From bcba1e7d0d520adba895d9e0800a056f734b0a6a Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 1 Apr 2021 22:03:41 -0400 Subject: take LOOKUP_{ROOT,ROOT_GRABBED,JUMPED} out of LOOKUP_... space Separate field in nameidata (nd->state) holding the flags that should be internal-only - that way we both get some spare bits in LOOKUP_... and get simpler rules for nd->root lifetime rules, since we can set the replacement of LOOKUP_ROOT (ND_ROOT_PRESET) at the same time we set nd->root. Signed-off-by: Al Viro --- fs/namei.c | 54 +++++++++++++++++++++++++++++++----------------------- 1 file changed, 31 insertions(+), 23 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index 4b6cf4974dd7..622b9f15bf1c 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -554,7 +554,7 @@ struct nameidata { struct qstr last; struct path root; struct inode *inode; /* path.dentry.d_inode */ - unsigned int flags; + unsigned int flags, state; unsigned seq, m_seq, r_seq; int last_type; unsigned depth; @@ -573,6 +573,10 @@ struct nameidata { umode_t dir_mode; } __randomize_layout; +#define ND_ROOT_PRESET 1 +#define ND_ROOT_GRABBED 2 +#define ND_JUMPED 4 + static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) { struct nameidata *old = current->nameidata; @@ -583,6 +587,7 @@ static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) p->path.dentry = NULL; p->total_link_count = old ? old->total_link_count : 0; p->saved = old; + p->state = 0; current->nameidata = p; } @@ -645,9 +650,9 @@ static void terminate_walk(struct nameidata *nd) path_put(&nd->path); for (i = 0; i < nd->depth; i++) path_put(&nd->stack[i].link); - if (nd->flags & LOOKUP_ROOT_GRABBED) { + if (nd->state & ND_ROOT_GRABBED) { path_put(&nd->root); - nd->flags &= ~LOOKUP_ROOT_GRABBED; + nd->state &= ~ND_ROOT_GRABBED; } } else { nd->flags &= ~LOOKUP_RCU; @@ -710,9 +715,9 @@ static bool legitimize_root(struct nameidata *nd) if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) return false; /* Nothing to do if nd->root is zero or is managed by the VFS user. */ - if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) + if (!nd->root.mnt || (nd->state & ND_ROOT_PRESET)) return true; - nd->flags |= LOOKUP_ROOT_GRABBED; + nd->state |= ND_ROOT_GRABBED; return legitimize_path(nd, &nd->root, nd->root_seq); } @@ -849,8 +854,9 @@ static int complete_walk(struct nameidata *nd) * We don't want to zero nd->root for scoped-lookups or * externally-managed nd->root. */ - if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) - nd->root.mnt = NULL; + if (!(nd->state & ND_ROOT_PRESET)) + if (!(nd->flags & LOOKUP_IS_SCOPED)) + nd->root.mnt = NULL; nd->flags &= ~LOOKUP_CACHED; if (!try_to_unlazy(nd)) return -ECHILD; @@ -877,7 +883,7 @@ static int complete_walk(struct nameidata *nd) return -EXDEV; } - if (likely(!(nd->flags & LOOKUP_JUMPED))) + if (likely(!(nd->state & ND_JUMPED))) return 0; if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) @@ -915,7 +921,7 @@ static int set_root(struct nameidata *nd) } while (read_seqcount_retry(&fs->seq, seq)); } else { get_fs_root(fs, &nd->root); - nd->flags |= LOOKUP_ROOT_GRABBED; + nd->state |= ND_ROOT_GRABBED; } return 0; } @@ -948,7 +954,7 @@ static int nd_jump_root(struct nameidata *nd) path_get(&nd->path); nd->inode = nd->path.dentry->d_inode; } - nd->flags |= LOOKUP_JUMPED; + nd->state |= ND_JUMPED; return 0; } @@ -976,7 +982,7 @@ int nd_jump_link(struct path *path) path_put(&nd->path); nd->path = *path; nd->inode = nd->path.dentry->d_inode; - nd->flags |= LOOKUP_JUMPED; + nd->state |= ND_JUMPED; return 0; err: @@ -1424,7 +1430,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, if (mounted) { path->mnt = &mounted->mnt; dentry = path->dentry = mounted->mnt.mnt_root; - nd->flags |= LOOKUP_JUMPED; + nd->state |= ND_JUMPED; *seqp = read_seqcount_begin(&dentry->d_seq); *inode = dentry->d_inode; /* @@ -1469,7 +1475,7 @@ static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, if (unlikely(nd->flags & LOOKUP_NO_XDEV)) ret = -EXDEV; else - nd->flags |= LOOKUP_JUMPED; + nd->state |= ND_JUMPED; } if (unlikely(ret)) { dput(path->dentry); @@ -2220,7 +2226,7 @@ static int link_path_walk(const char *name, struct nameidata *nd) case 2: if (name[1] == '.') { type = LAST_DOTDOT; - nd->flags |= LOOKUP_JUMPED; + nd->state |= ND_JUMPED; } break; case 1: @@ -2228,7 +2234,7 @@ static int link_path_walk(const char *name, struct nameidata *nd) } if (likely(type == LAST_NORM)) { struct dentry *parent = nd->path.dentry; - nd->flags &= ~LOOKUP_JUMPED; + nd->state &= ~ND_JUMPED; if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { struct qstr this = { { .hash_len = hash_len }, .name = name }; err = parent->d_op->d_hash(parent, &this); @@ -2302,14 +2308,15 @@ static const char *path_init(struct nameidata *nd, unsigned flags) if (flags & LOOKUP_RCU) rcu_read_lock(); - nd->flags = flags | LOOKUP_JUMPED; + nd->flags = flags; + nd->state |= ND_JUMPED; nd->depth = 0; nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); smp_rmb(); - if (flags & LOOKUP_ROOT) { + if (nd->state & ND_ROOT_PRESET) { struct dentry *root = nd->root.dentry; struct inode *inode = root->d_inode; if (*s && unlikely(!d_can_lookup(root))) @@ -2384,7 +2391,7 @@ static const char *path_init(struct nameidata *nd, unsigned flags) nd->root_seq = nd->seq; } else { path_get(&nd->root); - nd->flags |= LOOKUP_ROOT_GRABBED; + nd->state |= ND_ROOT_GRABBED; } } return s; @@ -2423,7 +2430,7 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path ; if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { err = handle_lookup_down(nd); - nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... + nd->state &= ~ND_JUMPED; // no d_weak_revalidate(), please... } if (!err) err = complete_walk(nd); @@ -2447,11 +2454,11 @@ int filename_lookup(int dfd, struct filename *name, unsigned flags, struct nameidata nd; if (IS_ERR(name)) return PTR_ERR(name); + set_nameidata(&nd, dfd, name); if (unlikely(root)) { nd.root = *root; - flags |= LOOKUP_ROOT; + nd.state = ND_ROOT_PRESET; } - set_nameidata(&nd, dfd, name); retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); if (unlikely(retval == -ECHILD)) retval = path_lookupat(&nd, flags, path); @@ -3539,7 +3546,7 @@ struct file *do_file_open_root(const struct path *root, struct nameidata nd; struct file *file; struct filename *filename; - int flags = op->lookup_flags | LOOKUP_ROOT; + int flags = op->lookup_flags; if (d_is_symlink(root->dentry) && op->intent & LOOKUP_OPEN) return ERR_PTR(-ELOOP); @@ -3548,8 +3555,9 @@ struct file *do_file_open_root(const struct path *root, if (IS_ERR(filename)) return ERR_CAST(filename); - nd.root = *root; set_nameidata(&nd, -1, filename); + nd.root = *root; + nd.state = ND_ROOT_PRESET; file = path_openat(&nd, op, flags | LOOKUP_RCU); if (unlikely(file == ERR_PTR(-ECHILD))) file = path_openat(&nd, op, flags); -- cgit