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[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: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Mingming Cao 2006-03-26 01:37:59 -08:00 committed by Linus Torvalds
parent faa569763a
commit d48589bfad
1 changed files with 31 additions and 1 deletions
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32
fs/ext3/balloc.c
View File

@ -1011,6 +1011,31 @@ static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
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();