Messages in this thread | | | Subject | Re: [PATCH] change b_size to size_t | From | Badari Pulavarty <> | Date | Thu, 23 Feb 2006 09:40:55 -0800 |
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On Thu, 2006-02-23 at 09:28 -0800, Badari Pulavarty wrote: > On Thu, 2006-02-23 at 11:32 -0500, Benjamin LaHaise wrote: > > On Thu, Feb 23, 2006 at 08:28:12AM -0800, Badari Pulavarty wrote: > > > Here is the updated version of the patch, which changes > > > buffer_head.b_size to size_t to support mapping large > > > amount of disk blocks (for large IOs). > > > > Your patch doesn't seem to be inline, so I can't quote it. Several > > problems: on 64 bit platforms you introduced 4 bytes of padding into > > buffer_head. atomic_t only takes up 4 byte, while size_t is 8 byte > > aligned. > > > Ignore my previous mail. > > How about doing this ? Change b_state to u32 and change b_size > to "size_t". This way, we don't increase the overall size of > the structure on 64-bit machines. Isn't it ?
I hate to correct myself again. But this won't work either. If we do this, we can use bit_spin_lock() helpers any more to do bh_state manipulation :(
Yes. Bottom line is, we would increase the size of the structure by 8-bytes on 64-bit machines. I don't see any way out of it. But this would provide ability to let the filesystems know that the we are dealing with large (> 4GB) of IOs (may be they can allocated as much as possible contiguously), even if we don't really do that big IOs.
Thanks, Badari
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