[LU-3557] open(2) an existing file with O_RDONLY|O_CREAT fails with -EROFS, ro mounted client

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.5.0
• Affects Version/s: Lustre 2.4.0
• Labels: patch
• Severity: 3
• Assignee: Emoly Liu
• Reporter: Li Dongyang (Inactive)

Description

Currently with a read only mount, open(2) with O_RDONLY|O_CREAT will fail with -EROFS, no matter the file exists or not.
If the file is already there and we don't need to create the file, we should make the open work.
The gcc-fortran runtime tends to add O_CREAT flag when it's trying to open a file, this prevents us from using the fortran based apps.