namei: untanlge lookup_fast()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namei.c b/fs/namei.c
index 50020b1..edec6b8 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1512,32 +1512,29 @@
return lookup_real(base->d_inode, dentry, flags);
}
-/*
- * It's more convoluted than I'd like it to be, but... it's still fairly
- * small and for now I'd prefer to have fast path as straight as possible.
- * It _is_ time-critical.
- */
static int lookup_fast(struct nameidata *nd,
struct path *path, struct inode **inode,
unsigned *seqp)
{
struct vfsmount *mnt = nd->path.mnt;
struct dentry *dentry, *parent = nd->path.dentry;
- int need_reval = 1;
int status = 1;
int err;
/*
* Rename seqlock is not required here because in the off chance
- * of a false negative due to a concurrent rename, we're going to
- * do the non-racy lookup, below.
+ * of a false negative due to a concurrent rename, the caller is
+ * going to fall back to non-racy lookup.
*/
if (nd->flags & LOOKUP_RCU) {
unsigned seq;
bool negative;
dentry = __d_lookup_rcu(parent, &nd->last, &seq);
- if (!dentry)
- goto unlazy;
+ if (unlikely(!dentry)) {
+ if (unlazy_walk(nd, NULL, 0))
+ return -ECHILD;
+ return 1;
+ }
/*
* This sequence count validates that the inode matches
@@ -1545,7 +1542,7 @@
*/
*inode = d_backing_inode(dentry);
negative = d_is_negative(dentry);
- if (read_seqcount_retry(&dentry->d_seq, seq))
+ if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
return -ECHILD;
/*
@@ -1555,63 +1552,57 @@
* The memory barrier in read_seqcount_begin of child is
* enough, we can use __read_seqcount_retry here.
*/
- if (__read_seqcount_retry(&parent->d_seq, nd->seq))
+ if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq)))
return -ECHILD;
*seqp = seq;
- if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
status = d_revalidate(dentry, nd->flags);
- if (unlikely(status <= 0)) {
- if (status != -ECHILD)
- need_reval = 0;
- goto unlazy;
- }
+ if (unlikely(status <= 0)) {
+ if (unlazy_walk(nd, dentry, seq))
+ return -ECHILD;
+ if (status == -ECHILD)
+ status = d_revalidate(dentry, nd->flags);
+ } else {
+ /*
+ * Note: do negative dentry check after revalidation in
+ * case that drops it.
+ */
+ if (unlikely(negative))
+ return -ENOENT;
+ path->mnt = mnt;
+ path->dentry = dentry;
+ if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
+ return 0;
+ if (unlazy_walk(nd, dentry, seq))
+ return -ECHILD;
}
- /*
- * Note: do negative dentry check after revalidation in
- * case that drops it.
- */
- if (negative)
- return -ENOENT;
- path->mnt = mnt;
- path->dentry = dentry;
- if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
- return 0;
-unlazy:
- if (unlazy_walk(nd, dentry, seq))
- return -ECHILD;
} else {
dentry = __d_lookup(parent, &nd->last);
+ if (unlikely(!dentry))
+ return 1;
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
+ status = d_revalidate(dentry, nd->flags);
}
-
- if (unlikely(!dentry))
- goto need_lookup;
-
- if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
- status = d_revalidate(dentry, nd->flags);
if (unlikely(status <= 0)) {
- if (status < 0) {
- dput(dentry);
- return status;
+ if (!status) {
+ d_invalidate(dentry);
+ status = 1;
}
- d_invalidate(dentry);
dput(dentry);
- goto need_lookup;
+ return status;
}
-
if (unlikely(d_is_negative(dentry))) {
dput(dentry);
return -ENOENT;
}
+
path->mnt = mnt;
path->dentry = dentry;
err = follow_managed(path, nd);
if (likely(!err))
*inode = d_backing_inode(path->dentry);
return err;
-
-need_lookup:
- return 1;
}
/* Fast lookup failed, do it the slow way */