The function dm_bufio_set_minimum_buffers sets the number of buffers
before freeing happens. dm-bufio may hold more buffers if enough memory is
available.
There is no guarantee that the specified number of buffers will be
available - if you need a guarantee, use the argument reserved_buffers for
dm_bufio_client_create.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-bufio.c | 14 ++++++++++++--
drivers/md/dm-bufio.h | 5 +++++
2 files changed, 17 insertions(+), 2 deletions(-)
Index: linux-3.13-rc7/drivers/md/dm-bufio.c
===================================================================
--- linux-3.13-rc7.orig/drivers/md/dm-bufio.c 2014-01-14 00:52:33.000000000 +0100
+++ linux-3.13-rc7/drivers/md/dm-bufio.c 2014-01-14 00:53:22.000000000 +0100
@@ -104,6 +104,8 @@ struct dm_bufio_client {
struct list_head reserved_buffers;
unsigned need_reserved_buffers;
+ unsigned minimum_buffers;
+
struct hlist_head *cache_hash;
wait_queue_head_t free_buffer_wait;
@@ -861,8 +863,8 @@ static void __get_memory_limit(struct dm
buffers = dm_bufio_cache_size_per_client >>
(c->sectors_per_block_bits + SECTOR_SHIFT);
- if (buffers < DM_BUFIO_MIN_BUFFERS)
- buffers = DM_BUFIO_MIN_BUFFERS;
+ if (buffers < c->minimum_buffers)
+ buffers = c->minimum_buffers;
*limit_buffers = buffers;
*threshold_buffers = buffers * DM_BUFIO_WRITEBACK_PERCENT / 100;
@@ -1372,6 +1374,12 @@ void dm_bufio_forget(struct dm_bufio_cli
}
EXPORT_SYMBOL(dm_bufio_forget);
+void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n)
+{
+ c->minimum_buffers = n;
+}
+EXPORT_SYMBOL(dm_bufio_set_minimum_buffers);
+
unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)
{
return c->block_size;
@@ -1568,6 +1576,8 @@ struct dm_bufio_client *dm_bufio_client_
INIT_LIST_HEAD(&c->reserved_buffers);
c->need_reserved_buffers = reserved_buffers;
+ c->minimum_buffers = DM_BUFIO_MIN_BUFFERS;
+
init_waitqueue_head(&c->free_buffer_wait);
c->async_write_error = 0;
Index: linux-3.13-rc7/drivers/md/dm-bufio.h
===================================================================
--- linux-3.13-rc7.orig/drivers/md/dm-bufio.h 2014-01-14 00:52:34.000000000 +0100
+++ linux-3.13-rc7/drivers/md/dm-bufio.h 2014-01-14 00:53:22.000000000 +0100
@@ -115,6 +115,11 @@ void dm_bufio_release_move(struct dm_buf
*/
void dm_bufio_forget(struct dm_bufio_client *c, sector_t block);
+/*
+ * Set the minimum number of buffers before cleanup happens.
+ */
+void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n);
+
unsigned dm_bufio_get_block_size(struct dm_bufio_client *c);
sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);
sector_t dm_bufio_get_block_number(struct dm_buffer *b);
--
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