Re: [PATCH] bcachefs: bch_member.btree_allocated_bitmap

[Kent Overstreet]

On Mon, Apr 15, 2024 at 09:12:11AM +0800, Hongbo Li wrote:
> 
> 
> On 2024/4/14 5:57, Kent Overstreet wrote:
> > For those interested, this is a good tour of the facilities for rolling
> > out new on disk format features.
> > 
> > -- >8 --
> > 
> > This adds a small (64 bit) per-device bitmap that tracks ranges that
> > have btree nodes, for accelerating btree node scan if it is ever needed.
> > 
> > - New helpers, bch2_dev_btree_bitmap_marked() and
> >    bch2_dev_bitmap_mark(), for checking and updating the bitmap
> > 
> > - Interior btree update path updates the bitmaps when required
> > 
> > - The check_allocations pass has a new fsck_err check,
> >    btree_bitmap_not_marked
> > 
> > - New on disk format version, mi_btree_mitmap, which indicates the new
> >    bitmap is present
> > 
> > - Upgrade table lists the required recovery pass and expected fsck error
> > 
> > - Btree node scan uses the bitmap to skip ranges if we're on the new
> >    version
> > 
> > Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
> > ---
> >   fs/bcachefs/bcachefs_format.h       |  7 ++--
> >   fs/bcachefs/btree_gc.c              | 13 +++++++
> >   fs/bcachefs/btree_node_scan.c       |  9 +++--
> >   fs/bcachefs/btree_update_interior.c | 24 +++++++++++++
> >   fs/bcachefs/sb-downgrade.c          |  5 ++-
> >   fs/bcachefs/sb-errors_types.h       |  3 +-
> >   fs/bcachefs/sb-members.c            | 53 +++++++++++++++++++++++++++++
> >   fs/bcachefs/sb-members.h            | 21 ++++++++++++
> >   fs/bcachefs/sb-members_types.h      |  2 ++
> >   9 files changed, 131 insertions(+), 6 deletions(-)
> > 
> > diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
> > index 9480f1b44f07..085987435a5e 100644
> > --- a/fs/bcachefs/bcachefs_format.h
> > +++ b/fs/bcachefs/bcachefs_format.h
> > @@ -578,7 +578,8 @@ struct bch_member {
> >   	__le64			nbuckets;	/* device size */
> >   	__le16			first_bucket;   /* index of first bucket used */
> >   	__le16			bucket_size;	/* sectors */
> > -	__le32			pad;
> > +	__u8			btree_bitmap_shift;
> > +	__u8			pad[3];
> >   	__le64			last_mount;	/* time_t */
> >   	__le64			flags;
> > @@ -587,6 +588,7 @@ struct bch_member {
> >   	__le64			errors_at_reset[BCH_MEMBER_ERROR_NR];
> >   	__le64			errors_reset_time;
> >   	__le64			seq;
> > +	__le64			btree_allocated_bitmap;
> >   };
> >   #define BCH_MEMBER_V1_BYTES	56
> > @@ -876,7 +878,8 @@ struct bch_sb_field_downgrade {
> >   	x(rebalance_work,		BCH_VERSION(1,  3))		\
> >   	x(member_seq,			BCH_VERSION(1,  4))		\
> >   	x(subvolume_fs_parent,		BCH_VERSION(1,  5))		\
> > -	x(btree_subvolume_children,	BCH_VERSION(1,  6))
> > +	x(btree_subvolume_children,	BCH_VERSION(1,  6))		\
> > +	x(mi_btree_bitmap,		BCH_VERSION(1,  7))
> >   enum bcachefs_metadata_version {
> >   	bcachefs_metadata_version_min = 9,
