1 files changed, 63 insertions, 0 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index d279ea8c4661..668d82e494dd 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2212,6 +2212,8 @@ static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
         return ret;
 }
 
+#define EXT4_EXT_ZERO_LEN 7
+
 /*
  * This function is called by ext4_ext_get_blocks() if someone tries to write
  * to an uninitialized extent. It may result in splitting the uninitialized
@@ -2254,6 +2256,18 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
         err = ext4_ext_get_access(handle, inode, path + depth);
         if (err)
                 goto out;
+        /* If extent has less than 2*EXT4_EXT_ZERO_LEN zerout directly */
+        if (ee_len <= 2*EXT4_EXT_ZERO_LEN) {
+                err =  ext4_ext_zeroout(inode, &orig_ex);
+                if (err)
+                        goto fix_extent_len;
+                /* update the extent length and mark as initialized */
+                ex->ee_block = orig_ex.ee_block;
+                ex->ee_len   = orig_ex.ee_len;
+                ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
+                ext4_ext_dirty(handle, inode, path + depth);
+                return le16_to_cpu(ex->ee_len);
+        }
 
         /* ex1: ee_block to iblock - 1 : uninitialized */
         if (iblock > ee_block) {
@@ -2272,6 +2286,38 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
         /* ex3: to ee_block + ee_len : uninitialised */
         if (allocated > max_blocks) {
                 unsigned int newdepth;
+                /* If extent has less than EXT4_EXT_ZERO_LEN zerout directly */
+                if (allocated <= EXT4_EXT_ZERO_LEN) {
+                        /* Mark first half uninitialized.
+                         * Mark second half initialized and zero out the
+                         * initialized extent
+                         */
+                        ex->ee_block = orig_ex.ee_block;
+                        ex->ee_len   = cpu_to_le16(ee_len - allocated);
+                        ext4_ext_mark_uninitialized(ex);
+                        ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
+                        ext4_ext_dirty(handle, inode, path + depth);
+
+                        ex3 = &newex;
+                        ex3->ee_block = cpu_to_le32(iblock);
+                        ext4_ext_store_pblock(ex3, newblock);
+                        ex3->ee_len = cpu_to_le16(allocated);
+                        err = ext4_ext_insert_extent(handle, inode, path, ex3);
+                        if (err == -ENOSPC) {
+                                err =  ext4_ext_zeroout(inode, &orig_ex);
+                                if (err)
+                                        goto fix_extent_len;
+                                ex->ee_block = orig_ex.ee_block;
+                                ex->ee_len   = orig_ex.ee_len;
+                                ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
+                                ext4_ext_dirty(handle, inode, path + depth);
+                                return le16_to_cpu(ex->ee_len);
+
+                        } else if (err)
+                                goto fix_extent_len;
+
+                        return allocated;
+                }
                 ex3 = &newex;
                 ex3->ee_block = cpu_to_le32(iblock + max_blocks);
                 ext4_ext_store_pblock(ex3, newblock + max_blocks);
@@ -2320,6 +2366,23 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
                                 goto out;
                 }
                 allocated = max_blocks;
+
+                /* If extent has less than EXT4_EXT_ZERO_LEN and we are trying
+                 * to insert a extent in the middle zerout directly
+                 * otherwise give the extent a chance to merge to left
+                 */
+                if (le16_to_cpu(orig_ex.ee_len) <= EXT4_EXT_ZERO_LEN &&
+                                                        iblock != ee_block) {
+                        err =  ext4_ext_zeroout(inode, &orig_ex);
+                        if (err)
+                                goto fix_extent_len;
+                        /* update the extent length and mark as initialized */
+                        ex->ee_block = orig_ex.ee_block;
+                        ex->ee_len   = orig_ex.ee_len;
+                        ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
+                        ext4_ext_dirty(handle, inode, path + depth);
+                        return le16_to_cpu(ex->ee_len);
+                }
         }
         /*
          * If there was a change of depth as part of the