Any API to get metadata?

Any API to get metadata?

[lollipop]

hello,there.
I am wondering if there is any API to get the metadata of a file .
I have the ceph file system run by mounting it to the /mnt/ceph
I want to know how many chunks the file has been parted,and where the chunks
have been stored.
Is there any API I can use to get the information?
Thank you very much!

Re: Any API to get metadata?

[Sage Weil]

On Wed, 26 Dec 2012, lollipop wrote:
> hello,there.
> I am wondering if there is any API to get the metadata of a file .
> I have the ceph file system run by mounting it to the /mnt/ceph
> I want to know how many chunks the file has been parted,and where the chunks
> have been stored.
> Is there any API I can use to get the information?
> Thank you very much!

This is available via an ioctl on the mounted file system (see 
linux.git/include/linux/ceph/ioctl.h) or via libcephfs 
(see ceph.git/src/include/cephfs/libcephfs.h):

/* expose file layout */
int ceph_get_file_stripe_unit(struct ceph_mount_info *cmount, int fh);
int ceph_get_file_pool(struct ceph_mount_info *cmount, int fh);
int ceph_get_file_replication(struct ceph_mount_info *cmount, int fh);
int ceph_get_file_stripe_address(struct ceph_mount_info *cmount, int fd, loff_t offset,
				 struct sockaddr_storage *addr, int naddr);

sage