From 697f514df10b0f46bcd7596c1be18b7e2e9b28bb Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 21 May 2012 17:30:05 +0200 Subject: [PATCH] vfs: split do_lookup() Split do_lookup() into two functions: lookup_fast() - does cached lookup without i_mutex lookup_slow() - does lookup with i_mutex Both follow managed dentries. The new functions are needed by atomic_open. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/namei.c | 59 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 45 insertions(+), 14 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 93ac9323b1f7..7f4ab820811a 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1125,8 +1125,8 @@ static struct dentry *__lookup_hash(struct qstr *name, * small and for now I'd prefer to have fast path as straight as possible. * It _is_ time-critical. */ -static int do_lookup(struct nameidata *nd, struct qstr *name, - struct path *path, struct inode **inode) +static int lookup_fast(struct nameidata *nd, struct qstr *name, + struct path *path, struct inode **inode) { struct vfsmount *mnt = nd->path.mnt; struct dentry *dentry, *parent = nd->path.dentry; @@ -1208,7 +1208,7 @@ unlazy: goto need_lookup; } } -done: + path->mnt = mnt; path->dentry = dentry; err = follow_managed(path, nd->flags); @@ -1222,6 +1222,17 @@ done: return 0; need_lookup: + return 1; +} + +/* Fast lookup failed, do it the slow way */ +static int lookup_slow(struct nameidata *nd, struct qstr *name, + struct path *path) +{ + struct dentry *dentry, *parent; + int err; + + parent = nd->path.dentry; BUG_ON(nd->inode != parent->d_inode); mutex_lock(&parent->d_inode->i_mutex); @@ -1229,7 +1240,16 @@ need_lookup: mutex_unlock(&parent->d_inode->i_mutex); if (IS_ERR(dentry)) return PTR_ERR(dentry); - goto done; + path->mnt = nd->path.mnt; + path->dentry = dentry; + err = follow_managed(path, nd->flags); + if (unlikely(err < 0)) { + path_put_conditional(path, nd); + return err; + } + if (err) + nd->flags |= LOOKUP_JUMPED; + return 0; } static inline int may_lookup(struct nameidata *nd) @@ -1301,21 +1321,26 @@ static inline int walk_component(struct nameidata *nd, struct path *path, */ if (unlikely(type != LAST_NORM)) return handle_dots(nd, type); - err = do_lookup(nd, name, path, &inode); + err = lookup_fast(nd, name, path, &inode); if (unlikely(err)) { - terminate_walk(nd); - return err; - } - if (!inode) { - path_to_nameidata(path, nd); - terminate_walk(nd); - return -ENOENT; + if (err < 0) + goto out_err; + + err = lookup_slow(nd, name, path); + if (err < 0) + goto out_err; + + inode = path->dentry->d_inode; } + err = -ENOENT; + if (!inode) + goto out_path_put; + if (should_follow_link(inode, follow)) { if (nd->flags & LOOKUP_RCU) { if (unlikely(unlazy_walk(nd, path->dentry))) { - terminate_walk(nd); - return -ECHILD; + err = -ECHILD; + goto out_err; } } BUG_ON(inode != path->dentry->d_inode); @@ -1324,6 +1349,12 @@ static inline int walk_component(struct nameidata *nd, struct path *path, path_to_nameidata(path, nd); nd->inode = inode; return 0; + +out_path_put: + path_to_nameidata(path, nd); +out_err: + terminate_walk(nd); + return err; } /* -- 2.20.1