diff options
| author | Daniel Rosenberg <drosen@google.com> | 2016-02-11 16:44:15 -0800 |
|---|---|---|
| committer | Daniel Rosenberg <drosen@google.com> | 2016-03-22 20:27:13 -0700 |
| commit | 530d9c5fc268b0c90ffbca40384f9ee657076724 (patch) | |
| tree | 1260e24f953d1dc8f4da588b600252cecf53ff4b | |
| parent | 1e2d3bbcf3f5a603e62dfa0514a43e13ee679d4f (diff) | |
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.
Change-Id: I09563baffad1711a045e45c1bd0bd8713c2cc0b6
Signed-off-by: Daniel Rosenberg <drosen@google.com>
| -rw-r--r-- | fs/notify/inotify/inotify_user.c | 17 | ||||
| -rw-r--r-- | include/linux/dcache.h | 1 |
2 files changed, 15 insertions, 3 deletions
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c index b8d08d0d0a4d..9a0cd02cf3dc 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.dentry, &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; @@ -814,7 +825,7 @@ static int __init inotify_user_setup(void) BUILD_BUG_ON(IN_ISDIR != FS_ISDIR); BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT); - BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21); + BUG_ON(hweight32(ALL_INOTIFY_BITS) != 22); inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC); diff --git a/include/linux/dcache.h b/include/linux/dcache.h index d67ae119cf4e..ebad56e31a8c 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -161,6 +161,7 @@ struct dentry_operations { struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(struct dentry *, bool); struct inode *(*d_select_inode)(struct dentry *, unsigned); + void (*d_canonical_path)(const struct dentry *, struct path *); } ____cacheline_aligned; /* |