From b2fa1b633bac0c3b2d04ae00e8801414d251aace Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sun, 21 Jan 2024 02:51:56 -0500
Subject: [PATCH] bcachefs; extents_format.h
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/bcachefs_format.h | 281 +--------------------------------
fs/bcachefs/extents_format.h | 282 ++++++++++++++++++++++++++++++++++
2 files changed, 284 insertions(+), 279 deletions(-)
create mode 100644 fs/bcachefs/extents_format.h
diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
index 5327514d96f9f..2921ecd49c6ee 100644
--- a/fs/bcachefs/bcachefs_format.h
+++ b/fs/bcachefs/bcachefs_format.h
@@ -417,272 +417,12 @@ struct bch_set {
struct bch_val v;
};
-/* Extents */
-
-/*
- * In extent bkeys, the value is a list of pointers (bch_extent_ptr), optionally
- * preceded by checksum/compression information (bch_extent_crc32 or
- * bch_extent_crc64).
- *
- * One major determining factor in the format of extents is how we handle and
- * represent extents that have been partially overwritten and thus trimmed:
- *
- * If an extent is not checksummed or compressed, when the extent is trimmed we
- * don't have to remember the extent we originally allocated and wrote: we can
- * merely adjust ptr->offset to point to the start of the data that is currently
- * live. The size field in struct bkey records the current (live) size of the
- * extent, and is also used to mean "size of region on disk that we point to" in
- * this case.
- *
- * Thus an extent that is not checksummed or compressed will consist only of a
- * list of bch_extent_ptrs, with none of the fields in
- * bch_extent_crc32/bch_extent_crc64.
- *
- * When an extent is checksummed or compressed, it's not possible to read only
- * the data that is currently live: we have to read the entire extent that was
- * originally written, and then return only the part of the extent that is
- * currently live.
- *
- * Thus, in addition to the current size of the extent in struct bkey, we need
- * to store the size of the originally allocated space - this is the
- * compressed_size and uncompressed_size fields in bch_extent_crc32/64. Also,
- * when the extent is trimmed, instead of modifying the offset field of the
- * pointer, we keep a second smaller offset field - "offset into the original
- * extent of the currently live region".
- *
- * The other major determining factor is replication and data migration:
- *
- * Each pointer may have its own bch_extent_crc32/64. When doing a replicated
- * write, we will initially write all the replicas in the same format, with the
- * same checksum type and compression format - however, when copygc runs later (or
- * tiering/cache promotion, anything that moves data), it is not in general
- * going to rewrite all the pointers at once - one of the replicas may be in a
- * bucket on one device that has very little fragmentation while another lives
- * in a bucket that has become heavily fragmented, and thus is being rewritten
- * sooner than the rest.
- *
- * Thus it will only move a subset of the pointers (or in the case of
- * tiering/cache promotion perhaps add a single pointer without dropping any
- * current pointers), and if the extent has been partially overwritten it must
- * write only the currently live portion (or copygc would not be able to reduce
- * fragmentation!) - which necessitates a different bch_extent_crc format for
- * the new pointer.
- *
- * But in the interests of space efficiency, we don't want to store one
- * bch_extent_crc for each pointer if we don't have to.
- *
- * Thus, a bch_extent consists of bch_extent_crc32s, bch_extent_crc64s, and
- * bch_extent_ptrs appended arbitrarily one after the other. We determine the
- * type of a given entry with a scheme similar to utf8 (except we're encoding a
- * type, not a size), encoding the type in the position of the first set bit:
- *
- * bch_extent_crc32 - 0b1
- * bch_extent_ptr - 0b10
- * bch_extent_crc64 - 0b100
- *
- * We do it this way because bch_extent_crc32 is _very_ constrained on bits (and
- * bch_extent_crc64 is the least constrained).
- *
- * Then, each bch_extent_crc32/64 applies to the pointers that follow after it,
- * until the next bch_extent_crc32/64.
- *
- * If there are no bch_extent_crcs preceding a bch_extent_ptr, then that pointer
- * is neither checksummed nor compressed.
- */
-
/* 128 bits, sufficient for cryptographic MACs: */
struct bch_csum {
__le64 lo;
__le64 hi;
} __packed __aligned(8);
-#define BCH_EXTENT_ENTRY_TYPES() \
- x(ptr, 0) \
- x(crc32, 1) \
- x(crc64, 2) \
- x(crc128, 3) \
- x(stripe_ptr, 4) \
- x(rebalance, 5)
-#define BCH_EXTENT_ENTRY_MAX 6
-
-enum bch_extent_entry_type {
-#define x(f, n) BCH_EXTENT_ENTRY_##f = n,
- BCH_EXTENT_ENTRY_TYPES()
-#undef x
-};
-
-/* Compressed/uncompressed size are stored biased by 1: */
-struct bch_extent_crc32 {
-#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u32 type:2,
- _compressed_size:7,
- _uncompressed_size:7,
- offset:7,
- _unused:1,
- csum_type:4,
- compression_type:4;
- __u32 csum;
-#elif defined (__BIG_ENDIAN_BITFIELD)
- __u32 csum;
- __u32 compression_type:4,
- csum_type:4,
- _unused:1,
- offset:7,
- _uncompressed_size:7,
- _compressed_size:7,
- type:2;
-#endif
-} __packed __aligned(8);
-
-#define CRC32_SIZE_MAX (1U << 7)
-#define CRC32_NONCE_MAX 0
-
-struct bch_extent_crc64 {
-#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u64 type:3,
- _compressed_size:9,
- _uncompressed_size:9,
- offset:9,
- nonce:10,
- csum_type:4,
- compression_type:4,
- csum_hi:16;
-#elif defined (__BIG_ENDIAN_BITFIELD)
- __u64 csum_hi:16,
- compression_type:4,
- csum_type:4,
- nonce:10,
- offset:9,
- _uncompressed_size:9,
- _compressed_size:9,
- type:3;
-#endif
- __u64 csum_lo;
-} __packed __aligned(8);
-
-#define CRC64_SIZE_MAX (1U << 9)
-#define CRC64_NONCE_MAX ((1U << 10) - 1)
-
-struct bch_extent_crc128 {
-#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u64 type:4,
- _compressed_size:13,
- _uncompressed_size:13,
- offset:13,
- nonce:13,
- csum_type:4,
- compression_type:4;
-#elif defined (__BIG_ENDIAN_BITFIELD)
- __u64 compression_type:4,
- csum_type:4,
- nonce:13,
- offset:13,
- _uncompressed_size:13,
- _compressed_size:13,
- type:4;
-#endif
- struct bch_csum csum;
-} __packed __aligned(8);
-
-#define CRC128_SIZE_MAX (1U << 13)
-#define CRC128_NONCE_MAX ((1U << 13) - 1)
-
-/*
- * @reservation - pointer hasn't been written to, just reserved
- */
-struct bch_extent_ptr {
-#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u64 type:1,
- cached:1,
- unused:1,
- unwritten:1,
- offset:44, /* 8 petabytes */
- dev:8,
- gen:8;
-#elif defined (__BIG_ENDIAN_BITFIELD)
- __u64 gen:8,
- dev:8,
- offset:44,
- unwritten:1,
- unused:1,
- cached:1,
- type:1;
-#endif
-} __packed __aligned(8);
-
-struct bch_extent_stripe_ptr {
-#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u64 type:5,
- block:8,
- redundancy:4,
- idx:47;
-#elif defined (__BIG_ENDIAN_BITFIELD)
- __u64 idx:47,
- redundancy:4,
- block:8,
- type:5;
-#endif
-};
-
-struct bch_extent_rebalance {
-#if defined(__LITTLE_ENDIAN_BITFIELD)
- __u64 type:6,
- unused:34,
- compression:8, /* enum bch_compression_opt */
- target:16;
-#elif defined (__BIG_ENDIAN_BITFIELD)
- __u64 target:16,
- compression:8,
- unused:34,
- type:6;
-#endif
-};
-
-union bch_extent_entry {
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ || __BITS_PER_LONG == 64
- unsigned long type;
-#elif __BITS_PER_LONG == 32
- struct {
- unsigned long pad;
- unsigned long type;
- };
-#else
-#error edit for your odd byteorder.
