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Commit 596207b5 authored by Alessio Balsini's avatar Alessio Balsini Committed by Pradeep P V K
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ANDROID: vfs: d_canonical_path for stacked FS 



Inotify does not currently know when a filesystem is acting as a wrapper
around another fs. This means that inotify watchers will miss any
modifications to the base file, as well as any made in a separate stacked
fs that points to the same file.
d_canonical_path solves this problem by allowing the fs to map a dentry to
a path in the lower fs. Inotify can use it to find the appropriate place to
watch to be informed of all changes to a file.


Change-Id: Icc7ff8f4798bf907d5c9ce32065a0471db751a26
Test: FileObserverTest and FileObserverTestLegacyPath on Cuttlefish
Bug: 171780975
Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
[astrachan: Folded 34df4102216e ("ANDROID: fsnotify: Notify lower fs of
 astrachan:           open") into this patch]
Signed-off-by: default avatarAlistair Strachan <astrachan@google.com>
Signed-off-by: default avatarYongqin Liu <yongqin.liu@linaro.org>
Signed-off-by: default avatarAlessio Balsini <balsini@google.com>
Git-commit: f37e05049bf8197901ec042818a64110e59fac41
Git-repo: https://android.googlesource.com/kernel/common/


Signed-off-by: default avatarPradeep P V K <ppvk@codeaurora.org>
parent af6e75fd

include/linux/fsnotify.h

+0 −7
Original line number Diff line number Diff line
@@ -210,19 +210,12 @@ static inline void fsnotify_modify(struct file *file) 
static inline void fsnotify_open(struct file *file)

{

	const struct path *path = &file->f_path;

	struct path lower_path;

	struct inode *inode = file_inode(file);

	__u32 mask = FS_OPEN;



	if (S_ISDIR(inode->i_mode))

		mask |= FS_ISDIR;



	if (path->dentry->d_op && path->dentry->d_op->d_canonical_path) {

		path->dentry->d_op->d_canonical_path(path, &lower_path);

		fsnotify_parent(&lower_path, NULL, mask);

		fsnotify(lower_path.dentry->d_inode, mask, &lower_path, FSNOTIFY_EVENT_PATH, NULL, 0);

		path_put(&lower_path);

	}

	fsnotify_parent(path, NULL, mask);

	fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);

}