[PATCH 37/38] vfs: Allow fsinfo() to query what's in an fs_context [ver #10]

David Howells
2018-07-27T17:35:35Z

Allow fsinfo() to be used to query the filesystem attached to an fs_context
once a superblock has been created or if it comes from fspick().

This is done with something like:

fd = fsopen("ext4", 0);
...
fsconfig(fd, fsconfig_cmd_create, ...);
fsinfo(fd, NULL, ...);

Signed-off-by: David Howells <dhowells@redhat.com>
---

fs/statfs.c | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/fs/statfs.c b/fs/statfs.c
index caf0773957e9..480ac4be8c2a 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -669,13 +669,40 @@ static int vfs_fsinfo_path(int dfd, const char __user *filename,
return ret;
}

+static int vfs_fsinfo_fscontext(struct fs_context *fc,
+ struct fsinfo_kparams *params)
+{
+ int ret;
+
+ if (fc->ops == &legacy_fs_context_ops)
+ return -EOPNOTSUPP;
+
+ ret = mutex_lock_interruptible(&fc->uapi_mutex);
+ if (ret < 0)
+ return ret;
+
+ ret = -EIO;
+ if (fc->root) {
+ struct path path = { .dentry = fc->root };
+
+ ret = vfs_fsinfo(&path, params);
+ }
+
+ mutex_unlock(&fc->uapi_mutex);
+ return ret;
+}
+
static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
{
struct fd f = fdget_raw(fd);
int ret = -EBADF;

if (f.file) {
- ret = vfs_fsinfo(&f.file->f_path, params);
+ if (f.file->f_op == &fscontext_fops)
+ ret = vfs_fsinfo_fscontext(f.file->private_data,
+ params);
+ else
+ ret = vfs_fsinfo(&f.file->f_path, params);
fdput(f);
}
return ret;