dm bufio: make the parameter "retain_bytes" unsigned long
authorMikulas Patocka <mpatocka@redhat.com>
Sun, 30 Apr 2017 21:32:28 +0000 (17:32 -0400)
committerMike Snitzer <snitzer@redhat.com>
Tue, 16 May 2017 19:12:08 +0000 (15:12 -0400)
commit13840d38016203f0095cd547b90352812d24b787
tree0f45c88b71acfc0a69ebdbf0736746b046faf076
parentf98e0eb68008aff9824d1c4dad7276c8bab83ca5
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: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
drivers/md/dm-bufio.c