[RFC][PATCH v4 46/69] move handle_dots(), follow_dotdot() and follow_dotdot_rcu() past step_into()

[Al Viro]

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

pure move; we are going to have step_into() called by that bunch.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
 fs/namei.c | 260 ++++++++++++++++++++++++++++++-------------------------------
 1 file changed, 130 insertions(+), 130 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 577dc541a4d4..3ee3b8719505 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1363,70 +1363,6 @@ static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
 	return ret;
 }
 
-static int follow_dotdot_rcu(struct nameidata *nd)
-{
-	struct dentry *parent = NULL;
-	struct inode *inode = nd->inode;
-	unsigned seq;
-
-	while (1) {
-		if (path_equal(&nd->path, &nd->root))
-			break;
-		if (nd->path.dentry != nd->path.mnt->mnt_root) {
-			struct dentry *old = nd->path.dentry;
-
-			parent = old->d_parent;
-			inode = parent->d_inode;
-			seq = read_seqcount_begin(&parent->d_seq);
-			if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
-				return -ECHILD;
-			if (unlikely(!path_connected(nd->path.mnt, parent)))
-				return -ECHILD;
-			break;
-		} else {
-			struct mount *mnt = real_mount(nd->path.mnt);
-			struct mount *mparent = mnt->mnt_parent;
-			struct dentry *mountpoint = mnt->mnt_mountpoint;
-			struct inode *inode2 = mountpoint->d_inode;
-			unsigned seq = read_seqcount_begin(&mountpoint->d_seq);
-			if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
-				return -ECHILD;
-			if (&mparent->mnt == nd->path.mnt)
-				break;
-			if (unlikely(nd->flags & LOOKUP_NO_XDEV))
-				return -ECHILD;
-			/* we know that mountpoint was pinned */
-			nd->path.dentry = mountpoint;
-			nd->path.mnt = &mparent->mnt;
-			inode = inode2;
-			nd->seq = seq;
-		}
-	}
-	if (unlikely(!parent)) {
-		if (unlikely(nd->flags & LOOKUP_BENEATH))
-			return -ECHILD;
-	} else {
-		nd->path.dentry = parent;
-		nd->seq = seq;
-	}
-	while (unlikely(d_mountpoint(nd->path.dentry))) {
-		struct mount *mounted;
-		mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
-		if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
-			return -ECHILD;
-		if (!mounted)
-			break;
-		if (unlikely(nd->flags & LOOKUP_NO_XDEV))
-			return -ECHILD;
-		nd->path.mnt = &mounted->mnt;
-		nd->path.dentry = mounted->mnt.mnt_root;
-		inode = nd->path.dentry->d_inode;
-		nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
-	}
-	nd->inode = inode;
-	return 0;
-}
-
 /*
  * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
  */
@@ -1443,38 +1379,6 @@ static void follow_mount(struct path *path)
 	}
 }
 
-static int follow_dotdot(struct nameidata *nd)
-{
-	struct dentry *parent = NULL;
-	while (1) {
-		if (path_equal(&nd->path, &nd->root))
-			break;
-		if (nd->path.dentry != nd->path.mnt->mnt_root) {
-			/* rare case of legitimate dget_parent()... */
-			parent = dget_parent(nd->path.dentry);
-			if (unlikely(!path_connected(nd->path.mnt, parent))) {
-				dput(parent);
-				return -ENOENT;
-			}
-			break;
-		}
-		if (!follow_up(&nd->path))
-			break;
-		if (unlikely(nd->flags & LOOKUP_NO_XDEV))
-			return -EXDEV;
-	}
-	if (unlikely(!parent)) {
-		if (unlikely(nd->flags & LOOKUP_BENEATH))
-			return -EXDEV;
-	} else {
-		dput(nd->path.dentry);
-		nd->path.dentry = parent;
-	}
-	follow_mount(&nd->path);
-	nd->inode = nd->path.dentry->d_inode;
-	return 0;
-}
-
 /*
  * This looks up the name in dcache and possibly revalidates the found dentry.
  * NULL is returned if the dentry does not exist in the cache.
@@ -1654,40 +1558,6 @@ static inline int may_lookup(struct nameidata *nd)
 	return inode_permission(nd->inode, MAY_EXEC);
 }
 
-static inline int handle_dots(struct nameidata *nd, int type)
-{
-	if (type == LAST_DOTDOT) {
-		int error = 0;
-
-		if (!nd->root.mnt) {
-			error = set_root(nd);
-			if (error)
-				return error;
-		}
-		if (nd->flags & LOOKUP_RCU)
-			error = follow_dotdot_rcu(nd);
-		else
-			error = follow_dotdot(nd);
-		if (error)
-			return error;
-
-		if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) {
-			/*
-			 * If there was a racing rename or mount along our
-			 * path, then we can't be sure that ".." hasn't jumped
-			 * above nd->root (and so userspace should retry or use
-			 * some fallback).
-			 */
-			smp_rmb();
-			if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq)))
-				return -EAGAIN;
-			if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq)))
-				return -EAGAIN;
-		}
-	}
-	return 0;
-}
-
 enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
 
 static const char *pick_link(struct nameidata *nd, struct path *link,
@@ -1817,6 +1687,136 @@ static const char *step_into(struct nameidata *nd, int flags,
 	return pick_link(nd, &path, inode, seq, flags);
 }
 
