diff mbox series

[v8,19/32] fanotify: Pre-allocate pool of error events

Message ID 20211019000015.1666608-20-krisman@collabora.com (mailing list archive)
State New, archived
Headers show
Series file system-wide error monitoring | expand

Commit Message

Gabriel Krisman Bertazi Oct. 19, 2021, midnight UTC
Pre-allocate slots for file system errors to have greater chances of
succeeding, since error events can happen in GFP_NOFS context.  This
patch introduces a group-wide mempool of error events, shared by all
FAN_FS_ERROR marks in this group.

For now, just allocate 128 positions.  A future patch allows this
array to be dynamically resized when a new mark is added.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v7:
  - Expand limit to 128. (Amir)
---
 fs/notify/fanotify/fanotify.c      |  3 +++
 fs/notify/fanotify/fanotify.h      | 11 +++++++++++
 fs/notify/fanotify/fanotify_user.c | 26 +++++++++++++++++++++++++-
 include/linux/fsnotify_backend.h   |  2 ++
 4 files changed, 41 insertions(+), 1 deletion(-)

Comments

Amir Goldstein Oct. 19, 2021, 5:38 a.m. UTC | #1
On Tue, Oct 19, 2021 at 3:03 AM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> Pre-allocate slots for file system errors to have greater chances of
> succeeding, since error events can happen in GFP_NOFS context.  This
> patch introduces a group-wide mempool of error events, shared by all
> FAN_FS_ERROR marks in this group.
>
> For now, just allocate 128 positions.  A future patch allows this
> array to be dynamically resized when a new mark is added.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
>
> ---
> Changes since v7:
>   - Expand limit to 128. (Amir)

