linux-kernel - [PATCH] vfs: allow O_PATH file descriptors for open_by_handle

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Message-id: <162217903209.27719.15641706922296023647@noble.neil.brown.name>
Date:   Fri, 28 May 2021 15:17:12 +1000
From:   "NeilBrown" <neilb@...e.de>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        James Simmons <jsimmons@...radead.org>
Subject: [PATCH] vfs: allow O_PATH file descriptors for open_by_handle_at()


The purpose of the "mount_fd" arg to open_by_handle_at() is solely to
identify a particular mount.  i.e.  it indicates "a location in the
filesystem tree" which is one of the purposes of O_PATH.

So change fdget() to fdget_raw().

Cc: stable@...r.kernel.org # O_PATH introduced in 3.0+
Signed-off-by: NeilBrown <neilb@...e.de>
---

This seems generally sensible, but will particularly be useful in
preparing the Lustre filesystem for upstream.

 fs/fhandle.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fhandle.c b/fs/fhandle.c
index ec6feeccc276..0020a0afdf86 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -122,7 +122,7 @@ static struct vfsmount *get_vfsmount_from_fd(int fd)
 		mnt = mntget(fs->pwd.mnt);
 		spin_unlock(&fs->lock);
 	} else {
-		struct fd f = fdget(fd);
+		struct fd f = fdget_raw(fd);
 		if (!f.file)
 			return ERR_PTR(-EBADF);
 		mnt = mntget(f.file->f_path.mnt);
-- 
2.31.1