bcachefs: LRU btree

This implements new persistent LRUs, to be used for buckets containing
cached data, as well as stripes ordered by time when a block became
empty.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/Makefile b/fs/bcachefs/Makefile
index d3808249948c98e2d3819932fbdfe686a72ec655..17423584a3f3678f5bece5904ac49787a0613d03 100644 (file)
--- a/fs/bcachefs/Makefile
+++ b/fs/bcachefs/Makefile
@@ -41,6 +41,7 @@ bcachefs-y            :=      \
        journal_sb.o            \
        journal_seq_blacklist.o \
        keylist.o               \
+       lru.o                   \
        migrate.o               \
        move.o                  \
        movinggc.o              \

diff --git a/fs/bcachefs/bcachefs.h b/fs/bcachefs/bcachefs.h
index 01e9ed5dfc611630c30159f0315e096b5773a5c7..7891ad208a33b5d8ed747cdf72e86e6153adace3 100644 (file)
--- a/fs/bcachefs/bcachefs.h
+++ b/fs/bcachefs/bcachefs.h
@@ -391,6 +391,7 @@ enum gc_phase {
        GC_PHASE_BTREE_reflink,
        GC_PHASE_BTREE_subvolumes,
        GC_PHASE_BTREE_snapshots,
+       GC_PHASE_BTREE_lru,
 
        GC_PHASE_PENDING_DELETE,
 };

diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
index 350317e8b34f907b4fc9ace11b2abe971c13e353..982409ed940e09a5a3458f129873248781ed6260 100644 (file)
--- a/fs/bcachefs/bcachefs_format.h
+++ b/fs/bcachefs/bcachefs_format.h
@@ -352,7 +352,8 @@ static inline void bkey_init(struct bkey *k)
        x(snapshot,             22)                     \
        x(inode_v2,             23)                     \
        x(alloc_v3,             24)                     \
-       x(set,                  25)
+       x(set,                  25)                     \
+       x(lru,                  26)
 
 enum bch_bkey_type {
 #define x(name, nr) KEY_TYPE_##name    = nr,
@@ -1024,6 +1025,15 @@ LE32_BITMASK(BCH_SNAPSHOT_DELETED,       struct bch_snapshot, flags,  0,  1)
 /* True if a subvolume points to this snapshot node: */
 LE32_BITMASK(BCH_SNAPSHOT_SUBVOL,      struct bch_snapshot, flags,  1,  2)
 
+/* LRU btree: */
+
+struct bch_lru {
+       struct bch_val          v;
+       __le64                  idx;
+} __attribute__((packed, aligned(8)));
+
+#define LRU_ID_STRIPES         (1U << 16)
+
 /* Optional/variable size superblock sections: */
 
 struct bch_sb_field {
@@ -1838,7 +1848,8 @@ LE32_BITMASK(JSET_NO_FLUSH,       struct jset, flags, 5, 6);
        x(stripes,      6)                      \
        x(reflink,      7)                      \
        x(subvolumes,   8)                      \
-       x(snapshots,    9)
+       x(snapshots,    9)                      \
+       x(lru,          10)
 
 enum btree_id {
 #define x(kwd, val) BTREE_ID_##kwd = val,

diff --git a/fs/bcachefs/bkey_methods.c b/fs/bcachefs/bkey_methods.c
index d938ee826c755df29e396c0a91d5ec47258cbc5c..8757218e571b60b32f253c67048602a678a337b9 100644 (file)
--- a/fs/bcachefs/bkey_methods.c
+++ b/fs/bcachefs/bkey_methods.c
@@ -9,6 +9,7 @@
 #include "error.h"
 #include "extents.h"
 #include "inode.h"
+#include "lru.h"
 #include "quota.h"
 #include "reflink.h"
 #include "subvolume.h"
@@ -165,6 +166,9 @@ static unsigned bch2_key_types_allowed[] = {
        [BKEY_TYPE_snapshots] =
                (1U << KEY_TYPE_deleted)|
                (1U << KEY_TYPE_snapshot),
+       [BKEY_TYPE_lru] =
+               (1U << KEY_TYPE_deleted)|
+               (1U << KEY_TYPE_lru),
        [BKEY_TYPE_btree] =
                (1U << KEY_TYPE_deleted)|
                (1U << KEY_TYPE_btree_ptr)|

