Messages in this thread | | | Subject | Re: [PATCH v2] kernel/ucounts: expose count of inotify watches in use | From | Matthias Brugger <> | Date | Thu, 25 Apr 2019 17:58:15 +0200 |
| |
On 22/02/2019 18:58, Albert Vaca Cintora wrote: > On Fri, Feb 1, 2019 at 9:42 PM Albert Vaca Cintora <albertvaka@gmail.com> wrote: >> >> Adds a readonly 'current_inotify_watches' entry to the user sysctl table. >> The handler for this entry is a custom function that ends up calling >> proc_dointvec. Said sysctl table already contains 'max_inotify_watches' >> and it gets mounted under /proc/sys/user/. >> >> Inotify watches are a finite resource, in a similar way to available file >> descriptors. The motivation for this patch is to be able to set up >> monitoring and alerting before an application starts failing because >> it runs out of inotify watches. >> >> Signed-off-by: Albert Vaca Cintora <albertvaka@gmail.com> >> Acked-by: Jan Kara <jack@suse.cz> >> Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> > > Friendly ping. Any comments on this? >
Any comments on this? Just to make it clear, Albert found this problem while working on montitoring software, so it fixes a real problem out there.
Regards, Matthias
>> --- >> kernel/ucount.c | 29 +++++++++++++++++++++++++++++ >> 1 file changed, 29 insertions(+) >> >> diff --git a/kernel/ucount.c b/kernel/ucount.c >> index f48d1b6376a4..d8b11e53f098 100644 >> --- a/kernel/ucount.c >> +++ b/kernel/ucount.c >> @@ -57,6 +57,11 @@ static struct ctl_table_root set_root = { >> .permissions = set_permissions, >> }; >> >> +#ifdef CONFIG_INOTIFY_USER >> +int proc_read_inotify_watches(struct ctl_table *table, int write, >> + void __user *buffer, size_t *lenp, loff_t *ppos); >> +#endif >> + >> static int zero = 0; >> static int int_max = INT_MAX; >> #define UCOUNT_ENTRY(name) \ >> @@ -79,6 +84,12 @@ static struct ctl_table user_table[] = { >> #ifdef CONFIG_INOTIFY_USER >> UCOUNT_ENTRY("max_inotify_instances"), >> UCOUNT_ENTRY("max_inotify_watches"), >> + { >> + .procname = "current_inotify_watches", >> + .maxlen = sizeof(int), >> + .mode = 0444, >> + .proc_handler = proc_read_inotify_watches, >> + }, >> #endif >> { } >> }; >> @@ -226,6 +237,24 @@ void dec_ucount(struct ucounts *ucounts, enum ucount_type type) >> put_ucounts(ucounts); >> } >> >> +#ifdef CONFIG_INOTIFY_USER >> +int proc_read_inotify_watches(struct ctl_table *table, int write, >> + void __user *buffer, size_t *lenp, loff_t *ppos) >> +{ >> + struct ucounts *ucounts; >> + struct ctl_table fake_table; >> + int count; >> + >> + ucounts = get_ucounts(current_user_ns(), current_euid()); >> + count = atomic_read(&ucounts->ucount[UCOUNT_INOTIFY_WATCHES]); >> + put_ucounts(ucounts); >> + >> + fake_table.data = &count; >> + fake_table.maxlen = sizeof(count); >> + return proc_dointvec(&fake_table, write, buffer, lenp, ppos); >> +} >> +#endif >> + >> static __init int user_namespace_sysctl_init(void) >> { >> #ifdef CONFIG_SYSCTL >> -- >> 2.20.1 >> >
| |