Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH 3/7] FS-Cache: Avoid ENFILE checking for kernel-specific open files | Date | Fri, 21 Apr 2006 13:33:47 +0100 |
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Andrew Morton <akpm@osdl.org> wrote:
> > static struct percpu_counter nr_files __cacheline_aligned_in_smp; > > +static atomic_t nr_kernel_files; > > So it's not performance-critical.
Hmmm... nowhere near as critical as the ENFILE accounting, plus the only place we actually read it is for the sysctl file.
It could actually be dispensed with entirely, I suppose.
> > -struct file *get_empty_filp(void) > > +struct file *get_empty_filp(int kernel) > > I'd suggest a new get_empty_kernel_filp(void) rather than providing a magic > argument. (we can still have the magic argument in the new > __get_empty_filp(int), but it shouldn't be part of the caller-visible API). > ... > It would be more flexible to make the caller pass in the flags directly.
So:
struct file *get_empty_kernel_filp(unsigned short flags);
which devolves to get_empty_filp() if flags == 0?
> > +EXPORT_SYMBOL(fget_light); > > fget_light is not otherwise referenced in this patch.
Good point. I'll move it into the cachefiles patch.
> > +EXPORT_SYMBOL(dentry_open_kernel); > > _GPL?
If you wish.
> That's unfortunate. There's still room in f_flags. Was it hard to use that?
Yeah... but the usage of f_flags is constrained by O_xxxx flags that are part of the userspace interface. Using those up for purely kernel things is a bad idea.
Note that I've not actually increased the size of the struct file - f_mode is a 16-bit value, hence why I chose an unsigned short.
> This changes the format of /proc/sys/fs/file-nr. What will break?
As far as I can tell, not a lot. I've grepped through various etc, lib and bin directories on my FC5 system, and the only match I've found is:
/usr/lib64/sa/sadc
I'll present the count through a separate file to make sure.
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