diff options
| author | Daniel Rosenberg <drosen@google.com> | 2016-02-11 16:44:15 -0800 |
|---|---|---|
| committer | Mattias Nissler <mnissler@google.com> | 2016-07-20 16:18:27 +0200 |
| commit | 45499ab41f7acf599a25f034a12c59f36219e0ab (patch) | |
| tree | 841dbe4c7a93af67abd3f8125cdac4aa6cac894d | |
| parent | 49f813ca0f7f33748ccea729f1f1f42fa04b417b (diff) | |
| download | v4.4-45499ab41f7acf599a25f034a12c59f36219e0ab.tar.gz | |
ANDROID: vfs: add d_canonical_path for stacked filesystem support
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.
Includes subsequent work and fixes:
Daniel Rosenberg <drosen@google.com>:
inotify: Fix erroneous update of bit count
Daniel Rosenberg <drosen@google.com>:
inotify: Fix erroneous update of bit count
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Bug: 23904372
Patchset: fs-dentry-canonical-path
Signed-off-by: Mattias Nissler <mnissler@google.com>
Change-Id: I3ed224cdcf589ac3b46fafd3d90b9775bf68f3cd
| -rw-r--r-- | fs/notify/inotify/inotify_user.c | 15 | ||||
| -rw-r--r-- | include/linux/dcache.h | 1 |
2 files changed, 14 insertions, 2 deletions
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c index b8d08d0d0a4d..e2893f17dde2 100644 --- a/fs/notify/inotify/inotify_user.c +++ b/fs/notify/inotify/inotify_user.c @@ -702,6 +702,8 @@ SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, struct fsnotify_group *group; struct inode *inode; struct path path; + struct path alteredpath; + struct path *canonical_path = &path; struct fd f; int ret; unsigned flags = 0; @@ -741,13 +743,22 @@ SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, if (ret) goto fput_and_out; + /* support stacked filesystems */ + if(path.dentry && path.dentry->d_op) { + if (path.dentry->d_op->d_canonical_path) { + path.dentry->d_op->d_canonical_path(&path, &alteredpath); + canonical_path = &alteredpath; + path_put(&path); + } + } + /* inode held in place by reference to path; group by fget on fd */ - inode = path.dentry->d_inode; + inode = canonical_path->dentry->d_inode; group = f.file->private_data; /* create/update an inode mark */ ret = inotify_update_watch(group, inode, mask); - path_put(&path); + path_put(canonical_path); fput_and_out: fdput(f); return ret; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index f513dd855cb2..da48880a76c6 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -162,6 +162,7 @@ struct dentry_operations { int (*d_manage)(struct dentry *, bool); struct inode *(*d_select_inode)(struct dentry *, unsigned); struct dentry *(*d_real)(struct dentry *, struct inode *); + void (*d_canonical_path)(const struct path *, struct path *); } ____cacheline_aligned; /* |