On Tue, Mar 21, 2023 at 09:39:41AM -0700, Luis Chamberlain wrote:
> On Tue, Mar 21, 2023 at 03:28:36PM +0100, Christian Brauner wrote:
> > On Tue, Mar 21, 2023 at 09:09:07PM +0800, Yangtao Li wrote:
> > > This moves the fs/drop_caches.c respective sysctls to its own file.
> > >
> > > Signed-off-by: Yangtao Li <frank.li@xxxxxxxx>
> > > ---
> > > fs/drop_caches.c | 25 ++++++++++++++++++++++---
> > > include/linux/mm.h | 6 ------
> > > kernel/sysctl.c | 9 ---------
> > > 3 files changed, 22 insertions(+), 18 deletions(-)
> > >
> > > diff --git a/fs/drop_caches.c b/fs/drop_caches.c
> > > index e619c31b6bd9..3032b83ce6f2 100644
> > > --- a/fs/drop_caches.c
> > > +++ b/fs/drop_caches.c
> > > @@ -12,8 +12,7 @@
> > > #include <linux/gfp.h>
> > > #include "internal.h"
> > >
> > > -/* A global variable is a bit ugly, but it keeps the code simple */
> > > -int sysctl_drop_caches;
> > > +static int sysctl_drop_caches;
> > >
> > > static void drop_pagecache_sb(struct super_block *sb, void *unused)
> > > {
> > > @@ -47,7 +46,7 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
> > > iput(toput_inode);
> > > }
> > >
> > > -int drop_caches_sysctl_handler(struct ctl_table *table, int write,
> > > +static int drop_caches_sysctl_handler(struct ctl_table *table, int write,
> > > void *buffer, size_t *length, loff_t *ppos)
> > > {
> > > int ret;
> > > @@ -75,3 +74,23 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write,
> > > }
> > > return 0;
> > > }
> > > +
> > > +static struct ctl_table drop_caches_table[] = {
> > > + {
> > > + .procname = "drop_caches",
> > > + .data = &sysctl_drop_caches,
> > > + .maxlen = sizeof(int),
> > > + .mode = 0200,
> > > + .proc_handler = drop_caches_sysctl_handler,
> > > + .extra1 = SYSCTL_ONE,
> > > + .extra2 = SYSCTL_FOUR,
> > > + },
> > > + {}
> > > +};
> > > +
> > > +static int __init drop_cache_init(void)
> > > +{
> > > + register_sysctl_init("vm", drop_caches_table);
> >
> > Does this belong under mm/ or fs/?
>
> To not break old userspace it must be kept under "vm" because the
> patch author is moving it from the kernel/sysctl.c table which used
> the "vm" table.
>
> Moving it to "fs" would be a highly functional change which should
> require review from maintainers it would not break existing userspace
> expecations.
No, I was asking whether this belongs under the fs/ or mm/ directory.
But I misread the patch. I thought at first, that the patch moved the
file from the mm/ to the fs/ directory. But that's obviously not the
case... So ignore me.
