Commit dd00aaeb authored by Abhi Das's avatar Abhi Das Committed by Andreas Gruenbacher
Browse files

gfs2: Use GL_NOBLOCK flag for non-blocking lookups 



Add the GL_NOBLOCK flag to the locking requests in gfs2_permission() and
gfs2_drevalidate() when called with the MAY_NOT_BLOCK flag and
LOOKUP_RCU flag, respectively.  This will cause the locking requests to
be handled without sleeping if possible.  We bail out with -ECHILD if we
can't grant the glock immediately.

Make sure not to dget() + dput() the parent dentry in gfs2_drevalidate()
in LOOKUP_RCU mode; dput() is a sleeping operation.

Signed-off-by: default avatarAbhi Das <adas@redhat.com>
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent f9f229c1

fs/gfs2/dentry.c

+14 −9
Original line number Diff line number Diff line
@@ -32,21 +32,25 @@ 


static int gfs2_drevalidate(struct dentry *dentry, unsigned int flags)

{

	struct dentry *parent;

	struct dentry *parent = NULL;

	struct gfs2_sbd *sdp;

	struct gfs2_inode *dip;

	struct inode *inode;

	struct inode *dinode, *inode;

	struct gfs2_holder d_gh;

	struct gfs2_inode *ip = NULL;

	int error, valid = 0;

	int had_lock = 0;



	if (flags & LOOKUP_RCU)

	if (flags & LOOKUP_RCU) {

		dinode = d_inode_rcu(READ_ONCE(dentry->d_parent));

		if (!dinode)

			return -ECHILD;



	} else {

		parent = dget_parent(dentry);

	sdp = GFS2_SB(d_inode(parent));

	dip = GFS2_I(d_inode(parent));

		dinode = d_inode(parent);

	}

	sdp = GFS2_SB(dinode);

	dip = GFS2_I(dinode);

	inode = d_inode(dentry);



	if (inode) {
@@ -62,7 +66,8 @@ static int gfs2_drevalidate(struct dentry *dentry, unsigned int flags) 


	had_lock = (gfs2_glock_is_locked_by_me(dip->i_gl) != NULL);

	if (!had_lock) {

		error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &d_gh);

		error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED,

					   flags & LOOKUP_RCU ? GL_NOBLOCK : 0, &d_gh);

		if (error)

			goto out;

	}

fs/gfs2/inode.c

+4 −4
Original line number Diff line number Diff line
@@ -1882,10 +1882,10 @@ int gfs2_permission(struct mnt_idmap *idmap, struct inode *inode, 
		WARN_ON_ONCE(!may_not_block);

		return -ECHILD;

        }

	if (gfs2_glock_is_locked_by_me(gl) == NULL) {

		if (may_not_block)

			return -ECHILD;

		error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);

	if (gfs2_glock_is_locked_by_me(ip->i_gl) == NULL) {

		int noblock = may_not_block ? GL_NOBLOCK : 0;

		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,

					   LM_FLAG_ANY | noblock, &i_gh);

		if (error)

			return error;

	}