4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mikulas Patocka <mpato...@redhat.com>
commit 13840d38016203f0095cd547b90352812d24b787 upstream.
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.
Signed-off-by: Mikulas Patocka <mpato...@redhat.com>
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/md/dm-bufio.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -215,7 +215,7 @@ 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;
@@ -1541,10 +1541,10 @@ static bool __try_evict_buffer(struct dm
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,
@@ -1554,7 +1554,7 @@ static unsigned long __scan(struct dm_bu
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) {
@@ -1780,8 +1780,8 @@ static bool older_than(struct dm_buffer
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);
@@ -1941,7 +1941,7 @@ MODULE_PARM_DESC(max_cache_size_bytes, "
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);
