Commit 46c9a946 authored Aug 17, 2018 by Arnd Bergmann Committed by Linus Torvalds Aug 17, 2018

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>

parent d6a24df0

mm/shmem.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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);

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