linux-kernel - [PATCH] afs: use a consistent interpretation of time values

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Date:   Wed, 20 Jun 2018 09:46:39 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     David Howells <dhowells@...hat.com>
Cc:     y2038@...ts.linaro.org, Arnd Bergmann <arnd@...db.de>,
        Anna Schumaker <anna.schumaker@...app.com>,
        linux-afs@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] afs: use a consistent interpretation of time values

afs uses 32-bit timestamps everywhere, but mixes signed and unsigned
usage, which is a bit inconsistent. In particular on 32-bit machines,
it currently uses unsigned timestamps (ranging from 1970 to 2106) for
locally modified files, but signed timestamps (rand 1902 to 2038) when
reading from a remote end. On 64-bit machines, we always interpret
timestamps as unsigned here.

This replaces the deprecated time_t and get_seconds() interfaces with the
modern time64_t and current_time() to locally store 64-bit timestamps,
taking care to use unsigned interpretation of the raw values everywhere,
which avoids the y2038 overflow and is consistent with the previous
usage on 64-bit machines.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 fs/afs/afs.h   | 6 +++---
 fs/afs/inode.c | 4 +---
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/fs/afs/afs.h b/fs/afs/afs.h
index b4ff1f7ae4ab..6ca50c293553 100644
--- a/fs/afs/afs.h
+++ b/fs/afs/afs.h
@@ -129,8 +129,8 @@ typedef u32 afs_access_t;
 struct afs_file_status {
 	u64			size;		/* file size */
 	afs_dataversion_t	data_version;	/* current data version */
-	time_t			mtime_client;	/* last time client changed data */
-	time_t			mtime_server;	/* last time server changed data */
+	time64_t		mtime_client;	/* last time client changed data */
+	time64_t		mtime_server;	/* last time server changed data */
 	unsigned		abort_code;	/* Abort if bulk-fetching this failed */
 
 	afs_file_type_t		type;		/* file type */
@@ -158,7 +158,7 @@ struct afs_file_status {
  * AFS volume synchronisation information
  */
 struct afs_volsync {
-	time_t			creation;	/* volume creation time */
+	time64_t		creation;	/* volume creation time */
 };
 
 /*
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 479b7fdda124..0507e52e3330 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -213,9 +213,7 @@ struct inode *afs_iget_pseudo_dir(struct super_block *sb, bool root)
 	set_nlink(inode, 2);
 	inode->i_uid		= GLOBAL_ROOT_UID;
 	inode->i_gid		= GLOBAL_ROOT_GID;
-	inode->i_ctime.tv_sec	= get_seconds();
-	inode->i_ctime.tv_nsec	= 0;
-	inode->i_atime		= inode->i_mtime = inode->i_ctime;
+	inode->i_ctime = inode->i_atime = inode->i_mtime = current_time(inode);
 	inode->i_blocks		= 0;
 	inode_set_iversion_raw(inode, 0);
 	inode->i_generation	= 0;
-- 
2.9.0