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author | Arnd Bergmann <arnd@arndb.de> | 2019-07-17 02:28:32 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-17 05:23:23 +0300 |
commit | 6ced9aa7b56baeb241a715df4539e60d5e3118e2 (patch) | |
tree | c4dee6c280f6222228737302d2cd1528100b78f0 /fs/coda | |
parent | 850622136ff2a1296b2c8aa5280a74a6a3aabe4e (diff) | |
download | linux-6ced9aa7b56baeb241a715df4539e60d5e3118e2.tar.xz |
coda: stop using 'struct timespec' in user API
We exchange file timestamps with user space using psdev device
read/write operations with a fixed but architecture specific binary
layout.
On 32-bit systems, this uses a 'timespec' structure that is defined by
the C library to contain two 32-bit values for seconds and nanoseconds.
As we get ready for the year 2038 overflow of the 32-bit signed seconds,
the kernel now uses 64-bit timestamps internally, and user space will do
the same change by changing the 'timespec' definition in the future.
Unfortunately, this breaks the layout of the coda_vattr structure, so we
need to redefine that in terms of something that does not change. I'm
introducing a new 'struct vtimespec' structure here that keeps the
existing layout, and the same change has to be done in the coda user
space copy of linux/coda.h before anyone can use that on a 32-bit
architecture with 64-bit time_t.
An open question is what should happen to actual times past y2038, as
they are now truncated to the last valid date when sent to user space,
and interpreted as pre-1970 times when a timestamp with the MSB set is
read back into the kernel. Alternatively, we could change the new
timespec64_to_coda()/coda_to_timespec64() functions to use a different
interpretation and extend the available range further to the future by
disallowing past timestamps. This would require more changes in the
user space side though.
Link: http://lkml.kernel.org/r/562b7324149461743e4fbe2fedbf7c242f7e274a.1558117389.git.jaharkes@cs.cmu.edu
Link: https://patchwork.kernel.org/patch/10474735/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu>
Acked-by: Jan Harkes <jaharkes@cs.cmu.edu>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: Sam Protsenko <semen.protsenko@linaro.org>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: Zhouyang Jia <jiazhouyang09@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/coda')
-rw-r--r-- | fs/coda/coda_linux.c | 50 |
1 files changed, 38 insertions, 12 deletions
diff --git a/fs/coda/coda_linux.c b/fs/coda/coda_linux.c index f3d543dd9a98..8addcd166908 100644 --- a/fs/coda/coda_linux.c +++ b/fs/coda/coda_linux.c @@ -66,6 +66,32 @@ unsigned short coda_flags_to_cflags(unsigned short flags) return coda_flags; } +static struct timespec64 coda_to_timespec64(struct vtimespec ts) +{ + /* + * We interpret incoming timestamps as 'signed' to match traditional + * usage and support pre-1970 timestamps, but this breaks in y2038 + * on 32-bit machines. + */ + struct timespec64 ts64 = { + .tv_sec = ts.tv_sec, + .tv_nsec = ts.tv_nsec, + }; + + return ts64; +} + +static struct vtimespec timespec64_to_coda(struct timespec64 ts64) +{ + /* clamp the timestamps to the maximum range rather than wrapping */ + struct vtimespec ts = { + .tv_sec = lower_32_bits(clamp_t(time64_t, ts64.tv_sec, + LONG_MIN, LONG_MAX)), + .tv_nsec = ts64.tv_nsec, + }; + + return ts; +} /* utility functions below */ void coda_vattr_to_iattr(struct inode *inode, struct coda_vattr *attr) @@ -105,11 +131,11 @@ void coda_vattr_to_iattr(struct inode *inode, struct coda_vattr *attr) if (attr->va_size != -1) inode->i_blocks = (attr->va_size + 511) >> 9; if (attr->va_atime.tv_sec != -1) - inode->i_atime = timespec_to_timespec64(attr->va_atime); + inode->i_atime = coda_to_timespec64(attr->va_atime); if (attr->va_mtime.tv_sec != -1) - inode->i_mtime = timespec_to_timespec64(attr->va_mtime); + inode->i_mtime = coda_to_timespec64(attr->va_mtime); if (attr->va_ctime.tv_sec != -1) - inode->i_ctime = timespec_to_timespec64(attr->va_ctime); + inode->i_ctime = coda_to_timespec64(attr->va_ctime); } @@ -130,12 +156,12 @@ void coda_iattr_to_vattr(struct iattr *iattr, struct coda_vattr *vattr) vattr->va_uid = (vuid_t) -1; vattr->va_gid = (vgid_t) -1; vattr->va_size = (off_t) -1; - vattr->va_atime.tv_sec = (time_t) -1; - vattr->va_atime.tv_nsec = (time_t) -1; - vattr->va_mtime.tv_sec = (time_t) -1; - vattr->va_mtime.tv_nsec = (time_t) -1; - vattr->va_ctime.tv_sec = (time_t) -1; - vattr->va_ctime.tv_nsec = (time_t) -1; + vattr->va_atime.tv_sec = (long) -1; + vattr->va_atime.tv_nsec = (long) -1; + vattr->va_mtime.tv_sec = (long) -1; + vattr->va_mtime.tv_nsec = (long) -1; + vattr->va_ctime.tv_sec = (long) -1; + vattr->va_ctime.tv_nsec = (long) -1; vattr->va_type = C_VNON; vattr->va_fileid = -1; vattr->va_gen = -1; @@ -175,13 +201,13 @@ void coda_iattr_to_vattr(struct iattr *iattr, struct coda_vattr *vattr) vattr->va_size = iattr->ia_size; } if ( valid & ATTR_ATIME ) { - vattr->va_atime = timespec64_to_timespec(iattr->ia_atime); + vattr->va_atime = timespec64_to_coda(iattr->ia_atime); } if ( valid & ATTR_MTIME ) { - vattr->va_mtime = timespec64_to_timespec(iattr->ia_mtime); + vattr->va_mtime = timespec64_to_coda(iattr->ia_mtime); } if ( valid & ATTR_CTIME ) { - vattr->va_ctime = timespec64_to_timespec(iattr->ia_ctime); + vattr->va_ctime = timespec64_to_coda(iattr->ia_ctime); } } |