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fs: kill MNT_ONRB

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Move mnt->mnt_node into the union with mnt->mnt_rcu and mnt->mnt_llist
instead of keeping it with mnt->mnt_list. This allows us to use
RB_CLEAR_NODE(&mnt->mnt_node) in umount_tree() as well as
list_empty(&mnt->mnt_node). That in turn allows us to remove MNT_ONRB.

Link: https://lore.kernel.org/r/20241215-vfs-6-14-mount-work-v1-1-fd55922c4af8@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2024-12-15 21:17:05 +01:00
parent 4a67de4df0
commit 5a4e727d1a
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
3 changed files with 16 additions and 16 deletions
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15
fs/mount.h
View File

@ -42,6 +42,7 @@ struct mount {
struct dentry *mnt_mountpoint;
struct vfsmount mnt;
union {
struct rb_node mnt_node; /* node in the ns->mounts rbtree */
struct rcu_head mnt_rcu;
struct llist_node mnt_llist;
};
@ -55,10 +56,7 @@ struct mount {
struct list_head mnt_child; /* and going through their mnt_child */
struct list_head mnt_instance; /* mount instance on sb->s_mounts */
const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
union {
struct rb_node mnt_node; /* Under ns->mounts */
struct list_head mnt_list;
};
struct list_head mnt_list;
struct list_head mnt_expire; /* link in fs-specific expiry list */
struct list_head mnt_share; /* circular list of shared mounts */
struct list_head mnt_slave_list;/* list of slave mounts */
@ -149,11 +147,16 @@ static inline bool is_anon_ns(struct mnt_namespace *ns)
return ns->seq == 0;
}
static inline bool mnt_ns_attached(const struct mount *mnt)
{
return !RB_EMPTY_NODE(&mnt->mnt_node);
}
static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list)
{
WARN_ON(!(mnt->mnt.mnt_flags & MNT_ONRB));
mnt->mnt.mnt_flags &= ~MNT_ONRB;
WARN_ON(!mnt_ns_attached(mnt));
rb_erase(&mnt->mnt_node, &mnt->mnt_ns->mounts);
RB_CLEAR_NODE(&mnt->mnt_node);
list_add_tail(&mnt->mnt_list, dt_list);
}

14
fs/namespace.c
View File

@ -375,6 +375,7 @@ static struct mount *alloc_vfsmnt(const char *name)
INIT_HLIST_NODE(&mnt->mnt_mp_list);
INIT_LIST_HEAD(&mnt->mnt_umounting);
INIT_HLIST_HEAD(&mnt->mnt_stuck_children);
RB_CLEAR_NODE(&mnt->mnt_node);
mnt->mnt.mnt_idmap = &nop_mnt_idmap;
}
return mnt;
@ -1155,7 +1156,7 @@ static void mnt_add_to_ns(struct mnt_namespace *ns, struct mount *mnt)
struct rb_node **link = &ns->mounts.rb_node;
struct rb_node *parent = NULL;
WARN_ON(mnt->mnt.mnt_flags & MNT_ONRB);
WARN_ON(mnt_ns_attached(mnt));
mnt->mnt_ns = ns;
while (*link) {
parent = *link;
@ -1166,7 +1167,6 @@ static void mnt_add_to_ns(struct mnt_namespace *ns, struct mount *mnt)
}
rb_link_node(&mnt->mnt_node, parent, link);
rb_insert_color(&mnt->mnt_node, &ns->mounts);
mnt->mnt.mnt_flags |= MNT_ONRB;
}
/*
@ -1336,7 +1336,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
}
mnt->mnt.mnt_flags = old->mnt.mnt_flags;
mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL|MNT_ONRB);
mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL);
atomic_inc(&sb->s_active);
mnt->mnt.mnt_idmap = mnt_idmap_get(mnt_idmap(&old->mnt));
@ -1794,7 +1794,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
/* Gather the mounts to umount */
for (p = mnt; p; p = next_mnt(p, mnt)) {
p->mnt.mnt_flags |= MNT_UMOUNT;
if (p->mnt.mnt_flags & MNT_ONRB)
if (mnt_ns_attached(p))
move_from_ns(p, &tmp_list);
else
list_move(&p->mnt_list, &tmp_list);
@ -1943,16 +1943,14 @@ static int do_umount(struct mount *mnt, int flags)
event++;
if (flags & MNT_DETACH) {
if (mnt->mnt.mnt_flags & MNT_ONRB ||
!list_empty(&mnt->mnt_list))
if (mnt_ns_attached(mnt) || !list_empty(&mnt->mnt_list))
umount_tree(mnt, UMOUNT_PROPAGATE);
retval = 0;
} else {
shrink_submounts(mnt);
retval = -EBUSY;
if (!propagate_mount_busy(mnt, 2)) {
if (mnt->mnt.mnt_flags & MNT_ONRB ||
!list_empty(&mnt->mnt_list))
if (mnt_ns_attached(mnt) || !list_empty(&mnt->mnt_list))
umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
retval = 0;
}

3
include/linux/mount.h
View File

@ -50,7 +50,7 @@ struct path;
#define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED | MNT_ONRB)
MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)
#define MNT_INTERNAL 0x4000
@ -64,7 +64,6 @@ struct path;
#define MNT_SYNC_UMOUNT 0x2000000
#define MNT_MARKED 0x4000000
#define MNT_UMOUNT 0x8000000
#define MNT_ONRB 0x10000000
struct vfsmount {
struct dentry *mnt_root; /* root of the mounted tree */