1 files changed, 29 insertions, 20 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0569c745475c..787497d536b6 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1904,34 +1904,48 @@ static int ext4_writepage(struct page *page,
  *
  * @mpd - extent of blocks
  * @lblk - logical number of the block in the file
- * @b_state - b_state of the buffer head added
+ * @bh - buffer head we want to add to the extent
  *
- * the function is used to collect contig. blocks in same state
+ * The function is used to collect contig. blocks in the same state. If the
+ * buffer doesn't require mapping for writeback and we haven't started the
+ * extent of buffers to map yet, the function returns 'true' immediately - the
+ * caller can write the buffer right away. Otherwise the function returns true
+ * if the block has been added to the extent, false if the block couldn't be
+ * added.
  */
-static int mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
-                                  unsigned long b_state)
+static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
+                                   struct buffer_head *bh)
 {
         struct ext4_map_blocks *map = &mpd->map;
 
-        /* Don't go larger than mballoc is willing to allocate */
-        if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
-                return 0;
+        /* Buffer that doesn't need mapping for writeback? */
+        if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
+            (!buffer_delay(bh) && !buffer_unwritten(bh))) {
+                /* So far no extent to map => we write the buffer right away */
+                if (map->m_len == 0)
+                        return true;
+                return false;
+        }
 
         /* First block in the extent? */
         if (map->m_len == 0) {
                 map->m_lblk = lblk;
                 map->m_len = 1;
-                map->m_flags = b_state & BH_FLAGS;
-                return 1;
+                map->m_flags = bh->b_state & BH_FLAGS;
+                return true;
         }
 
+        /* Don't go larger than mballoc is willing to allocate */
+        if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
+                return false;
+
         /* Can we merge the block to our big extent? */
         if (lblk == map->m_lblk + map->m_len &&
-            (b_state & BH_FLAGS) == map->m_flags) {
+            (bh->b_state & BH_FLAGS) == map->m_flags) {
                 map->m_len++;
-                return 1;
+                return true;
         }
-        return 0;
+        return false;
 }
 
 static bool add_page_bufs_to_extent(struct mpage_da_data *mpd,
@@ -1946,18 +1960,13 @@ static bool add_page_bufs_to_extent(struct mpage_da_data *mpd,
         do {
                 BUG_ON(buffer_locked(bh));
 
-                if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
-                    (!buffer_delay(bh) && !buffer_unwritten(bh)) ||
-                    lblk >= blocks) {
+                if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
                         /* Found extent to map? */
                         if (mpd->map.m_len)
                                 return false;
-                        if (lblk >= blocks)
-                                return true;
-                        continue;
+                        /* Everything mapped so far and we hit EOF */
+                        return true;
                 }
-                if (!mpage_add_bh_to_extent(mpd, lblk, bh->b_state))
-                        return false;
         } while (lblk++, (bh = bh->b_this_page) != head);
         return true;
 }