Commit 13840d38 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm bufio: make the parameter "retain_bytes" unsigned long 



Change the type of the parameter "retain_bytes" from unsigned to
unsigned long, so that on 64-bit machines the user can set more than
4GiB of data to be retained.

Also, change the type of the variable "count" in the function
"__evict_old_buffers" to unsigned long.  The assignment
"count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];"
could result in unsigned long to unsigned overflow and that could result
in buffers not being freed when they should.

While at it, avoid division in get_retain_buffers().  Division is slow,
we can change it to shift because we have precalculated the log2 of
block size.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent f98e0eb6

drivers/md/dm-bufio.c

+8 −8
Original line number Diff line number Diff line
@@ -218,7 +218,7 @@ static DEFINE_SPINLOCK(param_spinlock); 
 * Buffers are freed after this timeout

 */

static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS;

static unsigned dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;

static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES;



static unsigned long dm_bufio_peak_allocated;

static unsigned long dm_bufio_allocated_kmem_cache;
@@ -1558,10 +1558,10 @@ static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp) 
	return true;

}



static unsigned get_retain_buffers(struct dm_bufio_client *c)

static unsigned long get_retain_buffers(struct dm_bufio_client *c)

{

        unsigned retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes);

        return retain_bytes / c->block_size;

        unsigned long retain_bytes = ACCESS_ONCE(dm_bufio_retain_bytes);

        return retain_bytes >> (c->sectors_per_block_bits + SECTOR_SHIFT);

}



static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan,
@@ -1571,7 +1571,7 @@ static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, 
	struct dm_buffer *b, *tmp;

	unsigned long freed = 0;

	unsigned long count = nr_to_scan;

	unsigned retain_target = get_retain_buffers(c);

	unsigned long retain_target = get_retain_buffers(c);



	for (l = 0; l < LIST_SIZE; l++) {

		list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) {
@@ -1794,8 +1794,8 @@ static bool older_than(struct dm_buffer *b, unsigned long age_hz) 
static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz)

{

	struct dm_buffer *b, *tmp;

	unsigned retain_target = get_retain_buffers(c);

	unsigned count;

	unsigned long retain_target = get_retain_buffers(c);

	unsigned long count;

	LIST_HEAD(write_list);



	dm_bufio_lock(c);
@@ -1955,7 +1955,7 @@ MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache"); 
module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR);

MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds");



module_param_named(retain_bytes, dm_bufio_retain_bytes, uint, S_IRUGO | S_IWUSR);

module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, S_IRUGO | S_IWUSR);

MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory");



module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR);

CRA Git | Maintained and supported by SUSTech CRA and CCSE