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| author | Sage Weil <sage@newdream.net> | 2011-03-10 11:31:30 -0800 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2011-03-21 00:40:29 -0400 |
| commit | b7ed78f56575074f29ec99d8984f347f6c99c914 (patch) | |
| tree | 7bc901458a9f47b197052e98a25c4a4f10c52607 /arch/x86/include/asm/unistd_32.h | |
| parent | 1bef82917c74249ff21982127e57defd6ca2bb1b (diff) | |
| download | op-kernel-dev-b7ed78f56575074f29ec99d8984f347f6c99c914.zip op-kernel-dev-b7ed78f56575074f29ec99d8984f347f6c99c914.tar.gz | |
introduce sys_syncfs to sync a single file system
It is frequently useful to sync a single file system, instead of all
mounted file systems via sync(2):
- On machines with many mounts, it is not at all uncommon for some of
them to hang (e.g. unresponsive NFS server). sync(2) will get stuck on
those and may never get to the one you do care about (e.g., /).
- Some applications write lots of data to the file system and then
want to make sure it is flushed to disk. Calling fsync(2) on each
file introduces unnecessary ordering constraints that result in a large
amount of sub-optimal writeback/flush/commit behavior by the file
system.
There are currently two ways (that I know of) to sync a single super_block:
- BLKFLSBUF ioctl on the block device: That also invalidates the bdev
mapping, which isn't usually desirable, and doesn't work for non-block
file systems.
- 'mount -o remount,rw' will call sync_filesystem as an artifact of the
current implemention. Relying on this little-known side effect for
something like data safety sounds foolish.
Both of these approaches require root privileges, which some applications
do not have (nor should they need?) given that sync(2) is an unprivileged
operation.
This patch introduces a new system call syncfs(2) that takes an fd and
syncs only the file system it references. Maybe someday we can
$ sync /some/path
and not get
sync: ignoring all arguments
The syscall is motivated by comments by Al and Christoph at the last LSF.
syncfs(2) seems like an appropriate name given statfs(2).
A similar ioctl was also proposed a while back, see
http://marc.info/?l=linux-fsdevel&m=127970513829285&w=2
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'arch/x86/include/asm/unistd_32.h')
| -rw-r--r-- | arch/x86/include/asm/unistd_32.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/include/asm/unistd_32.h b/arch/x86/include/asm/unistd_32.h index ffaf183..a755ef5 100644 --- a/arch/x86/include/asm/unistd_32.h +++ b/arch/x86/include/asm/unistd_32.h @@ -349,10 +349,11 @@ #define __NR_name_to_handle_at 341 #define __NR_open_by_handle_at 342 #define __NR_clock_adjtime 343 +#define __NR_syncfs 344 #ifdef __KERNEL__ -#define NR_syscalls 344 +#define NR_syscalls 345 #define __ARCH_WANT_IPC_PARSE_VERSION #define __ARCH_WANT_OLD_READDIR |
