In the 2.6.37 kernel the function invalidate_inodes() is no longer
exported for use by modules. This memory management functionality
is needed to invalidate the inodes attached to a super block without
unmounting the filesystem.
Because this function still exists in the kernel and the prototype
is available is a common header all we strictly need is the symbol
address. The address is obtained using spl_kallsyms_lookup_name()
and assigned to the variable invalidate_inodes_fn. Then a #define
is used to replace all instances of invalidate_inodes() with a
call to the acquired address. All the complexity is hidden behind
HAVE_INVALIDATE_INODES and invalidate_inodes() can be used as usual.
Long term we should try to get this, or another, interface made
available to modules again.
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