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btrfs: use integrated bitmaps for btrfs_raid_bio::dbitmap and finish_…
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…pbitmap

Previsouly we use "unsigned long *" for those two bitmaps.

But since we only support fixed stripe length (64KiB, already checked in
tree-checker), "unsigned long *" is really a waste of memory, while we
can just use "unsigned long".

This saves us 8 bytes in total for btrfs_raid_bio.

To be extra safe, add an ASSERT() making sure calculated
@stripe_nsectors is always smaller than BITS_PER_LONG.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Qu Wenruo authored and David Sterba committed Jul 25, 2022
1 parent 099aa97 commit c67c68e
Showing 1 changed file with 22 additions and 20 deletions.
42 changes: 22 additions & 20 deletions fs/btrfs/raid56.c
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Original file line number Diff line number Diff line change
Expand Up @@ -164,6 +164,13 @@ struct btrfs_raid_bio {
atomic_t stripes_pending;

atomic_t error;

/* Bitmap to record which horizontal stripe has data */
unsigned long dbitmap;

/* Allocated with stripe_nsectors-many bits for finish_*() calls */
unsigned long finish_pbitmap;

/*
* these are two arrays of pointers. We allocate the
* rbio big enough to hold them both and setup their
Expand All @@ -184,14 +191,8 @@ struct btrfs_raid_bio {
*/
struct sector_ptr *stripe_sectors;

/* Bitmap to record which horizontal stripe has data */
unsigned long *dbitmap;

/* allocated with real_stripes-many pointers for finish_*() calls */
void **finish_pointers;

/* Allocated with stripe_nsectors-many bits for finish_*() calls */
unsigned long *finish_pbitmap;
};

static int __raid56_parity_recover(struct btrfs_raid_bio *rbio);
Expand Down Expand Up @@ -1038,14 +1039,17 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info,
ASSERT(IS_ALIGNED(stripe_len, PAGE_SIZE));
/* PAGE_SIZE must also be aligned to sectorsize for subpage support */
ASSERT(IS_ALIGNED(PAGE_SIZE, fs_info->sectorsize));
/*
* Our current stripe len should be fixed to 64k thus stripe_nsectors
* (at most 16) should be no larger than BITS_PER_LONG.
*/
ASSERT(stripe_nsectors <= BITS_PER_LONG);

rbio = kzalloc(sizeof(*rbio) +
sizeof(*rbio->stripe_pages) * num_pages +
sizeof(*rbio->bio_sectors) * num_sectors +
sizeof(*rbio->stripe_sectors) * num_sectors +
sizeof(*rbio->finish_pointers) * real_stripes +
sizeof(*rbio->dbitmap) * BITS_TO_LONGS(stripe_nsectors) +
sizeof(*rbio->finish_pbitmap) * BITS_TO_LONGS(stripe_nsectors),
sizeof(*rbio->finish_pointers) * real_stripes,
GFP_NOFS);
if (!rbio)
return ERR_PTR(-ENOMEM);
Expand Down Expand Up @@ -1081,8 +1085,6 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info,
CONSUME_ALLOC(rbio->bio_sectors, num_sectors);
CONSUME_ALLOC(rbio->stripe_sectors, num_sectors);
CONSUME_ALLOC(rbio->finish_pointers, real_stripes);
CONSUME_ALLOC(rbio->dbitmap, BITS_TO_LONGS(stripe_nsectors));
CONSUME_ALLOC(rbio->finish_pbitmap, BITS_TO_LONGS(stripe_nsectors));
#undef CONSUME_ALLOC

if (bioc->map_type & BTRFS_BLOCK_GROUP_RAID5)
Expand Down Expand Up @@ -1939,7 +1941,7 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
* which we have data when doing parity scrub.
*/
if (rbio->operation == BTRFS_RBIO_PARITY_SCRUB &&
!test_bit(sectornr, rbio->dbitmap))
!test_bit(sectornr, &rbio->dbitmap))
continue;

/*
Expand Down Expand Up @@ -2374,7 +2376,7 @@ struct btrfs_raid_bio *raid56_parity_alloc_scrub_rbio(struct bio *bio,
}
ASSERT(i < rbio->real_stripes);

bitmap_copy(rbio->dbitmap, dbitmap, stripe_nsectors);
bitmap_copy(&rbio->dbitmap, dbitmap, stripe_nsectors);

/*
* We have already increased bio_counter when getting bioc, record it
Expand Down Expand Up @@ -2412,7 +2414,7 @@ static int alloc_rbio_essential_pages(struct btrfs_raid_bio *rbio)
int stripe;
int sectornr;

for_each_set_bit(sectornr, rbio->dbitmap, rbio->stripe_nsectors) {
for_each_set_bit(sectornr, &rbio->dbitmap, rbio->stripe_nsectors) {
for (stripe = 0; stripe < rbio->real_stripes; stripe++) {
struct page *page;
int index = (stripe * rbio->stripe_nsectors + sectornr) *
Expand All @@ -2437,7 +2439,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
struct btrfs_io_context *bioc = rbio->bioc;
const u32 sectorsize = bioc->fs_info->sectorsize;
void **pointers = rbio->finish_pointers;
unsigned long *pbitmap = rbio->finish_pbitmap;
unsigned long *pbitmap = &rbio->finish_pbitmap;
int nr_data = rbio->nr_data;
int stripe;
int sectornr;
Expand All @@ -2460,7 +2462,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,

if (bioc->num_tgtdevs && bioc->tgtdev_map[rbio->scrubp]) {
is_replace = 1;
bitmap_copy(pbitmap, rbio->dbitmap, rbio->stripe_nsectors);
bitmap_copy(pbitmap, &rbio->dbitmap, rbio->stripe_nsectors);
}

/*
Expand Down Expand Up @@ -2497,7 +2499,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
/* Map the parity stripe just once */
pointers[nr_data] = kmap_local_page(p_sector.page);

for_each_set_bit(sectornr, rbio->dbitmap, rbio->stripe_nsectors) {
for_each_set_bit(sectornr, &rbio->dbitmap, rbio->stripe_nsectors) {
struct sector_ptr *sector;
void *parity;

Expand Down Expand Up @@ -2525,7 +2527,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
memcpy(parity, pointers[rbio->scrubp], sectorsize);
else
/* Parity is right, needn't writeback */
bitmap_clear(rbio->dbitmap, sectornr, 1);
bitmap_clear(&rbio->dbitmap, sectornr, 1);
kunmap_local(parity);

for (stripe = nr_data - 1; stripe >= 0; stripe--)
Expand All @@ -2547,7 +2549,7 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
* higher layers (the bio_list in our rbio) and our p/q. Ignore
* everything else.
*/
for_each_set_bit(sectornr, rbio->dbitmap, rbio->stripe_nsectors) {
for_each_set_bit(sectornr, &rbio->dbitmap, rbio->stripe_nsectors) {
struct sector_ptr *sector;

sector = rbio_stripe_sector(rbio, rbio->scrubp, sectornr);
Expand Down Expand Up @@ -2714,7 +2716,7 @@ static void raid56_parity_scrub_stripe(struct btrfs_raid_bio *rbio)
* stripe
*/
for (stripe = 0; stripe < rbio->real_stripes; stripe++) {
for_each_set_bit(sectornr , rbio->dbitmap, rbio->stripe_nsectors) {
for_each_set_bit(sectornr, &rbio->dbitmap, rbio->stripe_nsectors) {
struct sector_ptr *sector;
/*
* We want to find all the sectors missing from the
Expand Down

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