-#endif
-
-#define x(f, n) struct bch_extent_##f f;
- BCH_EXTENT_ENTRY_TYPES()
-#undef x
-};
-
-struct bch_btree_ptr {
- struct bch_val v;
-
- __u64 _data[0];
- struct bch_extent_ptr start[];
-} __packed __aligned(8);
-
-struct bch_btree_ptr_v2 {
- struct bch_val v;
-
- __u64 mem_ptr;
- __le64 seq;
- __le16 sectors_written;
- __le16 flags;
- struct bpos min_key;
- __u64 _data[0];
- struct bch_extent_ptr start[];
-} __packed __aligned(8);
-
-LE16_BITMASK(BTREE_PTR_RANGE_UPDATED, struct bch_btree_ptr_v2, flags, 0, 1);
-
-struct bch_extent {
- struct bch_val v;
-
- __u64 _data[0];
- union bch_extent_entry start[];
-} __packed __aligned(8);
-
struct bch_reservation {
struct bch_val v;
@@ -691,25 +431,6 @@ struct bch_reservation {
__u8 pad[3];
} __packed __aligned(8);
-/* Maximum size (in u64s) a single pointer could be: */
-#define BKEY_EXTENT_PTR_U64s_MAX\
- ((sizeof(struct bch_extent_crc128) + \
- sizeof(struct bch_extent_ptr)) / sizeof(__u64))
-
-/* Maximum possible size of an entire extent value: */
-#define BKEY_EXTENT_VAL_U64s_MAX \
- (1 + BKEY_EXTENT_PTR_U64s_MAX * (BCH_REPLICAS_MAX + 1))
-
-/* * Maximum possible size of an entire extent, key + value: */
-#define BKEY_EXTENT_U64s_MAX (BKEY_U64s + BKEY_EXTENT_VAL_U64s_MAX)
-
-/* Btree pointers don't carry around checksums: */
-#define BKEY_BTREE_PTR_VAL_U64s_MAX \
- ((sizeof(struct bch_btree_ptr_v2) + \
- sizeof(struct bch_extent_ptr) * BCH_REPLICAS_MAX) / sizeof(__u64))
-#define BKEY_BTREE_PTR_U64s_MAX \
- (BKEY_U64s + BKEY_BTREE_PTR_VAL_U64s_MAX)
-
struct bch_backpointer {
struct bch_val v;
__u8 btree_id;
@@ -720,6 +441,8 @@ struct bch_backpointer {
struct bpos pos;
} __packed __aligned(8);
+#include "extents_format.h"
+
/* Reflink: */
struct bch_reflink_p {
diff --git a/fs/bcachefs/extents_format.h b/fs/bcachefs/extents_format.h
new file mode 100644
index 0000000000000..939d09f9d3b84
--- /dev/null
+++ b/fs/bcachefs/extents_format.h
@@ -0,0 +1,282 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHEFS_EXTENTS_FORMAT_H
+#define _BCACHEFS_EXTENTS_FORMAT_H
+
+/*
+ * In extent bkeys, the value is a list of pointers (bch_extent_ptr), optionally
+ * preceded by checksum/compression information (bch_extent_crc32 or
+ * bch_extent_crc64).
+ *
+ * One major determining factor in the format of extents is how we handle and
+ * represent extents that have been partially overwritten and thus trimmed:
+ *
+ * If an extent is not checksummed or compressed, when the extent is trimmed we
+ * don't have to remember the extent we originally allocated and wrote: we can
+ * merely adjust ptr->offset to point to the start of the data that is currently
+ * live. The size field in struct bkey records the current (live) size of the
+ * extent, and is also used to mean "size of region on disk that we point to" in
+ * this case.
+ *
+ * Thus an extent that is not checksummed or compressed will consist only of a
+ * list of bch_extent_ptrs, with none of the fields in
+ * bch_extent_crc32/bch_extent_crc64.
+ *
+ * When an extent is checksummed or compressed, it's not possible to read only
+ * the data that is currently live: we have to read the entire extent that was
+ * originally written, and then return only the part of the extent that is
+ * currently live.
