Commit 764665c6 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Clean up after gfs2_create_inode rework 



Since commit 3d36e57f ("gfs2: gfs2_create_inode rework"),
gfs2_evict_inode() and gfs2_create_inode() / gfs2_inode_lookup() will
synchronize via the inode hash table and we can be certain that once a
new inode is inserted into the inode hash table(), gfs2_evict_inode()
has completely destroyed any previous versions.  We no longer need to
worry about overlapping inode object lifespans.  Update the code and
comments accordingly.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 97236ad5

fs/gfs2/glock.h

+0 −14
Original line number Diff line number Diff line
@@ -322,20 +322,6 @@ static inline void glock_set_object(struct gfs2_glock *gl, void *object) 
/**

 * glock_clear_object - clear the gl_object field of a glock

 * @gl: the glock

 * @object: the object

 *

 * I'd love to similarly add this:

 *	else if (gfs2_assert_warn(gl->gl_sbd, gl->gl_object == object))

 *		gfs2_dump_glock(NULL, gl, true);

 * Unfortunately, that's not possible because as soon as gfs2_delete_inode

 * frees the block in the rgrp, another process can reassign it for an I_NEW

 * inode in gfs2_create_inode because that calls new_inode, not gfs2_iget.

 * That means gfs2_delete_inode may subsequently try to call this function

 * for a glock that's already pointing to a brand new inode. If we clear the

 * new inode's gl_object, we'll introduce metadata corruption. Function

 * gfs2_delete_inode calls clear_inode which calls gfs2_clear_inode which also

 * tries to clear gl_object, so it's more than just gfs2_delete_inode.

 *

 */

static inline void glock_clear_object(struct gfs2_glock *gl, void *object)

{

fs/gfs2/super.c

+14 −7
Original line number Diff line number Diff line
@@ -1304,14 +1304,21 @@ static int evict_unlinked_inode(struct inode *inode) 
			goto out;

	}



	/* We're about to clear the bitmap for the dinode, but as soon as we

	   do, gfs2_create_inode can create another inode at the same block

	   location and try to set gl_object again. We clear gl_object here so

	   that subsequent inode creates don't see an old gl_object. */

	if (ip->i_gl) {

		glock_clear_object(ip->i_gl, ip);

	if (ip->i_gl)

		gfs2_inode_remember_delete(ip->i_gl, ip->i_no_formal_ino);

	}



	/*

	 * As soon as we clear the bitmap for the dinode, gfs2_create_inode()

	 * can get called to recreate it, or even gfs2_inode_lookup() if the

	 * inode was recreated on another node in the meantime.

	 *

	 * However, inserting the new inode into the inode hash table will not

	 * succeed until the old inode is removed, and that only happens after

	 * ->evict_inode() returns.  The new inode is attached to its inode and

	 *  iopen glocks after inserting it into the inode hash table, so at

	 *  that point we can be sure that both glocks are unused.

	 */



	ret = gfs2_dinode_dealloc(ip);

out:

	return ret;