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aio_read_events_ring(): make a bit more readable

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The logics for 'avail' is
	* not past the tail of cyclic buffer
	* no more than asked
	* not past the end of buffer
	* not past the end of a page

Unobfuscate the last part.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2018-05-26 19:13:10 -04:00
parent 9061d14a8a
commit d2988bd412
1 changed files with 3 additions and 4 deletions
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7
fs/aio.c
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@ -1197,14 +1197,13 @@ static long aio_read_events_ring(struct kioctx *ctx,
if (head == tail)
break;
avail = min(avail, nr - ret);
avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
pos = head + AIO_EVENTS_OFFSET;
page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
pos %= AIO_EVENTS_PER_PAGE;
avail = min(avail, nr - ret);
avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
ev = kmap(page);
copy_ret = copy_to_user(event + ret, ev + pos,
sizeof(*ev) * avail);