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-rw-r--r--fs/devpts/inode.c188
1 files changed, 46 insertions, 142 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index bff4052..63a4a59 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -322,177 +322,81 @@ static int compare_init_pts_sb(struct super_block *s, void *p)
}
/*
- * Safely parse the mount options in @data and update @opts.
+ * devpts_get_sb()
*
- * devpts ends up parsing options two times during mount, due to the
- * two modes of operation it supports. The first parse occurs in
- * devpts_get_sb() when determining the mode (single-instance or
- * multi-instance mode). The second parse happens in devpts_remount()
- * or new_pts_mount() depending on the mode.
+ * If the '-o newinstance' mount option was specified, mount a new
+ * (private) instance of devpts. PTYs created in this instance are
+ * independent of the PTYs in other devpts instances.
*
- * Parsing of options modifies the @data making subsequent parsing
- * incorrect. So make a local copy of @data and parse it.
+ * If the '-o newinstance' option was not specified, mount/remount the
+ * initial kernel mount of devpts. This type of mount gives the
+ * legacy, single-instance semantics.
*
- * Return: 0 On success, -errno on error
- */
-static int safe_parse_mount_options(void *data, struct pts_mount_opts *opts)
-{
- int rc;
- void *datacp;
-
- if (!data)
- return 0;
-
- /* Use kstrdup() ? */
- datacp = kmalloc(PAGE_SIZE, GFP_KERNEL);
- if (!datacp)
- return -ENOMEM;
-
- memcpy(datacp, data, PAGE_SIZE);
- rc = parse_mount_options((char *)datacp, PARSE_MOUNT, opts);
- kfree(datacp);
-
- return rc;
-}
-
-/*
- * Mount a new (private) instance of devpts. PTYs created in this
- * instance are independent of the PTYs in other devpts instances.
- */
-static int new_pts_mount(struct file_system_type *fs_type, int flags,
- void *data, struct vfsmount *mnt)
-{
- int err;
- struct pts_fs_info *fsi;
- struct pts_mount_opts *opts;
-
- err = get_sb_nodev(fs_type, flags, data, devpts_fill_super, mnt);
- if (err)
- return err;
-
- fsi = DEVPTS_SB(mnt->mnt_sb);
- opts = &fsi->mount_opts;
-
- err = parse_mount_options(data, PARSE_MOUNT, opts);
- if (err)
- goto fail;
-
- err = mknod_ptmx(mnt->mnt_sb);
- if (err)
- goto fail;
-
- return 0;
-
-fail:
- dput(mnt->mnt_sb->s_root);
- deactivate_super(mnt->mnt_sb);
- return err;
-}
-
-/*
- * Check if 'newinstance' mount option was specified in @data.
+ * The 'newinstance' option is needed to support multiple namespace
+ * semantics in devpts while preserving backward compatibility of the
+ * current 'single-namespace' semantics. i.e all mounts of devpts
+ * without the 'newinstance' mount option should bind to the initial
+ * kernel mount, like get_sb_single().
*
- * Return: -errno on error (eg: invalid mount options specified)
- * : 1 if 'newinstance' mount option was specified
- * : 0 if 'newinstance' mount option was NOT specified
- */
-static int is_new_instance_mount(void *data)
-{
- int rc;
- struct pts_mount_opts opts;
-
- if (!data)
- return 0;
-
- rc = safe_parse_mount_options(data, &opts);
- if (!rc)
- rc = opts.newinstance;
-
- return rc;
-}
-
-/*
- * get_init_pts_sb()
- *
- * This interface is needed to support multiple namespace semantics in
- * devpts while preserving backward compatibility of the current 'single-
- * namespace' semantics. i.e all mounts of devpts without the 'newinstance'
- * mount option should bind to the initial kernel mount, like
- * get_sb_single().
+ * Mounts with 'newinstance' option create a new, private namespace.
*
- * Mounts with 'newinstance' option create a new private namespace.
+ * NOTE:
*
- * But for single-mount semantics, devpts cannot use get_sb_single(),
+ * For single-mount semantics, devpts cannot use get_sb_single(),
* because get_sb_single()/sget() find and use the super-block from
* the most recent mount of devpts. But that recent mount may be a
* 'newinstance' mount and get_sb_single() would pick the newinstance
* super-block instead of the initial super-block.
- *
- * This interface is identical to get_sb_single() except that it
- * consistently selects the 'single-namespace' superblock even in the
- * presence of the private namespace (i.e 'newinstance') super-blocks.
*/
-static int get_init_pts_sb(struct file_system_type *fs_type, int flags,
- void *data, struct vfsmount *mnt)
+static int devpts_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
- struct super_block *s;
int error;
+ struct pts_mount_opts opts;
+ struct super_block *s;
+
+ memset(&opts, 0, sizeof(opts));
+ if (data) {
+ error = parse_mount_options(data, PARSE_MOUNT, &opts);
+ if (error)
+ return error;
+ }
+
+ if (opts.newinstance)
+ s = sget(fs_type, NULL, set_anon_super, NULL);
+ else
+ s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL);
- s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL);
if (IS_ERR(s))
return PTR_ERR(s);
if (!s->s_root) {
s->s_flags = flags;
error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
- if (error) {
- up_write(&s->s_umount);
- deactivate_super(s);
- return error;
- }
+ if (error)
+ goto out_undo_sget;
s->s_flags |= MS_ACTIVE;
}
- do_remount_sb(s, flags, data, 0);
- return simple_set_mnt(mnt, s);
-}
-/*
- * Mount or remount the initial kernel mount of devpts. This type of
- * mount maintains the legacy, single-instance semantics, while the
- * kernel still allows multiple-instances.
- */
-static int init_pts_mount(struct file_system_type *fs_type, int flags,
- void *data, struct vfsmount *mnt)
-{
- int err;
+ simple_set_mnt(mnt, s);
- err = get_init_pts_sb(fs_type, flags, data, mnt);
- if (err)
- return err;
+ memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
- err = mknod_ptmx(mnt->mnt_sb);
- if (err) {
- dput(mnt->mnt_sb->s_root);
- deactivate_super(mnt->mnt_sb);
- }
+ error = mknod_ptmx(s);
+ if (error)
+ goto out_dput;
- return err;
-}
-
-static int devpts_get_sb(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data, struct vfsmount *mnt)
-{
- int new;
-
- new = is_new_instance_mount(data);
- if (new < 0)
- return new;
+ return 0;
- if (new)
- return new_pts_mount(fs_type, flags, data, mnt);
+out_dput:
+ dput(s->s_root);
- return init_pts_mount(fs_type, flags, data, mnt);
+out_undo_sget:
+ up_write(&s->s_umount);
+ deactivate_super(s);
+ return error;
}
+
#else
/*
* This supports only the legacy single-instance semantics (no
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