diff mbox series

[1/3] ceph: add some lockdep assertions around snaprealm handling

Message ID 20210603165231.110559-2-jlayton@kernel.org (mailing list archive)
State New, archived
Headers show
Series ceph: locking fixes for snaprealm handling | expand

Commit Message

Jeff Layton June 3, 2021, 4:52 p.m. UTC
Turn some comments into lockdep asserts.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/ceph/snap.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Comments

Ilya Dryomov June 21, 2021, 8:05 p.m. UTC | #1
On Thu, Jun 3, 2021 at 6:52 PM Jeff Layton <jlayton@kernel.org> wrote:
>
> Turn some comments into lockdep asserts.
>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/ceph/snap.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> index 2a63fb37778b..bc6c33d485e6 100644
> --- a/fs/ceph/snap.c
> +++ b/fs/ceph/snap.c
> @@ -65,6 +65,8 @@
>  void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
>                          struct ceph_snap_realm *realm)
>  {
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> +
>         dout("get_realm %p %d -> %d\n", realm,
>              atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
>         /*
> @@ -113,6 +115,8 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
>  {
>         struct ceph_snap_realm *realm;
>
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> +
>         realm = kzalloc(sizeof(*realm), GFP_NOFS);
>         if (!realm)
>                 return ERR_PTR(-ENOMEM);
> @@ -143,6 +147,8 @@ static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
>         struct rb_node *n = mdsc->snap_realms.rb_node;
>         struct ceph_snap_realm *r;
>
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> +
>         while (n) {
>                 r = rb_entry(n, struct ceph_snap_realm, node);
>                 if (ino < r->ino)
> @@ -176,6 +182,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
>  static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
>                                  struct ceph_snap_realm *realm)
>  {
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> +
>         dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
>
>         rb_erase(&realm->node, &mdsc->snap_realms);
> @@ -198,6 +206,8 @@ static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
>  static void __put_snap_realm(struct ceph_mds_client *mdsc,
>                              struct ceph_snap_realm *realm)
>  {
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);

This one appears to be redundant since the only caller is
__destroy_snap_realm().

> +
>         dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
>              atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
>         if (atomic_dec_and_test(&realm->nref))
> @@ -236,6 +246,8 @@ static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
>  {
>         struct ceph_snap_realm *realm;
>
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);

This too since it boils down to calling __destroy_snap_realm().

> +
>         spin_lock(&mdsc->snap_empty_lock);
>         while (!list_empty(&mdsc->snap_empty)) {
>                 realm = list_first_entry(&mdsc->snap_empty,
> @@ -269,6 +281,8 @@ static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
>  {
>         struct ceph_snap_realm *parent;
>
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);

And this since ceph_lookup_snap_realm() is called right away.

> +
>         if (realm->parent_ino == parentino)
>                 return 0;
>
> @@ -696,6 +710,8 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
>         int err = -ENOMEM;
>         LIST_HEAD(dirty_realms);
>
> +       lockdep_assert_held_write(&mdsc->snap_rwsem);

Ditto.

