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authorArnd Bergmann <arnd@arndb.de>2018-08-17 15:45:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-17 16:20:28 -0700
commit46c9a946d766fa830a85d6599de5891fe9e717d2 (patch)
tree2ebec8c8aaa86693b0b94da193650d0bb8b0d8ca /mm/shmem.c
parentd6a24df00638a09abd8fb99bdb5a1c7fdd536e59 (diff)
downloadlinux-46c9a946d766fa830a85d6599de5891fe9e717d2.tar.bz2
shmem: use monotonic time for i_generation
get_seconds() is deprecated because it will lead to a 32-bit overflow in 2038 or 2106. We don't need the i_generation to be strictly monotonic anyway, and other file systems like ext4 and xfs just use prandom_u32(), so let's use the same one here. If this is considered too slow, we could also use ktime_get_seconds() or ktime_get_real_seconds() to keep the previous behavior. Both of these return a time64_t and are not deprecated, but only return a unique value once per second, and are predictable. Link: http://lkml.kernel.org/r/20180620082556.581543-1-arnd@arndb.de Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 06ebe17bb924..c48c79018a7c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -29,6 +29,7 @@
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mm.h>
+#include <linux/random.h>
#include <linux/sched/signal.h>
#include <linux/export.h>
#include <linux/swap.h>
@@ -2188,7 +2189,7 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
inode_init_owner(inode, dir, mode);
inode->i_blocks = 0;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
- inode->i_generation = get_seconds();
+ inode->i_generation = prandom_u32();
info = SHMEM_I(inode);
memset(info, 0, (char *)inode - (char *)info);
spin_lock_init(&info->lock);