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| -rw-r--r-- | fs/devpts/inode.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 542364bf923e..e072e955ce33 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -152,6 +152,24 @@ static int devpts_ptmx_path(struct path *path) return 0; } +/* + * Try to find a suitable devpts filesystem. We support the following + * scenarios: + * - The ptmx device node is located in the same directory as the devpts + * mount where the pts device nodes are located. + * This is e.g. the case when calling open on the /dev/pts/ptmx device + * node when the devpts filesystem is mounted at /dev/pts. + * - The ptmx device node is located outside the devpts filesystem mount + * where the pts device nodes are located. For example, the ptmx device + * is a symlink, separate device node, or bind-mount. + * A supported scenario is bind-mounting /dev/pts/ptmx to /dev/ptmx and + * then calling open on /dev/ptmx. In this case a suitable pts + * subdirectory can be found in the common parent directory /dev of the + * devpts mount and the ptmx bind-mount, after resolving the /dev/ptmx + * bind-mount. + * If no suitable pts subdirectory can be found this function will fail. + * This is e.g. the case when bind-mounting /dev/pts/ptmx to /ptmx. + */ struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) { struct path path; |