1 files changed, 54 insertions, 20 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8dd22eade42c..d1906d9a22de 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1848,29 +1848,53 @@ static void mpage_da_map_blocks(struct mpage_da_data *mpd)
 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
                                    sector_t logical, struct buffer_head *bh)
 {
-        struct buffer_head *lbh = &mpd->lbh;
         sector_t next;
+        size_t b_size = bh->b_size;
+        struct buffer_head *lbh = &mpd->lbh;
+        int nrblocks = lbh->b_size >> mpd->inode->i_blkbits;
 
-        next = lbh->b_blocknr + (lbh->b_size >> mpd->inode->i_blkbits);
-
+        /* check if thereserved journal credits might overflow */
+        if (!(EXT4_I(mpd->inode)->i_flags & EXT4_EXTENTS_FL)) {
+                if (nrblocks >= EXT4_MAX_TRANS_DATA) {
+                        /*
+                         * With non-extent format we are limited by the journal
+                         * credit available.  Total credit needed to insert
+                         * nrblocks contiguous blocks is dependent on the
+                         * nrblocks.  So limit nrblocks.
+                         */
+                        goto flush_it;
+                } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
+                                EXT4_MAX_TRANS_DATA) {
+                        /*
+                         * Adding the new buffer_head would make it cross the
+                         * allowed limit for which we have journal credit
+                         * reserved. So limit the new bh->b_size
+                         */
+                        b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
+                                                mpd->inode->i_blkbits;
+                        /* we will do mpage_da_submit_io in the next loop */
+                }
+        }
         /*
          * First block in the extent
          */
         if (lbh->b_size == 0) {
                 lbh->b_blocknr = logical;
-                lbh->b_size = bh->b_size;
+                lbh->b_size = b_size;
                 lbh->b_state = bh->b_state & BH_FLAGS;
                 return;
         }
 
+        next = lbh->b_blocknr + nrblocks;
         /*
          * Can we merge the block to our big extent?
          */
         if (logical == next && (bh->b_state & BH_FLAGS) == lbh->b_state) {
-                lbh->b_size += bh->b_size;
+                lbh->b_size += b_size;
                 return;
         }
 
+flush_it:
         /*
          * We couldn't merge the block to our extent, so we
          * need to flush current  extent and start new one
@@ -2231,17 +2255,29 @@ static int ext4_da_writepage(struct page *page,
 }
 
 /*
- * For now just follow the DIO way to estimate the max credits
- * needed to write out EXT4_MAX_WRITEBACK_PAGES.
- * todo: need to calculate the max credits need for
- * extent based files, currently the DIO credits is based on
- * indirect-blocks mapping way.
- *
- * Probably should have a generic way to calculate credits
- * for DIO, writepages, and truncate
+ * This is called via ext4_da_writepages() to
+ * calulate the total number of credits to reserve to fit
+ * a single extent allocation into a single transaction,
+ * ext4_da_writpeages() will loop calling this before
+ * the block allocation.
  */
-#define EXT4_MAX_WRITEBACK_PAGES      DIO_MAX_BLOCKS
-#define EXT4_MAX_WRITEBACK_CREDITS    25
+
+static int ext4_da_writepages_trans_blocks(struct inode *inode)
+{
+        int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
+
+        /*
+         * With non-extent format the journal credit needed to
+         * insert nrblocks contiguous block is dependent on
+         * number of contiguous block. So we will limit
+         * number of contiguous block to a sane value
+         */
+        if (!(inode->i_flags & EXT4_EXTENTS_FL) &&
+            (max_blocks > EXT4_MAX_TRANS_DATA))
+                max_blocks = EXT4_MAX_TRANS_DATA;
+
+        return ext4_chunk_trans_blocks(inode, max_blocks);
+}
 
 static int ext4_da_writepages(struct address_space *mapping,
                               struct writeback_control *wbc)
@@ -2283,7 +2319,7 @@ restart_loop:
                  * by delalloc
                  */
                 BUG_ON(ext4_should_journal_data(inode));
-                needed_blocks = EXT4_DATA_TRANS_BLOCKS(inode->i_sb);
+                needed_blocks = ext4_da_writepages_trans_blocks(inode);
 
                 /* start a new transaction*/
                 handle = ext4_journal_start(inode, needed_blocks);
@@ -4461,11 +4497,9 @@ int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
  * the modification of a single pages into a single transaction,
  * which may include multiple chunks of block allocations.
  *
- * This could be called via ext4_write_begin() or later
- * ext4_da_writepages() in delalyed allocation case.
+ * This could be called via ext4_write_begin()
  *
- * In both case it's possible that we could allocating multiple
- * chunks of blocks. We need to consider the worse case, when
+ * We need to consider the worse case, when
  * one new block per extent.
  */
 int ext4_writepage_trans_blocks(struct inode *inode)