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SubjectRe: [RFC PATCH] sysfs: refill attribute buffer when reading from offset 0

Andrew Morton wrote:
>> The application for this change is to allow a userspace
>> RAID metadata handler to check the state of an array without causing any
>> memory allocations. Thus not causing writeback to a raid array that might
>> be blocked waiting for userspace to take action.
> Although that sounds like a rather, umm, optimistic application. I guess
> if everything's mlocked you might get lucky.
>> Cc: NeilBrown <>
>> Cc: Tejun Heo <>
>> Signed-off-by: Dan Williams <>

Acked-by: Tejun Heo <>

> Has this been tested with pread()? That should work - doing an lseek+read
> is plain dopey.
> Can we now remove need_read_fill? Not if we want to support
> open+lseek+read, I guess - this initial read might not be at offset
> zero.

Heh.. needs_read_fill is set after read and poll regardless of file pos
and I bet there are applications depending on it. :-(


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