Commit bd7c4b50 authored by Al Viro's avatar Al Viro
Browse files

handle_mounts(): start building a sane wrapper for follow_managed() 



All callers of follow_managed() follow it on success with the same steps -
d_backing_inode(path->dentry) is calculated and stored into some struct inode *
variable and, in all but one case, an unsigned variable (nd->seq to be) is
zeroed.  The single exception is lookup_fast() and there zeroing is correct
thing to do - not doing it is a pointless microoptimization.

	Add a wrapper for follow_managed() that would do that combination.
It's mostly a vehicle for code massage - it will be changing quite a bit,
and the current calling conventions are by no means final.  Right now it
takes path, nameidata and (as out params) inode and seq, similar to
__follow_mount_rcu().  Which will soon get folded into it...

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 31d1726d

fs/namei.c

+16 −16
Original line number Diff line number Diff line
@@ -1385,6 +1385,18 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 
		!(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);

}



static inline int handle_mounts(struct path *path, struct nameidata *nd,

			  struct inode **inode, unsigned int *seqp)

{

	int ret = follow_managed(path, nd);



	if (likely(ret >= 0)) {

		*inode = d_backing_inode(path->dentry);

		*seqp = 0; /* out of RCU mode, so the value doesn't matter */

	}

	return ret;

}



static int follow_dotdot_rcu(struct nameidata *nd)

{

	struct inode *inode = nd->inode;
@@ -1607,7 +1619,6 @@ static int lookup_fast(struct nameidata *nd, 
	struct vfsmount *mnt = nd->path.mnt;

	struct dentry *dentry, *parent = nd->path.dentry;

	int status = 1;

	int err;



	/*

	 * Rename seqlock is not required here because in the off chance
@@ -1677,10 +1688,7 @@ static int lookup_fast(struct nameidata *nd, 


	path->mnt = mnt;

	path->dentry = dentry;

	err = follow_managed(path, nd);

	if (likely(err > 0))

		*inode = d_backing_inode(path->dentry);

	return err;

	return handle_mounts(path, nd, inode, seqp);

}



/* Fast lookup failed, do it the slow way */
@@ -1875,12 +1883,9 @@ static int walk_component(struct nameidata *nd, int flags) 
			return PTR_ERR(path.dentry);



		path.mnt = nd->path.mnt;

		err = follow_managed(&path, nd);

		err = handle_mounts(&path, nd, &inode, &seq);

		if (unlikely(err < 0))

			return err;



		seq = 0;	/* we are already out of RCU mode */

		inode = d_backing_inode(path.dentry);

	}



	return step_into(nd, &path, flags, inode, seq);
@@ -2365,11 +2370,9 @@ static int handle_lookup_down(struct nameidata *nd) 
			return -ECHILD;

	} else {

		dget(path.dentry);

		err = follow_managed(&path, nd);

		err = handle_mounts(&path, nd, &inode, &seq);

		if (unlikely(err < 0))

			return err;

		inode = d_backing_inode(path.dentry);

		seq = 0;

	}

	path_to_nameidata(&path, nd);

	nd->inode = inode;
@@ -3392,12 +3395,9 @@ static int do_last(struct nameidata *nd, 
		got_write = false;

	}



	error = follow_managed(&path, nd);

	error = handle_mounts(&path, nd, &inode, &seq);

	if (unlikely(error < 0))

		return error;



	seq = 0;	/* out of RCU mode, so the value doesn't matter */

	inode = d_backing_inode(path.dentry);

finish_lookup:

	error = step_into(nd, &path, 0, inode, seq);

	if (unlikely(error))