From: Arnd Bergmann <arnd@xxxxxxxx> Subject: 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@xxxxxxxxxx Link: https://patchwork.kernel.org/patch/10474735/ Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: Jan Harkes <jaharkes@xxxxxxxxxx> Acked-by: Jan Harkes <jaharkes@xxxxxxxxxx> Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx> Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: Fabian Frederick <fabf@xxxxxxxxx> Cc: Mikko Rapeli <mikko.rapeli@xxxxxx> Cc: Sam Protsenko <semen.protsenko@xxxxxxxxxx> Cc: Yann Droneaud <ydroneaud@xxxxxxxxxx> Cc: Zhouyang Jia <jiazhouyang09@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/filesystems/coda.txt | 11 +++-- fs/coda/coda_linux.c | 50 ++++++++++++++++++++------- include/uapi/linux/coda.h | 20 +++++++++- 3 files changed, 62 insertions(+), 19 deletions(-) --- a/Documentation/filesystems/coda.txt~coda-stop-using-struct-timespec-in-user-api +++ a/Documentation/filesystems/coda.txt @@ -481,7 +481,10 @@ kernel support. - + struct vtimespec { + long tv_sec; /* seconds */ + long tv_nsec; /* nanoseconds */ + }; struct coda_vattr { enum coda_vtype va_type; /* vnode type (for create) */ @@ -493,9 +496,9 @@ kernel support. long va_fileid; /* file id */ u_quad_t va_size; /* file size in bytes */ long va_blocksize; /* blocksize preferred for i/o */ - struct timespec va_atime; /* time of last access */ - struct timespec va_mtime; /* time of last modification */ - struct timespec va_ctime; /* time file changed */ + struct vtimespec va_atime; /* time of last access */ + struct vtimespec va_mtime; /* time of last modification */ + struct vtimespec va_ctime; /* time file changed */ u_long va_gen; /* generation number of file */ u_long va_flags; /* flags defined for file */ dev_t va_rdev; /* device special file represents */ --- a/fs/coda/coda_linux.c~coda-stop-using-struct-timespec-in-user-api +++ a/fs/coda/coda_linux.c @@ -66,6 +66,32 @@ unsigned short coda_flags_to_cflags(unsi 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 *i 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 *i 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 *i 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); } } --- a/include/uapi/linux/coda.h~coda-stop-using-struct-timespec-in-user-api +++ a/include/uapi/linux/coda.h @@ -211,6 +211,20 @@ struct CodaFid { */ enum coda_vtype { C_VNON, C_VREG, C_VDIR, C_VBLK, C_VCHR, C_VLNK, C_VSOCK, C_VFIFO, C_VBAD }; +#ifdef __linux__ +/* + * This matches the traditional Linux 'timespec' structure binary layout, + * before using 64-bit time_t everywhere. Overflows in y2038 on 32-bit + * architectures. + */ +struct vtimespec { + long tv_sec; /* seconds */ + long tv_nsec; /* nanoseconds */ +}; +#else +#define vtimespec timespec +#endif + struct coda_vattr { long va_type; /* vnode type (for create) */ u_short va_mode; /* files access mode and type */ @@ -220,9 +234,9 @@ struct coda_vattr { long va_fileid; /* file id */ u_quad_t va_size; /* file size in bytes */ long va_blocksize; /* blocksize preferred for i/o */ - struct timespec va_atime; /* time of last access */ - struct timespec va_mtime; /* time of last modification */ - struct timespec va_ctime; /* time file changed */ + struct vtimespec va_atime; /* time of last access */ + struct vtimespec va_mtime; /* time of last modification */ + struct vtimespec va_ctime; /* time file changed */ u_long va_gen; /* generation number of file */ u_long va_flags; /* flags defined for file */ cdev_t va_rdev; /* device special file represents */ _