Thanks,

                Ilya
Jeff Layton June 21, 2021, 8:51 p.m. UTC | #2
On Mon, 2021-06-21 at 22:05 +0200, Ilya Dryomov wrote:
> On Thu, Jun 3, 2021 at 6:52 PM Jeff Layton <jlayton@kernel.org> wrote:
> > 
> > Turn some comments into lockdep asserts.
> > 
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > ---
> >  fs/ceph/snap.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> > 
> > diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> > index 2a63fb37778b..bc6c33d485e6 100644
> > --- a/fs/ceph/snap.c
> > +++ b/fs/ceph/snap.c
> > @@ -65,6 +65,8 @@
> >  void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
> >                          struct ceph_snap_realm *realm)
> >  {
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > +
> >         dout("get_realm %p %d -> %d\n", realm,
> >              atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
> >         /*
> > @@ -113,6 +115,8 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
> >  {
> >         struct ceph_snap_realm *realm;
> > 
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > +
> >         realm = kzalloc(sizeof(*realm), GFP_NOFS);
> >         if (!realm)
> >                 return ERR_PTR(-ENOMEM);
> > @@ -143,6 +147,8 @@ static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
> >         struct rb_node *n = mdsc->snap_realms.rb_node;
> >         struct ceph_snap_realm *r;
> > 
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > +
> >         while (n) {
> >                 r = rb_entry(n, struct ceph_snap_realm, node);
> >                 if (ino < r->ino)
> > @@ -176,6 +182,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
> >  static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
> >                                  struct ceph_snap_realm *realm)
> >  {
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > +
> >         dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
> > 
> >         rb_erase(&realm->node, &mdsc->snap_realms);
> > @@ -198,6 +206,8 @@ static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
> >  static void __put_snap_realm(struct ceph_mds_client *mdsc,
> >                              struct ceph_snap_realm *realm)
> >  {
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> 
> This one appears to be redundant since the only caller is
> __destroy_snap_realm().
> 
> > +
> >         dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> >              atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> >         if (atomic_dec_and_test(&realm->nref))
> > @@ -236,6 +246,8 @@ static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
> >  {
> >         struct ceph_snap_realm *realm;
> > 
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> 
> This too since it boils down to calling __destroy_snap_realm().
> 
> > +
> >         spin_lock(&mdsc->snap_empty_lock);
> >         while (!list_empty(&mdsc->snap_empty)) {
> >                 realm = list_first_entry(&mdsc->snap_empty,
> > @@ -269,6 +281,8 @@ static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
> >  {
> >         struct ceph_snap_realm *parent;
> > 
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> 
> And this since ceph_lookup_snap_realm() is called right away.
> 
> > +
> >         if (realm->parent_ino == parentino)
> >                 return 0;
> > 
> > @@ -696,6 +710,8 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
> >         int err = -ENOMEM;
> >         LIST_HEAD(dirty_realms);
> > 
> > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> 
> Ditto.
> 
> Thanks,
> 
>                 Ilya

Some of these calls may be redundant, but I'd still like to keep them.

The locking in this code is a mess, and this is the most reliable way
I've found to approach cleaning it up. These all compile out unless
you're running with lockdep enabled anyway.
Ilya Dryomov June 21, 2021, 9:27 p.m. UTC | #3
On Mon, Jun 21, 2021 at 10:51 PM Jeff Layton <jlayton@kernel.org> wrote:
>
> On Mon, 2021-06-21 at 22:05 +0200, Ilya Dryomov wrote:
> > On Thu, Jun 3, 2021 at 6:52 PM Jeff Layton <jlayton@kernel.org> wrote:
> > >
> > > Turn some comments into lockdep asserts.
> > >
> > > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > > ---
> > >  fs/ceph/snap.c | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > >
> > > diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> > > index 2a63fb37778b..bc6c33d485e6 100644
> > > --- a/fs/ceph/snap.c
> > > +++ b/fs/ceph/snap.c
> > > @@ -65,6 +65,8 @@
> > >  void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
> > >                          struct ceph_snap_realm *realm)
> > >  {
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > > +
> > >         dout("get_realm %p %d -> %d\n", realm,
> > >              atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
> > >         /*
> > > @@ -113,6 +115,8 @@ static struct ceph_snap_realm *ceph_create_snap_realm(
> > >  {
> > >         struct ceph_snap_realm *realm;
> > >
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > > +
> > >         realm = kzalloc(sizeof(*realm), GFP_NOFS);
> > >         if (!realm)
> > >                 return ERR_PTR(-ENOMEM);
> > > @@ -143,6 +147,8 @@ static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
> > >         struct rb_node *n = mdsc->snap_realms.rb_node;
> > >         struct ceph_snap_realm *r;
> > >
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > > +
> > >         while (n) {
> > >                 r = rb_entry(n, struct ceph_snap_realm, node);
> > >                 if (ino < r->ino)
> > > @@ -176,6 +182,8 @@ static void __put_snap_realm(struct ceph_mds_client *mdsc,
> > >  static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
> > >                                  struct ceph_snap_realm *realm)
> > >  {
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> > > +
> > >         dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
> > >
> > >         rb_erase(&realm->node, &mdsc->snap_realms);
> > > @@ -198,6 +206,8 @@ static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
> > >  static void __put_snap_realm(struct ceph_mds_client *mdsc,
> > >                              struct ceph_snap_realm *realm)
> > >  {
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> >
> > This one appears to be redundant since the only caller is
> > __destroy_snap_realm().
> >
> > > +
> > >         dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
> > >              atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
> > >         if (atomic_dec_and_test(&realm->nref))
> > > @@ -236,6 +246,8 @@ static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
> > >  {
> > >         struct ceph_snap_realm *realm;
> > >
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> >
> > This too since it boils down to calling __destroy_snap_realm().
> >
> > > +
> > >         spin_lock(&mdsc->snap_empty_lock);
> > >         while (!list_empty(&mdsc->snap_empty)) {
> > >                 realm = list_first_entry(&mdsc->snap_empty,
> > > @@ -269,6 +281,8 @@ static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
> > >  {
> > >         struct ceph_snap_realm *parent;
> > >
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> >
> > And this since ceph_lookup_snap_realm() is called right away.
> >
> > > +
> > >         if (realm->parent_ino == parentino)
> > >                 return 0;
> > >
> > > @@ -696,6 +710,8 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
> > >         int err = -ENOMEM;
> > >         LIST_HEAD(dirty_realms);
> > >
> > > +       lockdep_assert_held_write(&mdsc->snap_rwsem);
> >
> > Ditto.
> >
> > Thanks,
> >
> >                 Ilya
>
> Some of these calls may be redundant, but I'd still like to keep them.
>
> The locking in this code is a mess, and this is the most reliable way
> I've found to approach cleaning it up. These all compile out unless
> you're running with lockdep enabled anyway.