+ *
+ * Thus, in addition to the current size of the extent in struct bkey, we need
+ * to store the size of the originally allocated space - this is the
+ * compressed_size and uncompressed_size fields in bch_extent_crc32/64. Also,
+ * when the extent is trimmed, instead of modifying the offset field of the
+ * pointer, we keep a second smaller offset field - "offset into the original
+ * extent of the currently live region".
+ *
+ * The other major determining factor is replication and data migration:
+ *
+ * Each pointer may have its own bch_extent_crc32/64. When doing a replicated
+ * write, we will initially write all the replicas in the same format, with the
+ * same checksum type and compression format - however, when copygc runs later (or
+ * tiering/cache promotion, anything that moves data), it is not in general
+ * going to rewrite all the pointers at once - one of the replicas may be in a
+ * bucket on one device that has very little fragmentation while another lives
+ * in a bucket that has become heavily fragmented, and thus is being rewritten
+ * sooner than the rest.
+ *
+ * Thus it will only move a subset of the pointers (or in the case of
+ * tiering/cache promotion perhaps add a single pointer without dropping any
+ * current pointers), and if the extent has been partially overwritten it must
+ * write only the currently live portion (or copygc would not be able to reduce
+ * fragmentation!) - which necessitates a different bch_extent_crc format for
+ * the new pointer.
+ *
+ * But in the interests of space efficiency, we don't want to store one
+ * bch_extent_crc for each pointer if we don't have to.
+ *
+ * Thus, a bch_extent consists of bch_extent_crc32s, bch_extent_crc64s, and
+ * bch_extent_ptrs appended arbitrarily one after the other. We determine the
+ * type of a given entry with a scheme similar to utf8 (except we're encoding a
+ * type, not a size), encoding the type in the position of the first set bit:
+ *
+ * bch_extent_crc32 - 0b1
+ * bch_extent_ptr - 0b10
+ * bch_extent_crc64 - 0b100
+ *
+ * We do it this way because bch_extent_crc32 is _very_ constrained on bits (and
+ * bch_extent_crc64 is the least constrained).
+ *
+ * Then, each bch_extent_crc32/64 applies to the pointers that follow after it,
+ * until the next bch_extent_crc32/64.
+ *
+ * If there are no bch_extent_crcs preceding a bch_extent_ptr, then that pointer
+ * is neither checksummed nor compressed.
+ */
+
+#define BCH_EXTENT_ENTRY_TYPES() \
+ x(ptr, 0) \
+ x(crc32, 1) \
+ x(crc64, 2) \
+ x(crc128, 3) \
+ x(stripe_ptr, 4) \
+ x(rebalance, 5)
+#define BCH_EXTENT_ENTRY_MAX 6
+
+enum bch_extent_entry_type {
+#define x(f, n) BCH_EXTENT_ENTRY_##f = n,
+ BCH_EXTENT_ENTRY_TYPES()
+#undef x
+};
+
+/* Compressed/uncompressed size are stored biased by 1: */
+struct bch_extent_crc32 {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u32 type:2,
+ _compressed_size:7,
+ _uncompressed_size:7,
+ offset:7,
+ _unused:1,
+ csum_type:4,
+ compression_type:4;
+ __u32 csum;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ __u32 csum;
+ __u32 compression_type:4,
+ csum_type:4,
+ _unused:1,
+ offset:7,
+ _uncompressed_size:7,
+ _compressed_size:7,
+ type:2;
+#endif
+} __packed __aligned(8);
+
+#define CRC32_SIZE_MAX (1U << 7)
+#define CRC32_NONCE_MAX 0
+
+struct bch_extent_crc64 {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u64 type:3,
+ _compressed_size:9,
+ _uncompressed_size:9,
+ offset:9,
+ nonce:10,
+ csum_type:4,
+ compression_type:4,
