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fanotify: Pre-allocate pool of error events

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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: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Gabriel Krisman Bertazi 2021-10-25 16:27:34 -03:00 committed by Jan Kara
parent 8d11a4f43e
commit 734a1a5ecc
4 changed files with 41 additions and 1 deletions
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3
fs/notify/fanotify/fanotify.c
View File

@ -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)

11
fs/notify/fanotify/fanotify.h
View File

@ -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)

26
fs/notify/fanotify/fanotify_user.c
View File

@ -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 @@ out_dec_ucounts:
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,

2
include/linux/fsnotify_backend.h
View File

@ -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 */
};