Commit 734a1a5e authored by Gabriel Krisman Bertazi's avatar Gabriel Krisman Bertazi Committed by Jan Kara
Browse files

fanotify: Pre-allocate pool of error events 

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.

Link: https://lore.kernel.org/r/20211025192746.66445-20-krisman@collabora.com


Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 8d11a4f4

fs/notify/fanotify/fanotify.c

+3 −0
Original line number Diff line number Diff line
@@ -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)

fs/notify/fanotify/fanotify.h

+11 −0
Original line number Diff line number Diff line
@@ -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)

fs/notify/fanotify/fanotify_user.c

+25 −1
Original line number Diff line number Diff line
@@ -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_FEE_POOL_SIZE	32



/*

 * 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_FEE_POOL_SIZE,

					 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,

include/linux/fsnotify_backend.h

+2 −0
Original line number Diff line number Diff line
@@ -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
@@ -246,6 +247,7 @@ 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 */

	};