FUSE and specifically virtiofs should be able to handle the asynchronous event notifications originating from the FUSE server. To this end we add the FUSE_NOTIFY_FSNOTIFY switch case to the "virtio_fs_handle_notify" in fs/fuse/virtio_fs.c to handle these specific notifications.
The event notification contains the information that a user space application would receive when monitoring an inode for events. The information is the mask of the inode watch, a file name corresponding to the inode the remote event was generated for and finally, the inotify cookie. Then a new event should be generated corresponding to the event notification received from the FUSE server. Specifically, FUSE in the guest kernel will call the "__fsnotify" function in fs/notify/fsnotify.c to send the event to user space. Signed-off-by: Ioannis Angelakopoulos <[email protected]> --- fs/fuse/virtio_fs.c | 64 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 62 insertions(+), 2 deletions(-) diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index d3dba9e3a07e..4c48c2812caa 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -16,6 +16,7 @@ #include <linux/fs_parser.h> #include <linux/highmem.h> #include <linux/uio.h> +#include <linux/fsnotify_backend.h> #include "fuse_i.h" /* Used to help calculate the FUSE connection's max_pages limit for a request's @@ -655,14 +656,69 @@ static void notify_node_reuse(struct virtio_fs_vq *notify_fsvq, spin_unlock(¬ify_fsvq->lock); } +static int fsnotify_remote_event(struct inode *inode, uint32_t mask, + struct qstr *filename, uint32_t cookie) +{ + return __fsnotify(mask, NULL, 0, NULL, + (const struct qstr *)filename, inode, cookie); +} + +/* + * Function to generate a new event when a fsnotify notification comes from the + * fuse server + */ +static int generate_fsnotify_event(struct fuse_conn *fc, + struct fuse_notify_fsnotify_out *fsnotify_out) +{ + struct inode *inode; + uint32_t mask, cookie; + struct fuse_mount *fm; + int ret = -1; + struct qstr name; + + down_read(&fc->killsb); + inode = fuse_ilookup(fc, fsnotify_out->inode, &fm); + /* + * The inode that corresponds to the event does not exist in this case + * so do not generate any new event and just return an error + */ + if (!inode) + goto out; + + mask = fsnotify_out->mask; + cookie = fsnotify_out->cookie; + + /* + * If the notification contained the name of the file/dir the event + * occurred for, it will be placed after the fsnotify_out struct in the + * notification message + */ + if (fsnotify_out->namelen > 0) { + name.len = fsnotify_out->namelen; + name.name = (char *)fsnotify_out + sizeof(struct fuse_notify_fsnotify_out); + ret = fsnotify_remote_event(inode, mask, &name, cookie); + } else { + ret = fsnotify_remote_event(inode, mask, NULL, cookie); + } + + up_read(&fc->killsb); +out: + if (ret < 0) + return -EINVAL; + + return ret; +} + static int virtio_fs_handle_notify(struct virtio_fs *vfs, - struct virtio_fs_notify_node *notifyn) + struct virtio_fs_notify_node *notifyn, + struct fuse_conn *fc) { int ret = 0, no_reuse = 0; struct virtio_fs_notify *notify = ¬ifyn->notify; struct virtio_fs_vq *notify_fsvq = &vfs->vqs[VQ_NOTIFY_IDX]; struct fuse_out_header *oh = ¬ify->out_hdr; struct fuse_notify_lock_out *lo; + struct fuse_notify_fsnotify_out *fsnotify_out; /* * For notifications, oh.unique is 0 and oh->error contains code @@ -673,6 +729,10 @@ static int virtio_fs_handle_notify(struct virtio_fs *vfs, lo = (struct fuse_notify_lock_out *) ¬ify->outarg; no_reuse = notify_complete_waiting_req(vfs, lo); break; + case FUSE_NOTIFY_FSNOTIFY: + fsnotify_out = (struct fuse_notify_fsnotify_out *) ¬ify->outarg; + generate_fsnotify_event(fc, fsnotify_out); + break; default: pr_err("virtio-fs: Unexpected notification %d\n", oh->error); } @@ -711,7 +771,7 @@ static void virtio_fs_notify_done_work(struct work_struct *work) WARN_ON(oh->unique); list_del_init(¬ifyn->list); /* Handle notification */ - virtio_fs_handle_notify(vfs, notifyn); + virtio_fs_handle_notify(vfs, notifyn, fsvq->fud->fc); spin_lock(&fsvq->lock); dec_in_flight_req(fsvq); spin_unlock(&fsvq->lock); -- 2.33.0 _______________________________________________ Virtio-fs mailing list [email protected] https://listman.redhat.com/mailman/listinfo/virtio-fs
