Commit b065556a authored by Tao Ma's avatar Tao Ma Committed by Joel Becker
Browse files

ocfs2: make ocfs2_adjust_resv_from_alloc simple. 



When we allocate some bits from the reservation, we always
allocate from the r_start(see ocfs2_resmap_resv_bits).
So there should be no reason to check between r_start
and start. And I don't think we will change this behaviour
later by allocating from some bits after r_start.  Why not make
ocfs2_adjust_resv_from_alloc simple for now?

The only chance we have to adjust the reservation is when we haven't
reached the end. With this patch, the function is more readable.

Note:
btw, this patch also fixes an original bug in the function
which I haven't found before.
	if (end < ocfs2_resv_end(resv))
		rhs = end - ocfs2_resv_end(resv);
This code is of course buggy. ;)

Signed-off-by: default avatarTao Ma <tao.ma@oracle.com>
Acked-by: default avatarMark Fasheh <mfasheh@suse.com>
Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
parent 4b37fcb7

fs/ocfs2/reservations.c

+12 −20
Original line number Diff line number Diff line
@@ -408,7 +408,7 @@ ocfs2_find_resv_lhs(struct ocfs2_reservation_map *resmap, unsigned int goal) 
 * The start value of *rstart is insignificant.

 *

 * This function searches the bitmap range starting at search_start

 * with length csearch_len for a set of contiguous free bits. We try

 * with length search_len for a set of contiguous free bits. We try

 * to find up to 'wanted' bits, but can sometimes return less.

 *

 * Returns the length of allocation, 0 if no free bits are found.
@@ -778,38 +778,28 @@ static void 
				     struct ocfs2_alloc_reservation *resv,

				     unsigned int start, unsigned int end)

{

	unsigned int lhs = 0, rhs = 0;

	unsigned int rhs = 0;

	unsigned int old_end = ocfs2_resv_end(resv);



	BUG_ON(start < resv->r_start);

	BUG_ON(start != resv->r_start || old_end < end);



	/*

	 * Completely used? We can remove it then.

	 */

	if (ocfs2_resv_end(resv) <= end && resv->r_start >= start) {

	if (old_end == end) {

		__ocfs2_resv_discard(resmap, resv);

		return;

	}



	if (end < ocfs2_resv_end(resv))

		rhs = end - ocfs2_resv_end(resv);



	if (start > resv->r_start)

		lhs = start - resv->r_start;

	rhs = old_end - end;



	/*

	 * This should have been trapped above. At the very least, rhs

	 * should be non zero.

	 * This should have been trapped above.

	 */

	BUG_ON(rhs == 0 && lhs == 0);



	if (rhs >= lhs) {

		unsigned int old_end = ocfs2_resv_end(resv);

	BUG_ON(rhs == 0);



	resv->r_start = end + 1;

	resv->r_len = old_end - resv->r_start + 1;

	} else {

		resv->r_len = start - resv->r_start;

	}

}



void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
@@ -824,6 +814,8 @@ void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap, 
	if (resv == NULL)

		return;



	BUG_ON(cstart != resv->r_start);



	spin_lock(&resv_lock);



	mlog(0, "claim bits: cstart: %u cend: %u clen: %u r_start: %u "

fs/ocfs2/reservations.h

+2 −1
Original line number Diff line number Diff line
@@ -149,7 +149,8 @@ int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap, 
 * reservation. But we must always call this function when bits are claimed.

 * Internally, the reservations code will use this information to mark the

 * reservations bitmap. If resv is passed, it's next allocation window will be

 * calculated.

 * calculated. It also expects that 'cstart' is the same as we passed back

 * from ocfs2_resmap_resv_bits().

 */

void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,

			       struct ocfs2_alloc_reservation *resv,

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