[RFC PATCH v4 15/34] ext4: update delalloc data reserve spcae in ext4_es_insert_extent()

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

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

Now we update data reserved space for delalloc after allocating new
blocks in ext4_{ind|ext}_map_blocks(). If bigalloc feature is enabled,
we also need to query the extents_status tree and calculate the exact
reserved clusters. This is complicated and it appears
ext4_es_insert_extent() is a better place to do this job, it could make
things simple because __es_remove_extent() could count delalloc blocks
and __revise_pending() and return newly added pending count.

One special case needs to concern is the quota claiming, when bigalloc
is enabled, if the delayed cluster allocation has been raced by another
no-delayed allocation which doesn't overlap the delayed blocks (from
fallocate, filemap, DIO...) , we cannot claim quota as usual because the
racer have already done it, so we also need to check the counted
reserved blocks.

  |               one cluster               |
  -------------------------------------------
  |                            | delayed es |
  -------------------------------------------
  ^           ^
  | fallocate | <- don't claim quota

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/ext4/extents.c        | 37 -------------------------------------
 fs/ext4/extents_status.c | 22 +++++++++++++++++++++-
 fs/ext4/indirect.c       |  7 -------
 3 files changed, 21 insertions(+), 45 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e57054bdc5fd..8bc8a519f745 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4355,43 +4355,6 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 		goto out;
 	}
 
-	/*
-	 * Reduce the reserved cluster count to reflect successful deferred
-	 * allocation of delayed allocated clusters or direct allocation of
-	 * clusters discovered to be delayed allocated.  Once allocated, a
-	 * cluster is not included in the reserved count.
-	 */
-	if (test_opt(inode->i_sb, DELALLOC) && allocated_clusters) {
-		if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
-			/*
-			 * When allocating delayed allocated clusters, simply
-			 * reduce the reserved cluster count and claim quota
-			 */
-			ext4_da_update_reserve_space(inode, allocated_clusters,
-							1);
-		} else {
-			ext4_lblk_t lblk, len;
-			unsigned int n;
-
-			/*
-			 * When allocating non-delayed allocated clusters
-			 * (from fallocate, filemap, DIO, or clusters
-			 * allocated when delalloc has been disabled by
-			 * ext4_nonda_switch), reduce the reserved cluster
-			 * count by the number of allocated clusters that
-			 * have previously been delayed allocated.  Quota
-			 * has been claimed by ext4_mb_new_blocks() above,
-			 * so release the quota reservations made for any
-			 * previously delayed allocated clusters.
-			 */
-			lblk = EXT4_LBLK_CMASK(sbi, map->m_lblk);
-			len = allocated_clusters << sbi->s_cluster_bits;
-			n = ext4_es_delayed_clu(inode, lblk, len);
-			if (n > 0)
-				ext4_da_update_reserve_space(inode, (int) n, 0);
-		}
-	}
-
 	/*
 	 * Cache the extent and update transaction to commit on fdatasync only
 	 * when it is _not_ an unwritten extent.
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 38ec2cc5ae3b..75227f151b8f 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -856,6 +856,8 @@ void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 	struct extent_status newes;
 	ext4_lblk_t end = lblk + len - 1;
 	int err1 = 0, err2 = 0, err3 = 0;
+	struct rsvd_info rinfo;
+	int resv_used, pending = 0;
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	struct extent_status *es1 = NULL;
 	struct extent_status *es2 = NULL;
@@ -894,7 +896,7 @@ void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 		pr = __alloc_pending(true);
 	write_lock(&EXT4_I(inode)->i_es_lock);
 
-	err1 = __es_remove_extent(inode, lblk, end, NULL, es1);
+	err1 = __es_remove_extent(inode, lblk, end, &rinfo, es1);
 	if (err1 != 0)
 		goto error;
 	/* Free preallocated extent if it didn't get used. */
@@ -924,9 +926,27 @@ void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 			__free_pending(pr);
 			pr = NULL;
 		}
+		pending = err3;
 	}
 error:
 	write_unlock(&EXT4_I(inode)->i_es_lock);
+	/*
+	 * Reduce the reserved cluster count to reflect successful deferred
+	 * allocation of delayed allocated clusters or direct allocation of
+	 * clusters discovered to be delayed allocated.  Once allocated, a
+	 * cluster is not included in the reserved count.
+	 *
+	 * When bigalloc is enabled, allocating non-delayed allocated blocks
+	 * which belong to delayed allocated clusters (from fallocate, filemap,
+	 * DIO, or clusters allocated when delalloc has been disabled by
+	 * ext4_nonda_switch()). Quota has been claimed by ext4_mb_new_blocks(),
+	 * so release the quota reservations made for any previously delayed
+	 * allocated clusters.
+	 */
+	resv_used = rinfo.delonly_cluster + pending;
+	if (resv_used)
+		ext4_da_update_reserve_space(inode, resv_used,
+					     rinfo.delonly_block);
 	if (err1 || err2 || err3 < 0)
 		goto retry;
 
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index d8ca7f64f952..7404f0935c90 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -652,13 +652,6 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
 	ext4_update_inode_fsync_trans(handle, inode, 1);
 	count = ar.len;
 
-	/*
-	 * Update reserved blocks/metadata blocks after successful block
-	 * allocation which had been deferred till now.
-	 */
-	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
-		ext4_da_update_reserve_space(inode, count, 1);
-
 got_it:
 	map->m_flags |= EXT4_MAP_MAPPED;
 	map->m_pblk = le32_to_cpu(chain[depth-1].key);
-- 
2.39.2