock);
+		write_seqlock(&vnode->cb_lock);
 		i_size = i_size_read(&vnode->vfs_inode);
 		if (maybe_i_size > i_size)
 			i_size_write(&vnode->vfs_inode, maybe_i_size);
-		spin_unlock(&vnode->wb_lock);
+		write_sequnlock(&vnode->cb_lock);
 	}
 
 	if (!PageUptodate(page)) {
-- 
2.25.1