1 files changed, 46 insertions, 25 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 4ea4fe92e..23e56c1ff 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3089,6 +3089,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 				struct ext4_allocation_request *ar)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
+	struct ext4_super_block *es = sbi->s_es;
 	int bsbits, max;
 	ext4_lblk_t end;
 	loff_t size, start_off;
@@ -3269,18 +3270,21 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	ac->ac_g_ex.fe_len = EXT4_NUM_B2C(sbi, size);
 
 	/* define goal start in order to merge */
-	if (ar->pright && (ar->lright == (start + size))) {
+	if (ar->pright && (ar->lright == (start + size)) &&
+	    ar->pright >= size &&
+	    ar->pright - size >= le32_to_cpu(es->s_first_data_block)) {
 		/* merge to the right */
 		ext4_get_group_no_and_offset(ac->ac_sb, ar->pright - size,
-						&ac->ac_f_ex.fe_group,
-						&ac->ac_f_ex.fe_start);
+						&ac->ac_g_ex.fe_group,
+						&ac->ac_g_ex.fe_start);
 		ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;
 	}
-	if (ar->pleft && (ar->lleft + 1 == start)) {
+	if (ar->pleft && (ar->lleft + 1 == start) &&
+	    ar->pleft + 1 < ext4_blocks_count(es)) {
 		/* merge to the left */
 		ext4_get_group_no_and_offset(ac->ac_sb, ar->pleft + 1,
-						&ac->ac_f_ex.fe_group,
-						&ac->ac_f_ex.fe_start);
+						&ac->ac_g_ex.fe_group,
+						&ac->ac_g_ex.fe_start);
 		ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;
 	}
 
@@ -3372,6 +3376,7 @@ static void ext4_mb_use_inode_pa(struct ext4_allocation_context *ac,
 	BUG_ON(start < pa->pa_pstart);
 	BUG_ON(end > pa->pa_pstart + EXT4_C2B(sbi, pa->pa_len));
 	BUG_ON(pa->pa_free < len);
+	BUG_ON(ac->ac_b_ex.fe_len <= 0);
 	pa->pa_free -= len;
 
 	mb_debug(1, "use %llu/%u from inode pa %p\n", start, len, pa);
@@ -3676,10 +3681,8 @@ ext4_mb_new_inode_pa(struct ext4_allocation_context *ac)
 		return -ENOMEM;
 
 	if (ac->ac_b_ex.fe_len < ac->ac_g_ex.fe_len) {
-		int winl;
-		int wins;
-		int win;
-		int offs;
+		int new_bex_start;
+		int new_bex_end;
 
 		/* we can't allocate as much as normalizer wants.
 		 * so, found space must get proper lstart
@@ -3687,26 +3690,40 @@ ext4_mb_new_inode_pa(struct ext4_allocation_context *ac)
 		BUG_ON(ac->ac_g_ex.fe_logical > ac->ac_o_ex.fe_logical);
 		BUG_ON(ac->ac_g_ex.fe_len < ac->ac_o_ex.fe_len);
 
-		/* we're limited by original request in that
-		 * logical block must be covered any way
-		 * winl is window we can move our chunk within */
-		winl = ac->ac_o_ex.fe_logical - ac->ac_g_ex.fe_logical;
+		/*
+		 * Use the below logic for adjusting best extent as it keeps
+		 * fragmentation in check while ensuring logical range of best
+		 * extent doesn't overflow out of goal extent:
+		 *
+		 * 1. Check if best ex can be kept at end of goal and still
+		 *    cover original start
+		 * 2. Else, check if best ex can be kept at start of goal and
+		 *    still cover original start
+		 * 3. Else, keep the best ex at start of original request.
+		 */
+		new_bex_end = ac->ac_g_ex.fe_logical +
+			EXT4_C2B(sbi, ac->ac_g_ex.fe_len);
+		new_bex_start = new_bex_end - EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
+		if (ac->ac_o_ex.fe_logical >= new_bex_start)
+			goto adjust_bex;
 
-		/* also, we should cover whole original request */
-		wins = EXT4_C2B(sbi, ac->ac_b_ex.fe_len - ac->ac_o_ex.fe_len);
+		new_bex_start = ac->ac_g_ex.fe_logical;
+		new_bex_end =
+			new_bex_start + EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
+		if (ac->ac_o_ex.fe_logical < new_bex_end)
+			goto adjust_bex;
 
-		/* the smallest one defines real window */
-		win = min(winl, wins);
+		new_bex_start = ac->ac_o_ex.fe_logical;
+		new_bex_end =
+			new_bex_start + EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
 
-		offs = ac->ac_o_ex.fe_logical %
-			EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
-		if (offs && offs < win)
-			win = offs;
+adjust_bex:
+		ac->ac_b_ex.fe_logical = new_bex_start;
 
-		ac->ac_b_ex.fe_logical = ac->ac_o_ex.fe_logical -
-			EXT4_NUM_B2C(sbi, win);
 		BUG_ON(ac->ac_o_ex.fe_logical < ac->ac_b_ex.fe_logical);
 		BUG_ON(ac->ac_o_ex.fe_len > ac->ac_b_ex.fe_len);
+		BUG_ON(new_bex_end > (ac->ac_g_ex.fe_logical +
+				      EXT4_C2B(sbi, ac->ac_g_ex.fe_len)));
 	}
 
 	/* preallocation can change ac_b_ex, thus we store actually
@@ -3893,7 +3910,11 @@ ext4_mb_release_group_pa(struct ext4_buddy *e4b,
 	trace_ext4_mb_release_group_pa(sb, pa);
 	BUG_ON(pa->pa_deleted == 0);
 	ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit);
-	BUG_ON(group != e4b->bd_group && pa->pa_len != 0);
+	if (unlikely(group != e4b->bd_group && pa->pa_len != 0)) {
+		ext4_warning(sb, "bad group: expected %u, group %u, pa_start %llu",
+			     e4b->bd_group, group, pa->pa_pstart);
+		return 0;
+	}
 	mb_free_blocks(pa->pa_inode, e4b, bit, pa->pa_len);
 	atomic_add(pa->pa_len, &EXT4_SB(sb)->s_mb_discarded);
 	trace_ext4_mballoc_discard(sb, NULL, group, bit, pa->pa_len);