Commit 9acaa641 authored by Johannes Thumshirn's avatar Johannes Thumshirn Committed by David Sterba
Browse files

btrfs: scrub: implement raid stripe tree support 



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.

In case we're scrubbing a filesystem which uses the RAID stripe tree for
multi-device logical to physical address translation, perform an extra
block mapping step to get the real on-disk stripe length from the stripe
tree when scrubbing the sectors.

This prevents a double completion of the btrfs_bio caused by splitting the
underlying bio and ultimately a use-after-free.

Signed-off-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 10e27980

fs/btrfs/bio.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

fs/btrfs/raid-stripe-tree.c

+6 −1
Original line number Diff line number Diff line
@@ -171,6 +171,11 @@ 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;
@@ -246,7 +251,7 @@ 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) {

		if (IS_ENABLED(CONFIG_BTRFS_DEBUG))

			btrfs_print_tree(leaf, 1);

		btrfs_err(fs_info,

fs/btrfs/scrub.c

+71 −0
Original line number Diff line number Diff line
@@ -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 +1635,71 @@ 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;

	u64 stripe_len = BTRFS_STRIPE_LEN;

	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 >= stripe_len)) {

			ASSERT(bbio->bio.bi_iter.bi_size);

			atomic_inc(&stripe->pending_io);

			btrfs_submit_bio(bbio, mirror);

			bbio = NULL;

		}



		if (!bbio) {

			struct btrfs_io_stripe io_stripe = {};

			struct btrfs_io_context *bioc = NULL;

			const u64 logical = stripe->logical +

					    (i << fs_info->sectorsize_bits);

			int err;



			bbio = btrfs_bio_alloc(stripe->nr_sectors, REQ_OP_READ,

					       fs_info, scrub_read_endio, stripe);

			bbio->bio.bi_iter.bi_sector = logical >> SECTOR_SHIFT;



			io_stripe.is_scrub = true;

			err = btrfs_map_block(fs_info, BTRFS_MAP_READ, logical,

					      &stripe_len, &bioc, &io_stripe,

					      &mirror);

			btrfs_put_bioc(bioc);

			if (err) {

				btrfs_bio_end_io(bbio,

						 errno_to_blk_status(err));

				return;

			}

		}



		__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 +1711,11 @@ 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);

fs/btrfs/volumes.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

};