On Fri, Aug 13, 2021 at 12:41 AM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> Some file system events (i.e. FS_ERROR) might not be associated with an
> inode. For these, it makes sense to associate them directly with the
> super block of the file system they apply to. This patch allows the
> event to be reported with a NULL inode, by recovering the superblock
> directly from the data field, if needed.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
>
> --
> Changes since v5:
> - add fsnotify_data_sb handle to retrieve sb from the data field. (jan)
> ---
> fs/notify/fsnotify.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
> index 30d422b8c0fc..536db02cb26e 100644
> --- a/fs/notify/fsnotify.c
> +++ b/fs/notify/fsnotify.c
> @@ -98,6 +98,14 @@ void fsnotify_sb_delete(struct super_block *sb)
> fsnotify_clear_marks_by_sb(sb);
> }
>
> +static struct super_block *fsnotify_data_sb(const void *data, int data_type)
> +{
> + struct inode *inode = fsnotify_data_inode(data, data_type);
> + struct super_block *sb = inode ? inode->i_sb : NULL;
> +
> + return sb;
> +}
> +
> /*
> * Given an inode, first check if we care what happens to our children. Inotify
> * and dnotify both tell their parents about events. If we care about any event
> @@ -455,8 +463,10 @@ static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
> * @file_name is relative to
> * @file_name: optional file name associated with event
> * @inode: optional inode associated with event -
> - * either @dir or @inode must be non-NULL.
> - * if both are non-NULL event may be reported to both.
> + * If @dir and @inode are NULL, @data must have a type that
> + * allows retrieving the file system associated with this
Irrelevant comment. sb must always be available from @data.
> + * event. if both are non-NULL event may be reported to
> + * both.
> * @cookie: inotify rename cookie
> */
> int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
> @@ -483,7 +493,7 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
> */
> parent = dir;
> }
> - sb = inode->i_sb;
> + sb = inode ? inode->i_sb : fsnotify_data_sb(data, data_type);
const struct path *path = fsnotify_data_path(data, data_type);
+ const struct super_block *sb = fsnotify_data_sb(data, data_type);
All the games with @data @inode and @dir args are irrelevant to this.
sb should always be available from @data and it does not matter
if fsnotify_data_inode() is the same as @inode, @dir or neither.
All those inodes are anyway on the same sb.
Thanks,
Amir.
