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Description of problem:
Coverity reports:

CHECKED_RETURN (block/gluster.c:335)
Calling "fcntl(s->fds[0], 4, 2048)" without checking return value. This library function may fail and return an error code. 

Error occurs in function qemu_gluster_open.

Version-Release number of selected component (if applicable):
qemu-kvm-0.12.1.2-2.474.el6

Additional info:
Appears to be legitimate defect. Present in rhel7 too, but has been around for years.

No, it is not valid. We know that nothing can fail here. IIRC without having the code in front of me this is a F_SETFL.

>IIRC without having the code in front of me this is a F_SETFL.

It is.

>We know that nothing can fail here.

fcntl is documented as returning specific error conditions when a given operation is attempted; the F_SETFL command is not specifically mentioned, so these error conditions cannot occur. However, several generic error conditions are documented--without mentioning a command--so it is reasonable to assume they could occur:

 EACCES or EAGAIN
   Operation is prohibited by locks held by other processes.

 EAGAIN
   The operation is prohibited because the file has been memory-mapped by another process.

 EBADF
   fd is not an open file descriptor

 ENOLCK
   Too many segment locks open, lock table is full, or a remote locking protocol failed (e.g., locking over NFS).

 EPERM
   Attempted to clear the O_APPEND flag on a file that has the append-only attribute set.

Out of all these, I'd be most concerned about ENOLCK (given that this is in a glusterfs function). Are you sure that nothing can fail here?

The file descriptor is a pipe that has been just opened, so it cannot be any of the above.