In fs/namespace.c, we verify whether a path is a mountpoint by
comparing path->dentry and path->mnt->mnt_root. Introduce
path_unmounted() to make code more readable.
Signed-off-by: Yan Hong <clouds.yan@xxxxxxxxx>
---
fs/namespace.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 4d31f73..3fdc239 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1234,6 +1234,11 @@ static int do_umount(struct mount *mnt, int flags)
return retval;
}
+static inline bool path_unmounted(struct path *path)
+{
+ return path->dentry != path->mnt->mnt_root;
+}
+
/*
* Now umount can handle mount points as well as block devices.
* This is important for filesystems which use unnamed block devices.
@@ -1260,7 +1265,7 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
goto out;
mnt = real_mount(path.mnt);
retval = -EINVAL;
- if (path.dentry != path.mnt->mnt_root)
+ if (path_unmounted(&path))
goto dput_and_out;
if (!check_mnt(mnt))
goto dput_and_out;
@@ -1613,7 +1618,7 @@ static int do_change_type(struct path *path, int flag)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (path->dentry != path->mnt->mnt_root)
+ if (path_unmounted(path))
return -EINVAL;
type = flags_to_propagation_type(flag);
@@ -1727,7 +1732,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
if (!check_mnt(mnt))
return -EINVAL;
- if (path->dentry != path->mnt->mnt_root)
+ if (path_unmounted(path))
return -EINVAL;
err = security_sb_remount(sb, data);
@@ -1793,7 +1798,7 @@ static int do_move_mount(struct path *path, char *old_name)
goto out1;
err = -EINVAL;
- if (old_path.dentry != old_path.mnt->mnt_root)
+ if (path_unmounted(&old_path))
goto out1;
if (!mnt_has_parent(old))
@@ -1892,7 +1897,7 @@ static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
/* Refuse the same filesystem on the same mount point */
err = -EBUSY;
if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb &&
- path->mnt->mnt_root == path->dentry)
+ !path_unmounted(path))
goto unlock;
err = -EINVAL;
@@ -2534,11 +2539,11 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
old.mnt == root.mnt)
goto out4; /* loop, on the same file system */
error = -EINVAL;
- if (root.mnt->mnt_root != root.dentry)
+ if (path_unmounted(&root))
goto out4; /* not a mountpoint */
if (!mnt_has_parent(root_mnt))
goto out4; /* not attached */
- if (new.mnt->mnt_root != new.dentry)
+ if (path_unmounted(&new))
goto out4; /* not a mountpoint */
if (!mnt_has_parent(new_mnt))
goto out4; /* not attached */
--
1.7.9.5
--
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