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Date: Wed, 4 Aug 2021 12:06:06 -0400
From: Gabriel Krisman Bertazi <krisman@...labora.com>
To: jack@...e.com, amir73il@...il.com
Cc: djwong@...nel.org, tytso@....edu, david@...morbit.com,
dhowells@...hat.com, khazhy@...gle.com,
linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-api@...r.kernel.org,
Gabriel Krisman Bertazi <krisman@...labora.com>,
kernel@...labora.com
Subject: [PATCH v5 17/23] fanotify: Preallocate per superblock mark error event
Error reporting needs to be done in an atomic context. This patch
introduces a single error slot for superblock marks that report the
FAN_FS_ERROR event, to be used during event submission.
Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>
---
fs/notify/fanotify/fanotify.c | 22 +++++++++++++++++
fs/notify/fanotify/fanotify.h | 13 ++++++++++
fs/notify/fanotify/fanotify_user.c | 39 +++++++++++++++++++++++++++++-
3 files changed, 73 insertions(+), 1 deletion(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index ca74199f11e2..0678d35432a7 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -828,6 +828,24 @@ static void fanotify_free_name_event(struct fanotify_event *event)
kfree(FANOTIFY_NE(event));
}
+static void fanotify_free_error_event(struct fanotify_event *event)
+{
+ struct fanotify_error_event *fee;
+
+ if (!event)
+ return;
+
+ fee = FANOTIFY_EE(event);
+ /*
+ * If this is an active error event, disassociate it from the
+ * mark prior to removal.
+ */
+ if (fee->sb_mark->fee_slot == fee)
+ fee->sb_mark->fee_slot = NULL;
+
+ kfree(fee);
+}
+
static void fanotify_free_event(struct fsnotify_event *fsn_event)
{
struct fanotify_event *event;
@@ -850,6 +868,9 @@ static void fanotify_free_event(struct fsnotify_event *fsn_event)
case FANOTIFY_EVENT_TYPE_OVERFLOW:
kfree(event);
break;
+ case FANOTIFY_EVENT_TYPE_FS_ERROR:
+ fanotify_free_error_event(event);
+ break;
default:
WARN_ON_ONCE(1);
}
@@ -867,6 +888,7 @@ static void fanotify_free_mark(struct fsnotify_mark *mark)
if (mark->flags & FANOTIFY_MARK_FLAG_SB_MARK) {
struct fanotify_sb_mark *fa_mark = FANOTIFY_SB_MARK(mark);
+ fanotify_free_error_event(&fa_mark->fee_slot->fae);
kmem_cache_free(fanotify_sb_mark_cache, fa_mark);
} else {
kmem_cache_free(fanotify_mark_cache, mark);
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index aa555975c0f8..206dc6cfd671 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -142,6 +142,7 @@ FANOTIFY_MARK_FLAG(SB_MARK);
struct fanotify_sb_mark {
struct fsnotify_mark fsn_mark;
+ struct fanotify_error_event *fee_slot;
};
static inline
@@ -164,6 +165,7 @@ 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
};
@@ -219,6 +221,17 @@ FANOTIFY_NE(struct fanotify_event *event)
return container_of(event, struct fanotify_name_event, fae);
}
+struct fanotify_error_event {
+ struct fanotify_event fae;
+ struct fanotify_sb_mark *sb_mark; /* Back reference to the mark. */
+};
+
+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 6dad2a00e337..76c1c805af3d 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -167,6 +167,22 @@ static void fanotify_unhash_event(struct fsnotify_group *group,
hlist_del_init(&event->merge_list);
}
+static struct fanotify_error_event *fanotify_alloc_error_event(
+ struct fanotify_sb_mark *sb_mark)
+
+{
+ struct fanotify_error_event *fee;
+
+ fee = kzalloc(sizeof(*fee), GFP_KERNEL_ACCOUNT);
+ if (!fee)
+ return NULL;
+
+ fanotify_init_event(&fee->fae, 0, FS_ERROR);
+ fee->sb_mark = sb_mark;
+
+ return fee;
+}
+
/*
* Get an fanotify notification event if one exists and is small
* enough to fit in "count". Return an error pointer if the count
@@ -994,6 +1010,7 @@ 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);
@@ -1004,13 +1021,33 @@ static int fanotify_add_mark(struct fsnotify_group *group,
return PTR_ERR(fsn_mark);
}
}
+
+ /*
+ * Error events are allocated per super-block mark only if
+ * strictly needed (i.e. FAN_FS_ERROR was requested).
+ */
+ if (type == FSNOTIFY_OBJ_TYPE_SB && !(flags & FAN_MARK_IGNORED_MASK) &&
+ (mask & FAN_FS_ERROR)) {
+ struct fanotify_sb_mark *sb_mark = FANOTIFY_SB_MARK(fsn_mark);
+
+ if (!sb_mark->fee_slot) {
+ sb_mark->fee_slot = fanotify_alloc_error_event(sb_mark);
+ if (!sb_mark->fee_slot) {
+ ret = -ENOMEM;
+ 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,
--
2.32.0
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