linux-kernel - [V9fs-developer][PATCH v2] 9p: create writeback fid on shared writable mmap

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Message-ID: <20201207143329.32730-1-cgxu519@mykernel.net>
Date:   Mon,  7 Dec 2020 22:33:29 +0800
From:   Chengguang Xu <cgxu519@...ernel.net>
To:     ericvh@...il.com, lucho@...kov.net, asmadeus@...ewreck.org
Cc:     v9fs-developer@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        Chengguang Xu <cgxu519@...ernel.net>
Subject: [V9fs-developer][PATCH v2] 9p: create writeback fid on shared writable mmap

If vma is shared and the file was opened for writing,
we should also create writeback fid because vma may be
mprotected writable even if now readonly.

Signed-off-by: Chengguang Xu <cgxu519@...ernel.net>
---
 fs/9p/vfs_file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index b177fd3b1eb3..e4256dbcb754 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -517,7 +517,7 @@ v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma)
 	mutex_lock(&v9inode->v_mutex);
 	if (!v9inode->writeback_fid &&
 	    (vma->vm_flags & VM_SHARED) &&
-	    (vma->vm_flags & VM_WRITE)) {
+	    (vma->vm_flags & VM_MAYWRITE)) {
 		/*
 		 * clone a fid and add it to writeback_fid
 		 * we do it during mmap instead of
-- 
2.26.2