linux/arch/x86/kernel
Sage Weil b7ed78f565 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>
2011-03-21 00:40:29 -04:00
..
acpi Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-16 10:10:02 -07:00
apic Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-18 10:45:21 -07:00
cpu Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-18 10:45:21 -07:00
.gitignore
alternative.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
amd_iommu_init.c
amd_iommu.c
amd_nb.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp 2011-03-17 17:21:32 -07:00
apb_timer.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 20:01:36 -07:00
aperture_64.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
apm_32.c Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-18 10:45:21 -07:00
asm-offsets_32.c x86: Partly unify asm-offsets_{32,64}.c 2011-02-10 13:31:37 +01:00
asm-offsets_64.c x86: Partly unify asm-offsets_{32,64}.c 2011-02-10 13:31:37 +01:00
asm-offsets.c x86, asm: Cleanup unnecssary macros in asm-offsets.c 2011-02-25 16:37:32 -08:00
audit_64.c
bootflag.c
check.c x86: Don't check for BIOS corruption in first 64K when there's no need to 2011-03-09 16:36:41 +01:00
cpuid.c
crash_dump_32.c
crash_dump_64.c
crash.c
devicetree.c x86: dt: Cleanup local apic setup 2011-02-25 16:18:52 +01:00
doublefault_32.c
dumpstack_32.c x86, dumpstack: Correct stack dump info when frame pointer is available 2011-03-18 10:51:42 +01:00
dumpstack_64.c x86, dumpstack: Correct stack dump info when frame pointer is available 2011-03-18 10:51:42 +01:00
dumpstack.c x86, dumpstack: Correct stack dump info when frame pointer is available 2011-03-18 10:51:42 +01:00
e820.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 20:01:36 -07:00
early_printk.c
early-quirks.c x86, quirk: Fix SB600 revision check 2011-03-16 14:03:32 +01:00
entry_32.S Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-16 10:10:02 -07:00
entry_64.S x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
ftrace.c ftrace/graph: Trace function entry before updating index 2011-03-10 10:34:43 -05:00
head32.c x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
head64.c
head_32.S Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 20:01:36 -07:00
head_64.S x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
head.c
hpet.c x86: Cleanup the genirq name space 2011-03-12 14:12:00 +01:00
hw_breakpoint.c x86: Use this_cpu_ops to optimize code 2010-12-30 12:20:28 +01:00
i386_ksyms_32.c
i387.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
i8237.c
i8253.c
i8259.c x86: Cleanup the genirq name space 2011-03-12 14:12:00 +01:00
init_task.c
io_delay.c
ioport.c x86: Use bitmap library functions 2011-02-17 14:59:22 +01:00
irq_32.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
irq_64.c
irq_work.c
irq.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 20:01:36 -07:00
irqinit.c Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-15 20:01:36 -07:00
jump_label.c
kdebugfs.c
kgdb.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
kprobes.c kprobes: Disabling optimized kprobes for entry text section 2011-03-08 17:22:12 +01:00
kvm.c KVM guest: Fix section mismatch derived from kvm_guest_cpu_online() 2011-03-17 13:08:25 -03:00
kvmclock.c KVM paravirt: Move kvm_smp_prepare_boot_cpu() from kvmclock.c to kvm.c. 2011-01-12 11:23:10 +02:00
ldt.c
machine_kexec_32.c
machine_kexec_64.c
Makefile Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-16 10:10:02 -07:00
mca_32.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
microcode_amd.c x86, microcode, AMD: Fix signedness bug in generic_load_microcode() 2011-02-20 14:01:32 +01:00
microcode_core.c x86, microcode: Correct sysdev_add error path 2011-02-09 16:05:31 +01:00
microcode_intel.c x86/microcode: Fix double vfree() and remove redundant pointer checks before vfree() 2010-12-27 14:33:30 +01:00
mmconf-fam10h_64.c
module.c mm: unify module_alloc code for vmalloc 2011-01-13 17:32:34 -08:00
mpparse.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
msr.c
paravirt_patch_32.c
paravirt_patch_64.c
paravirt-spinlocks.c
paravirt.c thp: add pmd paravirt ops 2011-01-13 17:32:39 -08:00
pci-calgary_64.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
pci-dma.c
pci-gart_64.c
pci-iommu_table.c
pci-nommu.c
pci-swiotlb.c
pcspeaker.c
probe_roms_32.c
process_32.c cpuidle/x86/perf: fix power:cpu_idle double end events and throw cpu_idle events from the cpuidle layer 2011-01-12 18:05:16 -05:00
process_64.c cpuidle/x86/perf: fix power:cpu_idle double end events and throw cpu_idle events from the cpuidle layer 2011-01-12 18:05:16 -05:00
process.c x86, dumpstack: Correct stack dump info when frame pointer is available 2011-03-18 10:51:42 +01:00
ptrace.c
pvclock.c
quirks.c
reboot_32.S x86, reboot: Fix the use of passed arguments in 32-bit BIOS reboot 2011-02-18 15:47:42 -08:00
reboot_fixups_32.c
reboot.c Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-16 10:10:02 -07:00
relocate_kernel_32.S
relocate_kernel_64.S
resource.c x86: avoid high BIOS area when allocating address space 2010-12-17 10:01:30 -08:00
rtc.c rtc: cmos: Add OF bindings 2011-02-23 22:27:55 +01:00
setup_percpu.c x86: Unify CPU -> NUMA node mapping between 32 and 64bit 2011-01-28 14:54:09 +01:00
setup.c Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-16 10:10:02 -07:00
signal.c
smp.c
smpboot.c Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-16 10:10:02 -07:00
stacktrace.c x86, dumpstack: Correct stack dump info when frame pointer is available 2011-03-18 10:51:42 +01:00
step.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
sys_i386_32.c
sys_x86_64.c
syscall_64.c
syscall_table_32.S introduce sys_syncfs to sync a single file system 2011-03-21 00:40:29 -04:00
tboot.c thp: pte alloc trans splitting 2011-01-13 17:32:40 -08:00
tce_64.c
test_nx.c
test_rodata.c
time.c
tls.c
tls.h
topology.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
trampoline_32.S x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
trampoline_64.S x86-64, trampoline: Remove unused variable 2011-02-18 15:50:36 -08:00
trampoline.c x86, trampoline: Common infrastructure for low memory trampolines 2011-02-17 21:02:43 -08:00
traps.c x86, NMI: Clean-up default_do_nmi() 2011-01-07 15:08:53 +01:00
tsc_sync.c
tsc.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
verify_cpu.S x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
vm86_32.c thp: split_huge_page_mm/vma 2011-01-13 17:32:41 -08:00
vmlinux.lds.S Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-03-16 10:10:02 -07:00
vsmp_64.c
vsyscall_64.c
x86_init.c x86/platform: Add a wallclock_init func to x86_init.timers ops 2011-02-14 18:20:43 +01:00
x8664_ksyms_64.c x86-64, mem: Convert memmove() to assembly file and fix return value bug 2011-01-25 16:58:39 -08:00
xsave.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00