linux-kernel - [PATCH v2 1/2] ext4: prevent used blocks from being allocated during fast commit replay

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Message-Id: <20220110035141.1980-2-yinxin.x@bytedance.com>
Date:   Mon, 10 Jan 2022 11:51:40 +0800
From:   Xin Yin <yinxin.x@...edance.com>
To:     harshadshirwadkar@...il.com, tytso@....edu,
        adilger.kernel@...ger.ca
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xin Yin <yinxin.x@...edance.com>
Subject: [PATCH v2 1/2] ext4: prevent used blocks from being allocated during fast commit replay

during fast commit replay procedure, we clear inode blocks bitmap in
ext4_ext_clear_bb(), this may cause ext4_mb_new_blocks_simple() allocate
blocks still in use.

make ext4_fc_record_regions() also record physical disk regions used by
inodes during replay procedure. Then ext4_mb_new_blocks_simple() can
excludes these blocks in use.

Signed-off-by: Xin Yin <yinxin.x@...edance.com>
---
v2: add comments for behavior change of ext4_fc_record_regions().
---
 fs/ext4/ext4.h        |  2 ++
 fs/ext4/extents.c     |  4 ++++
 fs/ext4/fast_commit.c | 20 +++++++++++++++-----
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 82fa51d6f145..7b0686758691 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2932,6 +2932,8 @@ bool ext4_fc_replay_check_excluded(struct super_block *sb, ext4_fsblk_t block);
 void ext4_fc_replay_cleanup(struct super_block *sb);
 int ext4_fc_commit(journal_t *journal, tid_t commit_tid);
 int __init ext4_fc_init_dentry_cache(void);
+int ext4_fc_record_regions(struct super_block *sb, int ino,
+		     ext4_lblk_t lblk, ext4_fsblk_t pblk, int len, int replay);
 
 /* mballoc.c */
 extern const struct seq_operations ext4_mb_seq_groups_ops;
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index c3e76a5de661..9b6c76629c93 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -6096,11 +6096,15 @@ int ext4_ext_clear_bb(struct inode *inode)
 
 					ext4_mb_mark_bb(inode->i_sb,
 							path[j].p_block, 1, 0);
+					ext4_fc_record_regions(inode->i_sb, inode->i_ino,
+							0, path[j].p_block, 1, 1);
 				}
 				ext4_ext_drop_refs(path);
 				kfree(path);
 			}
 			ext4_mb_mark_bb(inode->i_sb, map.m_pblk, map.m_len, 0);
+			ext4_fc_record_regions(inode->i_sb, inode->i_ino,
+					map.m_lblk, map.m_pblk, map.m_len, 1);
 		}
 		cur = cur + map.m_len;
 	}
diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 23d13983a281..0812438d10cc 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -1564,16 +1564,23 @@ static int ext4_fc_replay_create(struct super_block *sb, struct ext4_fc_tl *tl,
 }
 
 /*
- * Record physical disk regions which are in use as per fast commit area. Our
- * simple replay phase allocator excludes these regions from allocation.
+ * Record physical disk regions which are in use as per fast commit area,
+ * and used by inodes during replay phase. Our simple replay phase
+ * allocator excludes these regions from allocation.
  */
-static int ext4_fc_record_regions(struct super_block *sb, int ino,
-		ext4_lblk_t lblk, ext4_fsblk_t pblk, int len)
+int ext4_fc_record_regions(struct super_block *sb, int ino,
+		ext4_lblk_t lblk, ext4_fsblk_t pblk, int len, int replay)
 {
 	struct ext4_fc_replay_state *state;
 	struct ext4_fc_alloc_region *region;
 
 	state = &EXT4_SB(sb)->s_fc_replay_state;
+	/*
+	 * during replay phase, the fc_regions_valid may not same as
+	 * fc_regions_used, update it when do new additions.
+	 */
+	if (replay && state->fc_regions_used != state->fc_regions_valid)
+		state->fc_regions_used = state->fc_regions_valid;
 	if (state->fc_regions_used == state->fc_regions_size) {
 		state->fc_regions_size +=
 			EXT4_FC_REPLAY_REALLOC_INCREMENT;
@@ -1591,6 +1598,9 @@ static int ext4_fc_record_regions(struct super_block *sb, int ino,
 	region->pblk = pblk;
 	region->len = len;
 
+	if (replay)
+		state->fc_regions_valid++;
+
 	return 0;
 }
 
@@ -1938,7 +1948,7 @@ static int ext4_fc_replay_scan(journal_t *journal,
 			ret = ext4_fc_record_regions(sb,
 				le32_to_cpu(ext.fc_ino),
 				le32_to_cpu(ex->ee_block), ext4_ext_pblock(ex),
-				ext4_ext_get_actual_len(ex));
+				ext4_ext_get_actual_len(ex), 0);
 			if (ret < 0)
 				break;
 			ret = JBD2_FC_REPLAY_CONTINUE;
-- 
2.20.1