linux-kernel - [PATCH 2/3] hfsplus: stop using timespec based interfaces

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Date:   Tue, 19 Jun 2018 18:02:08 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Al Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     y2038@...ts.linaro.org, Arnd Bergmann <arnd@...db.de>,
        Vyacheslav Dubeyko <slava@...eyko.com>,
        "Ernesto A. Fernandez" <ernesto.mnd.fernandez@...il.com>,
        Jan Kara <jack@...e.cz>,
        Dave Kleikamp <dave.kleikamp@...cle.com>,
        Jeff Layton <jlayton@...hat.com>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] hfsplus: stop using timespec based interfaces

The native HFS+ timestamps overflow in year 2040, two years after the Unix
y2038 overflow. However, the way that the conversion between on-disk
timestamps and in-kernel timestamps was implemented, 64-bit machines
actually ended up converting negative UTC timestamps (1902 through 1969)
into times between 2038 and 2106.

Rather than making all machines faithfully represent timestamps in the
ancient past but break after 2040, this changes the file system to
always use the unsigned UTC interpretation, reading back times between
1970 and 2106.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 fs/hfsplus/hfsplus_fs.h |  7 ++++---
 fs/hfsplus/inode.c      | 12 ++++++------
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index d9255abafb81..646c207be38d 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -530,13 +530,14 @@ int hfsplus_submit_bio(struct super_block *sb, sector_t sector, void *buf,
 		       void **data, int op, int op_flags);
 int hfsplus_read_wrapper(struct super_block *sb);
 
-/* time macros */
+/* time macros: convert between 1904-2040 and 1970-2106 range,
+ * pre-1970 timestamps are interpreted as post-2038 times after wrap-around */
 #define __hfsp_mt2ut(t)		(be32_to_cpu(t) - 2082844800U)
 #define __hfsp_ut2mt(t)		(cpu_to_be32(t + 2082844800U))
 
 /* compatibility */
-#define hfsp_mt2ut(t)		(struct timespec){ .tv_sec = __hfsp_mt2ut(t) }
+#define hfsp_mt2ut(t)		(struct timespec64){ .tv_sec = __hfsp_mt2ut(t) }
 #define hfsp_ut2mt(t)		__hfsp_ut2mt((t).tv_sec)
-#define hfsp_now2mt()		__hfsp_ut2mt(get_seconds())
+#define hfsp_now2mt()		__hfsp_ut2mt(ktime_get_real_seconds())
 
 #endif
diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index c824f702feec..c0c8d433864f 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -493,9 +493,9 @@ int hfsplus_cat_read_inode(struct inode *inode, struct hfs_find_data *fd)
 		hfsplus_get_perms(inode, &folder->permissions, 1);
 		set_nlink(inode, 1);
 		inode->i_size = 2 + be32_to_cpu(folder->valence);
-		inode->i_atime = timespec_to_timespec64(hfsp_mt2ut(folder->access_date));
-		inode->i_mtime = timespec_to_timespec64(hfsp_mt2ut(folder->content_mod_date));
-		inode->i_ctime = timespec_to_timespec64(hfsp_mt2ut(folder->attribute_mod_date));
+		inode->i_atime = hfsp_mt2ut(folder->access_date);
+		inode->i_mtime = hfsp_mt2ut(folder->content_mod_date);
+		inode->i_ctime = hfsp_mt2ut(folder->attribute_mod_date);
 		HFSPLUS_I(inode)->create_date = folder->create_date;
 		HFSPLUS_I(inode)->fs_blocks = 0;
 		if (folder->flags & cpu_to_be16(HFSPLUS_HAS_FOLDER_COUNT)) {
@@ -531,9 +531,9 @@ int hfsplus_cat_read_inode(struct inode *inode, struct hfs_find_data *fd)
 			init_special_inode(inode, inode->i_mode,
 					   be32_to_cpu(file->permissions.dev));
 		}
-		inode->i_atime = timespec_to_timespec64(hfsp_mt2ut(file->access_date));
-		inode->i_mtime = timespec_to_timespec64(hfsp_mt2ut(file->content_mod_date));
-		inode->i_ctime = timespec_to_timespec64(hfsp_mt2ut(file->attribute_mod_date));
+		inode->i_atime = hfsp_mt2ut(file->access_date);
+		inode->i_mtime = hfsp_mt2ut(file->content_mod_date);
+		inode->i_ctime = hfsp_mt2ut(file->attribute_mod_date);
 		HFSPLUS_I(inode)->create_date = file->create_date;
 	} else {
 		pr_err("bad catalog entry used to create inode\n");
-- 
2.9.0