Serge E. Hallyn wrote: > Quoting Pavel Emelyanov (xemul@xxxxxxxxxx): >> sukadev@xxxxxxxxxx wrote: >>> From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx> >>> Subject: [RFC][PATCH 3/4]: Enable multiple mounts of /dev/pts >>> >>> To support multiple PTY namespaces, we should be allow multiple mounts of >>> /dev/pts, once within each PTY namespace. >>> >>> This patch removes the get_sb_single() in devpts_get_sb() and uses test and >>> set sb interfaces to allow remounting /dev/pts. The patch also removes the >>> globals, 'devpts_root' and uses current_pts_mnt() to access 'devpts_mnt' >>> >>> Changelog: >>> - Version 0: Based on earlier versions from Serge Hallyn and >>> Matt Helsley. >>> >>> Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx> >>> --- >>> fs/devpts/inode.c | 120 +++++++++++++++++++++++++++++++++++++++++++++--------- >>> 1 file changed, 101 insertions(+), 19 deletions(-) >>> >>> Index: linux-2.6.24/fs/devpts/inode.c >>> =================================================================== >>> --- linux-2.6.24.orig/fs/devpts/inode.c 2008-02-05 17:30:52.000000000 -0800 >>> +++ linux-2.6.24/fs/devpts/inode.c 2008-02-05 19:16:39.000000000 -0800 >>> @@ -34,7 +34,10 @@ static inline struct idr *current_pts_ns >>> } >>> >>> static struct vfsmount *devpts_mnt; >>> -static struct dentry *devpts_root; >>> +static inline struct vfsmount *current_pts_ns_mnt(void) >>> +{ >>> + return devpts_mnt; >>> +} >>> >>> static struct { >>> int setuid; >>> @@ -130,7 +133,7 @@ devpts_fill_super(struct super_block *s, >>> inode->i_fop = &simple_dir_operations; >>> inode->i_nlink = 2; >>> >>> - devpts_root = s->s_root = d_alloc_root(inode); >>> + s->s_root = d_alloc_root(inode); >>> if (s->s_root) >>> return 0; >>> >>> @@ -140,10 +143,53 @@ fail: >>> return -ENOMEM; >>> } >>> >>> +/* >>> + * We use test and set super-block operations to help determine whether we >>> + * need a new super-block for this namespace. get_sb() walks the list of >>> + * existing devpts supers, comparing them with the @data ptr. Since we >>> + * passed 'current's namespace as the @data pointer we can compare the >>> + * namespace pointer in the super-block's 's_fs_info'. If the test is >>> + * TRUE then get_sb() returns a new active reference to the super block. >>> + * Otherwise, it helps us build an active reference to a new one. >>> + */ >>> + >>> +static int devpts_test_sb(struct super_block *sb, void *data) >>> +{ >>> + return sb->s_fs_info == data; >>> +} >>> + >>> +static int devpts_set_sb(struct super_block *sb, void *data) >>> +{ >>> + sb->s_fs_info = data; >>> + return set_anon_super(sb, NULL); >>> +} >>> + >>> static int devpts_get_sb(struct file_system_type *fs_type, >>> int flags, const char *dev_name, void *data, struct vfsmount *mnt) >>> { >>> - return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); >>> + struct super_block *sb; >>> + int err; >>> + >>> + /* hereafter we're very simlar to get_sb_nodev */ >>> + sb = sget(fs_type, devpts_test_sb, devpts_set_sb, data); >>> + if (IS_ERR(sb)) >>> + return PTR_ERR(sb); >>> + >>> + if (sb->s_root) >>> + return simple_set_mnt(mnt, sb); >>> + >>> + sb->s_flags = flags; >>> + err = devpts_fill_super(sb, data, flags & MS_SILENT ? 1 : 0); >>> + if (err) { >>> + up_write(&sb->s_umount); >>> + deactivate_super(sb); >>> + return err; >>> + } >>> + >> That stuff becomes very very similar to that in proc :) >> Makes sense to consolidate. Maybe... > > Yeah, and the mqns that Cedric sent too. I think Cedric said he'd > started an a patch implementing a helper. Cedric? yes. it's basically a get_sb_single_per_ns() routine using ->s_fs_info to distinguish the ns but there seems to be more to do to support correctly namespaces using internal filesystems (circular ref) C. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers