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authorKent Overstreet <kent.overstreet@linux.dev>2023-07-12 19:55:03 +0200
committerKent Overstreet <kent.overstreet@linux.dev>2023-10-22 23:10:07 +0200
commit8479938d7a0f6c6cf6362c72880e753b3d7a707a (patch)
tree2fcef58d98c02334138389be77b5177437e30a70 /fs/bcachefs
parentbcachefs: Add a race_fault() for write buffer slowpath (diff)
downloadlinux-8479938d7a0f6c6cf6362c72880e753b3d7a707a.tar.xz
linux-8479938d7a0f6c6cf6362c72880e753b3d7a707a.zip
bcachefs: Convert snapshot table to RCU array
This switches the generic radix tree for the in-memory table of snapshot nodes to a simple rcu array. This means we have to add new locking to deal with reallocations, but is faster than traversing the radix tree. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs')
-rw-r--r--fs/bcachefs/bcachefs.h5
-rw-r--r--fs/bcachefs/btree_update_leaf.c4
-rw-r--r--fs/bcachefs/fsck.c2
-rw-r--r--fs/bcachefs/quota.c2
-rw-r--r--fs/bcachefs/subvolume.c142
-rw-r--r--fs/bcachefs/subvolume.h95
-rw-r--r--fs/bcachefs/subvolume_types.h4
7 files changed, 207 insertions, 47 deletions
diff --git a/fs/bcachefs/bcachefs.h b/fs/bcachefs/bcachefs.h
index d8c020644f54..445d010c83b3 100644
--- a/fs/bcachefs/bcachefs.h
+++ b/fs/bcachefs/bcachefs.h
@@ -774,9 +774,10 @@ struct bch_fs {
struct mutex sb_lock;
/* snapshot.c: */
- GENRADIX(struct snapshot_t) snapshots;
- struct bch_snapshot_table __rcu *snapshot_table;
+ struct snapshot_table __rcu *snapshots;
+ size_t snapshot_table_size;
struct mutex snapshot_table_lock;
+
struct work_struct snapshot_delete_work;
struct work_struct snapshot_wait_for_pagecache_and_delete_work;
snapshot_id_list snapshots_unlinked;
diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_update_leaf.c
index 53219fdcff66..3638cef211b2 100644
--- a/fs/bcachefs/btree_update_leaf.c
+++ b/fs/bcachefs/btree_update_leaf.c
@@ -311,7 +311,7 @@ static inline void btree_insert_entry_checks(struct btree_trans *trans,
!(i->flags & BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) &&
test_bit(JOURNAL_REPLAY_DONE, &trans->c->journal.flags) &&
i->k->k.p.snapshot &&
- bch2_snapshot_internal_node(trans->c, i->k->k.p.snapshot));
+ bch2_snapshot_is_internal_node(trans->c, i->k->k.p.snapshot));
}
static noinline int
@@ -1229,7 +1229,7 @@ static inline int check_pos_snapshot_overwritten(struct btree_trans *trans,
struct bpos pos)
{
if (!btree_type_has_snapshots(id) ||
- !snapshot_t(trans->c, pos.snapshot)->children[0])
+ bch2_snapshot_is_leaf(trans->c, pos.snapshot))
return 0;
return __check_pos_snapshot_overwritten(trans, id, pos);
diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index ddc2782fc5b1..bc769b3e932a 100644
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -894,7 +894,7 @@ static int check_inode(struct btree_trans *trans,
* particular is not atomic, so on the internal snapshot nodes
* we can see inodes marked for deletion after a clean shutdown
*/
- if (bch2_snapshot_internal_node(c, k.k->p.snapshot))
+ if (bch2_snapshot_is_internal_node(c, k.k->p.snapshot))
return 0;
if (!bkey_is_inode(k.k))
diff --git a/fs/bcachefs/quota.c b/fs/bcachefs/quota.c
index d90db3fb823e..4f0654ff816f 100644
--- a/fs/bcachefs/quota.c
+++ b/fs/bcachefs/quota.c
@@ -562,7 +562,7 @@ static int bch2_fs_quota_read_inode(struct btree_trans *trans,
int ret;
ret = bch2_snapshot_tree_lookup(trans,
- snapshot_t(c, k.k->p.snapshot)->tree, &s_t);
+ bch2_snapshot_tree(c, k.k->p.snapshot), &s_t);
bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
"%s: snapshot tree %u not found", __func__,
snapshot_t(c, k.k->p.snapshot)->tree);
diff --git a/fs/bcachefs/subvolume.c b/fs/bcachefs/subvolume.c
index cdaaf49d3b3e..c2c2cfd74e71 100644
--- a/fs/bcachefs/subvolume.c
+++ b/fs/bcachefs/subvolume.c
@@ -12,9 +12,9 @@
static int bch2_subvolume_delete(struct btree_trans *, u32);
-static inline u32 get_ancestor_below(struct bch_fs *c, u32 id, u32 ancestor)
+static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor)
{
- struct snapshot_t *s = snapshot_t(c, id);
+ const struct snapshot_t *s = __snapshot_t(t, id);
if (s->skip[2] <= ancestor)
return s->skip[2];
@@ -27,22 +27,102 @@ static inline u32 get_ancestor_below(struct bch_fs *c, u32 id, u32 ancestor)
bool bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
{
+ struct snapshot_table *t;
+
EBUG_ON(c->curr_recovery_pass <= BCH_RECOVERY_PASS_check_snapshots);
+ rcu_read_lock();
+ t = rcu_dereference(c->snapshots);
+
while (id && id < ancestor)
- id = get_ancestor_below(c, id, ancestor);
+ id = get_ancestor_below(t, id, ancestor);
+ rcu_read_unlock();
return id == ancestor;
}
static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)
{
+ struct snapshot_table *t;
+
+ rcu_read_lock();
+ t = rcu_dereference(c->snapshots);
+
while (id && id < ancestor)
- id = snapshot_t(c, id)->parent;
+ id = __snapshot_t(t, id)->parent;
+ rcu_read_unlock();
return id == ancestor;
}
+static inline u32 bch2_snapshot_depth(struct bch_fs *c, u32 parent)
+{
+ u32 depth;
+
+ rcu_read_lock();
+ depth = parent ? snapshot_t(c, parent)->depth + 1 : 0;
+ rcu_read_unlock();
+
+ return depth;
+}
+
+struct snapshot_t_free_rcu {
+ struct rcu_head rcu;
+ struct snapshot_table *t;
+};
+
+static void snapshot_t_free_rcu(struct rcu_head *rcu)
+{
+ struct snapshot_t_free_rcu *free_rcu =
+ container_of(rcu, struct snapshot_t_free_rcu, rcu);
+
+ kvfree(free_rcu->t);
+ kfree(free_rcu);
+}
+
+static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id)
+{
+ size_t idx = U32_MAX - id;
+ size_t new_size;
+ struct snapshot_table *new, *old;
+
+ new_size = max(16UL, roundup_pow_of_two(idx + 1));
+
+ new = kvzalloc(struct_size(new, s, new_size), GFP_KERNEL);
+ if (!new)
+ return NULL;
+
+ old = rcu_dereference_protected(c->snapshots, true);
+ if (old)
+ memcpy(new->s,
+ rcu_dereference_protected(c->snapshots, true)->s,
+ sizeof(new->s[0]) * c->snapshot_table_size);
+
+ rcu_assign_pointer(c->snapshots, new);
+ c->snapshot_table_size = new_size;
+ if (old) {
+ struct snapshot_t_free_rcu *rcu =
+ kmalloc(sizeof(*rcu), GFP_KERNEL|__GFP_NOFAIL);
+
+ rcu->t = old;
+ call_rcu(&rcu->rcu, snapshot_t_free_rcu);
+ }
+
+ return &rcu_dereference_protected(c->snapshots, true)->s[idx];
+}
+
+static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id)
+{
+ size_t idx = U32_MAX - id;
+
+ lockdep_assert_held(&c->snapshot_table_lock);
+
+ if (likely(idx < c->snapshot_table_size))
+ return &rcu_dereference_protected(c->snapshots, true)->s[idx];
+
+ return __snapshot_t_mut(c, id);
+}
+
/* Snapshot tree: */
void bch2_snapshot_tree_to_text(struct printbuf *out, struct bch_fs *c,
@@ -209,12 +289,15 @@ int bch2_mark_snapshot(struct btree_trans *trans,
{
struct bch_fs *c = trans->c;
struct snapshot_t *t;
+ int ret = 0;
- t = genradix_ptr_alloc(&c->snapshots,
- U32_MAX - new.k->p.offset,
- GFP_KERNEL);
- if (!t)
- return -BCH_ERR_ENOMEM_mark_snapshot;
+ mutex_lock(&c->snapshot_table_lock);
+
+ t = snapshot_t_mut(c, new.k->p.offset);
+ if (!t) {
+ ret = -BCH_ERR_ENOMEM_mark_snapshot;
+ goto err;
+ }
if (new.k->type == KEY_TYPE_snapshot) {
struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new);
@@ -246,8 +329,9 @@ int bch2_mark_snapshot(struct btree_trans *trans,
t->subvol = 0;
t->tree = 0;
}
-
- return 0;
+err:
+ mutex_unlock(&c->snapshot_table_lock);
+ return ret;
}
static int snapshot_lookup(struct btree_trans *trans, u32 id,
