Commit 5921aaa1 authored by LiFan's avatar LiFan Committed by Jaegeuk Kim
Browse files

f2fs: fix concurrent problem for updating free bitmap 



alloc_nid_failed and scan_nat_page can be called at the same time,
and we haven't protected add_free_nid and update_free_nid_bitmap
with the same nid_list_lock. That could lead to

Thread A				Thread B
- __build_free_nids
 - scan_nat_page
  - add_free_nid
					- alloc_nid_failed
					 - update_free_nid_bitmap
  - update_free_nid_bitmap

scan_nat_page will clear the free bitmap since the nid is PREALLOC_NID,
but alloc_nid_failed needs to set the free bitmap. This results in
free nid with free bitmap cleared.
This patch update the bitmap under the same nid_list_lock in add_free_nid.
And use __GFP_NOFAIL to make sure to update status of free nid correctly.

Signed-off-by: default avatarFan li <fanofcode.li@samsung.com>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 2ab56a59

fs/f2fs/node.c

+43 −42
Original line number Diff line number Diff line
@@ -1812,8 +1812,33 @@ static void __move_free_nid(struct f2fs_sb_info *sbi, struct free_nid *i, 
	}

}



static void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid,

							bool set, bool build)

{

	struct f2fs_nm_info *nm_i = NM_I(sbi);

	unsigned int nat_ofs = NAT_BLOCK_OFFSET(nid);

	unsigned int nid_ofs = nid - START_NID(nid);



	if (!test_bit_le(nat_ofs, nm_i->nat_block_bitmap))

		return;



	if (set) {

		if (test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))

			return;

		__set_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);

		nm_i->free_nid_count[nat_ofs]++;

	} else {

		if (!test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))

			return;

		__clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);

		if (!build)

			nm_i->free_nid_count[nat_ofs]--;

	}

}



/* return if the nid is recognized as free */

static bool add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build)

static bool add_free_nid(struct f2fs_sb_info *sbi,

				nid_t nid, bool build, bool update)

{

	struct f2fs_nm_info *nm_i = NM_I(sbi);

	struct free_nid *i, *e;
@@ -1829,8 +1854,7 @@ static bool add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build) 
	i->nid = nid;

	i->state = FREE_NID;



	if (radix_tree_preload(GFP_NOFS))

		goto err;

	radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);



	spin_lock(&nm_i->nid_list_lock);
@@ -1871,9 +1895,14 @@ static bool add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build) 
	ret = true;

	err = __insert_free_nid(sbi, i, FREE_NID);

err_out:

	if (update) {

		update_free_nid_bitmap(sbi, nid, ret, build);

		if (!build)

			nm_i->available_nids++;

	}

	spin_unlock(&nm_i->nid_list_lock);

	radix_tree_preload_end();

err:



	if (err)

		kmem_cache_free(free_nid_slab, i);

	return ret;
@@ -1897,30 +1926,6 @@ static void remove_free_nid(struct f2fs_sb_info *sbi, nid_t nid) 
		kmem_cache_free(free_nid_slab, i);

}



static void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid,

							bool set, bool build)

{

	struct f2fs_nm_info *nm_i = NM_I(sbi);

	unsigned int nat_ofs = NAT_BLOCK_OFFSET(nid);

	unsigned int nid_ofs = nid - START_NID(nid);



	if (!test_bit_le(nat_ofs, nm_i->nat_block_bitmap))

		return;



	if (set) {

		if (test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))

			return;

		__set_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);

		nm_i->free_nid_count[nat_ofs]++;

	} else {

		if (!test_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]))

			return;

		__clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);

		if (!build)

			nm_i->free_nid_count[nat_ofs]--;

	}

}



static void scan_nat_page(struct f2fs_sb_info *sbi,

			struct page *nat_page, nid_t start_nid)

{
@@ -1935,20 +1940,20 @@ static void scan_nat_page(struct f2fs_sb_info *sbi, 
	i = start_nid % NAT_ENTRY_PER_BLOCK;



	for (; i < NAT_ENTRY_PER_BLOCK; i++, start_nid++) {

		bool freed = false;



		if (unlikely(start_nid >= nm_i->max_nid))

			break;



		blk_addr = le32_to_cpu(nat_blk->entries[i].block_addr);

		f2fs_bug_on(sbi, blk_addr == NEW_ADDR);

		if (blk_addr == NULL_ADDR)

			freed = add_free_nid(sbi, start_nid, true);

		if (blk_addr == NULL_ADDR) {

			add_free_nid(sbi, start_nid, true, true);

		} else {

			spin_lock(&NM_I(sbi)->nid_list_lock);

		update_free_nid_bitmap(sbi, start_nid, freed, true);

			update_free_nid_bitmap(sbi, start_nid, false, true);

			spin_unlock(&NM_I(sbi)->nid_list_lock);

		}

	}

}



static void scan_curseg_cache(struct f2fs_sb_info *sbi)

{
@@ -1964,7 +1969,7 @@ static void scan_curseg_cache(struct f2fs_sb_info *sbi) 
		addr = le32_to_cpu(nat_in_journal(journal, i).block_addr);

		nid = le32_to_cpu(nid_in_journal(journal, i));

		if (addr == NULL_ADDR)

			add_free_nid(sbi, nid, true);

			add_free_nid(sbi, nid, true, false);

		else

			remove_free_nid(sbi, nid);

	}
@@ -1991,7 +1996,7 @@ static void scan_free_nid_bits(struct f2fs_sb_info *sbi) 
				break;



			nid = i * NAT_ENTRY_PER_BLOCK + idx;

			add_free_nid(sbi, nid, true);

			add_free_nid(sbi, nid, true, false);



			if (nm_i->nid_cnt[FREE_NID] >= MAX_FREE_NIDS)

				goto out;
@@ -2497,11 +2502,7 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi, 
		nat_reset_flag(ne);

		__clear_nat_cache_dirty(NM_I(sbi), set, ne);

		if (nat_get_blkaddr(ne) == NULL_ADDR) {

			add_free_nid(sbi, nid, false);

			spin_lock(&NM_I(sbi)->nid_list_lock);

			NM_I(sbi)->available_nids++;

			update_free_nid_bitmap(sbi, nid, true, false);

			spin_unlock(&NM_I(sbi)->nid_list_lock);

			add_free_nid(sbi, nid, false, true);

		} else {

			spin_lock(&NM_I(sbi)->nid_list_lock);

			update_free_nid_bitmap(sbi, nid, false, false);

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