Commit d48589bf authored by Mingming Cao's avatar Mingming Cao Committed by Linus Torvalds
Browse files

[PATCH] ext3_get_blocks: Adjust reservation window size for mblocks 



Optimize the block reservation and the multiple block allocation: with the
knowledge of the total number of blocks ahead, set or adjust the reservation
window size properly (based on the number of blocks needed) before block
allocation happens: if there isn't any reservation yet, make sure the
reservation window equals to or greater than the number of blocks needed,
before create an reservation window; if a reservation window is already
exists, try to extends the window size to match the number of blocks to
allocate.  This could increase the possibility of completing multiple blocks
allocation in a single request, as blocks are only allocated in the range of
the inode's reservation window.

Signed-off-by: default avatarMingming Cao <cmm@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent faa56976

fs/ext3/balloc.c

+31 −1
Original line number Diff line number Diff line
@@ -1011,6 +1011,31 @@ retry: 
	goto retry;

}



static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,

			struct super_block *sb, int size)

{

	struct ext3_reserve_window_node *next_rsv;

	struct rb_node *next;

	spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;



	if (!spin_trylock(rsv_lock))

		return;



	next = rb_next(&my_rsv->rsv_node);



	if (!next)

		my_rsv->rsv_end += size;

	else {

		next_rsv = list_entry(next, struct ext3_reserve_window_node, rsv_node);



		if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)

			my_rsv->rsv_end += size;

		else

			my_rsv->rsv_end = next_rsv->rsv_start - 1;

	}

	spin_unlock(rsv_lock);

}



/*

 * This is the main function used to allocate a new block and its reservation

 * window.
@@ -1095,6 +1120,8 @@ ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle, 
	while (1) {

		if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||

			!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb)) {

			if (my_rsv->rsv_goal_size < *count)

				my_rsv->rsv_goal_size = *count;

			ret = alloc_new_reservation(my_rsv, goal, sb,

							group, bitmap_bh);

			if (ret < 0)
@@ -1102,7 +1129,10 @@ ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle, 


			if (!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb))

				goal = -1;

		}

		} else if (goal > 0 && (my_rsv->rsv_end-goal+1) < *count)

			try_to_extend_reservation(my_rsv, sb,

					*count-my_rsv->rsv_end + goal - 1);



		if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))

		    || (my_rsv->rsv_end < group_first_block))

			BUG();

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