570df4e9c2
To support snapshot nfs re-export, we need a way to lookup snapped inode by file handle. For directory inode, snapped metadata are always stored together with head inode. Client just need to pass vinodeno_t to MDS. For non-directory inode, there can be multiple version of snapped inodes and they can be stored in different dirfrags. Besides vinodeno_t, client also need to tell mds from which dirfrag it got the snapped inode. Another problem of supporting snapshot nfs re-export is that there can be multiple paths to access a snapped inode. For example: mkdir -p d1/d2/d3 mkdir d1/.snap/s1 Paths 'd1/.snap/s1/d2/d3', 'd1/d2/.snap/_s1_<inode number of d1>/d3' and 'd1/d2/d3/.snap/_s1_<inode number of d1>' are all reference to the same snapped inode. For a given snapped inode, There is no convenient way to get the first form and the second form paths. For simplicity, ceph_get_parent() return snapdir for snapped directory inode. Furthermore, client may access snapshot of deleted directory. For example: mkdir -p d1/d2 mkdir d1/.snap/s1 open d1/.snap/s1/d2 rm -rf d1/d2 <nfs server restart> The path constucted by ceph_get_parent() and ceph_get_name() is '<inode of d2>/.snap/_s1_<inode number of d1>'. Futher lookup parent of <inode of d2> will fail. To workaround this case, this patch uses d_obtain_root() to get dentry for snapdir of deleted directory. snapdir dentry has no DCACHE_DISCONNECTED flag set, reconnect_path() stops when it reaches snapdir dentry. Link: http://tracker.ceph.com/issues/22105 Signed-off-by: "Yan, Zheng" <zyan@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.