From b2dba1af3c4157040303a76d25216b1713d333d0 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 23 Nov 2011 19:26:23 -0500 Subject: vfs: new internal helper: mnt_has_parent(mnt) vfsmounts have ->mnt_parent pointing either to a different vfsmount or to itself; it's never NULL and termination condition in loops traversing the tree towards root is mnt == mnt->mnt_parent. At least one place (see the next patch) is confused about what's going on; let's add an explicit helper checking it right way and use it in all places where we need it. Not that there had been too many, but... Signed-off-by: Al Viro --- fs/dcache.c | 6 +++--- fs/mount.h | 6 ++++++ fs/namespace.c | 14 +++++++------- fs/pnode.c | 2 +- fs/pnode.h | 2 +- 5 files changed, 18 insertions(+), 12 deletions(-) create mode 100644 fs/mount.h diff --git a/fs/dcache.c b/fs/dcache.c index 89509b5a090e..8a75e3b0f49d 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -38,6 +38,7 @@ #include #include #include "internal.h" +#include "mount.h" /* * Usage: @@ -2460,9 +2461,8 @@ static int prepend_path(const struct path *path, if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { /* Global root? */ - if (vfsmnt->mnt_parent == vfsmnt) { + if (!mnt_has_parent(vfsmnt)) goto global_root; - } dentry = vfsmnt->mnt_mountpoint; vfsmnt = vfsmnt->mnt_parent; continue; @@ -2862,7 +2862,7 @@ int path_is_under(struct path *path1, struct path *path2) br_read_lock(vfsmount_lock); if (mnt != path2->mnt) { for (;;) { - if (mnt->mnt_parent == mnt) { + if (!mnt_has_parent(mnt)) { br_read_unlock(vfsmount_lock); return 0; } diff --git a/fs/mount.h b/fs/mount.h new file mode 100644 index 000000000000..7890e49f74ef --- /dev/null +++ b/fs/mount.h @@ -0,0 +1,6 @@ +#include + +static inline int mnt_has_parent(struct vfsmount *mnt) +{ + return mnt != mnt->mnt_parent; +} diff --git a/fs/namespace.c b/fs/namespace.c index 31d357450f7f..ec8512478b04 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1182,7 +1182,7 @@ void release_mounts(struct list_head *head) while (!list_empty(head)) { mnt = list_first_entry(head, struct vfsmount, mnt_hash); list_del_init(&mnt->mnt_hash); - if (mnt->mnt_parent != mnt) { + if (mnt_has_parent(mnt)) { struct dentry *dentry; struct vfsmount *m; @@ -1222,7 +1222,7 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) p->mnt_ns = NULL; __mnt_make_shortterm(p); list_del_init(&p->mnt_child); - if (p->mnt_parent != p) { + if (mnt_has_parent(p)) { p->mnt_parent->mnt_ghosts++; dentry_reset_mounted(p->mnt_parent, p->mnt_mountpoint); } @@ -1867,7 +1867,7 @@ static int do_move_mount(struct path *path, char *old_name) if (old_path.dentry != old_path.mnt->mnt_root) goto out1; - if (old_path.mnt == old_path.mnt->mnt_parent) + if (!mnt_has_parent(old_path.mnt)) goto out1; if (S_ISDIR(path->dentry->d_inode->i_mode) != @@ -1887,7 +1887,7 @@ static int do_move_mount(struct path *path, char *old_name) tree_contains_unbindable(old_path.mnt)) goto out1; err = -ELOOP; - for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent) + for (p = path->mnt; mnt_has_parent(p); p = p->mnt_parent) if (p == old_path.mnt) goto out1; @@ -2604,17 +2604,17 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, error = -EINVAL; if (root.mnt->mnt_root != root.dentry) goto out4; /* not a mountpoint */ - if (root.mnt->mnt_parent == root.mnt) + if (!mnt_has_parent(root.mnt)) goto out4; /* not attached */ if (new.mnt->mnt_root != new.dentry) goto out4; /* not a mountpoint */ - if (new.mnt->mnt_parent == new.mnt) + if (!mnt_has_parent(new.mnt)) goto out4; /* not attached */ /* make sure we can reach put_old from new_root */ tmp = old.mnt; if (tmp != new.mnt) { for (;;) { - if (tmp->mnt_parent == tmp) + if (!mnt_has_parent(tmp)) goto out4; /* already mounted on put_old */ if (tmp->mnt_parent == new.mnt) break; diff --git a/fs/pnode.c b/fs/pnode.c index d42514e32380..f1cd958b92e5 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -36,7 +36,7 @@ static inline struct vfsmount *next_slave(struct vfsmount *p) static bool is_path_reachable(struct vfsmount *mnt, struct dentry *dentry, const struct path *root) { - while (mnt != root->mnt && mnt->mnt_parent != mnt) { + while (mnt != root->mnt && mnt_has_parent(mnt)) { dentry = mnt->mnt_mountpoint; mnt = mnt->mnt_parent; } diff --git a/fs/pnode.h b/fs/pnode.h index 391287110274..7f0c13ae9484 100644 --- a/fs/pnode.h +++ b/fs/pnode.h @@ -9,7 +9,7 @@ #define _LINUX_PNODE_H #include -#include +#include "mount.h" #define IS_MNT_SHARED(mnt) (mnt->mnt_flags & MNT_SHARED) #define IS_MNT_SLAVE(mnt) (mnt->mnt_master) -- cgit v1.2.3-70-g09d2