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SubjectRe: [PATCH v9 06/11] btrfs: implement RST version of scrub
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On 2023/9/15 01:37, Johannes Thumshirn wrote:
> A filesystem that uses the RAID stripe tree for logical to physical
> address translation can't use the regular scrub path, that reads all
> stripes and then checks if a sector is unused afterwards.
>
> When using the RAID stripe tree, this will result in lookup errors, as the
> stripe tree doesn't know the requested logical addresses.
>
> Instead, look up stripes that are backed by the extent bitmap.
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
> fs/btrfs/bio.c | 2 ++
> fs/btrfs/raid-stripe-tree.c | 8 ++++++-
> fs/btrfs/scrub.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/volumes.h | 1 +
> 4 files changed, 63 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
> index ddbe6f8d4ea2..bdb6e3effdbb 100644
> --- a/fs/btrfs/bio.c
> +++ b/fs/btrfs/bio.c
> @@ -663,6 +663,8 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
> blk_status_t ret;
> int error;
>
> + smap.is_scrub = !bbio->inode;
> +
> btrfs_bio_counter_inc_blocked(fs_info);
> error = btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,
> &bioc, &smap, &mirror_num, 1);
> diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
> index 697a6e1fd255..63bf62c33436 100644
> --- a/fs/btrfs/raid-stripe-tree.c
> +++ b/fs/btrfs/raid-stripe-tree.c
> @@ -334,6 +334,11 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
> if (!path)
> return -ENOMEM;
>
> + if (stripe->is_scrub) {
> + path->skip_locking = 1;
> + path->search_commit_root = 1;
> + }
> +
> ret = btrfs_search_slot(NULL, stripe_root, &stripe_key, path, 0, 0);
> if (ret < 0)
> goto free_path;
> @@ -420,7 +425,8 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
> out:
> if (ret > 0)
> ret = -ENOENT;
> - if (ret && ret != -EIO) {
> + if (ret && ret != -EIO && !stripe->is_scrub) {
> +

One extra newline.

And why scrub path doesn't need the warning?
IIRC if our rst doesn't match extent tree, it can be a problem and we
need some error messages.

Thanks,
Qu
> if (IS_ENABLED(CONFIG_BTRFS_DEBUG))
> btrfs_print_tree(leaf, 1);
> btrfs_err(fs_info,
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index f16220ce5fba..42948b66d4be 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -23,6 +23,7 @@
> #include "accessors.h"
> #include "file-item.h"
> #include "scrub.h"
> +#include "raid-stripe-tree.h"
>
> /*
> * This is only the first step towards a full-features scrub. It reads all
> @@ -1634,6 +1635,53 @@ static void scrub_reset_stripe(struct scrub_stripe *stripe)
> }
> }
>
> +static void scrub_submit_extent_sector_read(struct scrub_ctx *sctx,
> + struct scrub_stripe *stripe)
> +{
> + struct btrfs_fs_info *fs_info = stripe->bg->fs_info;
> + struct btrfs_bio *bbio = NULL;
> + int mirror = stripe->mirror_num;
> + int i;
> +
> + atomic_inc(&stripe->pending_io);
> +
> + for_each_set_bit(i, &stripe->extent_sector_bitmap, stripe->nr_sectors) {
> + struct page *page = scrub_stripe_get_page(stripe, i);
> + unsigned int pgoff = scrub_stripe_get_page_offset(stripe, i);
> +
> + /* The current sector cannot be merged, submit the bio. */
> + if (bbio &&
> + ((i > 0 && !test_bit(i - 1, &stripe->extent_sector_bitmap)) ||
> + bbio->bio.bi_iter.bi_size >= BTRFS_STRIPE_LEN)) {
> + ASSERT(bbio->bio.bi_iter.bi_size);
> + atomic_inc(&stripe->pending_io);
> + btrfs_submit_bio(bbio, mirror);
> + bbio = NULL;
> + }
> +
> + if (!bbio) {
> + bbio = btrfs_bio_alloc(stripe->nr_sectors, REQ_OP_READ,
> + fs_info, scrub_read_endio, stripe);
> + bbio->bio.bi_iter.bi_sector = (stripe->logical +
> + (i << fs_info->sectorsize_bits)) >> SECTOR_SHIFT;
> + }
> +
> + __bio_add_page(&bbio->bio, page, fs_info->sectorsize, pgoff);
> + }
> +
> + if (bbio) {
> + ASSERT(bbio->bio.bi_iter.bi_size);
> + atomic_inc(&stripe->pending_io);
> + btrfs_submit_bio(bbio, mirror);
> + }
> +
> + if (atomic_dec_and_test(&stripe->pending_io)) {
> + wake_up(&stripe->io_wait);
> + INIT_WORK(&stripe->work, scrub_stripe_read_repair_worker);
> + queue_work(stripe->bg->fs_info->scrub_workers, &stripe->work);
> + }
> +}
> +
> static void scrub_submit_initial_read(struct scrub_ctx *sctx,
> struct scrub_stripe *stripe)
> {
> @@ -1645,6 +1693,11 @@ static void scrub_submit_initial_read(struct scrub_ctx *sctx,
> ASSERT(stripe->mirror_num > 0);
> ASSERT(test_bit(SCRUB_STRIPE_FLAG_INITIALIZED, &stripe->state));
>
> + if (btrfs_need_stripe_tree_update(fs_info, stripe->bg->flags)) {
> + scrub_submit_extent_sector_read(sctx, stripe);
> + return;
> + }
> +
> bbio = btrfs_bio_alloc(SCRUB_STRIPE_PAGES, REQ_OP_READ, fs_info,
> scrub_read_endio, stripe);
>
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 2043aff6e966..067859de8f4c 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -393,6 +393,7 @@ struct btrfs_io_stripe {
> /* Block mapping */
> u64 physical;
> u64 length;
> + bool is_scrub;
> /* For the endio handler */
> struct btrfs_io_context *bioc;
> };
>

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