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: Abhi Das <adas@redhat.com> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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@ -32,21 +32,25 @@
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static int gfs2_drevalidate(struct dentry *dentry, unsigned int flags)
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static int gfs2_drevalidate(struct dentry *dentry, unsigned int flags)
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{
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{
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struct dentry *parent;
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struct dentry *parent = NULL;
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struct gfs2_sbd *sdp;
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struct gfs2_sbd *sdp;
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struct gfs2_inode *dip;
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struct gfs2_inode *dip;
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struct inode *inode;
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struct inode *dinode, *inode;
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struct gfs2_holder d_gh;
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struct gfs2_holder d_gh;
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struct gfs2_inode *ip = NULL;
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struct gfs2_inode *ip = NULL;
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int error, valid = 0;
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int error, valid = 0;
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int had_lock = 0;
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int had_lock = 0;
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if (flags & LOOKUP_RCU)
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if (flags & LOOKUP_RCU) {
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return -ECHILD;
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dinode = d_inode_rcu(READ_ONCE(dentry->d_parent));
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if (!dinode)
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parent = dget_parent(dentry);
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return -ECHILD;
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sdp = GFS2_SB(d_inode(parent));
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} else {
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dip = GFS2_I(d_inode(parent));
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parent = dget_parent(dentry);
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dinode = d_inode(parent);
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}
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sdp = GFS2_SB(dinode);
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dip = GFS2_I(dinode);
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inode = d_inode(dentry);
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inode = d_inode(dentry);
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if (inode) {
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if (inode) {
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@ -62,7 +66,8 @@ static int gfs2_drevalidate(struct dentry *dentry, unsigned int flags)
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had_lock = (gfs2_glock_is_locked_by_me(dip->i_gl) != NULL);
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had_lock = (gfs2_glock_is_locked_by_me(dip->i_gl) != NULL);
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if (!had_lock) {
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if (!had_lock) {
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error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &d_gh);
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error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED,
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flags & LOOKUP_RCU ? GL_NOBLOCK : 0, &d_gh);
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if (error)
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if (error)
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goto out;
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goto out;
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}
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}
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@ -1882,10 +1882,10 @@ int gfs2_permission(struct mnt_idmap *idmap, struct inode *inode,
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WARN_ON_ONCE(!may_not_block);
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WARN_ON_ONCE(!may_not_block);
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return -ECHILD;
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return -ECHILD;
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}
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}
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if (gfs2_glock_is_locked_by_me(gl) == NULL) {
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if (gfs2_glock_is_locked_by_me(ip->i_gl) == NULL) {
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if (may_not_block)
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int noblock = may_not_block ? GL_NOBLOCK : 0;
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return -ECHILD;
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error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
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error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
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LM_FLAG_ANY | noblock, &i_gh);
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if (error)
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if (error)
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return error;
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return error;
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}
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}
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