Commit bbf9f7d9 authored by Sahitya Tummala's avatar Sahitya Tummala Committed by Jaegeuk Kim
Browse files

f2fs: Fix indefinite loop in f2fs_gc() 



Policy - Foreground GC, LFS and greedy GC mode.

Under this policy, f2fs_gc() loops forever to GC as it doesn't have
enough free segements to proceed and thus it keeps calling gc_more
for the same victim segment.  This can happen if the selected victim
segment could not be GC'd due to failed blkaddr validity check i.e.
is_alive() returns false for the blocks set in current validity map.

Fix this by keeping track of such invalid segments and skip those
segments for selection in get_victim_by_default() to avoid endless
GC loop under such error scenarios. Currently, add this logic under
CONFIG_F2FS_CHECK_FS to be able to root cause the issue in debug
version.

Signed-off-by: default avatarSahitya Tummala <stummala@codeaurora.org>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: fix wrong bitmap size]
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 2fde3dd1

fs/f2fs/gc.c

+24 −1
Original line number Diff line number Diff line
@@ -382,6 +382,16 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi, 
			nsearched++;

		}



#ifdef CONFIG_F2FS_CHECK_FS

		/*

		 * skip selecting the invalid segno (that is failed due to block

		 * validity check failure during GC) to avoid endless GC loop in

		 * such cases.

		 */

		if (test_bit(segno, sm->invalid_segmap))

			goto next;

#endif



		secno = GET_SEC_FROM_SEG(sbi, segno);



		if (sec_usage_check(sbi, secno))
@@ -627,8 +637,21 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, 
	source_blkaddr = datablock_addr(NULL, node_page, ofs_in_node);

	f2fs_put_page(node_page, 1);



	if (source_blkaddr != blkaddr)

	if (source_blkaddr != blkaddr) {

#ifdef CONFIG_F2FS_CHECK_FS

		unsigned int segno = GET_SEGNO(sbi, blkaddr);

		unsigned long offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);



		if (unlikely(check_valid_map(sbi, segno, offset))) {

			if (!test_and_set_bit(segno, SIT_I(sbi)->invalid_segmap)) {

				f2fs_err(sbi, "mismatched blkaddr %u (source_blkaddr %u) in seg %u\n",

						blkaddr, source_blkaddr, segno);

				f2fs_bug_on(sbi, 1);

			}

		}

#endif

		return false;

	}

	return true;

}

fs/f2fs/segment.c

+19 −8
Original line number Diff line number Diff line
@@ -817,9 +817,13 @@ static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno, 
		if (test_and_clear_bit(segno, dirty_i->dirty_segmap[t]))

			dirty_i->nr_dirty[t]--;



		if (get_valid_blocks(sbi, segno, true) == 0)

		if (get_valid_blocks(sbi, segno, true) == 0) {

			clear_bit(GET_SEC_FROM_SEG(sbi, segno),

						dirty_i->victim_secmap);

#ifdef CONFIG_F2FS_CHECK_FS

			clear_bit(segno, SIT_I(sbi)->invalid_segmap);

#endif

		}

	}

}
@@ -3946,7 +3950,7 @@ static int build_sit_info(struct f2fs_sb_info *sbi) 
	struct sit_info *sit_i;

	unsigned int sit_segs, start;

	char *src_bitmap, *bitmap;

	unsigned int bitmap_size;

	unsigned int bitmap_size, main_bitmap_size, sit_bitmap_size;



	/* allocate memory for SIT information */

	sit_i = f2fs_kzalloc(sbi, sizeof(struct sit_info), GFP_KERNEL);
@@ -3962,8 +3966,8 @@ static int build_sit_info(struct f2fs_sb_info *sbi) 
	if (!sit_i->sentries)

		return -ENOMEM;



	bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));

	sit_i->dirty_sentries_bitmap = f2fs_kvzalloc(sbi, bitmap_size,

	main_bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));

	sit_i->dirty_sentries_bitmap = f2fs_kvzalloc(sbi, main_bitmap_size,

								GFP_KERNEL);

	if (!sit_i->dirty_sentries_bitmap)

		return -ENOMEM;
@@ -4012,17 +4016,23 @@ static int build_sit_info(struct f2fs_sb_info *sbi) 
	sit_segs = le32_to_cpu(raw_super->segment_count_sit) >> 1;



	/* setup SIT bitmap from ckeckpoint pack */

	bitmap_size = __bitmap_size(sbi, SIT_BITMAP);

	sit_bitmap_size = __bitmap_size(sbi, SIT_BITMAP);

	src_bitmap = __bitmap_ptr(sbi, SIT_BITMAP);



	sit_i->sit_bitmap = kmemdup(src_bitmap, bitmap_size, GFP_KERNEL);

	sit_i->sit_bitmap = kmemdup(src_bitmap, sit_bitmap_size, GFP_KERNEL);

	if (!sit_i->sit_bitmap)

		return -ENOMEM;



#ifdef CONFIG_F2FS_CHECK_FS

	sit_i->sit_bitmap_mir = kmemdup(src_bitmap, bitmap_size, GFP_KERNEL);

	sit_i->sit_bitmap_mir = kmemdup(src_bitmap,

					sit_bitmap_size, GFP_KERNEL);

	if (!sit_i->sit_bitmap_mir)

		return -ENOMEM;



	sit_i->invalid_segmap = f2fs_kvzalloc(sbi,

					main_bitmap_size, GFP_KERNEL);

	if (!sit_i->invalid_segmap)

		return -ENOMEM;

#endif



	/* init SIT information */
@@ -4031,7 +4041,7 @@ static int build_sit_info(struct f2fs_sb_info *sbi) 
	sit_i->sit_base_addr = le32_to_cpu(raw_super->sit_blkaddr);

	sit_i->sit_blocks = sit_segs << sbi->log_blocks_per_seg;

	sit_i->written_valid_blocks = 0;

	sit_i->bitmap_size = bitmap_size;

	sit_i->bitmap_size = sit_bitmap_size;

	sit_i->dirty_sentries = 0;

	sit_i->sents_per_block = SIT_ENTRY_PER_BLOCK;

	sit_i->elapsed_time = le64_to_cpu(sbi->ckpt->elapsed_time);
@@ -4514,6 +4524,7 @@ static void destroy_sit_info(struct f2fs_sb_info *sbi) 
	kvfree(sit_i->sit_bitmap);

#ifdef CONFIG_F2FS_CHECK_FS

	kvfree(sit_i->sit_bitmap_mir);

	kvfree(sit_i->invalid_segmap);

#endif

	kvfree(sit_i);

}

fs/f2fs/segment.h

+3 −0
Original line number Diff line number Diff line
@@ -230,6 +230,9 @@ struct sit_info { 
	char *sit_bitmap;		/* SIT bitmap pointer */

#ifdef CONFIG_F2FS_CHECK_FS

	char *sit_bitmap_mir;		/* SIT bitmap mirror */



	/* bitmap of segments to be ignored by GC in case of errors */

	unsigned long *invalid_segmap;

#endif

	unsigned int bitmap_size;	/* SIT bitmap size */

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