I am not sure if Jan was also on board with this request but otherwise

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

> ---
>  fs/notify/fanotify/fanotify.c      |  3 +++
>  fs/notify/fanotify/fanotify.h      | 11 +++++++++++
>  fs/notify/fanotify/fanotify_user.c | 26 +++++++++++++++++++++++++-
>  include/linux/fsnotify_backend.h   |  2 ++
>  4 files changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 8f152445d75c..01d68dfc74aa 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -819,6 +819,9 @@ static void fanotify_free_group_priv(struct fsnotify_group *group)
>         if (group->fanotify_data.ucounts)
>                 dec_ucount(group->fanotify_data.ucounts,
>                            UCOUNT_FANOTIFY_GROUPS);
> +
> +       if (mempool_initialized(&group->fanotify_data.error_events_pool))
> +               mempool_exit(&group->fanotify_data.error_events_pool);
>  }
>
>  static void fanotify_free_path_event(struct fanotify_event *event)
> diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> index c42cf8fd7d79..a577e87fac2b 100644
> --- a/fs/notify/fanotify/fanotify.h
> +++ b/fs/notify/fanotify/fanotify.h
> @@ -141,6 +141,7 @@ enum fanotify_event_type {
>         FANOTIFY_EVENT_TYPE_PATH,
>         FANOTIFY_EVENT_TYPE_PATH_PERM,
>         FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
> +       FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */
>         __FANOTIFY_EVENT_TYPE_NUM
>  };
>
> @@ -196,6 +197,16 @@ FANOTIFY_NE(struct fanotify_event *event)
>         return container_of(event, struct fanotify_name_event, fae);
>  }
>
> +struct fanotify_error_event {
> +       struct fanotify_event fae;
> +};
> +
> +static inline struct fanotify_error_event *
> +FANOTIFY_EE(struct fanotify_event *event)
> +{
> +       return container_of(event, struct fanotify_error_event, fae);
> +}
> +
>  static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
>  {
>         if (event->type == FANOTIFY_EVENT_TYPE_FID)
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 66ee3c2805c7..f77581c5b97f 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -30,6 +30,7 @@
>  #define FANOTIFY_DEFAULT_MAX_EVENTS    16384
>  #define FANOTIFY_OLD_DEFAULT_MAX_MARKS 8192
>  #define FANOTIFY_DEFAULT_MAX_GROUPS    128
> +#define FANOTIFY_DEFAULT_MAX_FEE_POOL  128
>
>  /*
>   * Legacy fanotify marks limits (8192) is per group and we introduced a tunable
> @@ -1054,6 +1055,15 @@ static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
>         return ERR_PTR(ret);
>  }
>
> +static int fanotify_group_init_error_pool(struct fsnotify_group *group)
> +{
> +       if (mempool_initialized(&group->fanotify_data.error_events_pool))
> +               return 0;
> +
> +       return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool,
> +                                        FANOTIFY_DEFAULT_MAX_FEE_POOL,
> +                                        sizeof(struct fanotify_error_event));
> +}
>
>  static int fanotify_add_mark(struct fsnotify_group *group,
>                              fsnotify_connp_t *connp, unsigned int type,
> @@ -1062,6 +1072,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
>  {
>         struct fsnotify_mark *fsn_mark;
>         __u32 added;
> +       int ret = 0;
>
>         mutex_lock(&group->mark_mutex);
>         fsn_mark = fsnotify_find_mark(connp, group);
> @@ -1072,13 +1083,26 @@ static int fanotify_add_mark(struct fsnotify_group *group,
>                         return PTR_ERR(fsn_mark);
>                 }
>         }
> +
> +       /*
> +        * Error events are pre-allocated per group, only if strictly
> +        * needed (i.e. FAN_FS_ERROR was requested).
> +        */
> +       if (!(flags & FAN_MARK_IGNORED_MASK) && (mask & FAN_FS_ERROR)) {
> +               ret = fanotify_group_init_error_pool(group);
> +               if (ret)
> +                       goto out;
> +       }
> +
>         added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
>         if (added & ~fsnotify_conn_mask(fsn_mark->connector))
>                 fsnotify_recalc_mask(fsn_mark->connector);
> +
> +out:
>         mutex_unlock(&group->mark_mutex);
>
>         fsnotify_put_mark(fsn_mark);
> -       return 0;
> +       return ret;
>  }
>
>  static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
> diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> index a378a314e309..9941c06b8c8a 100644
> --- a/include/linux/fsnotify_backend.h
> +++ b/include/linux/fsnotify_backend.h
> @@ -19,6 +19,7 @@
>  #include <linux/atomic.h>
>  #include <linux/user_namespace.h>
>  #include <linux/refcount.h>
> +#include <linux/mempool.h>
>
>  /*
>   * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
> @@ -245,6 +246,7 @@ struct fsnotify_group {
>                         int flags;           /* flags from fanotify_init() */
>                         int f_flags; /* event_f_flags from fanotify_init() */
>                         struct ucounts *ucounts;
> +                       mempool_t error_events_pool;
>                 } fanotify_data;
>  #endif /* CONFIG_FANOTIFY */
>         };
> --
> 2.33.0
>
Jan Kara Oct. 19, 2021, 11:52 a.m. UTC | #2
On Tue 19-10-21 08:38:34, Amir Goldstein wrote:
> On Tue, Oct 19, 2021 at 3:03 AM Gabriel Krisman Bertazi
> <krisman@collabora.com> wrote:
> >
> > Pre-allocate slots for file system errors to have greater chances of
> > succeeding, since error events can happen in GFP_NOFS context.  This
> > patch introduces a group-wide mempool of error events, shared by all
> > FAN_FS_ERROR marks in this group.
> >
> > For now, just allocate 128 positions.  A future patch allows this
> > array to be dynamically resized when a new mark is added.
> >
> > Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> >
> > ---
> > Changes since v7:
> >   - Expand limit to 128. (Amir)
> 
> I am not sure if Jan was also on board with this request but otherwise
> 
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>

I don't really care. I don't see a strong reason to go above original 32
(so I'd slightly prefer that) but OTOH I also don't think those few KB per
notification group using FS_ERROR matter since I don't expect such groups
to be that common.

> > diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> > index 66ee3c2805c7..f77581c5b97f 100644
> > --- a/fs/notify/fanotify/fanotify_user.c
> > +++ b/fs/notify/fanotify/fanotify_user.c
> > @@ -30,6 +30,7 @@
> >  #define FANOTIFY_DEFAULT_MAX_EVENTS    16384
> >  #define FANOTIFY_OLD_DEFAULT_MAX_MARKS 8192
> >  #define FANOTIFY_DEFAULT_MAX_GROUPS    128
> > +#define FANOTIFY_DEFAULT_MAX_FEE_POOL  128

Perhaps FANOTIFY_DEFAULT_FEE_POOL_SIZE would better describe what this
constant is about?

