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teach handle_mounts() to handle RCU mode 

... and make the callers of __follow_mount_rcu() use handle_mounts().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-01-09 14:50:18 -05:00
parent b023e1728b
commit c153007b7b
1 changed files with 17 additions and 29 deletions
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46
fs/namei.c
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@ -1393,6 +1393,18 @@ static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
path->mnt = nd->path.mnt;
path->dentry = dentry;
if (nd->flags & LOOKUP_RCU) {
unsigned int seq = *seqp;
if (unlikely(!*inode))
return -ENOENT;
if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
return 1;
if (unlazy_child(nd, dentry, seq))
return -ECHILD;
// *path might've been clobbered by __follow_mount_rcu()
path->mnt = nd->path.mnt;
path->dentry = dentry;
}
ret = follow_managed(path, nd);
if (likely(ret >= 0)) {
*inode = d_backing_inode(path->dentry);
@ -1620,7 +1632,6 @@ 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 status = 1;
@ -1658,21 +1669,8 @@ static int lookup_fast(struct nameidata *nd,
*seqp = seq;
status = d_revalidate(dentry, nd->flags);
if (likely(status > 0)) {
/*
* Note: do negative dentry check after revalidation in
* case that drops it.
*/
if (unlikely(!*inode))
return -ENOENT;
path->mnt = mnt;
path->dentry = dentry;
if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
return 1;
if (unlazy_child(nd, dentry, seq))
return -ECHILD;
if (likely(status > 0))
return handle_mounts(nd, dentry, path, inode, seqp);
}
if (unlazy_child(nd, dentry, seq))
return -ECHILD;
if (unlikely(status == -ECHILD))
@ -2361,21 +2359,11 @@ static int handle_lookup_down(struct nameidata *nd)
unsigned seq = nd->seq;
int err;
if (nd->flags & LOOKUP_RCU) {
/*
* don't bother with unlazy_walk on failure - we are
* at the very beginning of walk, so we lose nothing
* if we simply redo everything in non-RCU mode
*/
path = nd->path;
if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
return -ECHILD;
} else {
if (!(nd->flags & LOOKUP_RCU))
dget(nd->path.dentry);
err = handle_mounts(nd, nd->path.dentry, &path, &inode, &seq);
if (unlikely(err < 0))
return err;
}
err = handle_mounts(nd, nd->path.dentry, &path, &inode, &seq);
if (unlikely(err < 0))
return err;
path_to_nameidata(&path, nd);
nd->inode = inode;
nd->seq = seq;