Commit 18d758a2 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: replace btrfs_io_context::raid_map with a fixed u64 value 



In btrfs_io_context structure, we have a pointer raid_map, which
indicates the logical bytenr for each stripe.

But considering we always call sort_parity_stripes(), the result
raid_map[] is always sorted, thus raid_map[0] is always the logical
bytenr of the full stripe.

So why we waste the space and time (for sorting) for raid_map?

This patch will replace btrfs_io_context::raid_map with a single u64
number, full_stripe_start, by:

- Replace btrfs_io_context::raid_map with full_stripe_start

- Replace call sites using raid_map[0] to use full_stripe_start

- Replace call sites using raid_map[i] to compare with nr_data_stripes.

The benefits are:

- Less memory wasted on raid_map
  It's sizeof(u64) * num_stripes vs sizeof(u64).
  It'll always save at least one u64, and the benefit grows larger with
  num_stripes.

- No more weird alloc_btrfs_io_context() behavior
  As there is only one fixed size + one variable length array.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 1faf3885

fs/btrfs/raid56.c

+15 −16
Original line number Diff line number Diff line
@@ -202,7 +202,7 @@ static void cache_rbio_pages(struct btrfs_raid_bio *rbio) 
 */

static int rbio_bucket(struct btrfs_raid_bio *rbio)

{

	u64 num = rbio->bioc->raid_map[0];

	u64 num = rbio->bioc->full_stripe_logical;



	/*

	 * we shift down quite a bit.  We're using byte
@@ -567,7 +567,7 @@ static int rbio_can_merge(struct btrfs_raid_bio *last, 
	    test_bit(RBIO_CACHE_BIT, &cur->flags))

		return 0;



	if (last->bioc->raid_map[0] != cur->bioc->raid_map[0])

	if (last->bioc->full_stripe_logical != cur->bioc->full_stripe_logical)

		return 0;



	/* we can't merge with different operations */
@@ -661,7 +661,7 @@ static noinline int lock_stripe_add(struct btrfs_raid_bio *rbio) 


	spin_lock(&h->lock);

	list_for_each_entry(cur, &h->hash_list, hash_list) {

		if (cur->bioc->raid_map[0] != rbio->bioc->raid_map[0])

		if (cur->bioc->full_stripe_logical != rbio->bioc->full_stripe_logical)

			continue;



		spin_lock(&cur->bio_list_lock);
@@ -1113,7 +1113,7 @@ static void index_one_bio(struct btrfs_raid_bio *rbio, struct bio *bio) 
	struct bio_vec bvec;

	struct bvec_iter iter;

	u32 offset = (bio->bi_iter.bi_sector << SECTOR_SHIFT) -

		     rbio->bioc->raid_map[0];

		     rbio->bioc->full_stripe_logical;



	bio_for_each_segment(bvec, bio, iter) {

		u32 bvec_offset;
@@ -1337,7 +1337,7 @@ static void set_rbio_range_error(struct btrfs_raid_bio *rbio, struct bio *bio) 
{

	struct btrfs_fs_info *fs_info = rbio->bioc->fs_info;

	u32 offset = (bio->bi_iter.bi_sector << SECTOR_SHIFT) -

		     rbio->bioc->raid_map[0];

		     rbio->bioc->full_stripe_logical;

	int total_nr_sector = offset >> fs_info->sectorsize_bits;



	ASSERT(total_nr_sector < rbio->nr_data * rbio->stripe_nsectors);
@@ -1614,7 +1614,7 @@ static void rbio_add_bio(struct btrfs_raid_bio *rbio, struct bio *orig_bio) 
{

	const struct btrfs_fs_info *fs_info = rbio->bioc->fs_info;

	const u64 orig_logical = orig_bio->bi_iter.bi_sector << SECTOR_SHIFT;

	const u64 full_stripe_start = rbio->bioc->raid_map[0];

	const u64 full_stripe_start = rbio->bioc->full_stripe_logical;

	const u32 orig_len = orig_bio->bi_iter.bi_size;

	const u32 sectorsize = fs_info->sectorsize;

	u64 cur_logical;
@@ -1801,9 +1801,8 @@ static int recover_vertical(struct btrfs_raid_bio *rbio, int sector_nr, 
		 * here due to a crc mismatch and we can't give them the

		 * data they want.

