[PATCH v2 31/40] afs: Defer volume record destruction to a workqueue

David Howells
2023-12-13T13:51:00Z

Defer volume record destruction to a workqueue so that afs_put_volume()
isn't going to run the destruction process in the callback workqueue whilst
the server is holding up other clients whilst waiting for us to reply to a
CB.CallBack notification RPC.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
---
fs/afs/cell.c | 2 +-
fs/afs/fs_operation.c | 2 +-
fs/afs/internal.h | 3 ++-
fs/afs/super.c | 7 +++----
fs/afs/vl_alias.c | 6 +++---
fs/afs/volume.c | 15 +++++++++------
6 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 69716fc0ee36..6b389f2bcd0c 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -816,7 +816,7 @@ static void afs_manage_cell(struct afs_cell *cell)

final_destruction:
/* The root volume is pinning the cell */
- afs_put_volume(cell->net, cell->root_volume, afs_volume_trace_put_cell_root);
+ afs_put_volume(cell->root_volume, afs_volume_trace_put_cell_root);
cell->root_volume = NULL;
afs_put_cell(cell, afs_cell_trace_put_destroy);
}
diff --git a/fs/afs/fs_operation.c b/fs/afs/fs_operation.c
index 8c6d827f999d..10137681aa7d 100644
--- a/fs/afs/fs_operation.c
+++ b/fs/afs/fs_operation.c
@@ -265,7 +265,7 @@ int afs_put_operation(struct afs_operation *op)
}

afs_put_serverlist(op->net, op->server_list);
- afs_put_volume(op->net, op->volume, afs_volume_trace_put_put_op);
+ afs_put_volume(op->volume, afs_volume_trace_put_put_op);
key_put(op->key);
kfree(op);
return ret;
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 0b726bd2cf8c..a50dfb2f8d7d 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -636,6 +636,7 @@ struct afs_volume {
struct rb_node cell_node; /* Link in cell->volumes */
struct hlist_node proc_link; /* Link in cell->proc_volumes */
struct super_block __rcu *sb; /* Superblock on which inodes reside */
+ struct work_struct destructor; /* Deferred destructor */
unsigned long flags;
#define AFS_VOLUME_NEEDS_UPDATE 0 /* - T if an update needs performing */
#define AFS_VOLUME_UPDATING 1 /* - T if an update is in progress */
@@ -1613,7 +1614,7 @@ extern int afs_activate_volume(struct afs_volume *);
extern void afs_deactivate_volume(struct afs_volume *);
bool afs_try_get_volume(struct afs_volume *volume, enum afs_volume_trace reason);
extern struct afs_volume *afs_get_volume(struct afs_volume *, enum afs_volume_trace);
-extern void afs_put_volume(struct afs_net *, struct afs_volume *, enum afs_volume_trace);
+void afs_put_volume(struct afs_volume *volume, enum afs_volume_trace reason);
extern int afs_check_volume_status(struct afs_volume *, struct afs_operation *);

/*
diff --git a/fs/afs/super.c b/fs/afs/super.c
index a01a0fb2cdbb..ae2d66a52add 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -381,8 +381,7 @@ static int afs_validate_fc(struct fs_context *fc)
ctx->key = key;

if (ctx->volume) {
- afs_put_volume(ctx->net, ctx->volume,
- afs_volume_trace_put_validate_fc);
+ afs_put_volume(ctx->volume, afs_volume_trace_put_validate_fc);
ctx->volume = NULL;
}

@@ -529,7 +528,7 @@ static void afs_destroy_sbi(struct afs_super_info *as)
{
if (as) {
struct afs_net *net = afs_net(as->net_ns);
- afs_put_volume(net, as->volume, afs_volume_trace_put_destroy_sbi);
+ afs_put_volume(as->volume, afs_volume_trace_put_destroy_sbi);
afs_unuse_cell(net, as->cell, afs_cell_trace_unuse_sbi);
put_net(as->net_ns);
kfree(as);
@@ -615,7 +614,7 @@ static void afs_free_fc(struct fs_context *fc)
struct afs_fs_context *ctx = fc->fs_private;

