linux-ext4 - [PATCH v3 3/3] ext4: support flex_bg in ext4_mb_normalize

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Date:   Sat, 28 May 2022 19:00:17 +0800
From:   Baokun Li <libaokun1@...wei.com>
To:     <linux-ext4@...r.kernel.org>
CC:     <tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
        <ritesh.list@...il.com>, <lczerner@...hat.com>,
        <linux-kernel@...r.kernel.org>, <yi.zhang@...wei.com>,
        <yebin10@...wei.com>, <yukuai3@...wei.com>, <libaokun1@...wei.com>
Subject: [PATCH v3 3/3] ext4: support flex_bg in ext4_mb_normalize_request

In ext4_mb_normalize_request, the size of the allocation request is
limited to no more than EXT4_BLOCKS_PER_GROUP. Ritesh mentions that this
does not take into account the case of flex_bg groups. So we should add
support for flex_bg to make the physical blocks of large files contiguous.

Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
 fs/ext4/mballoc.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 9e06334771a3..253fc250e9a0 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4028,6 +4028,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	loff_t size, start_off;
 	loff_t orig_size __maybe_unused;
 	ext4_lblk_t start;
+	ext4_lblk_t bpg;
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_prealloc_space *pa;
 
@@ -4051,6 +4052,11 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	}
 
 	bsbits = ac->ac_sb->s_blocksize_bits;
+	bpg = EXT4_BLOCKS_PER_GROUP(ac->ac_sb);
+	if (ext4_has_feature_flex_bg(ac->ac_sb) && sbi->s_log_groups_per_flex) {
+		if (check_shl_overflow(bpg, sbi->s_log_groups_per_flex, &bpg))
+			bpg = EXT_MAX_BLOCKS;
+	}
 
 	/* first, let's learn actual file size
 	 * given current request is allocated */
@@ -4110,8 +4116,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	 * alignment does not move allocation to a different group which
 	 * makes mballoc fail assertions later.
 	 */
-	start = max(start, rounddown(ac->ac_o_ex.fe_logical,
-			(ext4_lblk_t)EXT4_BLOCKS_PER_GROUP(ac->ac_sb)));
+	start = max(start, rounddown(ac->ac_o_ex.fe_logical, bpg));
 
 	/* don't cover already allocated blocks in selected range */
 	if (ar->pleft && start <= ar->lleft) {
@@ -4125,8 +4130,8 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	 * Trim allocation request for filesystems with artificially small
 	 * groups.
 	 */
-	if (size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb))
-		size = EXT4_BLOCKS_PER_GROUP(ac->ac_sb);
+	if (size > bpg)
+		size = bpg;
 
 	end = start + size;
 
@@ -4208,7 +4213,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 			 (unsigned long) ac->ac_o_ex.fe_logical);
 		BUG();
 	}
-	BUG_ON(size <= 0 || size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
+	BUG_ON(size <= 0 || size > bpg);
 
 	/* now prepare goal request */
 
-- 
2.31.1