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gfs2: gl_object races fix 

Function glock_clear_object() checks if the specified glock is still
pointing at the right object and clears the gl_object pointer.  To
handle the case of incompletely constructed inodes, glock_clear_object()
also allows gl_object to be NULL.

However, in the teardown case, when iget_failed() is called and the
inode is removed from the inode hash, by the time we get to the
glock_clear_object() calls in gfs2_put_super() and its helpers, we don't
have exclusion against concurrent gfs2_inode_lookup() and
gfs2_create_inode() calls, and the inode and iopen glocks may already be
pointing at another inode, so the checks in glock_clear_object() are
incorrect.

To better handle this case, always completely disassociate an inode from
its glocks before tearing it down.  In addition, get rid of a duplicate
glock_clear_object() call in gfs2_evict_inode().  That way,
glock_clear_object() will only ever be called when the glock points at
the current inode, and the NULL check in glock_clear_object() can be
removed.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2023-01-23 18:58:27 +01:00
parent 63510d9f2f
commit 9ffa18884c
3 changed files with 11 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/gfs2/glock.c
View File

@ -883,6 +883,7 @@ 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: object the glock currently points at
*/
void glock_clear_object(struct gfs2_glock *gl, void *object)
{
@ -892,8 +893,7 @@ void glock_clear_object(struct gfs2_glock *gl, void *object)
prev_object = gl->gl_object;
gl->gl_object = NULL;
spin_unlock(&gl->gl_lockref.lock);
if (gfs2_assert_warn(gl->gl_name.ln_sbd,
prev_object == object || prev_object == NULL)) {
if (gfs2_assert_warn(gl->gl_name.ln_sbd, prev_object == object)) {
pr_warn("glock=%u/%llx\n",
gl->gl_name.ln_type,
(unsigned long long)gl->gl_name.ln_number);

8
fs/gfs2/inode.c
View File

@ -225,6 +225,10 @@ fail:
gfs2_glock_dq_uninit(&ip->i_iopen_gh);
if (gfs2_holder_initialized(&i_gh))
gfs2_glock_dq_uninit(&i_gh);
if (ip->i_gl) {
gfs2_glock_put(ip->i_gl);
ip->i_gl = NULL;
}
iget_failed(inode);
return ERR_PTR(error);
}
@ -816,6 +820,10 @@ fail_gunlock3:
fail_gunlock2:
gfs2_glock_put(io_gl);
fail_free_inode:
if (ip->i_gl) {
gfs2_glock_put(ip->i_gl);
ip->i_gl = NULL;
}
gfs2_rs_deltree(&ip->i_res);
gfs2_qa_put(ip);
fail_free_acls:

4
fs/gfs2/super.c
View File

@ -1401,10 +1401,8 @@ static void gfs2_evict_inode(struct inode *inode)
if (gfs2_rs_active(&ip->i_res))
gfs2_rs_deltree(&ip->i_res);
if (gfs2_holder_initialized(&gh)) {
glock_clear_object(ip->i_gl, ip);
if (gfs2_holder_initialized(&gh))
gfs2_glock_dq_uninit(&gh);
}
if (ret && ret != GLR_TRYFAILED && ret != -EROFS)
fs_warn(sdp, "gfs2_evict_inode: %d\n", ret);
out: