[PATCH v4 04/12] ext4: pass out extent seq counter when mapping blocks

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

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

When creating or querying mapping blocks using the ext4_map_blocks() and
ext4_map_{query|create}_blocks() helpers, also pass out the extent
sequence number of the block mapping info through the ext4_map_blocks
structure. This sequence number can later serve as a valid cookie within
iomap infrastructure and the move extents procedure.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/ext4.h  |  1 +
 fs/ext4/inode.c | 24 ++++++++++++++++--------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index eff97b3a1093..9f127aedbaee 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -260,6 +260,7 @@ struct ext4_map_blocks {
 	ext4_lblk_t m_lblk;
 	unsigned int m_len;
 	unsigned int m_flags;
+	u64 m_seq;
 };
 
 /*
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 10792772b450..ad8deae1c7c3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -550,10 +550,13 @@ static int ext4_map_query_blocks(handle_t *handle, struct inode *inode,
 		retval = ext4_ext_map_blocks(handle, inode, map, flags);
 	else
 		retval = ext4_ind_map_blocks(handle, inode, map, flags);
-
-	if (retval <= 0)
+	if (retval < 0)
 		return retval;
 
+	/* A hole? */
+	if (retval == 0)
+		goto out;
+
 	if (unlikely(retval != map->m_len)) {
 		ext4_warning(inode->i_sb,
 			     "ES len assertion failed for inode "
@@ -573,11 +576,13 @@ static int ext4_map_query_blocks(handle_t *handle, struct inode *inode,
 				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
 		ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
 				      map->m_pblk, status, false);
-		return retval;
+	} else {
+		retval = ext4_map_query_blocks_next_in_leaf(handle, inode, map,
+							    orig_mlen);
 	}
-
-	return ext4_map_query_blocks_next_in_leaf(handle, inode, map,
-						  orig_mlen);
+out:
+	map->m_seq = READ_ONCE(EXT4_I(inode)->i_es_seq);
+	return retval;
 }
 
 static int ext4_map_create_blocks(handle_t *handle, struct inode *inode,
@@ -649,7 +654,7 @@ static int ext4_map_create_blocks(handle_t *handle, struct inode *inode,
 	 * extent status tree.
 	 */
 	if (flags & EXT4_GET_BLOCKS_PRE_IO &&
-	    ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
+	    ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, &map->m_seq)) {
 		if (ext4_es_is_written(&es))
 			return retval;
 	}
@@ -658,6 +663,7 @@ static int ext4_map_create_blocks(handle_t *handle, struct inode *inode,
 			EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
 	ext4_es_insert_extent(inode, map->m_lblk, map->m_len, map->m_pblk,
 			      status, flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE);
+	map->m_seq = READ_ONCE(EXT4_I(inode)->i_es_seq);
 
 	return retval;
 }
@@ -723,7 +729,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 		ext4_check_map_extents_env(inode);
 
 	/* Lookup extent status tree firstly */
-	if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, NULL)) {
+	if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es, &map->m_seq)) {
 		if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
 			map->m_pblk = ext4_es_pblock(&es) +
 					map->m_lblk - es.es_lblk;
@@ -1979,6 +1985,8 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map)
 
 	map->m_flags |= EXT4_MAP_DELAYED;
 	retval = ext4_insert_delayed_blocks(inode, map->m_lblk, map->m_len);
+	if (!retval)
+		map->m_seq = READ_ONCE(EXT4_I(inode)->i_es_seq);
 	up_write(&EXT4_I(inode)->i_data_sem);
 
 	return retval;
-- 
2.46.1