+static int follow_dotdot_rcu(struct nameidata *nd)
+{
+	struct dentry *parent = NULL;
+	struct inode *inode = nd->inode;
+	unsigned seq;
+
+	while (1) {
+		if (path_equal(&nd->path, &nd->root))
+			break;
+		if (nd->path.dentry != nd->path.mnt->mnt_root) {
+			struct dentry *old = nd->path.dentry;
+
+			parent = old->d_parent;
+			inode = parent->d_inode;
+			seq = read_seqcount_begin(&parent->d_seq);
+			if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
+				return -ECHILD;
+			if (unlikely(!path_connected(nd->path.mnt, parent)))
+				return -ECHILD;
+			break;
+		} else {
+			struct mount *mnt = real_mount(nd->path.mnt);
+			struct mount *mparent = mnt->mnt_parent;
+			struct dentry *mountpoint = mnt->mnt_mountpoint;
+			struct inode *inode2 = mountpoint->d_inode;
+			unsigned seq = read_seqcount_begin(&mountpoint->d_seq);
+			if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
+				return -ECHILD;
+			if (&mparent->mnt == nd->path.mnt)
+				break;
+			if (unlikely(nd->flags & LOOKUP_NO_XDEV))
+				return -ECHILD;
+			/* we know that mountpoint was pinned */
+			nd->path.dentry = mountpoint;
+			nd->path.mnt = &mparent->mnt;
+			inode = inode2;
+			nd->seq = seq;
+		}
+	}
+	if (unlikely(!parent)) {
+		if (unlikely(nd->flags & LOOKUP_BENEATH))
+			return -ECHILD;
+	} else {
+		nd->path.dentry = parent;
+		nd->seq = seq;
+	}
+	while (unlikely(d_mountpoint(nd->path.dentry))) {
+		struct mount *mounted;
+		mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
+		if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
+			return -ECHILD;
+		if (!mounted)
+			break;
+		if (unlikely(nd->flags & LOOKUP_NO_XDEV))
+			return -ECHILD;
+		nd->path.mnt = &mounted->mnt;
+		nd->path.dentry = mounted->mnt.mnt_root;
+		inode = nd->path.dentry->d_inode;
+		nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+	}
+	nd->inode = inode;
+	return 0;
+}
+
+static int follow_dotdot(struct nameidata *nd)
+{
+	struct dentry *parent = NULL;
+	while (1) {
+		if (path_equal(&nd->path, &nd->root))
+			break;
+		if (nd->path.dentry != nd->path.mnt->mnt_root) {
+			/* rare case of legitimate dget_parent()... */
+			parent = dget_parent(nd->path.dentry);
+			if (unlikely(!path_connected(nd->path.mnt, parent))) {
+				dput(parent);
+				return -ENOENT;
+			}
+			break;
+		}
+		if (!follow_up(&nd->path))
+			break;
+		if (unlikely(nd->flags & LOOKUP_NO_XDEV))
+			return -EXDEV;
+	}
+	if (unlikely(!parent)) {
+		if (unlikely(nd->flags & LOOKUP_BENEATH))
+			return -EXDEV;
+	} else {
+		dput(nd->path.dentry);
+		nd->path.dentry = parent;
+	}
+	follow_mount(&nd->path);
+	nd->inode = nd->path.dentry->d_inode;
+	return 0;
+}
+
+static inline int handle_dots(struct nameidata *nd, int type)
+{
+	if (type == LAST_DOTDOT) {
+		int error = 0;
+
+		if (!nd->root.mnt) {
+			error = set_root(nd);
+			if (error)
+				return error;
+		}
+		if (nd->flags & LOOKUP_RCU)
+			error = follow_dotdot_rcu(nd);
+		else
+			error = follow_dotdot(nd);
+		if (error)
+			return error;
+
+		if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) {
+			/*
+			 * If there was a racing rename or mount along our
+			 * path, then we can't be sure that ".." hasn't jumped
+			 * above nd->root (and so userspace should retry or use
+			 * some fallback).
+			 */
+			smp_rmb();
+			if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq)))
+				return -EAGAIN;
+			if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq)))
+				return -EAGAIN;
+		}
+	}
+	return 0;
+}
+
 static const char *walk_component(struct nameidata *nd, int flags)
 {
 	struct dentry *dentry;
-- 
2.11.0