[RFC PATCH 10/16] ext4: reserve meta blocks in ext4_da_reserve_space()

[Zhang Yi <yi.zhang@huaweicloud.com>]

From: Zhang Yi <yi.zhang@huawei.com>

Prepare to reserve metadata blocks for delay allocation in
ext4_da_reserve_space(), claim reserved space from the global
sbi->s_dirtyclusters_counter, and also updating tracepoints to show the
new reserved metadata blocks. This patch is just a preparation, the
reserved ext_len is always zero.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/ext4/inode.c             | 28 ++++++++++++++++------------
 include/trace/events/ext4.h | 10 ++++++++--
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index dda17b3340ce..a189009d20fa 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1439,31 +1439,37 @@ static int ext4_journalled_write_end(struct file *file,
 }
 
 /*
- * Reserve space for a single cluster
+ * Reserve space for a 'rsv_dlen' data blocks/clusters and 'rsv_extlen'
+ * extent metadata blocks.
  */
-static int ext4_da_reserve_space(struct inode *inode)
+static int ext4_da_reserve_space(struct inode *inode, unsigned int rsv_dlen,
+				 unsigned int rsv_extlen)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	struct ext4_inode_info *ei = EXT4_I(inode);
 	int ret;
 
+	if (!rsv_dlen && !rsv_extlen)
+		return 0;
+
 	/*
 	 * We will charge metadata quota at writeout time; this saves
 	 * us from metadata over-estimation, though we may go over by
 	 * a small amount in the end.  Here we just reserve for data.
 	 */
-	ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
+	ret = dquot_reserve_block(inode, EXT4_C2B(sbi, rsv_dlen));
 	if (ret)
 		return ret;
 
 	spin_lock(&ei->i_block_reservation_lock);
-	if (ext4_claim_free_clusters(sbi, 1, 0)) {
+	if (ext4_claim_free_clusters(sbi, rsv_dlen + rsv_extlen, 0)) {
 		spin_unlock(&ei->i_block_reservation_lock);
-		dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
+		dquot_release_reservation_block(inode, EXT4_C2B(sbi, rsv_dlen));
 		return -ENOSPC;
 	}
-	ei->i_reserved_data_blocks++;
-	trace_ext4_da_reserve_space(inode);
+	ei->i_reserved_data_blocks += rsv_dlen;
+	ei->i_reserved_ext_blocks += rsv_extlen;
+	trace_ext4_da_reserve_space(inode, rsv_dlen, rsv_extlen);
 	spin_unlock(&ei->i_block_reservation_lock);
 
 	return 0;       /* success */
@@ -1659,11 +1665,9 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
 		}
 	}
 
-	if (rsv_dlen > 0) {
-		ret = ext4_da_reserve_space(inode);
-		if (ret)   /* ENOSPC */
-			return ret;
-	}
+	ret = ext4_da_reserve_space(inode, rsv_dlen, 0);
+	if (ret)   /* ENOSPC */
+		return ret;
 
 	ext4_es_insert_delayed_block(inode, lblk, allocated);
 	return 0;
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 115f96f444ff..7a9839f2d681 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -1251,14 +1251,16 @@ TRACE_EVENT(ext4_da_update_reserve_space,
 );
 
 TRACE_EVENT(ext4_da_reserve_space,
-	TP_PROTO(struct inode *inode),
+	TP_PROTO(struct inode *inode, int data_blocks, int meta_blocks),
 
-	TP_ARGS(inode),
+	TP_ARGS(inode, data_blocks, meta_blocks),
 
 	TP_STRUCT__entry(
 		__field(	dev_t,	dev			)
 		__field(	ino_t,	ino			)
 		__field(	__u64,	i_blocks		)
+		__field(	int,	data_blocks		)
+		__field(	int,	meta_blocks		)
 		__field(	int,	reserved_data_blocks	)
 		__field(	int,	reserved_ext_blocks	)
 		__field(	__u16,  mode			)
@@ -1268,16 +1270,20 @@ TRACE_EVENT(ext4_da_reserve_space,
 		__entry->dev	= inode->i_sb->s_dev;
 		__entry->ino	= inode->i_ino;
 		__entry->i_blocks = inode->i_blocks;
+		__entry->data_blocks = data_blocks;
+		__entry->meta_blocks = meta_blocks;
 		__entry->reserved_data_blocks = EXT4_I(inode)->i_reserved_data_blocks;
 		__entry->reserved_ext_blocks = EXT4_I(inode)->i_reserved_ext_blocks;
 		__entry->mode	= inode->i_mode;
 	),
 
 	TP_printk("dev %d,%d ino %lu mode 0%o i_blocks %llu "
+		  "data_blocks %d meta_blocks %d "
 		  "reserved_data_blocks %d reserved_ext_blocks %d",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  (unsigned long) __entry->ino,
 		  __entry->mode, __entry->i_blocks,
+		  __entry->data_blocks, __entry->meta_blocks,
 		  __entry->reserved_data_blocks,
 		  __entry->reserved_ext_blocks)
 );
-- 
2.39.2