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Re: [PATCH 04/12] fsnotify: support overlayfs

From Jan Kara <jack@suse.cz>
Newsgroups linux.kernel
Subject Re: [PATCH 04/12] fsnotify: support overlayfs
Date 2016-09-16 21:10 +0200
Message-ID <si6Gm-rc-5@gated-at.bofh.it> (permalink)
References <si0hz-4BJ-1@gated-at.bofh.it> <si0rg-4Fp-59@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Fri 16-09-16 14:19:23, Miklos Szeredi wrote:
> From: Aihua Zhang <zhangaihua1@huawei.com>
> 
> When an event occurs direct it to the overlay inode instead of the real
> underlying inode.
> 
> This will work even if the file was first on the lower layer and then
> copied up, while the watch is there.  This is because the watch is on the
> overlay inode, which stays the same through the copy-up.
> 
> For filesystems other than overlayfs this is a no-op, except for the
> performance impact of an extra pointer dereferece.
> 
> Verified to work correctly with the inotify/fanotify tests in LTP.
> 
> Signed-off-by: Aihua Zhang <zhangaihua1@huawei.com>
> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Eric Paris <eparis@redhat.com>
> ---
>  include/linux/fsnotify.h | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
> index eed9e853a06f..b8bcc058e031 100644
> --- a/include/linux/fsnotify.h
> +++ b/include/linux/fsnotify.h
> @@ -29,7 +29,11 @@ static inline int fsnotify_parent(struct path *path, struct dentry *dentry, __u3
>  static inline int fsnotify_perm(struct file *file, int mask)
>  {
>  	struct path *path = &file->f_path;
> -	struct inode *inode = file_inode(file);
> +	/*
> +	 * Do not use file_inode() here or anywhere in this file to get the
> +	 * inode.  That would break *notity on overlayfs.
> +	 */
> +	struct inode *inode = path->dentry->d_inode;

So shouldn't we rather have d_backing_inode(path->dentry) here and
everywhere else?

									Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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Thread

[PATCH 00/12] misc filesystem patches for 4.9 Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:20 +0200
  [PATCH 10/12] posix_acl: don't ignore return value of posix_acl_create_masq() Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
    Re: [PATCH 10/12] posix_acl: don't ignore return value of posix_acl_create_masq() Andreas Grünbacher <andreas.gruenbacher@gmail.com> - 2016-09-16 14:50 +0200
  [PATCH 01/12] ima: use file_dentry() Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 12/12] vfat: don't use ->d_time Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 05/12] locks: fix file locking on overlayfs Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 08/12] btrfs: use filemap_check_errors() Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 11/12] cifs: don't use ->d_time Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 07/12] vfs: do get_write_access() on upper layer of overlayfs Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 02/12] vfs: move permission checking into notify_change() for utimes(NULL) Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 09/12] f2fs: use filemap_check_errors() Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 03/12] vfs: update ovl inode before relatime check Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
  [PATCH 04/12] fsnotify: support overlayfs Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200
    Re: [PATCH 04/12] fsnotify: support overlayfs Jan Kara <jack@suse.cz> - 2016-09-16 21:10 +0200
      Re: [PATCH 04/12] fsnotify: support overlayfs Amir Goldstein <amir73il@gmail.com> - 2016-09-17 08:30 +0200
  [PATCH 06/12] vfs: make argument of d_real_inode() const Miklos Szeredi <mszeredi@redhat.com> - 2016-09-16 14:30 +0200

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