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| author | Arnd Bergmann <arnd@arndb.de> | 2019-07-17 02:28:32 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-17 05:23:23 +0300 |
| commit | 6ced9aa7b56baeb241a715df4539e60d5e3118e2 (patch) | |
| tree | c4dee6c280f6222228737302d2cd1528100b78f0 /Documentation | |
| 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 'Documentation')
| -rw-r--r-- | Documentation/filesystems/coda.txt | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/Documentation/filesystems/coda.txt b/Documentation/filesystems/coda.txt index 61311356025d..ea5969068895 100644 --- a/Documentation/filesystems/coda.txt +++ b/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 */ |