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From:   Gabriel Krisman Bertazi <krisman@collabora.com>
To:     amir73il@gmail.com
Cc:     kernel@collabora.com, djwong@kernel.org, tytso@mit.edu,
        david@fromorbit.com, jack@suse.com, dhowells@redhat.com,
        khazhy@google.com, linux-fsdevel@vger.kernel.org,
        linux-ext4@vger.kernel.org,
        Gabriel Krisman Bertazi <krisman@collabora.com>
Subject: [PATCH v2 09/14] fsnotify: Support FS_ERROR event type
Date:   Tue, 15 Jun 2021 19:55:51 -0400
Message-Id: <20210615235556.970928-10-krisman@collabora.com>
In-Reply-To: <20210615235556.970928-1-krisman@collabora.com>
References: <20210615235556.970928-1-krisman@collabora.com>
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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_ERROR events.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v1:
  - Overload FS_ERROR with FS_IN_IGNORED
  - IMplement support for this type on fsnotify_data_inode
---
 include/linux/fsnotify_backend.h | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 8222fe12a6c9..ea5f5c7cc381 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 | \
@@ -263,6 +270,12 @@ 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;
 };
 
 static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
@@ -272,6 +285,8 @@ 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;
 	}
-- 
2.31.0