Otherwise feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza
diff mbox series

Patch

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 8f152445d75c..01d68dfc74aa 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -819,6 +819,9 @@  static void fanotify_free_group_priv(struct fsnotify_group *group)
 	if (group->fanotify_data.ucounts)
 		dec_ucount(group->fanotify_data.ucounts,
 			   UCOUNT_FANOTIFY_GROUPS);
+
+	if (mempool_initialized(&group->fanotify_data.error_events_pool))
+		mempool_exit(&group->fanotify_data.error_events_pool);
 }
 
 static void fanotify_free_path_event(struct fanotify_event *event)
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index c42cf8fd7d79..a577e87fac2b 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -141,6 +141,7 @@  enum fanotify_event_type {
 	FANOTIFY_EVENT_TYPE_PATH,
 	FANOTIFY_EVENT_TYPE_PATH_PERM,
 	FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
+	FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */
 	__FANOTIFY_EVENT_TYPE_NUM
 };
 
@@ -196,6 +197,16 @@  FANOTIFY_NE(struct fanotify_event *event)
 	return container_of(event, struct fanotify_name_event, fae);
 }
 
+struct fanotify_error_event {
+	struct fanotify_event fae;
+};
+
+static inline struct fanotify_error_event *
+FANOTIFY_EE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_error_event, fae);
+}
+
 static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
 {
 	if (event->type == FANOTIFY_EVENT_TYPE_FID)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 66ee3c2805c7..f77581c5b97f 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -30,6 +30,7 @@ 
 #define FANOTIFY_DEFAULT_MAX_EVENTS	16384
 #define FANOTIFY_OLD_DEFAULT_MAX_MARKS	8192
 #define FANOTIFY_DEFAULT_MAX_GROUPS	128
+#define FANOTIFY_DEFAULT_MAX_FEE_POOL	128
 
 /*
  * Legacy fanotify marks limits (8192) is per group and we introduced a tunable
@@ -1054,6 +1055,15 @@  static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
 	return ERR_PTR(ret);
 }
 
+static int fanotify_group_init_error_pool(struct fsnotify_group *group)
+{
+	if (mempool_initialized(&group->fanotify_data.error_events_pool))
+		return 0;
+
+	return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool,
+					 FANOTIFY_DEFAULT_MAX_FEE_POOL,
+					 sizeof(struct fanotify_error_event));
+}
 
 static int fanotify_add_mark(struct fsnotify_group *group,
 			     fsnotify_connp_t *connp, unsigned int type,
@@ -1062,6 +1072,7 @@  static int fanotify_add_mark(struct fsnotify_group *group,
 {
 	struct fsnotify_mark *fsn_mark;
 	__u32 added;
+	int ret = 0;
 
 	mutex_lock(&group->mark_mutex);
 	fsn_mark = fsnotify_find_mark(connp, group);
@@ -1072,13 +1083,26 @@  static int fanotify_add_mark(struct fsnotify_group *group,
 			return PTR_ERR(fsn_mark);
 		}
 	}
+
+	/*
+	 * Error events are pre-allocated per group, only if strictly
+	 * needed (i.e. FAN_FS_ERROR was requested).
+	 */
+	if (!(flags & FAN_MARK_IGNORED_MASK) && (mask & FAN_FS_ERROR)) {
+		ret = fanotify_group_init_error_pool(group);
+		if (ret)
+			goto out;
+	}
+
 	added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
 	if (added & ~fsnotify_conn_mask(fsn_mark->connector))
 		fsnotify_recalc_mask(fsn_mark->connector);
+
+out:
 	mutex_unlock(&group->mark_mutex);
 
 	fsnotify_put_mark(fsn_mark);
-	return 0;
+	return ret;
 }
 
 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index a378a314e309..9941c06b8c8a 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -19,6 +19,7 @@ 
 #include <linux/atomic.h>
 #include <linux/user_namespace.h>
 #include <linux/refcount.h>
+#include <linux/mempool.h>
 
 /*
  * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
@@ -245,6 +246,7 @@  struct fsnotify_group {
 			int flags;           /* flags from fanotify_init() */
 			int f_flags; /* event_f_flags from fanotify_init() */
 			struct ucounts *ucounts;
+			mempool_t error_events_pool;
 		} fanotify_data;
 #endif /* CONFIG_FANOTIFY */
 	};