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authorDavid Howells <dhowells@redhat.com>2017-07-06 17:50:27 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-10 00:40:12 +0300
commitd3e3b7eac886fb1383db2f22b81550fa6d87f62f (patch)
treef3a8e5d9775aeb053290e2157a946425e9803cd2 /fs/afs/xattr.c
parentfd2498211a551fd42b2d6b9050d649d43536e75c (diff)
downloadlinux-d3e3b7eac886fb1383db2f22b81550fa6d87f62f.tar.xz
afs: Add metadata xattrs
Add xattrs to allow the user to get/set metadata in lieu of having pioctl() available. The following xattrs are now available: - "afs.cell" The name of the cell in which the vnode's volume resides. - "afs.fid" The volume ID, vnode ID and vnode uniquifier of the file as three hex numbers separated by colons. - "afs.volume" The name of the volume in which the vnode resides. For example: # getfattr -d -m ".*" /mnt/scratch getfattr: Removing leading '/' from absolute path names # file: mnt/scratch afs.cell="mycell.myorg.org" afs.fid="10000b:1:1" afs.volume="scratch" Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/afs/xattr.c')
-rw-r--r--fs/afs/xattr.c121
1 files changed, 121 insertions, 0 deletions
diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c
new file mode 100644
index 000000000000..2830e4f48d85
--- /dev/null
+++ b/fs/afs/xattr.c
@@ -0,0 +1,121 @@
+/* Extended attribute handling for AFS. We use xattrs to get and set metadata
+ * instead of providing pioctl().
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/xattr.h>
+#include "internal.h"
+
+static const char afs_xattr_list[] =
+ "afs.cell\0"
+ "afs.fid\0"
+ "afs.volume";
+
+/*
+ * Retrieve a list of the supported xattrs.
+ */
+ssize_t afs_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+ if (size == 0)
+ return sizeof(afs_xattr_list);
+ if (size < sizeof(afs_xattr_list))
+ return -ERANGE;
+ memcpy(buffer, afs_xattr_list, sizeof(afs_xattr_list));
+ return sizeof(afs_xattr_list);
+}
+
+/*
+ * Get the name of the cell on which a file resides.
+ */
+static int afs_xattr_get_cell(const struct xattr_handler *handler,
+ struct dentry *dentry,
+ struct inode *inode, const char *name,
+ void *buffer, size_t size)
+{
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ struct afs_cell *cell = vnode->volume->cell;
+ size_t namelen;
+
+ namelen = strlen(cell->name);
+ if (size == 0)
+ return namelen;
+ if (namelen > size)
+ return -ERANGE;
+ memcpy(buffer, cell->name, size);
+ return namelen;
+}
+
+static const struct xattr_handler afs_xattr_afs_cell_handler = {
+ .name = "afs.cell",
+ .get = afs_xattr_get_cell,
+};
+
+/*
+ * Get the volume ID, vnode ID and vnode uniquifier of a file as a sequence of
+ * hex numbers separated by colons.
+ */
+static int afs_xattr_get_fid(const struct xattr_handler *handler,
+ struct dentry *dentry,
+ struct inode *inode, const char *name,
+ void *buffer, size_t size)
+{
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ char text[8 + 1 + 8 + 1 + 8 + 1];
+ size_t len;
+
+ len = sprintf(text, "%x:%x:%x",
+ vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
+ if (size == 0)
+ return len;
+ if (len > size)
+ return -ERANGE;
+ memcpy(buffer, text, len);
+ return len;
+}
+
+static const struct xattr_handler afs_xattr_afs_fid_handler = {
+ .name = "afs.fid",
+ .get = afs_xattr_get_fid,
+};
+
+/*
+ * Get the name of the volume on which a file resides.
+ */
+static int afs_xattr_get_volume(const struct xattr_handler *handler,
+ struct dentry *dentry,
+ struct inode *inode, const char *name,
+ void *buffer, size_t size)
+{
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ const char *volname = vnode->volume->vlocation->vldb.name;
+ size_t namelen;
+
+ namelen = strlen(volname);
+ if (size == 0)
+ return namelen;
+ if (namelen > size)
+ return -ERANGE;
+ memcpy(buffer, volname, size);
+ return namelen;
+}
+
+static const struct xattr_handler afs_xattr_afs_volume_handler = {
+ .name = "afs.volume",
+ .get = afs_xattr_get_volume,
+};
+
+const struct xattr_handler *afs_xattr_handlers[] = {
+ &afs_xattr_afs_cell_handler,
+ &afs_xattr_afs_fid_handler,
+ &afs_xattr_afs_volume_handler,
+ NULL
+};