> > diff --git a/fs/bcachefs/btree_gc.c b/fs/bcachefs/btree_gc.c
> > index 10c41cf89212..a77c723a9cef 100644
> > --- a/fs/bcachefs/btree_gc.c
> > +++ b/fs/bcachefs/btree_gc.c
> > @@ -822,6 +822,7 @@ static int bch2_gc_mark_key(struct btree_trans *trans, enum btree_id btree_id,
> >   	struct bch_fs *c = trans->c;
> >   	struct bkey deleted = KEY(0, 0, 0);
> >   	struct bkey_s_c old = (struct bkey_s_c) { &deleted, NULL };
> > +	struct printbuf buf = PRINTBUF;
> >   	int ret = 0;
> >   	deleted.p = k->k->p;
> > @@ -842,11 +843,23 @@ static int bch2_gc_mark_key(struct btree_trans *trans, enum btree_id btree_id,
> >   	if (ret)
> >   		goto err;
> > +	if (mustfix_fsck_err_on(level && !bch2_dev_btree_bitmap_marked(c, *k),
> > +				c, btree_bitmap_not_marked,
> > +				"btree ptr not marked in member info btree allocated bitmap\n  %s",
> > +				(bch2_bkey_val_to_text(&buf, c, *k),
> > +				 buf.buf))) {
> > +		mutex_lock(&c->sb_lock);
> > +		bch2_dev_btree_bitmap_mark(c, *k);
> > +		bch2_write_super(c);
> > +		mutex_unlock(&c->sb_lock);
> > +	}
> > +
> >   	ret = commit_do(trans, NULL, NULL, 0,
> >   			bch2_key_trigger(trans, btree_id, level, old,
> >   					 unsafe_bkey_s_c_to_s(*k), BTREE_TRIGGER_gc));
> >   fsck_err:
> >   err:
> > +	printbuf_exit(&buf);
> >   	bch_err_fn(c, ret);
> >   	return ret;
> >   }
> > diff --git a/fs/bcachefs/btree_node_scan.c b/fs/bcachefs/btree_node_scan.c
> > index 20f2b37c4474..866bd278439f 100644
> > --- a/fs/bcachefs/btree_node_scan.c
> > +++ b/fs/bcachefs/btree_node_scan.c
> > @@ -205,8 +205,13 @@ static int read_btree_nodes_worker(void *p)
> >   				last_print = jiffies;
> >   			}
> > -			try_read_btree_node(w->f, ca, bio, buf,
> > -					    bucket * ca->mi.bucket_size + bucket_offset);
> > +			u64 sector = bucket * ca->mi.bucket_size + bucket_offset;
> > +
> > +			if (c->sb.version_upgrade_complete >= bcachefs_metadata_version_mi_btree_bitmap &&
> > +			    !bch2_dev_btree_bitmap_marked_sectors(ca, sector, btree_sectors(c)))
> > +				continue;
> > +
> > +			try_read_btree_node(w->f, ca, bio, buf, sector);
> >   		}
> >   err:
> >   	bio_put(bio);
> > diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c
> > index 593241b15aa8..12ce6287416f 100644
> > --- a/fs/bcachefs/btree_update_interior.c
> > +++ b/fs/bcachefs/btree_update_interior.c
> > @@ -21,6 +21,7 @@
> >   #include "keylist.h"
> >   #include "recovery_passes.h"
> >   #include "replicas.h"
> > +#include "sb-members.h"
> >   #include "super-io.h"
> >   #include "trace.h"
> > @@ -644,6 +645,26 @@ static int btree_update_nodes_written_trans(struct btree_trans *trans,
> >   	return 0;
> >   }
> > +static bool btree_update_new_nodes_marked_sb(struct btree_update *as)
> > +{
> > +	for_each_keylist_key(&as->new_keys, k)
> > +		if (!bch2_dev_btree_bitmap_marked(as->c, bkey_i_to_s_c(k)))
> > +			return false;
> > +	return true;
> > +}
