4 files changed, 36 insertions, 4 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ffc6ab000c78..ae900b530d37 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -557,6 +557,10 @@ enum {
 #define EXT4_GET_BLOCKS_KEEP_SIZE               0x0080
         /* Convert written extents to unwritten */
 #define EXT4_GET_BLOCKS_CONVERT_UNWRITTEN       0x0100
+        /* Write zeros to newly created written extents */
+#define EXT4_GET_BLOCKS_ZERO                    0x0200
+#define EXT4_GET_BLOCKS_CREATE_ZERO             (EXT4_GET_BLOCKS_CREATE |\
+                                        EXT4_GET_BLOCKS_ZERO)
 
 /*
  * The bit position of these flags must not overlap with any of the
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 867e98b6bc6c..b52fea3b7219 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4044,6 +4044,14 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
         }
         /* IO end_io complete, convert the filled extent to written */
         if (flags & EXT4_GET_BLOCKS_CONVERT) {
+                if (flags & EXT4_GET_BLOCKS_ZERO) {
+                        if (allocated > map->m_len)
+                                allocated = map->m_len;
+                        err = ext4_issue_zeroout(inode, map->m_lblk, newblock,
+                                                 allocated);
+                        if (err < 0)
+                                goto out2;
+                }
                 ret = ext4_convert_unwritten_extents_endio(handle, inode, map,
                                                            ppath);
                 if (ret >= 0) {
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0c9a5ee3e106..4241d0cff062 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -637,13 +637,29 @@ found:
                 }
 
                 /*
+                 * We have to zeroout blocks before inserting them into extent
+                 * status tree. Otherwise someone could look them up there and
+                 * use them before they are really zeroed.
+                 */
+                if (flags & EXT4_GET_BLOCKS_ZERO &&
+                    map->m_flags & EXT4_MAP_MAPPED &&
+                    map->m_flags & EXT4_MAP_NEW) {
+                        ret = ext4_issue_zeroout(inode, map->m_lblk,
+                                                 map->m_pblk, map->m_len);
+                        if (ret) {
+                                retval = ret;
+                                goto out_sem;
+                        }
+                }
+
+                /*
                  * If the extent has been zeroed out, we don't need to update
                  * extent status tree.
                  */
                 if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
                     ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
                         if (ext4_es_is_written(&es))
-                                goto has_zeroout;
+                                goto out_sem;
                 }
                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
@@ -654,11 +670,13 @@ found:
                         status |= EXTENT_STATUS_DELAYED;
                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
                                             map->m_pblk, status);
-                if (ret < 0)
+                if (ret < 0) {
                         retval = ret;
+                        goto out_sem;
+                }
         }
 
-has_zeroout:
+out_sem:
         up_write((&EXT4_I(inode)->i_data_sem));
         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
                 ret = check_block_validity(inode, map);
@@ -3083,6 +3101,7 @@ int ext4_get_block_dax(struct inode *inode, sector_t iblock,
                    struct buffer_head *bh_result, int create)
 {
         int flags = EXT4_GET_BLOCKS_PRE_IO | EXT4_GET_BLOCKS_UNWRIT_EXT;
+
         if (create)
                 flags |= EXT4_GET_BLOCKS_CREATE;
         ext4_debug("ext4_get_block_dax: inode %lu, create flag %d\n",
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 5f2ace56efc5..4e4b2fa78609 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -42,7 +42,8 @@ struct extent_status;
         { EXT4_GET_BLOCKS_CONVERT,              "CONVERT" },            \
         { EXT4_GET_BLOCKS_METADATA_NOFAIL,      "METADATA_NOFAIL" },    \
         { EXT4_GET_BLOCKS_NO_NORMALIZE,         "NO_NORMALIZE" },       \
-        { EXT4_GET_BLOCKS_KEEP_SIZE,            "KEEP_SIZE" })
+        { EXT4_GET_BLOCKS_KEEP_SIZE,            "KEEP_SIZE" },          \
+        { EXT4_GET_BLOCKS_ZERO,                 "ZERO" })
 
 #define show_mflags(flags) __print_flags(flags, "",     \
         { EXT4_MAP_NEW,         "N" },                  \