+ csum_hi:16;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ __u64 csum_hi:16,
+ compression_type:4,
+ csum_type:4,
+ nonce:10,
+ offset:9,
+ _uncompressed_size:9,
+ _compressed_size:9,
+ type:3;
+#endif
+ __u64 csum_lo;
+} __packed __aligned(8);
+
+#define CRC64_SIZE_MAX (1U << 9)
+#define CRC64_NONCE_MAX ((1U << 10) - 1)
+
+struct bch_extent_crc128 {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u64 type:4,
+ _compressed_size:13,
+ _uncompressed_size:13,
+ offset:13,
+ nonce:13,
+ csum_type:4,
+ compression_type:4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ __u64 compression_type:4,
+ csum_type:4,
+ nonce:13,
+ offset:13,
+ _uncompressed_size:13,
+ _compressed_size:13,
+ type:4;
+#endif
+ struct bch_csum csum;
+} __packed __aligned(8);
+
+#define CRC128_SIZE_MAX (1U << 13)
+#define CRC128_NONCE_MAX ((1U << 13) - 1)
+
+/*
+ * @reservation - pointer hasn't been written to, just reserved
+ */
+struct bch_extent_ptr {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u64 type:1,
+ cached:1,
+ unused:1,
+ unwritten:1,
+ offset:44, /* 8 petabytes */
+ dev:8,
+ gen:8;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ __u64 gen:8,
+ dev:8,
+ offset:44,
+ unwritten:1,
+ unused:1,
+ cached:1,
+ type:1;
+#endif
+} __packed __aligned(8);
+
+struct bch_extent_stripe_ptr {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u64 type:5,
+ block:8,
+ redundancy:4,
+ idx:47;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ __u64 idx:47,
+ redundancy:4,
+ block:8,
+ type:5;
+#endif
+};
+
+struct bch_extent_rebalance {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u64 type:6,
+ unused:34,
+ compression:8, /* enum bch_compression_opt */
+ target:16;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+ __u64 target:16,
+ compression:8,
+ unused:34,
+ type:6;
+#endif
+};
+
+union bch_extent_entry {
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ || __BITS_PER_LONG == 64
+ unsigned long type;
+#elif __BITS_PER_LONG == 32
+ struct {
+ unsigned long pad;
+ unsigned long type;
+ };
+#else
+#error edit for your odd byteorder.
+#endif
+
+#define x(f, n) struct bch_extent_##f f;
+ BCH_EXTENT_ENTRY_TYPES()
+#undef x
+};
+
+struct bch_btree_ptr {
+ struct bch_val v;
+
+ __u64 _data[0];
+ struct bch_extent_ptr start[];
+} __packed __aligned(8);
+
+struct bch_btree_ptr_v2 {
+ struct bch_val v;
+
+ __u64 mem_ptr;
+ __le64 seq;
+ __le16 sectors_written;
+ __le16 flags;
+ struct bpos min_key;
+ __u64 _data[0];
+ struct bch_extent_ptr start[];
+} __packed __aligned(8);
+
+LE16_BITMASK(BTREE_PTR_RANGE_UPDATED, struct bch_btree_ptr_v2, flags, 0, 1);
+
+struct bch_extent {
+ struct bch_val v;
+
+ __u64 _data[0];
+ union bch_extent_entry start[];
+} __packed __aligned(8);
+
+/* Maximum size (in u64s) a single pointer could be: */
+#define BKEY_EXTENT_PTR_U64s_MAX\
+ ((sizeof(struct bch_extent_crc128) + \
+ sizeof(struct bch_extent_ptr)) / sizeof(__u64))
+
+/* Maximum possible size of an entire extent value: */
+#define BKEY_EXTENT_VAL_U64s_MAX \
+ (1 + BKEY_EXTENT_PTR_U64s_MAX * (BCH_REPLICAS_MAX + 1))
+
+/* * Maximum possible size of an entire extent, key + value: */
+#define BKEY_EXTENT_U64s_MAX (BKEY_U64s + BKEY_EXTENT_VAL_U64s_MAX)
+
+/* Btree pointers don't carry around checksums: */
+#define BKEY_BTREE_PTR_VAL_U64s_MAX \
+ ((sizeof(struct bch_btree_ptr_v2) + \
+ sizeof(struct bch_extent_ptr) * BCH_REPLICAS_MAX) / sizeof(__u64))
+#define BKEY_BTREE_PTR_U64s_MAX \
+ (BKEY_U64s + BKEY_BTREE_PTR_VAL_U64s_MAX)
+
+#endif /* _BCACHEFS_EXTENTS_FORMAT_H */
--
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