ext4: Wait for proper transaction commit on fsync

We cannot rely on buffer dirty bits during fsync because pdflush can come
before fsync is called and clear dirty bits without forcing a transaction
commit. What we do is that we track which transaction has last changed
the inode and which transaction last changed allocation and force it to
disk on fsync.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 12 insertions, 2 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 5967f18fd7e7..700206e525da 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3058,6 +3058,8 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
         if (flags == EXT4_GET_BLOCKS_DIO_CONVERT_EXT) {
                 ret = ext4_convert_unwritten_extents_dio(handle, inode,
                                                         path);
+                if (ret >= 0)
+                        ext4_update_inode_fsync_trans(handle, inode, 1);
                 goto out2;
         }
         /* buffered IO case */
@@ -3085,6 +3087,8 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
         ret = ext4_ext_convert_to_initialized(handle, inode,
                                                 path, iblock,
                                                 max_blocks);
+        if (ret >= 0)
+                ext4_update_inode_fsync_trans(handle, inode, 1);
 out:
         if (ret <= 0) {
                 err = ret;
@@ -3323,10 +3327,16 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
         allocated = ext4_ext_get_actual_len(&newex);
         set_buffer_new(bh_result);
 
-        /* Cache only when it is _not_ an uninitialized extent */
-        if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0)
+        /*
+         * Cache the extent and update transaction to commit on fdatasync only
+         * when it is _not_ an uninitialized extent.
+         */
+        if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) {
                 ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
                                                 EXT4_EXT_CACHE_EXTENT);
+                ext4_update_inode_fsync_trans(handle, inode, 1);
+        } else
+                ext4_update_inode_fsync_trans(handle, inode, 0);
 out:
         if (allocated > max_blocks)
                 allocated = max_blocks;