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authorLinus Torvalds <torvalds@linux-foundation.org>2011-06-20 20:13:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-06-20 20:13:49 -0700
commit79568f5be06c91071697c065f01f3ebfbeb25a61 (patch)
tree81fc2bb54bebffc7ef22390bfc37c7ba818a30df /Makefile
parentf5fc5567dd24c15b1d95aa9ee2aaada04d835a0c (diff)
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vfs: i_state needs to be 'unsigned long' for now
Commit 13e12d14e2dc ("vfs: reorganize 'struct inode' layout a bit") moved things around a bit changed i_state to be unsigned int instead of unsigned long. That was to help structure layout for the 64-bit case, and shrink 'struct inode' a bit (admittedly that only happened when spinlock debugging was on and i_flags didn't pack with i_lock). However, Meelis Roos reports that this results in unaligned exceptions on sprc, and it turns out that the bit-locking primitives that we use for the I_NEW bit want to use the bitops. Which want 'unsigned long', not 'unsigned int'. We really should fix the bit locking code to not have that kind of requirement, but that's a much bigger change. So for now, revert that field back to 'unsigned long' (but keep the other re-ordering changes from the commit that caused this). Andi points out that we have played games with this in 'struct page', so it's solvable with other hacks too, but since right now the struct inode size advantage only happens with some rare config options, it's not worth fighting. It _would_ be worth fixing the bitlocking code, though. Especially since there is no type safety in the bitlocking code (this never caused any warnings, and worked fine on x86-64, because the bitlocks take a 'void *' and x86-64 doesn't care that deeply about alignment). So it's currently a very easy problem to trigger by mistake and never notice. Reported-by: Meelis Roos <mroos@linux.ee> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Miller <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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