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Date:   Mon, 16 Aug 2021 15:23:32 +0200
From:   Jan Kara <jack@suse.cz>
To:     Gabriel Krisman Bertazi <krisman@collabora.com>
Cc:     amir73il@gmail.com, jack@suse.com, linux-api@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        khazhy@google.com, dhowells@redhat.com, david@fromorbit.com,
        tytso@mit.edu, djwong@kernel.org, repnop@google.com,
        kernel@collabora.com
Subject: Re: [PATCH v6 10/21] fsnotify: Support FS_ERROR event type
Message-ID: <20210816132332.GD30215@quack2.suse.cz>
References: <20210812214010.3197279-1-krisman@collabora.com>
 <20210812214010.3197279-11-krisman@collabora.com>
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On Thu 12-08-21 17:39:59, Gabriel Krisman Bertazi wrote:
> Expose a new type of fsnotify event for filesystems to report errors for
> userspace monitoring tools.  fanotify will send this type of
> notification for FAN_FS_ERROR events.  This also introduce a helper for
> generating the new event.
> 
> 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 v5:
>   - pass sb inside data field (jan)
> Changes since v3:
>   - Squash patch ("fsnotify: Introduce helpers to send error_events")
>   - Drop reviewed-bys!
> 
> Changes since v2:
>   - FAN_ERROR->FAN_FS_ERROR (Amir)
> 
> Changes since v1:
>   - Overload FS_ERROR with FS_IN_IGNORED
>   - Implement support for this type on fsnotify_data_inode (Amir)
> ---
>  fs/notify/fsnotify.c             |  3 +++
>  include/linux/fsnotify.h         | 13 +++++++++++++
>  include/linux/fsnotify_backend.h | 18 +++++++++++++++++-
>  3 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
> index 536db02cb26e..6d3b3de4f8ee 100644
> --- a/fs/notify/fsnotify.c
> +++ b/fs/notify/fsnotify.c
> @@ -103,6 +103,9 @@ 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;
>  
> +	if (!sb && data_type == FSNOTIFY_EVENT_ERROR)
> +		sb = ((struct fs_error_report *) data)->sb;
> +
>  	return sb;
>  }
>  
> diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
> index f8acddcf54fb..521234af1827 100644
> --- a/include/linux/fsnotify.h
> +++ b/include/linux/fsnotify.h
> @@ -317,4 +317,17 @@ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
>  		fsnotify_dentry(dentry, mask);
>  }
>  
> +static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode,
> +				    int error)
> +{
> +	struct fs_error_report report = {
> +		.error = error,
> +		.inode = inode,
> +		.sb = sb,
> +	};
> +
> +	return fsnotify(FS_ERROR, &report, FSNOTIFY_EVENT_ERROR,
> +			NULL, NULL, NULL, 0);
> +}
> +
>  #endif	/* _LINUX_FS_NOTIFY_H */
> diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> index e027af3cd8dd..277b6f3e0998 100644
> --- a/include/linux/fsnotify_backend.h
> +++ b/include/linux/fsnotify_backend.h
> @@ -42,6 +42,12 @@
>  
>  #define FS_UNMOUNT		0x00002000	/* inode on umount fs */
>  #define FS_Q_OVERFLOW		0x00004000	/* Event queued overflowed */
> +#define FS_ERROR		0x00008000	/* Filesystem Error (fanotify) */
> +
> +/*
> + * FS_IN_IGNORED overloads FS_ERROR.  It is only used internally by inotify
> + * which does not support FS_ERROR.
> + */
>  #define FS_IN_IGNORED		0x00008000	/* last inotify event here */
>  
>  #define FS_OPEN_PERM		0x00010000	/* open event in an permission hook */
> @@ -95,7 +101,8 @@
>  #define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
>  			     FS_EVENTS_POSS_ON_CHILD | \
>  			     FS_DELETE_SELF | FS_MOVE_SELF | FS_DN_RENAME | \
> -			     FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED)
> +			     FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
> +			     FS_ERROR)
>  
>  /* Extra flags that may be reported with event or control handling of events */
>  #define ALL_FSNOTIFY_FLAGS  (FS_EXCL_UNLINK | FS_ISDIR | FS_IN_ONESHOT | \
> @@ -248,6 +255,13 @@ enum fsnotify_data_type {
>  	FSNOTIFY_EVENT_NONE,
>  	FSNOTIFY_EVENT_PATH,
>  	FSNOTIFY_EVENT_INODE,
> +	FSNOTIFY_EVENT_ERROR,
> +};
> +
> +struct fs_error_report {
> +	int error;
> +	struct inode *inode;
> +	struct super_block *sb;
>  };
>  
>  static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
> @@ -257,6 +271,8 @@ static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
>  		return (struct inode *)data;
>  	case FSNOTIFY_EVENT_PATH:
>  		return d_inode(((const struct path *)data)->dentry);
> +	case FSNOTIFY_EVENT_ERROR:
> +		return ((struct fs_error_report *)data)->inode;
>  	default:
>  		return NULL;
>  	}
> -- 
> 2.32.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR