[LU-6030] cleanup for ldiskfs patches

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.8.0
• Assignee: Yang Sheng
• Reporter: Yang Sheng

Description

Some ldiskfs patch need cleanup. From comments in http://review.whamcloud.com/#/c/10249/21 and http://review.whamcloud.com/#/c/10249/27:

• ext4-extents-mount-option.patch: We format the OST with the EXT4_FEATURE_INCOMPAT_EXTENTS, and avoid it for the MDT. At most we would need to have a dummy mount option that accepts the "-o extents" option from Lustre (to avoid LU-5425), and returns an error at mount time if INCOMPAT_EXTENTS is not already set. It would be possible to delete the whole patch by removing the "extents" option from the mount options in osd_mount()
• ext4-misc.patch: It would be possible to remove the stub "mballoc", "iopen", "noiopen", "iopen_nopriv" mount option handling by removing those strings from the mount options in osd_mount()
• ext4-fiemap.patch: this patch can be removed entirely, even from older RHEL6 kernels. ext4_fiemap() is accessible via ext4_file_inode_operations, so we could just call inode->i_op->fiemap(), and move the rest of the code into osd-ldiskfs/osd-fiemap.c
• ext4-nocmtime.patch: this could be simplified by changing only ext4_current_time(inode) to return inode->i_ctime if NOCMTIME is set on the inode
• ext4-pdirops.patch: it would be nice to split this into two separate patches. One for implementing 3-level htree and EXT4_FEATURE_INCOMPAT_LARGEDIR, and the other for pdirops. The 3-level htree LARGEDIR feature might be accepted upstream, while pdirops/htree_lock is harder since it has no VFS interface
• ext4-pdirops.patch: remove i_append_sem and use i_data_sem or xattr_sem (if possible, not sure if there would be deadlocks in some code path)
• ext4-max-dir-size.patch: add deprecation warning for max_dir_size /sysfs entry if used

Issue Links

• is related to: LU-6978 mkfs.lustre: LDISKFS-fs (loop0): Unrecognized mount option "force_over_128tb" or missing value
• is related to: LU-6201 remove duplicate fiemap code/defines
• is related to: LU-6220 push ext4/ldiskfs patches upstream if possible
• is related to: LU-896 change e2fsprogs to make it allow directories over 2GB
• is related to: LU-6141 Merge ldiskfs patches into upstream ext4 linux sources
• is related to: LU-5424 Test failuresanity test_154b: create lov data thru .lustre should fail
• is related to: LU-6215 Sync Lustre external tree with lustre linux kernel client