[LU-14131] reduce credits for overwritting

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.14.0
• Severity: 3
• Assignee: Wang Shilong (Inactive)
• Reporter: Wang Shilong (Inactive)

Description

If all blocks are mapped which means this is overwritting case or space has been allocated by fallocate. There is no need to modify exten tree, and we only need 1 credits for inode.