		 */

		if (rbio->bioc->raid_map[failb] == RAID6_Q_STRIPE) {

			if (rbio->bioc->raid_map[faila] ==

			    RAID5_P_STRIPE)

		if (failb == rbio->real_stripes - 1) {

			if (faila == rbio->real_stripes - 2)

				/*

				 * Only P and Q are corrupted.

				 * We only care about data stripes recovery,
@@ -1817,7 +1816,7 @@ static int recover_vertical(struct btrfs_raid_bio *rbio, int sector_nr, 
			goto pstripe;

		}



		if (rbio->bioc->raid_map[failb] == RAID5_P_STRIPE) {

		if (failb == rbio->real_stripes - 2) {

			raid6_datap_recov(rbio->real_stripes, sectorsize,

					  faila, pointers);

		} else {
@@ -2080,8 +2079,8 @@ static void fill_data_csums(struct btrfs_raid_bio *rbio) 
{

	struct btrfs_fs_info *fs_info = rbio->bioc->fs_info;

	struct btrfs_root *csum_root = btrfs_csum_root(fs_info,

						       rbio->bioc->raid_map[0]);

	const u64 start = rbio->bioc->raid_map[0];

						       rbio->bioc->full_stripe_logical);

	const u64 start = rbio->bioc->full_stripe_logical;

	const u32 len = (rbio->nr_data * rbio->stripe_nsectors) <<

			fs_info->sectorsize_bits;

	int ret;
@@ -2129,7 +2128,7 @@ static void fill_data_csums(struct btrfs_raid_bio *rbio) 
	 */

	btrfs_warn_rl(fs_info,

"sub-stripe write for full stripe %llu is not safe, failed to get csum: %d",

			rbio->bioc->raid_map[0], ret);

			rbio->bioc->full_stripe_logical, ret);

no_csum:

	kfree(rbio->csum_buf);

	bitmap_free(rbio->csum_bitmap);
@@ -2385,10 +2384,10 @@ void raid56_add_scrub_pages(struct btrfs_raid_bio *rbio, struct page *page, 
	int stripe_offset;

	int index;



	ASSERT(logical >= rbio->bioc->raid_map[0]);

	ASSERT(logical + sectorsize <= rbio->bioc->raid_map[0] +

	ASSERT(logical >= rbio->bioc->full_stripe_logical);

	ASSERT(logical + sectorsize <= rbio->bioc->full_stripe_logical +

				       BTRFS_STRIPE_LEN * rbio->nr_data);

	stripe_offset = (int)(logical - rbio->bioc->raid_map[0]);

	stripe_offset = (int)(logical - rbio->bioc->full_stripe_logical);

	index = stripe_offset / sectorsize;

	rbio->bio_sectors[index].page = page;

	rbio->bio_sectors[index].pgoff = pgoff;

fs/btrfs/scrub.c

+14 −11
Original line number Diff line number Diff line
@@ -1430,7 +1430,7 @@ static inline int scrub_nr_raid_mirrors(struct btrfs_io_context *bioc) 
}



static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type,

						 u64 *raid_map,

						 u64 full_stripe_logical,

						 int nstripes, int mirror,

						 int *stripe_index,

						 u64 *stripe_offset)
@@ -1438,19 +1438,22 @@ static inline void scrub_stripe_index_and_offset(u64 logical, u64 map_type, 
	int i;



	if (map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) {

		const int nr_data_stripes = (map_type & BTRFS_BLOCK_GROUP_RAID5) ?

					    nstripes - 1 : nstripes - 2;