@@ -300,9 +384,14 @@ static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)
nr_live += ret;
}
- snapshot_t(c, id)->equiv = nr_live == 1
- ? snapshot_t(c, child[live_idx])->equiv
+ mutex_lock(&c->snapshot_table_lock);
+
+ snapshot_t_mut(c, id)->equiv = nr_live == 1
+ ? snapshot_t_mut(c, child[live_idx])->equiv
: id;
+
+ mutex_unlock(&c->snapshot_table_lock);
+
return 0;
}
@@ -520,16 +609,18 @@ static int snapshot_tree_ptr_good(struct btree_trans *trans,
static u32 snapshot_skiplist_get(struct bch_fs *c, u32 id)
{
- struct snapshot_t *s;
+ const struct snapshot_t *s;
if (!id)
return 0;
+ rcu_read_lock();
s = snapshot_t(c, id);
- if (!s->parent)
- return id;
+ if (s->parent)
+ id = bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth));
+ rcu_read_unlock();
- return bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth));
+ return id;
}
static int snapshot_skiplist_good(struct btree_trans *trans, struct bch_snapshot s)
@@ -633,9 +724,6 @@ static int check_snapshot(struct btree_trans *trans,
struct bkey_i_snapshot *u;
u32 parent_id = bch2_snapshot_parent_early(c, k.k->p.offset);
u32 real_depth;
- struct snapshot_t *parent = parent_id
- ? snapshot_t(c, parent_id)
- : NULL;
struct printbuf buf = PRINTBUF;
bool should_have_subvol;
u32 i, id;
@@ -726,7 +814,7 @@ static int check_snapshot(struct btree_trans *trans,
}
ret = 0;
- real_depth = parent ? parent->depth + 1 : 0;
+ real_depth = bch2_snapshot_depth(c, parent_id);
if (le32_to_cpu(s.depth) != real_depth &&
(c->sb.version_upgrade_complete < bcachefs_metadata_version_snapshot_skiplists ||
@@ -823,9 +911,13 @@ static int check_subvol(struct btree_trans *trans,
if (!BCH_SUBVOLUME_SNAP(subvol.v)) {
u32 snapshot_root = bch2_snapshot_root(c, le32_to_cpu(subvol.v->snapshot));
- u32 snapshot_tree = snapshot_t(c, snapshot_root)->tree;
+ u32 snapshot_tree;
struct bch_snapshot_tree st;
+ rcu_read_lock();
+ snapshot_tree = snapshot_t(c, snapshot_root)->tree;
+ rcu_read_unlock();
+
ret = bch2_snapshot_tree_lookup(trans, snapshot_tree, &st);
bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
@@ -869,7 +961,7 @@ int bch2_check_subvols(struct bch_fs *c)
void bch2_fs_snapshots_exit(struct bch_fs *c)
{
- genradix_free(&c->snapshots);
+ kfree(rcu_dereference_protected(c->snapshots, true));
}
int bch2_snapshots_read(struct bch_fs *c)
@@ -1011,7 +1103,7 @@ static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree,
struct bkey_i_snapshot *n;
struct bkey_s_c k;
unsigned i, j;
- u32 depth = parent ? snapshot_t(c, parent)->depth + 1 : 0;
+ u32 depth = bch2_snapshot_depth(c, parent);
int ret;
bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots,
@@ -1150,7 +1242,7 @@ static int snapshot_delete_key(struct btree_trans *trans,
struct bpos *last_pos)
{
struct bch_fs *c = trans->c;
- u32 equiv = snapshot_t(c, k.k->p.snapshot)->equiv;
+ u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);
if (!bkey_eq(k.k->p, *last_pos))
equiv_seen->nr = 0;
diff --git a/fs/bcachefs/subvolume.h b/fs/bcachefs/subvolume.h
index ab0b4a6de255..12a08a34e9bb 100644
--- a/fs/bcachefs/subvolume.h
+++ b/fs/bcachefs/subvolume.h
@@ -32,17 +32,40 @@ int bch2_mark_snapshot(struct btree_trans *, enum btree_id, unsigned,
.min_val_size = 24, \
})
-static inline struct snapshot_t *snapshot_t(struct bch_fs *c, u32 id)
+static inline struct snapshot_t *__snapshot_t(struct snapshot_table *t, u32 id)
{
- return genradix_ptr(&c->snapshots, U32_MAX - id);
+ return &t->s[U32_MAX - id];
}
-static inline u32 bch2_snapshot_parent_early(struct bch_fs *c, u32 id)
+static inline const struct snapshot_t *snapshot_t(struct bch_fs *c, u32 id)
+{
+ return __snapshot_t(rcu_dereference(c->snapshots), id);
