linux-kernel - [PATCH v4 1/4] fs/9p: remove unnecessary and overrestrictive check

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Message-Id: <20230716-fixes-overly-restrictive-mmap-v4-1-a3cd1cd32af2@kernel.org>
Date:   Wed, 19 Jul 2023 16:22:30 +0000
From:   Eric Van Hensbergen <ericvh@...nel.org>
To:     Latchesar Ionkov <lucho@...kov.net>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Christian Schoenebeck <linux_oss@...debyte.com>
Cc:     v9fs@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, stable@...r.kernel.org,
        Robert Schwebel <r.schwebel@...gutronix.de>,
        Eric Van Hensbergen <ericvh@...nel.org>
Subject: [PATCH v4 1/4] fs/9p: remove unnecessary and overrestrictive check

This eliminates a check for shared that was overrestrictive and
prevented read-only mmaps when writeback caches weren't enabled.

Cc: stable@...r.kernel.org
Fixes: 1543b4c5071c ("fs/9p: remove writeback fid and fix per-file modes")
Reported-by: Robert Schwebel <r.schwebel@...gutronix.de>
Closes: https://lore.kernel.org/v9fs/ZK25XZ%2BGpR3KHIB%2F@pengutronix.de
Reviewed-by: Dominique Martinet <asmadeus@...ewreck.org>
Reviewed-by: Christian Schoenebeck <linux_oss@...debyte.com>
Signed-off-by: Eric Van Hensbergen <ericvh@...nel.org>
---
 fs/9p/vfs_file.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 2996fb00387f..9b61b480a9b0 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -505,9 +505,7 @@ v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 	p9_debug(P9_DEBUG_MMAP, "filp :%p\n", filp);
 
 	if (!(v9ses->cache & CACHE_WRITEBACK)) {
-		p9_debug(P9_DEBUG_CACHE, "(no mmap mode)");
-		if (vma->vm_flags & VM_MAYSHARE)
-			return -ENODEV;
+		p9_debug(P9_DEBUG_CACHE, "(read-only mmap mode)");
 		invalidate_inode_pages2(filp->f_mapping);
 		return generic_file_readonly_mmap(filp, vma);
 	}

-- 
2.39.2