diff --git a/fs/bcachefs/lru.c b/fs/bcachefs/lru.c
new file mode 100644 (file)
index 0000000..2ababca
--- /dev/null
+++ b/fs/bcachefs/lru.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "btree_iter.h"
+#include "btree_update.h"
+#include "error.h"
+#include "lru.h"
+
+const char *bch2_lru_invalid(const struct bch_fs *c, struct bkey_s_c k)
+{
+       const struct bch_lru *lru = bkey_s_c_to_lru(k).v;
+
+       if (bkey_val_bytes(k.k) < sizeof(*lru))
+               return "incorrect value size";
+
+       return NULL;
+}
+
+void bch2_lru_to_text(struct printbuf *out, struct bch_fs *c,
+                     struct bkey_s_c k)
+{
+       const struct bch_lru *lru = bkey_s_c_to_lru(k).v;
+
+       pr_buf(out, "idx %llu", le64_to_cpu(lru->idx));
+}
+
+static int lru_delete(struct btree_trans *trans, u64 id, u64 idx, u64 time)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       u64 existing_idx;
+       int ret = 0;
+
+       if (!time)
+               return 0;
+
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_lru,
+                            POS(id, time),
+                            BTREE_ITER_INTENT|
+                            BTREE_ITER_WITH_UPDATES);
+       k = bch2_btree_iter_peek_slot(&iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
+
+       if (k.k->type != KEY_TYPE_lru) {
+               bch2_fs_inconsistent(c,
+                       "pointer to nonexistent lru %llu:%llu",
+                       id, time);
+               ret = -EIO;
+               goto err;
+       }
+
+       existing_idx = le64_to_cpu(bkey_s_c_to_lru(k).v->idx);
+       if (existing_idx != idx) {
+               bch2_fs_inconsistent(c,
+                       "lru %llu:%llu with wrong backpointer: got %llu, should be %llu",
+                       id, time, existing_idx, idx);
+               ret = -EIO;
+               goto err;
+       }
+
+       ret = bch2_btree_delete_at(trans, &iter, 0);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+static int lru_set(struct btree_trans *trans, u64 lru_id, u64 idx, u64 *time)
+{
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       struct bkey_i_lru *lru;
+       int ret = 0;
+
+       if (!*time)
+               return 0;
+
+       for_each_btree_key_norestart(trans, iter, BTREE_ID_lru,
+                       POS(lru_id, *time),
+                       BTREE_ITER_SLOTS|
+                       BTREE_ITER_INTENT|
+                       BTREE_ITER_WITH_UPDATES, k, ret)
+               if (bkey_deleted(k.k))
+                       break;
+
+       if (ret)
+               goto err;
+
+       BUG_ON(iter.pos.inode != lru_id);
+       *time = iter.pos.offset;
+
+       lru = bch2_trans_kmalloc(trans, sizeof(*lru));
+       ret = PTR_ERR_OR_ZERO(lru);
+       if (ret)
+               goto err;
+
+       bkey_lru_init(&lru->k_i);
+       lru->k.p        = iter.pos;
+       lru->v.idx      = cpu_to_le64(idx);
+
+       ret = bch2_trans_update(trans, &iter, &lru->k_i, 0);
+       if (ret)
+               goto err;
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+int bch2_lru_change(struct btree_trans *trans, u64 id, u64 idx,
+                   u64 old_time, u64 *new_time)
+{
+       if (old_time == *new_time)
+               return 0;
+
+       return  lru_delete(trans, id, idx, old_time) ?:
+               lru_set(trans, id, idx, new_time);
+}

diff --git a/fs/bcachefs/lru.h b/fs/bcachefs/lru.h
new file mode 100644 (file)
index 0000000..c3121cf
--- /dev/null
+++ b/fs/bcachefs/lru.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHEFS_LRU_H
+#define _BCACHEFS_LRU_H
+
+const char *bch2_lru_invalid(const struct bch_fs *, struct bkey_s_c);
+void bch2_lru_to_text(struct printbuf *, struct bch_fs *, struct bkey_s_c);
+
+#define bch2_bkey_ops_lru (struct bkey_ops) {  \
+       .key_invalid    = bch2_lru_invalid,     \
+       .val_to_text    = bch2_lru_to_text,     \
+}
+
+int bch2_lru_change(struct btree_trans *, u64, u64, u64, u64 *);
+
+#endif /* _BCACHEFS_LRU_H */