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([2a00:1370:812c:3592:c978:3583:27b6:cdc5]) by smtp.gmail.com with ESMTPSA id y189sm552055lfc.9.2019.11.12.22.00.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Nov 2019 22:00:00 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 13.0 \(3601.0.10\)) Subject: Re: [PATCH 13/16] hfs/hfsplus: use 64-bit inode timestamps From: Viacheslav Dubeyko In-Reply-To: <20191108213257.3097633-14-arnd@arndb.de> Date: Wed, 13 Nov 2019 08:59:58 +0300 Cc: y2038@lists.linaro.org, LKML , =?utf-8?B?IkVybmVzdG8gQS4gRmVybsOhbmRleiI=?= , Andrew Morton , linux-fsdevel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <2520E708-4636-4CA8-B953-0F46F8E7454A@dubeyko.com> References: <20191108213257.3097633-1-arnd@arndb.de> <20191108213257.3097633-14-arnd@arndb.de> To: Arnd Bergmann X-Mailer: Apple Mail (2.3601.0.10) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Nov 9, 2019, at 12:32 AM, Arnd Bergmann wrote: >=20 > The interpretation of on-disk timestamps in HFS and HFS+ differs > between 32-bit and 64-bit kernels at the moment. Use 64-bit timestamps > consistently so apply the current 64-bit behavior everyhere. >=20 > According to the official documentation for HFS+ [1], inode timestamps > are supposed to cover the time range from 1904 to 2040 as originally > used in classic MacOS. >=20 > The traditional Linux usage is to convert the timestamps into an = unsigned > 32-bit number based on the Unix epoch and from there to a time_t. On > 32-bit systems, that wraps the time from 2038 to 1902, so the last > two years of the valid time range become garbled. On 64-bit systems, > all times before 1970 get turned into timestamps between 2038 and = 2106, > which is more convenient but also different from the documented = behavior. >=20 > Looking at the Darwin sources [2], it seems that MacOS is inconsistent = in > yet another way: all timestamps are wrapped around to a 32-bit = unsigned > number when written to the disk, but when read back, all numeric = values > lower than 2082844800U are assumed to be invalid, so we cannot = represent > the times before 1970 or the times after 2040. >=20 > While all implementations seem to agree on the interpretation of = values > between 1970 and 2038, they often differ on the exact range they = support > when reading back values outside of the common range: >=20 > MacOS (traditional): 1904-2040 > Apple Documentation: 1904-2040 > MacOS X source comments: 1970-2040 > MacOS X source code: 1970-2038 > 32-bit Linux: 1902-2038 > 64-bit Linux: 1970-2106 > hfsfuse: 1970-2040 > hfsutils (32 bit, old libc) 1902-2038 > hfsutils (32 bit, new libc) 1970-2106 > hfsutils (64 bit) 1904-2040 > hfsplus-utils 1904-2040 > hfsexplorer 1904-2040 > 7-zip 1904-2040 >=20 > Out of the above, the range from 1970 to 2106 seems to be the most = useful, > as it allows using HFS and HFS+ beyond year 2038, and this matches the > behavior that most users would see today on Linux, as few people run > 32-bit kernels any more. >=20 > Link: [1] = https://developer.apple.com/library/archive/technotes/tn/tn1150.html > Link: [2] = https://opensource.apple.com/source/hfs/hfs-407.30.1/core/MacOSStubs.c.aut= o.html > Link: = https://lore.kernel.org/lkml/20180711224625.airwna6gzyatoowe@eaf/ > Cc: Viacheslav Dubeyko > Suggested-by: "Ernesto A. Fern=C3=A1ndez" = > Signed-off-by: Arnd Bergmann > --- > v3: revert back to 1970-2106 time range > fix bugs found in review > merge both patches into one > drop cc:stable tag > v2: treat pre-1970 dates as invalid following MacOS X behavior, > reword and expand changelog text > --- > fs/hfs/hfs_fs.h | 26 ++++++++++++++++++++------ > fs/hfs/inode.c | 4 ++-- > fs/hfsplus/hfsplus_fs.h | 26 +++++++++++++++++++++----- > fs/hfsplus/inode.c | 12 ++++++------ > 4 files changed, 49 insertions(+), 19 deletions(-) >=20 > diff --git a/fs/hfs/hfs_fs.h b/fs/hfs/hfs_fs.h > index 6d0783e2e276..26733051ee50 100644 > --- a/fs/hfs/hfs_fs.h > +++ b/fs/hfs/hfs_fs.h > @@ -242,19 +242,33 @@ extern void hfs_mark_mdb_dirty(struct = super_block *sb); > /* > * There are two time systems. Both are based on seconds since > * a particular time/date. > - * Unix: unsigned lil-endian since 00:00 GMT, Jan. 1, 1970 > + * Unix: signed little-endian since 00:00 GMT, Jan. 1, 1970 > * mac: unsigned big-endian since 00:00 GMT, Jan. 1, 1904 > * > + * HFS implementations are highly inconsistent, this one matches the > + * traditional behavior of 64-bit Linux, giving the most useful > + * time range between 1970 and 2106, by treating any on-disk = timestamp > + * under 2082844800U (Jan 1 1970) as a time between 2040 and 2106. > */ > -#define __hfs_u_to_mtime(sec) cpu_to_be32(sec + 2082844800U - = sys_tz.tz_minuteswest * 60) > -#define __hfs_m_to_utime(sec) (be32_to_cpu(sec) - 2082844800U = + sys_tz.tz_minuteswest * 60) I believe it makes sense to introduce some constant instead of hardcoded = value (2082844800U and 60). It will be easier to understand the code without necessity to take a = look into the comments. What do you think? > +static inline time64_t __hfs_m_to_utime(__be32 mt) > +{ > + time64_t ut =3D (u32)(be32_to_cpu(mt) - 2082844800U); Ditto. > + > + return ut + sys_tz.tz_minuteswest * 60; > +} >=20 > +static inline __be32 __hfs_u_to_mtime(time64_t ut) > +{ > + ut -=3D sys_tz.tz_minuteswest * 60; > + > + return cpu_to_be32(lower_32_bits(ut) + 2082844800U); Ditto. > +} > #define HFS_I(inode) (container_of(inode, struct hfs_inode_info, = vfs_inode)) > #define HFS_SB(sb) ((struct hfs_sb_info *)(sb)->s_fs_info) >=20 > -#define hfs_m_to_utime(time) (struct timespec){ .tv_sec =3D = __hfs_m_to_utime(time) } > -#define hfs_u_to_mtime(time) __hfs_u_to_mtime((time).tv_sec) > -#define hfs_mtime() __hfs_u_to_mtime(get_seconds()) > +#define hfs_m_to_utime(time) (struct timespec64){ .tv_sec =3D = __hfs_m_to_utime(time) } > +#define hfs_u_to_mtime(time) __hfs_u_to_mtime((time).tv_sec) > +#define hfs_mtime() = __hfs_u_to_mtime(ktime_get_real_seconds()) >=20 > static inline const char *hfs_mdb_name(struct super_block *sb) > { > diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c > index da243c84e93b..2f224b98ee94 100644 > --- a/fs/hfs/inode.c > +++ b/fs/hfs/inode.c > @@ -351,7 +351,7 @@ static int hfs_read_inode(struct inode *inode, = void *data) > inode->i_mode &=3D ~hsb->s_file_umask; > inode->i_mode |=3D S_IFREG; > inode->i_ctime =3D inode->i_atime =3D inode->i_mtime =3D > - = timespec_to_timespec64(hfs_m_to_utime(rec->file.MdDat)); > + hfs_m_to_utime(rec->file.MdDat); > inode->i_op =3D &hfs_file_inode_operations; > inode->i_fop =3D &hfs_file_operations; > inode->i_mapping->a_ops =3D &hfs_aops; > @@ -362,7 +362,7 @@ static int hfs_read_inode(struct inode *inode, = void *data) > HFS_I(inode)->fs_blocks =3D 0; > inode->i_mode =3D S_IFDIR | (S_IRWXUGO & = ~hsb->s_dir_umask); > inode->i_ctime =3D inode->i_atime =3D inode->i_mtime =3D > - = timespec_to_timespec64(hfs_m_to_utime(rec->dir.MdDat)); > + hfs_m_to_utime(rec->dir.MdDat); > inode->i_op =3D &hfs_dir_inode_operations; > inode->i_fop =3D &hfs_dir_operations; > break; > diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h > index b8471bf05def..22d0a22c41a3 100644 > --- a/fs/hfsplus/hfsplus_fs.h > +++ b/fs/hfsplus/hfsplus_fs.h > @@ -533,13 +533,29 @@ 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); >=20 > -/* time macros */ > -#define __hfsp_mt2ut(t) (be32_to_cpu(t) - 2082844800U) > -#define __hfsp_ut2mt(t) (cpu_to_be32(t + 2082844800U)) Ditto. > +/* > + * time helpers: convert between 1904-base and 1970-base timestamps > + * > + * HFS+ implementations are highly inconsistent, this one matches the > + * traditional behavior of 64-bit Linux, giving the most useful > + * time range between 1970 and 2106, by treating any on-disk = timestamp > + * under 2082844800U (Jan 1 1970) as a time between 2040 and 2106. > + */ > +static inline time64_t __hfsp_mt2ut(__be32 mt) > +{ > + time64_t ut =3D (u32)(be32_to_cpu(mt) - 2082844800U); Ditto. > + > + return ut; > +} > + > +static inline __be32 __hfsp_ut2mt(time64_t ut) > +{ > + return cpu_to_be32(lower_32_bits(ut) + 2082844800U); Ditto. > +} >=20 > /* compatibility */ > -#define hfsp_mt2ut(t) (struct timespec){ .tv_sec =3D = __hfsp_mt2ut(t) } > +#define hfsp_mt2ut(t) (struct timespec64){ .tv_sec =3D = __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()) >=20 > #endif > diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c > index d131c8ea7eb6..94bd83b36644 100644 > --- a/fs/hfsplus/inode.c > +++ b/fs/hfsplus/inode.c > @@ -504,9 +504,9 @@ 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 =3D 2 + be32_to_cpu(folder->valence); > - inode->i_atime =3D = timespec_to_timespec64(hfsp_mt2ut(folder->access_date)); > - inode->i_mtime =3D = timespec_to_timespec64(hfsp_mt2ut(folder->content_mod_date)); > - inode->i_ctime =3D = timespec_to_timespec64(hfsp_mt2ut(folder->attribute_mod_date)); > + inode->i_atime =3D hfsp_mt2ut(folder->access_date); > + inode->i_mtime =3D hfsp_mt2ut(folder->content_mod_date); > + inode->i_ctime =3D = hfsp_mt2ut(folder->attribute_mod_date); > HFSPLUS_I(inode)->create_date =3D folder->create_date; > HFSPLUS_I(inode)->fs_blocks =3D 0; > if (folder->flags & = cpu_to_be16(HFSPLUS_HAS_FOLDER_COUNT)) { > @@ -542,9 +542,9 @@ 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 =3D = timespec_to_timespec64(hfsp_mt2ut(file->access_date)); > - inode->i_mtime =3D = timespec_to_timespec64(hfsp_mt2ut(file->content_mod_date)); > - inode->i_ctime =3D = timespec_to_timespec64(hfsp_mt2ut(file->attribute_mod_date)); > + inode->i_atime =3D hfsp_mt2ut(file->access_date); > + inode->i_mtime =3D hfsp_mt2ut(file->content_mod_date); > + inode->i_ctime =3D hfsp_mt2ut(file->attribute_mod_date); > HFSPLUS_I(inode)->create_date =3D file->create_date; > } else { > pr_err("bad catalog entry used to create inode\n"); > =E2=80=94=20 > 2.20.0 >=20 The patch looks pretty clean and good. Thanks, Viacheslav Dubeyko.