Btrfs inode numbers are only unique inside a subvolume, and so NFS needs
helper routines to send along the subvolume id along with the inode number.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
new file mode 100644
index 0000000..85315d2
--- /dev/null
+++ b/fs/btrfs/export.c
@@ -0,0 +1,203 @@
+#include <linux/fs.h>
+#include <linux/types.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "btrfs_inode.h"
+#include "print-tree.h"
+#include "export.h"
+#include "compat.h"
+
+#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
+ parent_objectid) / 4)
+#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
+ parent_root_objectid) / 4)
+#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
+
+static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
+ int connectable)
+{
+ struct btrfs_fid *fid = (struct btrfs_fid *)fh;
+ struct inode *inode = dentry->d_inode;
+ int len = *max_len;
+ int type;
+
+ if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
+ (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
+ return 255;
+
+ len = BTRFS_FID_SIZE_NON_CONNECTABLE;
+ type = FILEID_BTRFS_WITHOUT_PARENT;
+
+ fid->objectid = BTRFS_I(inode)->location.objectid;
+ fid->root_objectid = BTRFS_I(inode)->root->objectid;
+ fid->gen = inode->i_generation;
+
+ if (connectable && !S_ISDIR(inode->i_mode)) {
+ struct inode *parent;
+ u64 parent_root_id;
+
+ spin_lock(&dentry->d_lock);
+
+ parent = dentry->d_parent->d_inode;
+ fid->parent_objectid = BTRFS_I(parent)->location.objectid;
+ fid->parent_gen = parent->i_generation;
+ parent_root_id = BTRFS_I(parent)->root->objectid;
+
+ spin_unlock(&dentry->d_lock);
+
+ if (parent_root_id != fid->root_objectid) {
+ fid->parent_root_objectid = parent_root_id;
+ len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
+ type = FILEID_BTRFS_WITH_PARENT_ROOT;
+ } else {
+ len = BTRFS_FID_SIZE_CONNECTABLE;
+ type = FILEID_BTRFS_WITH_PARENT;
+ }
+ }
+
+ *max_len = len;
+ return type;
+}
+
+static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
+ u64 root_objectid, u32 generation)
+{
+ struct btrfs_root *root;
+ struct inode *inode;
+ struct btrfs_key key;
+
+ key.objectid = root_objectid;
+ btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+ key.offset = (u64)-1;
+
+ root = btrfs_read_fs_root_no_name(btrfs_sb(sb)->fs_info, &key);
+ if (IS_ERR(root))
+ return ERR_CAST(root);
+
+ key.objectid = objectid;
+ btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
+ key.offset = 0;
+
+ inode = btrfs_iget(sb, &key, root, NULL);
+ if (IS_ERR(inode))
+ return (void *)inode;
+
+ if (generation != inode->i_generation) {
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+
+ return d_obtain_alias(inode);
+}
+
+static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
+ int fh_len, int fh_type)
+{
+ struct btrfs_fid *fid = (struct btrfs_fid *) fh;
+ u64 objectid, root_objectid;
+ u32 generation;
+
+ if (fh_type == FILEID_BTRFS_WITH_PARENT) {
+ if (fh_len != BTRFS_FID_SIZE_CONNECTABLE)
+ return NULL;
+ root_objectid = fid->root_objectid;
+ } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
+ if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
+ return NULL;
+ root_objectid = fid->parent_root_objectid;
+ } else
+ return NULL;
+
+ objectid = fid->parent_objectid;
+ generation = fid->parent_gen;
+
+ return btrfs_get_dentry(sb, objectid, root_objectid, generation);
+}
+
+static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
+ int fh_len, int fh_type)
+{
+ struct btrfs_fid *fid = (struct btrfs_fid *) fh;
+ u64 objectid, root_objectid;
+ u32 generation;
+
+ if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
+ fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
+ (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
+ fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
+ (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
+ fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
+ return NULL;
+
+ objectid = fid->objectid;
+ root_objectid = fid->root_objectid;
+ generation = fid->gen;
+
+ return btrfs_get_dentry(sb, objectid, root_objectid, generation);
+}
+
+static struct dentry *btrfs_get_parent(struct dentry *child)
+{
+ struct inode *dir = child->d_inode;
+ struct btrfs_root *root = BTRFS_I(dir)->root;
+ struct btrfs_key key;
+ struct btrfs_path *path;
+ struct extent_buffer *leaf;
+ int slot;
+ u64 objectid;
+ int ret;
+
+ path = btrfs_alloc_path();
+
+ key.objectid = dir->i_ino;
+ btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret < 0) {
+ /* Error */
+ btrfs_free_path(path);
+ return ERR_PTR(ret);
+ }
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+ if (ret) {
+ /* btrfs_search_slot() returns the slot where we'd want to
+ insert a backref for parent inode #0xFFFFFFFFFFFFFFFF.
+ The _real_ backref, telling us what the parent inode
+ _actually_ is, will be in the slot _before_ the one
+ that btrfs_search_slot() returns. */
+ if (!slot) {
+ /* Unless there is _no_ key in the tree before... */
+ btrfs_free_path(path);
+ return ERR_PTR(-EIO);
+ }
+ slot--;
+ }
+
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+ btrfs_free_path(path);
+
+ if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY)
+ return ERR_PTR(-EINVAL);
+
+ objectid = key.offset;
+
+ /* If we are already at the root of a subvol, return the real root */
+ if (objectid == dir->i_ino)
+ return dget(dir->i_sb->s_root);
+
+ /* Build a new key for the inode item */
+ key.objectid = objectid;
+ btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
+ key.offset = 0;
+
+ return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
+}
+
+const struct export_operations btrfs_export_ops = {
+ .encode_fh = btrfs_encode_fh,
+ .fh_to_dentry = btrfs_fh_to_dentry,
+ .fh_to_parent = btrfs_fh_to_parent,
+ .get_parent = btrfs_get_parent,
+};
diff --git a/fs/btrfs/export.h b/fs/btrfs/export.h
new file mode 100644
index 0000000..074348a
--- /dev/null
+++ b/fs/btrfs/export.h
@@ -0,0 +1,19 @@
+#ifndef BTRFS_EXPORT_H
+#define BTRFS_EXPORT_H
+
+#include <linux/exportfs.h>
+
+extern const struct export_operations btrfs_export_ops;
+
+struct btrfs_fid {
+ u64 objectid;
+ u64 root_objectid;
+ u32 gen;
+
+ u64 parent_objectid;
+ u32 parent_gen;
+
+ u64 parent_root_objectid;
+} __attribute__ ((packed));
+
+#endif
--
1.6.0.2
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