2 files changed, 39 insertions, 6 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e40332158340..e3a55eb8b26a 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1841,11 +1841,13 @@ ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
 {
         struct ext4_ext_cache *cex;
         BUG_ON(len == 0);
+        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
         cex = &EXT4_I(inode)->i_cached_extent;
         cex->ec_type = type;
         cex->ec_block = block;
         cex->ec_len = len;
         cex->ec_start = start;
+        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 }
 
 /*
@@ -1902,12 +1904,17 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
                         struct ext4_extent *ex)
 {
         struct ext4_ext_cache *cex;
+        int ret = EXT4_EXT_CACHE_NO;
 
+        /* 
+         * We borrow i_block_reservation_lock to protect i_cached_extent
+         */
+        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
         cex = &EXT4_I(inode)->i_cached_extent;
 
         /* has cache valid data? */
         if (cex->ec_type == EXT4_EXT_CACHE_NO)
-                return EXT4_EXT_CACHE_NO;
+                goto errout;
 
         BUG_ON(cex->ec_type != EXT4_EXT_CACHE_GAP &&
                         cex->ec_type != EXT4_EXT_CACHE_EXTENT);
@@ -1918,11 +1925,11 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
                 ext_debug("%u cached by %u:%u:%llu\n",
                                 block,
                                 cex->ec_block, cex->ec_len, cex->ec_start);
-                return cex->ec_type;
+                ret = cex->ec_type;
         }
-
-        /* not in cache */
-        return EXT4_EXT_CACHE_NO;
+errout:
+        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+        return ret;
 }
 
 /*
@@ -2875,6 +2882,8 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
                                 if (allocated > max_blocks)
                                         allocated = max_blocks;
                                 set_buffer_unwritten(bh_result);
+                                bh_result->b_bdev = inode->i_sb->s_bdev;
+                                bh_result->b_blocknr = newblock;
                                 goto out2;
                         }
 
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e91f978c7f12..2a9ffd528dd1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1149,6 +1149,7 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
         int retval;
 
         clear_buffer_mapped(bh);
+        clear_buffer_unwritten(bh);
 
         /*
          * Try to see if we can get  the block without requesting
@@ -1179,6 +1180,18 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
                 return retval;
 
         /*
+         * When we call get_blocks without the create flag, the
+         * BH_Unwritten flag could have gotten set if the blocks
+         * requested were part of a uninitialized extent.  We need to
+         * clear this flag now that we are committed to convert all or
+         * part of the uninitialized extent to be an initialized
+         * extent.  This is because we need to avoid the combination
+         * of BH_Unwritten and BH_Mapped flags being simultaneously
+         * set on the buffer_head.
+         */
+        clear_buffer_unwritten(bh);
+
+        /*
          * New blocks allocate and/or writing to uninitialized extent
          * will possibly result in updating i_data, so we take
          * the write lock of i_data_sem, and call get_blocks()
@@ -2297,6 +2310,10 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
                                   struct buffer_head *bh_result, int create)
 {
         int ret = 0;
+        sector_t invalid_block = ~((sector_t) 0xffff);
+
+        if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
+                invalid_block = ~0;
 
         BUG_ON(create == 0);
         BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
@@ -2318,11 +2335,18 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
                         /* not enough space to reserve */
                         return ret;
 
-                map_bh(bh_result, inode->i_sb, 0);
+                map_bh(bh_result, inode->i_sb, invalid_block);
                 set_buffer_new(bh_result);
                 set_buffer_delay(bh_result);
         } else if (ret > 0) {
                 bh_result->b_size = (ret << inode->i_blkbits);
+                /*
+                 * With sub-block writes into unwritten extents
+                 * we also need to mark the buffer as new so that
+                 * the unwritten parts of the buffer gets correctly zeroed.
+                 */
+                if (buffer_unwritten(bh_result))
+                        set_buffer_new(bh_result);
                 ret = 0;
         }