[LU-14734] enable large_dir on existing MDTs

Related — Thu, 13 Jan 2022 15:29:01 +0000

For filesystems with a large number of remote entries, either because of widespread striped directory usage, migration, or rename, the REMOTE_PARENT_DIR may become full without the large_dir, causing problems for new mkdirs, rename, and other remote directory operations.

Currently, osd-ldiskfs prints an error message:

LDISKFS-fs warning (device dm-14): ldiskfs_dx_add_entry:2625: inode 203423745: comm mdt_out01_005: index 2: reach max htree level 2 
LDISKFS-fs warning (device dm-14): ldiskfs_dx_add_entry:2629: Large directory feature is not enabled on this filesystem

but this is not very useful for the user, as enabling the large_dir feature requires the MDT to be unmounted (tune2fs is prevented from enabling it on the mounted filesystem due to MMP).

It makes sense to enable the large_dir feature automatically on existing ldiskfs MDT filesystems at mount time to prevent the problems associated with REMOTE_PARENT_DIR becoming full. This feature has been well supported for several releases already and is in e2fsprogs since 1.44, so there is little risk in enabling it automatically.

Whamcloud Community JIRA

[LU-14734] enable large_dir on existing MDTs