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authorSage Weil <sage@newdream.net>2011-03-10 22:31:30 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2011-03-21 07:40:29 +0300
commitb7ed78f56575074f29ec99d8984f347f6c99c914 (patch)
tree7bc901458a9f47b197052e98a25c4a4f10c52607 /include/linux/syscalls.h
parent1bef82917c74249ff21982127e57defd6ca2bb1b (diff)
downloadlinux-b7ed78f56575074f29ec99d8984f347f6c99c914.tar.xz
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 'include/linux/syscalls.h')
-rw-r--r--include/linux/syscalls.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 1f5c18e6f4f1..83ecc1749ef6 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -825,6 +825,7 @@ asmlinkage long sys_fanotify_init(unsigned int flags, unsigned int event_f_flags
asmlinkage long sys_fanotify_mark(int fanotify_fd, unsigned int flags,
u64 mask, int fd,
const char __user *pathname);
+asmlinkage long sys_syncfs(int fd);
int kernel_execve(const char *filename, const char *const argv[], const char *const envp[]);