> > +
> > +static void btree_update_new_nodes_mark_sb(struct btree_update *as)
> > +{
> > +	struct bch_fs *c = as->c;
> > +
> > +	mutex_lock(&c->sb_lock);
> > +	for_each_keylist_key(&as->new_keys, k)
> > +		bch2_dev_btree_bitmap_mark(c, bkey_i_to_s_c(k));
> > +
> > +	bch2_write_super(c);
> > +	mutex_unlock(&c->sb_lock);
> > +}
> > +
> >   static void btree_update_nodes_written(struct btree_update *as)
> >   {
> >   	struct bch_fs *c = as->c;
> > @@ -664,6 +685,9 @@ static void btree_update_nodes_written(struct btree_update *as)
> >   	if (ret)
> >   		goto err;
> > +	if (!btree_update_new_nodes_marked_sb(as))
> > +		btree_update_new_nodes_mark_sb(as);
> > +
> >   	/*
> >   	 * Wait for any in flight writes to finish before we free the old nodes
> >   	 * on disk:
> > diff --git a/fs/bcachefs/sb-downgrade.c b/fs/bcachefs/sb-downgrade.c
> > index 56ac8f35cdc3..90b06f8aa1df 100644
> > --- a/fs/bcachefs/sb-downgrade.c
> > +++ b/fs/bcachefs/sb-downgrade.c
> > @@ -51,7 +51,10 @@
> >   	  BCH_FSCK_ERR_subvol_fs_path_parent_wrong)		\
> >   	x(btree_subvolume_children,				\
> >   	  BIT_ULL(BCH_RECOVERY_PASS_check_subvols),		\
> > -	  BCH_FSCK_ERR_subvol_children_not_set)
> > +	  BCH_FSCK_ERR_subvol_children_not_set)			\
> > +	x(mi_btree_bitmap,					\
> > +	  BIT_ULL(BCH_RECOVERY_PASS_check_allocations),		\
> > +	  BCH_FSCK_ERR_btree_bitmap_not_marked)
> >   #define DOWNGRADE_TABLE()
> > diff --git a/fs/bcachefs/sb-errors_types.h b/fs/bcachefs/sb-errors_types.h
> > index d7d609131030..5b600c6d7aca 100644
> > --- a/fs/bcachefs/sb-errors_types.h
> > +++ b/fs/bcachefs/sb-errors_types.h
> > @@ -270,7 +270,8 @@
> >   	x(btree_ptr_v2_min_key_bad,				262)	\
> >   	x(btree_root_unreadable_and_scan_found_nothing,		263)	\
> >   	x(snapshot_node_missing,				264)	\
> > -	x(dup_backpointer_to_bad_csum_extent,			265)
> > +	x(dup_backpointer_to_bad_csum_extent,			265)	\
> > +	x(btree_bitmap_not_marked,				266)
> >   enum bch_sb_error_id {
> >   #define x(t, n) BCH_FSCK_ERR_##t = n,
> > diff --git a/fs/bcachefs/sb-members.c b/fs/bcachefs/sb-members.c
> > index 9b7a2f300182..d5937aba0910 100644
> > --- a/fs/bcachefs/sb-members.c
> > +++ b/fs/bcachefs/sb-members.c
> > @@ -1,6 +1,7 @@
> >   // SPDX-License-Identifier: GPL-2.0
> >   #include "bcachefs.h"
> > +#include "btree_cache.h"
> >   #include "disk_groups.h"
> >   #include "opts.h"
> >   #include "replicas.h"
> > @@ -378,3 +379,55 @@ void bch2_dev_errors_reset(struct bch_dev *ca)
> >   	bch2_write_super(c);
> >   	mutex_unlock(&c->sb_lock);
> >   }
> > +
> > +/*
> > + * Per member "range has btree nodes" bitmap:
> > + *
> > + * This is so that if we ever have to run the btree node scan to repair we don't
> > + * have to scan full devices:
> > + */
> > +
> > +bool bch2_dev_btree_bitmap_marked(struct bch_fs *c, struct bkey_s_c k)
> > +{
> > +	bkey_for_each_ptr(bch2_bkey_ptrs_c(k), ptr)