		/* RAID5/6 */

		for (i = 0; i < nstripes; i++) {

			if (raid_map[i] == RAID6_Q_STRIPE ||

			    raid_map[i] == RAID5_P_STRIPE)

				continue;

		for (i = 0; i < nr_data_stripes; i++) {

			const u64 data_stripe_start = full_stripe_logical +

						(i * BTRFS_STRIPE_LEN);



			if (logical >= raid_map[i] &&

			    logical < raid_map[i] + BTRFS_STRIPE_LEN)

			if (logical >= data_stripe_start &&

			    logical < data_stripe_start + BTRFS_STRIPE_LEN)

				break;

		}



		*stripe_index = i;

		*stripe_offset = logical - raid_map[i];

		*stripe_offset = (logical - full_stripe_logical) &

				 BTRFS_STRIPE_LEN_MASK;

	} else {

		/* The other RAID type */

		*stripe_index = mirror;
@@ -1538,7 +1541,7 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock, 


			scrub_stripe_index_and_offset(logical,

						      bioc->map_type,

						      bioc->raid_map,

						      bioc->full_stripe_logical,

						      bioc->num_stripes -

						      bioc->replace_nr_stripes,

						      mirror_index,
@@ -2398,7 +2401,7 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock) 
	btrfs_bio_counter_inc_blocked(fs_info);

	ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,

			       &length, &bioc);

	if (ret || !bioc || !bioc->raid_map)

	if (ret || !bioc)

		goto bioc_out;



	if (WARN_ON(!sctx->is_dev_replace ||
@@ -3007,7 +3010,7 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity) 
	btrfs_bio_counter_inc_blocked(fs_info);

	ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start,

			       &length, &bioc);

	if (ret || !bioc || !bioc->raid_map)

	if (ret || !bioc)

		goto bioc_out;



	bio = bio_alloc(NULL, BIO_MAX_VECS, REQ_OP_READ, GFP_NOFS);

fs/btrfs/volumes.c

+33 −51
Original line number Diff line number Diff line
@@ -5894,25 +5894,6 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info, 
	return preferred_mirror;

}



/* Bubble-sort the stripe set to put the parity/syndrome stripes last */

static void sort_parity_stripes(struct btrfs_io_context *bioc, int num_stripes)

{

	int i;

	int again = 1;



	while (again) {

		again = 0;

		for (i = 0; i < num_stripes - 1; i++) {

			/* Swap if parity is on a smaller index */

			if (bioc->raid_map[i] > bioc->raid_map[i + 1]) {

				swap(bioc->stripes[i], bioc->stripes[i + 1]);

				swap(bioc->raid_map[i], bioc->raid_map[i + 1]);

				again = 1;

			}

		}

	}

}



static struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_info,

						       u16 total_stripes)

{
@@ -5922,12 +5903,7 @@ static struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_ 
		 /* The size of btrfs_io_context */

		sizeof(struct btrfs_io_context) +

		/* Plus the variable array for the stripes */

		sizeof(struct btrfs_io_stripe) * (total_stripes) +

		/*

		 * Plus the raid_map, which includes both the tgt dev

		 * and the stripes.

		 */

		sizeof(u64) * (total_stripes),

		sizeof(struct btrfs_io_stripe) * (total_stripes),

		GFP_NOFS);



	if (!bioc)
@@ -5936,8 +5912,8 @@ static struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_ 
	refcount_set(&bioc->refs, 1);



	bioc->fs_info = fs_info;

	bioc->raid_map = (u64 *)(bioc->stripes + total_stripes);

	bioc->replace_stripe_src = -1;

	bioc->full_stripe_logical = (u64)-1;



	return bioc;

}
@@ -6541,33 +6517,39 @@ int __btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op, 
	}

	bioc->map_type = map->type;



	/*

	 * For RAID56 full map, we need to make sure the stripes[] follows the

	 * rule that data stripes are all ordered, then followed with P and Q

	 * (if we have).

	 *

	 * It's still mostly the same as other profiles, just with extra rotation.

