GFS2: Prevent delete work from occurring on glocks used for create

This patch tries to prevent delete work (queued via iopen callback)
from executing if the glock is currently being used to create
a new inode.

Signed-off-by: Bob Peterson <[e-mail]>
Acked-by: Steven Whitehouse <[e-mail]>

fs/gfs2/glock.c

···
 	struct inode *inode;
 	u64 no_addr = gl->gl_name.ln_number;
 
+	/* If someone's using this glock to create a new dinode, the block must
+	   have been freed by another node, then re-used, in which case our
+	   iopen callback is too late after the fact. Ignore it. */
+	if (test_bit(GLF_INODE_CREATING, &gl->gl_flags))
+		goto out;
+
 	ip = gl->gl_object;
 	/* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 
···
 		d_prune_aliases(inode);
 		iput(inode);
 	}
+out:
 	gfs2_glock_put(gl);
 }
 

fs/gfs2/incore.h

···
 	GLF_LRU				= 13,
 	GLF_OBJECT			= 14, /* Used only for tracing */
 	GLF_BLOCKING			= 15,
+	GLF_INODE_CREATING		= 16, /* Inode creation occurring */
 };
 
 struct gfs2_glock {

fs/gfs2/inode.c

···
 	struct inode *inode = NULL;
 	struct gfs2_inode *dip = GFS2_I(dir), *ip;
 	struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
-	struct gfs2_glock *io_gl;
+	struct gfs2_glock *io_gl = NULL;
 	int error, free_vfs_inode = 1;
 	u32 aflags = 0;
 	unsigned blocks = 1;
···
 	if (error)
 		goto fail_gunlock2;
 
+	BUG_ON(test_and_set_bit(GLF_INODE_CREATING, &io_gl->gl_flags));
+
 	error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
 	if (error)
 		goto fail_gunlock2;
···
 	}
 	gfs2_glock_dq_uninit(ghs);
 	gfs2_glock_dq_uninit(ghs + 1);
+	clear_bit(GLF_INODE_CREATING, &io_gl->gl_flags);
 	return error;
 
 fail_gunlock3:
 	gfs2_glock_dq_uninit(&ip->i_iopen_gh);
 	gfs2_glock_put(io_gl);
 fail_gunlock2:
+	if (io_gl)
+		clear_bit(GLF_INODE_CREATING, &io_gl->gl_flags);
 	gfs2_glock_dq_uninit(ghs + 1);
 fail_free_inode:
 	if (ip->i_gl)