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authorGreg Kurz <groug@kaod.org>2021-06-04 18:11:53 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2021-06-22 09:15:35 +0200
commitfe0a7bd81bfefe5eb73bce55682586c6c266e21e (patch)
treeb9e84e157d8022a19153d1833e562a5a86f95f17 /fs/fuse
parent2d82ab251ef0f6e7716279b04e9b5a01a86ca530 (diff)
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fuse: add dedicated filesystem context ops for submounts
The creation of a submount is open-coded in fuse_dentry_automount(). This brings a lot of complexity and we recently had to fix bugs because we weren't setting SB_BORN or because we were unlocking sb->s_umount before sb was fully configured. Most of these could have been avoided by using the mount API instead of open-coding. Basically, this means coming up with a proper ->get_tree() implementation for submounts and call vfs_get_tree(), or better fc_mount(). The creation of the superblock for submounts is quite different from the root mount. Especially, it doesn't require to allocate a FUSE filesystem context, nor to parse parameters. Introduce a dedicated context ops for submounts to make this clear. This is just a placeholder for now, fuse_get_tree_submount() will be populated in a subsequent patch. Only visible change is that we stop allocating/freeing a useless FUSE filesystem context with submounts. Signed-off-by: Greg Kurz <groug@kaod.org> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/fuse')
-rw-r--r--fs/fuse/fuse_i.h5
-rw-r--r--fs/fuse/inode.c16
-rw-r--r--fs/fuse/virtio_fs.c3
3 files changed, 24 insertions, 0 deletions
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index f48dd7ff32af..b5957c8274dd 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1101,6 +1101,11 @@ int fuse_fill_super_submount(struct super_block *sb,
bool fuse_mount_remove(struct fuse_mount *fm);
/*
+ * Setup context ops for submounts
+ */
+int fuse_init_fs_context_submount(struct fs_context *fsc);
+
+/*
* Shut down the connection (possibly sending DESTROY request).
*/
void fuse_conn_destroy(struct fuse_mount *fm);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 93d28dc1f572..a0a8228979a2 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1353,6 +1353,22 @@ int fuse_fill_super_submount(struct super_block *sb,
return 0;
}
+static int fuse_get_tree_submount(struct fs_context *fsc)
+{
+ return 0;
+}
+
+static const struct fs_context_operations fuse_context_submount_ops = {
+ .get_tree = fuse_get_tree_submount,
+};
+
+int fuse_init_fs_context_submount(struct fs_context *fsc)
+{
+ fsc->ops = &fuse_context_submount_ops;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(fuse_init_fs_context_submount);
+
int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
{
struct fuse_dev *fud = NULL;
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index f9809b1b82f0..8f52cdaa8445 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -1497,6 +1497,9 @@ static int virtio_fs_init_fs_context(struct fs_context *fsc)
{
struct fuse_fs_context *ctx;
+ if (fsc->purpose == FS_CONTEXT_FOR_SUBMOUNT)
+ return fuse_init_fs_context_submount(fsc);
+
ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
if (!ctx)
return -ENOMEM;