afs_destroy_sbi(fc->s_fs_info);
- afs_put_volume(ctx->net, ctx->volume, afs_volume_trace_put_free_fc);
+ afs_put_volume(ctx->volume, afs_volume_trace_put_free_fc);
afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
key_put(ctx->key);
kfree(ctx);
diff --git a/fs/afs/vl_alias.c b/fs/afs/vl_alias.c
index 63e7ed324af9..9f36e14f1c2d 100644
--- a/fs/afs/vl_alias.c
+++ b/fs/afs/vl_alias.c
@@ -156,7 +156,7 @@ static int afs_query_for_alias_one(struct afs_cell *cell, struct key *key,
/* And see if it's in the new cell. */
volume = afs_sample_volume(cell, key, pvol->name, pvol->name_len);
if (IS_ERR(volume)) {
- afs_put_volume(cell->net, pvol, afs_volume_trace_put_query_alias);
+ afs_put_volume(pvol, afs_volume_trace_put_query_alias);
if (PTR_ERR(volume) != -ENOMEDIUM)
return PTR_ERR(volume);
/* That volume is not in the new cell, so not an alias */
@@ -174,8 +174,8 @@ static int afs_query_for_alias_one(struct afs_cell *cell, struct key *key,
rcu_read_unlock();
}

- afs_put_volume(cell->net, volume, afs_volume_trace_put_query_alias);
- afs_put_volume(cell->net, pvol, afs_volume_trace_put_query_alias);
+ afs_put_volume(volume, afs_volume_trace_put_query_alias);
+ afs_put_volume(pvol, afs_volume_trace_put_query_alias);
return ret;
}

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index aefb982dee9a..4982fce25057 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -11,6 +11,8 @@

static unsigned __read_mostly afs_volume_record_life = 60 * 60;

+static void afs_destroy_volume(struct work_struct *work);
+
/*
* Insert a volume into a cell. If there's an existing volume record, that is
* returned instead with a ref held.
@@ -91,6 +93,7 @@ static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,

refcount_set(&volume->ref, 1);
INIT_HLIST_NODE(&volume->proc_link);
+ INIT_WORK(&volume->destructor, afs_destroy_volume);
rwlock_init(&volume->servers_lock);
rwlock_init(&volume->cb_v_break_lock);
memcpy(volume->name, vldb->name, vldb->name_len + 1);
@@ -133,7 +136,7 @@ static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
if (volume == candidate)
afs_attach_volume_to_servers(volume, slist);
else
- afs_put_volume(params->net, candidate, afs_volume_trace_put_cell_dup);
+ afs_put_volume(candidate, afs_volume_trace_put_cell_dup);
return volume;
}

@@ -223,8 +226,9 @@ struct afs_volume *afs_create_volume(struct afs_fs_context *params)
/*
* Destroy a volume record
*/
-static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
+static void afs_destroy_volume(struct work_struct *work)
{
+ struct afs_volume *volume = container_of(work, struct afs_volume, destructor);
struct afs_server_list *slist = rcu_access_pointer(volume->servers);

_enter("%p", volume);
@@ -235,7 +239,7 @@ static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)

afs_detach_volume_from_servers(volume, slist);
afs_remove_volume_from_cell(volume);
- afs_put_serverlist(net, slist);
+ afs_put_serverlist(volume->cell->net, slist);
afs_put_cell(volume->cell, afs_cell_trace_put_vol);
trace_afs_volume(volume->vid, refcount_read(&volume->ref),
afs_volume_trace_free);
@@ -277,8 +281,7 @@ struct afs_volume *afs_get_volume(struct afs_volume *volume,
/*
* Drop a reference on a volume record.
*/
-void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
- enum afs_volume_trace reason)
+void afs_put_volume(struct afs_volume *volume, enum afs_volume_trace reason)
{
if (volume) {
afs_volid_t vid = volume->vid;
@@ -288,7 +291,7 @@ void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
zero = __refcount_dec_and_test(&volume->ref, &r);
trace_afs_volume(vid, r - 1, reason);
if (zero)
- afs_destroy_volume(net, volume);
+ schedule_work(&volume->destructor);
}
}