Hi, Recently, I‘m doing some testing with fast commit feature , and found there is a slight difference on fsync compared with the normal journaling scheme. Here is the example: -mkdir test/ -create&write test/a.txt -fsync test/a.txt -crash (before a full commit) If fast commit is used then “a.txt” will lost. While the normal journaling can recover it. Refer to the description of fsync [1], fsync will not guarantee the parent directory to be persisted. So I think it is not an issue. But fast commit did change the behavior of fsync in ext4, is this as expected ? For the root cause of this difference, I found that fast commit will not add a EXT4_FC_TAG_CREAT tag for directory creation. In func ext4_fc_commit_dentry_updates(), only directories in s_fc_q list can be added with EXT4_FC_TAG_CREAT,but seams the newly created directory inode has no change to be added to s_fc_q. Shall we just change the “enqueue” param of ext4_fc_track_template() to 1 , which in __ext4_fc_track_create()? And make fast commit record all the inode creation, and do the same things as normal journaling. [1] https://man7.org/linux/man-pages/man2/fdatasync.2.html BR, Xin Yin
