I wrote:

Howard Chu writes:

...

Obviously this and the preceding line can be reduced to mp->mp_flags = fp->mp_flags ^ (P_DIRTY|P_SUBP|P_FAKE);

They are not equivalent. fp->mp_flags can be P_LEAF|P_DIRTY in branch "yes, convert it" and P_LEAF|P_DIRTY|P_SUBP|P_FAKE in the other branch.

Found by test043 + assert(the patches were equivalent).