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-rw-r--r--fs/devpts/inode.c65
1 files changed, 49 insertions, 16 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 108df2e3602c..7eae33ffa3fc 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -133,6 +133,50 @@ static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
return sb->s_fs_info;
}
+static int devpts_ptmx_path(struct path *path)
+{
+ struct super_block *sb;
+ int err;
+
+ /* Has the devpts filesystem already been found? */
+ if (path->mnt->mnt_sb->s_magic == DEVPTS_SUPER_MAGIC)
+ return 0;
+
+ /* Is a devpts filesystem at "pts" in the same directory? */
+ err = path_pts(path);
+ if (err)
+ return err;
+
+ /* Is the path the root of a devpts filesystem? */
+ sb = path->mnt->mnt_sb;
+ if ((sb->s_magic != DEVPTS_SUPER_MAGIC) ||
+ (path->mnt->mnt_root != sb->s_root))
+ return -ENODEV;
+
+ return 0;
+}
+
+struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi)
+{
+ struct path path;
+ int err;
+
+ path = filp->f_path;
+ path_get(&path);
+
+ err = devpts_ptmx_path(&path);
+ dput(path.dentry);
+ if (err) {
+ mntput(path.mnt);
+ path.mnt = ERR_PTR(err);
+ }
+ if (DEVPTS_SB(path.mnt->mnt_sb) != fsi) {
+ mntput(path.mnt);
+ path.mnt = ERR_PTR(-ENODEV);
+ }
+ return path.mnt;
+}
+
struct pts_fs_info *devpts_acquire(struct file *filp)
{
struct pts_fs_info *result;
@@ -143,27 +187,16 @@ struct pts_fs_info *devpts_acquire(struct file *filp)
path = filp->f_path;
path_get(&path);
- /* Has the devpts filesystem already been found? */
- sb = path.mnt->mnt_sb;
- if (sb->s_magic != DEVPTS_SUPER_MAGIC) {
- /* Is a devpts filesystem at "pts" in the same directory? */
- err = path_pts(&path);
- if (err) {
- result = ERR_PTR(err);
- goto out;
- }
-
- /* Is the path the root of a devpts filesystem? */
- result = ERR_PTR(-ENODEV);
- sb = path.mnt->mnt_sb;
- if ((sb->s_magic != DEVPTS_SUPER_MAGIC) ||
- (path.mnt->mnt_root != sb->s_root))
- goto out;
+ err = devpts_ptmx_path(&path);
+ if (err) {
+ result = ERR_PTR(err);
+ goto out;
}
/*
* pty code needs to hold extra references in case of last /dev/tty close
*/
+ sb = path.mnt->mnt_sb;
atomic_inc(&sb->s_active);
result = DEVPTS_SB(sb);