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Subject[RFC][PATCH v4 46/69] move handle_dots(), follow_dotdot() and follow_dotdot_rcu() past step_into()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
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
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