diff mbox series

[v3,01/15] fsnotify: Don't insert unmergeable events in hashtable

Message ID 20210629191035.681913-2-krisman@collabora.com
State Superseded
Headers show
Series File system wide monitoring | expand

Commit Message

Gabriel Krisman Bertazi June 29, 2021, 7:10 p.m. UTC
Some events, like the overflow event, are not mergeable, so they are not
hashed.  But, when failing inside fsnotify_add_event for lack of space,
fsnotify_add_event() still calls the insert hook, which adds the
overflow event to the merge list.  Add a check to prevent any kind of
unmergeable event to be inserted in the hashtable.

Fixes: 94e00d28a680 ("fsnotify: use hash table for faster events merge")
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Do check for hashed events inside the insert hook (Amir)
---
 fs/notify/fanotify/fanotify.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Amir Goldstein June 30, 2021, 3:12 a.m. UTC | #1
On Tue, Jun 29, 2021 at 10:11 PM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>
> Some events, like the overflow event, are not mergeable, so they are not
> hashed.  But, when failing inside fsnotify_add_event for lack of space,
> fsnotify_add_event() still calls the insert hook, which adds the
> overflow event to the merge list.  Add a check to prevent any kind of
> unmergeable event to be inserted in the hashtable.
>
> Fixes: 94e00d28a680 ("fsnotify: use hash table for faster events merge")
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
>

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

> ---
> Changes since v2:
>   - Do check for hashed events inside the insert hook (Amir)
> ---
>  fs/notify/fanotify/fanotify.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 057abd2cf887..310246f8d3f1 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -702,6 +702,9 @@ static void fanotify_insert_event(struct fsnotify_group *group,
>
>         assert_spin_locked(&group->notification_lock);
>
> +       if (!fanotify_is_hashed_event(event->mask))
> +               return;
> +
>         pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
>                  group, event, bucket);
>
> @@ -779,8 +782,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
>
>         fsn_event = &event->fse;
>         ret = fsnotify_add_event(group, fsn_event, fanotify_merge,
> -                                fanotify_is_hashed_event(mask) ?
> -                                fanotify_insert_event : NULL);
> +                                fanotify_insert_event);
>         if (ret) {
>                 /* Permission events shouldn't be merged */
>                 BUG_ON(ret == 1 && mask & FANOTIFY_PERM_EVENTS);
> --
> 2.32.0
>
Jan Kara July 7, 2021, 7:21 p.m. UTC | #2
On Tue 29-06-21 15:10:21, Gabriel Krisman Bertazi wrote:
> Some events, like the overflow event, are not mergeable, so they are not
> hashed.  But, when failing inside fsnotify_add_event for lack of space,
> fsnotify_add_event() still calls the insert hook, which adds the
> overflow event to the merge list.  Add a check to prevent any kind of
> unmergeable event to be inserted in the hashtable.
> 
> Fixes: 94e00d28a680 ("fsnotify: use hash table for faster events merge")
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

Looks good. Feel free to add:

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

								Honza

> 
> ---
> Changes since v2:
>   - Do check for hashed events inside the insert hook (Amir)
> ---
>  fs/notify/fanotify/fanotify.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 057abd2cf887..310246f8d3f1 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -702,6 +702,9 @@ static void fanotify_insert_event(struct fsnotify_group *group,
>  
>  	assert_spin_locked(&group->notification_lock);
>  
> +	if (!fanotify_is_hashed_event(event->mask))
> +		return;
> +
>  	pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
>  		 group, event, bucket);
>  
> @@ -779,8 +782,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
>  
>  	fsn_event = &event->fse;
>  	ret = fsnotify_add_event(group, fsn_event, fanotify_merge,
> -				 fanotify_is_hashed_event(mask) ?
> -				 fanotify_insert_event : NULL);
> +				 fanotify_insert_event);
>  	if (ret) {
>  		/* Permission events shouldn't be merged */
>  		BUG_ON(ret == 1 && mask & FANOTIFY_PERM_EVENTS);
> -- 
> 2.32.0
>
diff mbox series

Patch

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 057abd2cf887..310246f8d3f1 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -702,6 +702,9 @@  static void fanotify_insert_event(struct fsnotify_group *group,
 
 	assert_spin_locked(&group->notification_lock);
 
+	if (!fanotify_is_hashed_event(event->mask))
+		return;
+
 	pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
 		 group, event, bucket);
 
@@ -779,8 +782,7 @@  static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
 
 	fsn_event = &event->fse;
 	ret = fsnotify_add_event(group, fsn_event, fanotify_merge,
-				 fanotify_is_hashed_event(mask) ?
-				 fanotify_insert_event : NULL);
+				 fanotify_insert_event);
 	if (ret) {
 		/* Permission events shouldn't be merged */
 		BUG_ON(ret == 1 && mask & FANOTIFY_PERM_EVENTS);