cpukit/jffs2/gc.c: Prevent live lock for split reads

In some cases a file read is not completed in a single call into the
JFFS2 layer and the inode is left in the READING state. When this
happens, it's possible for a garbage collection pass to be initiated
before completion of the read. In some such cases, the garbage
collection pass is executed in a tight loop that expects granular
locking to allow forward progress of the read between collection passes.
With RTEMS monolithic locking of the JFFS2 layer, forward progress is
not possible in this situation since the monolithic lock is never
released inside the loop.

The solution is to have the garbage collection pass return failure when
no progress is possible due to a bad inode state. This allows the read
to complete and the collection pass can be attempted at a later time.

cpukit/libfs/src/jffs2/src/gc.c

@@ -417,7 +417,17 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 
 		   A: Small enough that I don't care :)
 		*/
+#ifndef __rtems__
 		return 0;
+#else
+		/*
+		 * Since RTEMS uses monolithic locking around JFFS2, returning 0
+		 * here results in a livelock since no other progress will ever
+		 * be made as some callers are in a tight loop with no relevant
+		 * lock modification.
+		 */
+		return -EIO;
+#endif
 	}
 
 	/* OK. Now if the inode is in state INO_STATE_GC, we are going to copy the