Messages in this thread | | | Date | Thu, 20 Apr 2006 17:07:54 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 3/7] FS-Cache: Avoid ENFILE checking for kernel-specific open files |
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David Howells <dhowells@redhat.com> wrote: > > Make it possible to avoid ENFILE checking for kernel specific open files, such > as are used by the CacheFiles module. > > After, for example, tarring up a kernel source tree over the network, the > CacheFiles module may easily have 20000+ files open in the backing filesystem, > thus causing all non-root processes to be given error ENFILE when they try to > open a file, socket, pipe, etc.. > > ... > > > static struct percpu_counter nr_files __cacheline_aligned_in_smp; > +static atomic_t nr_kernel_files;
So it's not performance-critical.
> -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).
> + if (!kernel) { > + if (get_nr_files() >= files_stat.max_files && > + !capable(CAP_SYS_ADMIN) > + ) {
ugly.
> + f->f_kernel_flags = kernel ? FKFLAGS_KERNEL : 0;
It would be more flexible to make the caller pass in the flags directly.
> f->f_uid = tsk->fsuid; > f->f_gid = tsk->fsgid; > eventpoll_init_file(f); > @@ -235,6 +250,7 @@ struct file fastcall *fget_light(unsigne > return file; > } > > +EXPORT_SYMBOL(fget_light);
fget_light is not otherwise referenced in this patch.
this change is not changelogged.
why non-GPL?
> +EXPORT_SYMBOL(dentry_open_kernel);
_GPL?
> @@ -640,6 +643,7 @@ struct file { > atomic_t f_count; > unsigned int f_flags; > mode_t f_mode; > + unsigned short f_kernel_flags; > loff_t f_pos; > struct fown_struct f_owner; > unsigned int f_uid, f_gid;
That's unfortunate. There's still room in f_flags. Was it hard to use that?
> @@ -943,7 +943,7 @@ static ctl_table fs_table[] = { > .ctl_name = FS_NRFILE, > .procname = "file-nr", > .data = &files_stat, > - .maxlen = 3*sizeof(int), > + .maxlen = 4*sizeof(int), > .mode = 0444, > .proc_handler = &proc_nr_files,
This changes the format of /proc/sys/fs/file-nr. What will break?
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