ext4: reimplement ext4_find_delay_alloc_range on extent status tree

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 18 insertions, 99 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 67660fa..e0bedd1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3461,115 +3461,34 @@ out:
 /**
  * ext4_find_delalloc_range: find delayed allocated block in the given range.
  *
- * Goes through the buffer heads in the range [lblk_start, lblk_end] and returns
- * whether there are any buffers marked for delayed allocation. It returns '1'
- * on the first delalloc'ed buffer head found. If no buffer head in the given
- * range is marked for delalloc, it returns 0.
- * lblk_start should always be <= lblk_end.
- * search_hint_reverse is to indicate that searching in reverse from lblk_end to
- * lblk_start might be more efficient (i.e., we will likely hit the delalloc'ed
- * block sooner). This is useful when blocks are truncated sequentially from
- * lblk_start towards lblk_end.
+ * Return 1 if there is a delalloc block in the range, otherwise 0.
  */
 static int ext4_find_delalloc_range(struct inode *inode,
 				    ext4_lblk_t lblk_start,
-				    ext4_lblk_t lblk_end,
-				    int search_hint_reverse)
+				    ext4_lblk_t lblk_end)
 {
-	struct address_space *mapping = inode->i_mapping;
-	struct buffer_head *head, *bh = NULL;
-	struct page *page;
-	ext4_lblk_t i, pg_lblk;
-	pgoff_t index;
-
-	if (!test_opt(inode->i_sb, DELALLOC))
-		return 0;
-
-	/* reverse search wont work if fs block size is less than page size */
-	if (inode->i_blkbits < PAGE_CACHE_SHIFT)
-		search_hint_reverse = 0;
+	struct extent_status es;
 
-	if (search_hint_reverse)
-		i = lblk_end;
+	es.start = lblk_start;
+	ext4_es_find_extent(inode, &es);
+	if (es.len == 0)
+		return 0; /* there is no delay extent in this tree */
+	else if (es.start <= lblk_start && lblk_start < es.start + es.len)
+		return 1;
+	else if (lblk_start <= es.start && es.start <= lblk_end)
+		return 1;
 	else
-		i = lblk_start;
-
-	index = i >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
-
-	while ((i >= lblk_start) && (i <= lblk_end)) {
-		page = find_get_page(mapping, index);
-		if (!page)
-			goto nextpage;
-
-		if (!page_has_buffers(page))
-			goto nextpage;
-
-		head = page_buffers(page);
-		if (!head)
-			goto nextpage;
-
-		bh = head;
-		pg_lblk = index << (PAGE_CACHE_SHIFT -
-						inode->i_blkbits);
-		do {
-			if (unlikely(pg_lblk < lblk_start)) {
-				/*
-				 * This is possible when fs block size is less
-				 * than page size and our cluster starts/ends in
-				 * middle of the page. So we need to skip the
-				 * initial few blocks till we reach the 'lblk'
-				 */
-				pg_lblk++;
-				continue;
-			}
-
-			/* Check if the buffer is delayed allocated and that it
-			 * is not yet mapped. (when da-buffers are mapped during
-			 * their writeout, their da_mapped bit is set.)
-			 */
-			if (buffer_delay(bh) && !buffer_da_mapped(bh)) {
-				page_cache_release(page);
-				trace_ext4_find_delalloc_range(inode,
-						lblk_start, lblk_end,
-						search_hint_reverse,
-						1, i);
-				return 1;
-			}
-			if (search_hint_reverse)
-				i--;
-			else
-				i++;
-		} while ((i >= lblk_start) && (i <= lblk_end) &&
-				((bh = bh->b_this_page) != head));
-nextpage:
-		if (page)
-			page_cache_release(page);
-		/*
-		 * Move to next page. 'i' will be the first lblk in the next
-		 * page.
-		 */
-		if (search_hint_reverse)
-			index--;
-		else
-			index++;
-		i = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-	}
-
-	trace_ext4_find_delalloc_range(inode, lblk_start, lblk_end,
-					search_hint_reverse, 0, 0);
-	return 0;
+		return 0;
 }
 
-int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk,
-			       int search_hint_reverse)
+int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	ext4_lblk_t lblk_start, lblk_end;
 	lblk_start = lblk & (~(sbi->s_cluster_ratio - 1));
 	lblk_end = lblk_start + sbi->s_cluster_ratio - 1;
 
-	return ext4_find_delalloc_range(inode, lblk_start, lblk_end,
-					search_hint_reverse);
+	return ext4_find_delalloc_range(inode, lblk_start, lblk_end);
 }
 
 /**
@@ -3630,7 +3549,7 @@ get_reserved_cluster_alloc(struct inode *inode, ext4_lblk_t lblk_start,
 		lblk_from = lblk_start & (~(sbi->s_cluster_ratio - 1));
 		lblk_to = lblk_from + c_offset - 1;
 
-		if (ext4_find_delalloc_range(inode, lblk_from, lblk_to, 0))
+		if (ext4_find_delalloc_range(inode, lblk_from, lblk_to))
 			allocated_clusters--;
 	}
 
@@ -3640,7 +3559,7 @@ get_reserved_cluster_alloc(struct inode *inode, ext4_lblk_t lblk_start,
 		lblk_from = lblk_start + num_blks;
 		lblk_to = lblk_from + (sbi->s_cluster_ratio - c_offset) - 1;
 
-		if (ext4_find_delalloc_range(inode, lblk_from, lblk_to, 0))
+		if (ext4_find_delalloc_range(inode, lblk_from, lblk_to))
 			allocated_clusters--;
 	}
 
@@ -3927,7 +3846,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) {
 		if (!newex.ee_start_lo && !newex.ee_start_hi) {
 			if ((sbi->s_cluster_ratio > 1) &&
-			    ext4_find_delalloc_cluster(inode, map->m_lblk, 0))
+			    ext4_find_delalloc_cluster(inode, map->m_lblk))
 				map->m_flags |= EXT4_MAP_FROM_CLUSTER;
 
 			if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
@@ -4015,7 +3934,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	}
 
 	if ((sbi->s_cluster_ratio > 1) &&
-	    ext4_find_delalloc_cluster(inode, map->m_lblk, 0))
+	    ext4_find_delalloc_cluster(inode, map->m_lblk))
 		map->m_flags |= EXT4_MAP_FROM_CLUSTER;
 
 	/*