	 */

	if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK && need_raid_map &&

	    (need_full_stripe(op) || mirror_num > 1)) {

		/*

		 * For RAID56 @stripe_nr is already the number of full stripes

		 * before us, which is also the rotation value (needs to modulo

		 * with num_stripes).

		 *

		 * In this case, we just add @stripe_nr with @i, then do the

		 * modulo, to reduce one modulo call.

		 */

		bioc->full_stripe_logical = em->start +

			((stripe_nr * data_stripes) << BTRFS_STRIPE_LEN_SHIFT);

		for (i = 0; i < num_stripes; i++)

			set_io_stripe(&bioc->stripes[i], map,

				      (i + stripe_nr) % num_stripes,

				      stripe_offset, stripe_nr);

	} else {

		/*

		 * For all other non-RAID56 profiles, just copy the target

		 * stripe into the bioc.

		 */

		for (i = 0; i < num_stripes; i++) {

		set_io_stripe(&bioc->stripes[i], map, stripe_index, stripe_offset,

			      stripe_nr);

			set_io_stripe(&bioc->stripes[i], map, stripe_index,

				      stripe_offset, stripe_nr);

			stripe_index++;

		}



	/* Build raid_map */

	if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK && need_raid_map &&

	    (need_full_stripe(op) || mirror_num > 1)) {

		u64 tmp;

		unsigned rot;



		/* Work out the disk rotation on this stripe-set */

		rot = stripe_nr % num_stripes;



		/* Fill in the logical address of each stripe */

		tmp = stripe_nr * data_stripes;

		for (i = 0; i < data_stripes; i++)

			bioc->raid_map[(i + rot) % num_stripes] =

				em->start + ((tmp + i) << BTRFS_STRIPE_LEN_SHIFT);



		bioc->raid_map[(i + rot) % map->num_stripes] = RAID5_P_STRIPE;

		if (map->type & BTRFS_BLOCK_GROUP_RAID6)

			bioc->raid_map[(i + rot + 1) % num_stripes] =

				RAID6_Q_STRIPE;



		sort_parity_stripes(bioc, num_stripes);

	}



	if (need_full_stripe(op))

fs/btrfs/volumes.h

+15 −4
Original line number Diff line number Diff line
@@ -460,11 +460,22 @@ struct btrfs_io_context { 
	u16 replace_nr_stripes;

	s16 replace_stripe_src;

	/*

	 * logical block numbers for the start of each stripe

	 * The last one or two are p/q.  These are sorted,

	 * so raid_map[0] is the start of our full stripe

	 * Logical bytenr of the full stripe start, only for RAID56 cases.

	 *

	 * When this value is set to other than (u64)-1, the stripes[] should

	 * follow this pattern:

	 *

	 * (real_stripes = num_stripes - replace_nr_stripes)

	 * (data_stripes = (is_raid6) ? (real_stripes - 2) : (real_stripes - 1))

	 *

	 * stripes[0]:			The first data stripe

	 * stripes[1]:			The second data stripe

	 * ...

	 * stripes[data_stripes - 1]:	The last data stripe

	 * stripes[data_stripes]:	The P stripe

	 * stripes[data_stripes + 1]:	The Q stripe (only for RAID6).

	 */

	u64 *raid_map;

	u64 full_stripe_logical;

	struct btrfs_io_stripe stripes[];

};

include/trace/events/btrfs.h

+1 −1
Original line number Diff line number Diff line
@@ -2422,7 +2422,7 @@ DECLARE_EVENT_CLASS(btrfs_raid56_bio, 
	),



	TP_fast_assign_btrfs(rbio->bioc->fs_info,

		__entry->full_stripe	= rbio->bioc->raid_map[0];

		__entry->full_stripe	= rbio->bioc->full_stripe_logical;

		__entry->physical	= bio->bi_iter.bi_sector << SECTOR_SHIFT;

		__entry->len		= bio->bi_iter.bi_size;

		__entry->opf		= bio_op(bio);