Reviewed-by: Ilya Dryomov <idryomov@gmail.com>

Thanks,

                Ilya
diff mbox series

Patch

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 2a63fb37778b..bc6c33d485e6 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -65,6 +65,8 @@ 
 void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
 			 struct ceph_snap_realm *realm)
 {
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	dout("get_realm %p %d -> %d\n", realm,
 	     atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
 	/*
@@ -113,6 +115,8 @@  static struct ceph_snap_realm *ceph_create_snap_realm(
 {
 	struct ceph_snap_realm *realm;
 
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	realm = kzalloc(sizeof(*realm), GFP_NOFS);
 	if (!realm)
 		return ERR_PTR(-ENOMEM);
@@ -143,6 +147,8 @@  static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
 	struct rb_node *n = mdsc->snap_realms.rb_node;
 	struct ceph_snap_realm *r;
 
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	while (n) {
 		r = rb_entry(n, struct ceph_snap_realm, node);
 		if (ino < r->ino)
@@ -176,6 +182,8 @@  static void __put_snap_realm(struct ceph_mds_client *mdsc,
 static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
 				 struct ceph_snap_realm *realm)
 {
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	dout("__destroy_snap_realm %p %llx\n", realm, realm->ino);
 
 	rb_erase(&realm->node, &mdsc->snap_realms);
@@ -198,6 +206,8 @@  static void __destroy_snap_realm(struct ceph_mds_client *mdsc,
 static void __put_snap_realm(struct ceph_mds_client *mdsc,
 			     struct ceph_snap_realm *realm)
 {
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	dout("__put_snap_realm %llx %p %d -> %d\n", realm->ino, realm,
 	     atomic_read(&realm->nref), atomic_read(&realm->nref)-1);
 	if (atomic_dec_and_test(&realm->nref))
@@ -236,6 +246,8 @@  static void __cleanup_empty_realms(struct ceph_mds_client *mdsc)
 {
 	struct ceph_snap_realm *realm;
 
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	spin_lock(&mdsc->snap_empty_lock);
 	while (!list_empty(&mdsc->snap_empty)) {
 		realm = list_first_entry(&mdsc->snap_empty,
@@ -269,6 +281,8 @@  static int adjust_snap_realm_parent(struct ceph_mds_client *mdsc,
 {
 	struct ceph_snap_realm *parent;
 
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	if (realm->parent_ino == parentino)
 		return 0;
 
@@ -696,6 +710,8 @@  int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
 	int err = -ENOMEM;
 	LIST_HEAD(dirty_realms);
 
+	lockdep_assert_held_write(&mdsc->snap_rwsem);
+
 	dout("update_snap_trace deletion=%d\n", deletion);
 more:
 	ceph_decode_need(&p, e, sizeof(*ri), bad);