+}
+
+static inline u32 bch2_snapshot_tree(struct bch_fs *c, u32 id)
+{
+ rcu_read_lock();
+ id = snapshot_t(c, id)->tree;
+ rcu_read_unlock();
+
+ return id;
+}
+
+static inline u32 __bch2_snapshot_parent_early(struct bch_fs *c, u32 id)
{
return snapshot_t(c, id)->parent;
}
-static inline u32 bch2_snapshot_parent(struct bch_fs *c, u32 id)
+static inline u32 bch2_snapshot_parent_early(struct bch_fs *c, u32 id)
+{
+ rcu_read_lock();
+ id = __bch2_snapshot_parent_early(c, id);
+ rcu_read_unlock();
+
+ return id;
+}
+
+static inline u32 __bch2_snapshot_parent(struct bch_fs *c, u32 id)
{
#ifdef CONFIG_BCACHEFS_DEBUG
u32 parent = snapshot_t(c, id)->parent;
@@ -59,10 +82,21 @@ static inline u32 bch2_snapshot_parent(struct bch_fs *c, u32 id)
#endif
}
+static inline u32 bch2_snapshot_parent(struct bch_fs *c, u32 id)
+{
+ rcu_read_lock();
+ id = __bch2_snapshot_parent(c, id);
+ rcu_read_unlock();
+
+ return id;
+}
+
static inline u32 bch2_snapshot_nth_parent(struct bch_fs *c, u32 id, u32 n)
{
+ rcu_read_lock();
while (n--)
- id = bch2_snapshot_parent(c, id);
+ id = __bch2_snapshot_parent(c, id);
+ rcu_read_unlock();
return id;
}
@@ -71,37 +105,60 @@ static inline u32 bch2_snapshot_root(struct bch_fs *c, u32 id)
{
u32 parent;
- while ((parent = bch2_snapshot_parent(c, id)))
+ rcu_read_lock();
+ while ((parent = __bch2_snapshot_parent(c, id)))
id = parent;
+ rcu_read_unlock();
+
return id;
}
-static inline u32 bch2_snapshot_equiv(struct bch_fs *c, u32 id)
+static inline u32 __bch2_snapshot_equiv(struct bch_fs *c, u32 id)
{
return snapshot_t(c, id)->equiv;
}
+static inline u32 bch2_snapshot_equiv(struct bch_fs *c, u32 id)
+{
+ rcu_read_lock();
+ id = __bch2_snapshot_equiv(c, id);
+ rcu_read_unlock();
+
+ return id;
+}
+
static inline bool bch2_snapshot_is_equiv(struct bch_fs *c, u32 id)
{
- return id == snapshot_t(c, id)->equiv;
+ return id == bch2_snapshot_equiv(c, id);
}
-static inline u32 bch2_snapshot_internal_node(struct bch_fs *c, u32 id)
+static inline bool bch2_snapshot_is_internal_node(struct bch_fs *c, u32 id)
{
- struct snapshot_t *s = snapshot_t(c, id);
+ const struct snapshot_t *s;
+ bool ret;
+
+ rcu_read_lock();
+ s = snapshot_t(c, id);
+ ret = s->children[0];
+ rcu_read_unlock();
- return s->children[0] || s->children[1];
+ return ret;
+}
+
+static inline u32 bch2_snapshot_is_leaf(struct bch_fs *c, u32 id)
+{
+ return !bch2_snapshot_is_internal_node(c, id);
}
static inline u32 bch2_snapshot_sibling(struct bch_fs *c, u32 id)
{
- struct snapshot_t *s;
- u32 parent = bch2_snapshot_parent(c, id);
+ const struct snapshot_t *s;
+ u32 parent = __bch2_snapshot_parent(c, id);
if (!parent)
return 0;
- s = snapshot_t(c, bch2_snapshot_parent(c, id));
+ s = snapshot_t(c, __bch2_snapshot_parent(c, id));
if (id == s->children[0])
return s->children[1];
if (id == s->children[1])
@@ -113,9 +170,15 @@ bool bch2_snapshot_is_ancestor(struct bch_fs *, u32, u32);
static inline bool bch2_snapshot_has_children(struct bch_fs *c, u32 id)
{
- struct snapshot_t *t = snapshot_t(c, id);
+ const struct snapshot_t *t;
+ bool ret;
- return (t->children[0]|t->children[1]) != 0;
+ rcu_read_lock();
+ t = snapshot_t(c, id);
+ ret = (t->children[0]|t->children[1]) != 0;
+ rcu_read_unlock();
+
+ return ret;
}
static inline bool snapshot_list_has_id(snapshot_id_list *s, u32 id)
diff --git a/fs/bcachefs/subvolume_types.h b/fs/bcachefs/subvolume_types.h
index 750d975ac468..c596e4270690 100644
--- a/fs/bcachefs/subvolume_types.h
+++ b/fs/bcachefs/subvolume_types.h
@@ -16,6 +16,10 @@ struct snapshot_t {
u32 equiv;
};
+struct snapshot_table {
+ struct snapshot_t s[0];
+};
+
typedef struct {
u32 subvol;
u64 inum;