fuse: implement i_op->atomic_open()

Add an ->atomic_open implementation which replaces the atomic open+create
operation implemented via ->create.  No functionality is changed.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 67 insertions, 27 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index f7543f72897e..e42442f1da16 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -369,8 +369,9 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
  * If the filesystem doesn't support this, then fall back to separate
  * 'mknod' + 'open' requests.
  */
-static int fuse_create_open(struct inode *dir, struct dentry *entry,
-                            umode_t mode, struct nameidata *nd)
+static struct file *fuse_create_open(struct inode *dir, struct dentry *entry,
+                                     struct opendata *od, unsigned flags,
+                                     umode_t mode)
 {
         int err;
         struct inode *inode;
@@ -382,14 +383,11 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
         struct fuse_entry_out outentry;
         struct fuse_file *ff;
         struct file *file;
-        int flags = nd->intent.open.flags;
-
-        if (fc->no_create)
-                return -ENOSYS;
 
         forget = fuse_alloc_forget();
+        err = -ENOMEM;
         if (!forget)
-                return -ENOMEM;
+                goto out_err;
 
         req = fuse_get_req(fc);
         err = PTR_ERR(req);
@@ -428,11 +426,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
         req->out.args[1].value = &outopen;
         fuse_request_send(fc, req);
         err = req->out.h.error;
-        if (err) {
-                if (err == -ENOSYS)
-                        fc->no_create = 1;
+        if (err)
                 goto out_free_ff;
-        }
 
         err = -EIO;
         if (!S_ISREG(outentry.attr.mode) || invalid_nodeid(outentry.nodeid))
@@ -448,28 +443,78 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
                 flags &= ~(O_CREAT | O_EXCL | O_TRUNC);
                 fuse_sync_release(ff, flags);
                 fuse_queue_forget(fc, forget, outentry.nodeid, 1);
-                return -ENOMEM;
+                err = -ENOMEM;
+                goto out_err;
         }
         kfree(forget);
         d_instantiate(entry, inode);
         fuse_change_entry_timeout(entry, &outentry);
         fuse_invalidate_attr(dir);
-        file = lookup_instantiate_filp(nd, entry, generic_file_open);
+        file = finish_open(od, entry, generic_file_open);
         if (IS_ERR(file)) {
                 fuse_sync_release(ff, flags);
-                return PTR_ERR(file);
+        } else {
+                file->private_data = fuse_file_get(ff);
+                fuse_finish_open(inode, file);
         }
-        file->private_data = fuse_file_get(ff);
-        fuse_finish_open(inode, file);
-        return 0;
+        return file;
 
- out_free_ff:
+out_free_ff:
         fuse_file_free(ff);
- out_put_request:
+out_put_request:
         fuse_put_request(fc, req);
- out_put_forget_req:
+out_put_forget_req:
         kfree(forget);
-        return err;
+out_err:
+        return ERR_PTR(err);
+}
+
+static int fuse_mknod(struct inode *, struct dentry *, umode_t, dev_t);
+static struct file *fuse_atomic_open(struct inode *dir, struct dentry *entry,
+                                     struct opendata *od, unsigned flags,
+                                     umode_t mode, bool *created)
+{
+        int err;
+        struct fuse_conn *fc = get_fuse_conn(dir);
+        struct file *file;
+        struct dentry *res = NULL;
+
+        if (d_unhashed(entry)) {
+                res = fuse_lookup(dir, entry, NULL);
+                if (IS_ERR(res))
+                        return ERR_CAST(res);
+
+                if (res)
+                        entry = res;
+        }
+
+        if (!(flags & O_CREAT) || entry->d_inode)
+                goto no_open;
+
+        /* Only creates */
+        *created = true;
+
+        if (fc->no_create)
+                goto mknod;
+
+        file = fuse_create_open(dir, entry, od, flags, mode);
+        if (PTR_ERR(file) == -ENOSYS) {
+                fc->no_create = 1;
+                goto mknod;
+        }
+out_dput:
+        dput(res);
+        return file;
+
+mknod:
+        err = fuse_mknod(dir, entry, mode, 0);
+        if (err) {
+                file = ERR_PTR(err);
+                goto out_dput;
+        }
+no_open:
+        finish_no_open(od, res);
+        return NULL;
 }
 
 /*
@@ -573,12 +618,6 @@ static int fuse_mknod(struct inode *dir, struct dentry *entry, umode_t mode,
 static int fuse_create(struct inode *dir, struct dentry *entry, umode_t mode,
                        struct nameidata *nd)
 {
-        if (nd) {
-                int err = fuse_create_open(dir, entry, mode, nd);
-                if (err != -ENOSYS)
-                        return err;
-                /* Fall back on mknod */
-        }
         return fuse_mknod(dir, entry, mode, 0);
 }
 
@@ -1646,6 +1685,7 @@ static const struct inode_operations fuse_dir_inode_operations = {
         .link           = fuse_link,
         .setattr        = fuse_setattr,
         .create         = fuse_create,
+        .atomic_open    = fuse_atomic_open,
         .mknod          = fuse_mknod,
         .permission     = fuse_permission,
         .getattr        = fuse_getattr,