> > +		if (!bch2_dev_btree_bitmap_marked_sectors(bch2_dev_bkey_exists(c, ptr->dev),
> > +							  ptr->offset, btree_sectors(c)))
> > +			return false;
> > +	return true;
> > +}
> > +
> > +static void __bch2_dev_btree_bitmap_mark(struct bch_sb_field_members_v2 *mi, unsigned dev,
> > +				u64 start, unsigned sectors)
> > +{
> > +	struct bch_member *m = __bch2_members_v2_get_mut(mi, dev);
> > +	u64 bitmap = le64_to_cpu(m->btree_allocated_bitmap);
> > +
> > +	u64 end = start + sectors;
> > +
> > +	int resize = ilog2(roundup_pow_of_two(end)) - (m->btree_bitmap_shift + 6);
> > +	if (resize > 0) {
> > +		u64 new_bitmap = 0;
> > +
> > +		for (unsigned i = 0; i < 64; i++)
> > +			if (bitmap & BIT_ULL(i))
> > +				new_bitmap |= BIT_ULL(i >> resize);
> > +		bitmap = new_bitmap;
> > +		m->btree_bitmap_shift += resize;
> > +	}
> > +
> > +	for (unsigned bit = sectors >> m->btree_bitmap_shift;
> > +	     bit << m->btree_bitmap_shift < end;
> > +	     bit++)
> > +		bitmap |= BIT_ULL(bit);
> > +
> > +	m->btree_allocated_bitmap = cpu_to_le64(bitmap);
> > +}
> > +
> > +void bch2_dev_btree_bitmap_mark(struct bch_fs *c, struct bkey_s_c k)
> > +{
> > +	lockdep_assert_held(&c->sb_lock);
> > +
> > +	struct bch_sb_field_members_v2 *mi = bch2_sb_field_get(c->disk_sb.sb, members_v2);
> > +	bkey_for_each_ptr(bch2_bkey_ptrs_c(k), ptr)
> > +		__bch2_dev_btree_bitmap_mark(mi, ptr->dev, ptr->offset, btree_sectors(c));
> > +}
> > diff --git a/fs/bcachefs/sb-members.h b/fs/bcachefs/sb-members.h
> > index bc3bcfef7b3a..8bbad30a4370 100644
> > --- a/fs/bcachefs/sb-members.h
> > +++ b/fs/bcachefs/sb-members.h
> > @@ -3,6 +3,7 @@
> >   #define _BCACHEFS_SB_MEMBERS_H
> >   #include "darray.h"
> > +#include "bkey_types.h"
> >   extern char * const bch2_member_error_strs[];
> > @@ -234,6 +235,8 @@ static inline struct bch_member_cpu bch2_mi_to_cpu(struct bch_member *mi)
> >   			: 1,
> >   		.freespace_initialized = BCH_MEMBER_FREESPACE_INITIALIZED(mi),
> >   		.valid		= bch2_member_alive(mi),
> > +		.btree_bitmap_shift	= mi->btree_bitmap_shift,
> > +		.btree_allocated_bitmap = le64_to_cpu(mi->btree_allocated_bitmap),
> >   	};
> >   }
> > @@ -242,4 +245,22 @@ void bch2_sb_members_from_cpu(struct bch_fs *);
> >   void bch2_dev_io_errors_to_text(struct printbuf *, struct bch_dev *);
> >   void bch2_dev_errors_reset(struct bch_dev *);
> > +static inline bool bch2_dev_btree_bitmap_marked_sectors(struct bch_dev *ca, u64 start, unsigned sectors)
> > +{
> > +	u64 end = start + sectors;
> > +
> > +	if (end > 64 << ca->mi.btree_bitmap_shift)
> > +		return false;
> > +
> > +	for (unsigned bit = sectors >> ca->mi.btree_bitmap_shift;
> > +	     bit << ca->mi.btree_bitmap_shift < end;
> > +	     bit++)
> > +		if (!(ca->mi.btree_allocated_bitmap & BIT_ULL(bit)))
> Should it be transferred by le64_to_cpu?

no, ca->mi is bch_member_cpu, a different type that has everything in
native byte order