errors during "mount" operations taints mount point

[thomas.doerfler]

When a mount operation fails, the (would be) mount point is tained. Performing a "stat" operation to that (would be) mount point later on will fail.

When a mount() call is performed to mount a filesystem (like dosfs) to a certain mount point, and the FS-specific mount function fails (e.g. due to a read error of the root fs to be mounted), then the "mount entry" (temp_mt_entry) that had been liked to the mount point node is not properly initialized and should be removed.

When an "evaluate_path" operation occures later, it detects the "mt_entry" linked to that node and presumes, that a valid "mt_fs_root" structure is attached to it, but the corresponding pointer is invalid, which leads to a system crash.

Release:
RTEMS-4.6.0pre1

Environment:
m68k, but presumably all targets

How-To-Repeat:

1. Create a directory as mount point in IMFS
2. start to mount another file system to that mount point, but let the "fsmount_me_h" operation fail->"mount" call will return an error code
3. perform a "stat" operation to the mount point

[Jennifer Averett]

State-Changed-From-To: feedback->closed
State-Changed-Why: Addressed in PR 297.