--- /dev/null
+/*
+ * fs/isofs/export.c
+ *
+ * (C) 2004 Paul Serice - The new inode scheme requires switching
+ * from iget() to iget5_locked() which means
+ * the NFS export operations have to be hand
+ * coded because the default routines rely on
+ * iget().
+ *
+ * The following files are helpful:
+ *
+ * Documentation/filesystems/nfs/Exporting
+ * fs/exportfs/expfs.c.
+ */
+
+#include "isofs.h"
+
+static struct dentry *
+isofs_export_iget(struct super_block *sb,
+ unsigned long block,
+ unsigned long offset,
+ __u32 generation)
+{
+ struct inode *inode;
+
+ if (block == 0)
+ return ERR_PTR(-ESTALE);
+ inode = isofs_iget(sb, block, offset);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+ if (generation && inode->i_generation != generation) {
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+ return d_obtain_alias(inode);
+}
+
+/* This function is surprisingly simple. The trick is understanding
+ * that "child" is always a directory. So, to find its parent, you
+ * simply need to find its ".." entry, normalize its block and offset,
+ * and return the underlying inode. See the comments for
+ * isofs_normalize_block_and_offset(). */
+static struct dentry *isofs_export_get_parent(struct dentry *child)
+{
+ unsigned long parent_block = 0;
+ unsigned long parent_offset = 0;
+ struct inode *child_inode = d_inode(child);
+ struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);
+ struct iso_directory_record *de = NULL;
+ struct buffer_head * bh = NULL;
+ struct dentry *rv = NULL;
+
+ /* "child" must always be a directory. */
+ if (!S_ISDIR(child_inode->i_mode)) {
+ printk(KERN_ERR "isofs: isofs_export_get_parent(): "
+ "child is not a directory!\n");
+ rv = ERR_PTR(-EACCES);
+ goto out;
+ }
+
+ /* It is an invariant that the directory offset is zero. If
+ * it is not zero, it means the directory failed to be
+ * normalized for some reason. */
+ if (e_child_inode->i_iget5_offset != 0) {
+ printk(KERN_ERR "isofs: isofs_export_get_parent(): "
+ "child directory not normalized!\n");
+ rv = ERR_PTR(-EACCES);
+ goto out;
+ }
+
+ /* The child inode has been normalized such that its
+ * i_iget5_block value points to the "." entry. Fortunately,
+ * the ".." entry is located in the same block. */
+ parent_block = e_child_inode->i_iget5_block;
+
+ /* Get the block in question. */
+ bh = sb_bread(child_inode->i_sb, parent_block);
+ if (bh == NULL) {
+ rv = ERR_PTR(-EACCES);
+ goto out;
+ }
+
+ /* This is the "." entry. */
+ de = (struct iso_directory_record*)bh->b_data;
+
+ /* The ".." entry is always the second entry. */
+ parent_offset = (unsigned long)isonum_711(de->length);
+ de = (struct iso_directory_record*)(bh->b_data + parent_offset);
+
+ /* Verify it is in fact the ".." entry. */
+ if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) {
+ printk(KERN_ERR "isofs: Unable to find the \"..\" "
+ "directory for NFS.\n");
+ rv = ERR_PTR(-EACCES);
+ goto out;
+ }
+
+ /* Normalize */
+ isofs_normalize_block_and_offset(de, &parent_block, &parent_offset);
+
+ rv = d_obtain_alias(isofs_iget(child_inode->i_sb, parent_block,
+ parent_offset));
+ out:
+ if (bh)
+ brelse(bh);
+ return rv;
+}
+
+static int
+isofs_export_encode_fh(struct inode *inode,
+ __u32 *fh32,
+ int *max_len,
+ struct inode *parent)
+{
+ struct iso_inode_info * ei = ISOFS_I(inode);
+ int len = *max_len;
+ int type = 1;
+ __u16 *fh16 = (__u16*)fh32;
+
+ /*
+ * WARNING: max_len is 5 for NFSv2. Because of this
+ * limitation, we use the lower 16 bits of fh32[1] to hold the
+ * offset of the inode and the upper 16 bits of fh32[1] to
+ * hold the offset of the parent.
+ */
+ if (parent && (len < 5)) {
+ *max_len = 5;
+ return FILEID_INVALID;
+ } else if (len < 3) {
+ *max_len = 3;
+ return FILEID_INVALID;
+ }
+
+ len = 3;
+ fh32[0] = ei->i_iget5_block;
+ fh16[2] = (__u16)ei->i_iget5_offset; /* fh16 [sic] */
+ fh16[3] = 0; /* avoid leaking uninitialized data */
+ fh32[2] = inode->i_generation;
+ if (parent) {
+ struct iso_inode_info *eparent;
+ eparent = ISOFS_I(parent);
+ fh32[3] = eparent->i_iget5_block;
+ fh16[3] = (__u16)eparent->i_iget5_offset; /* fh16 [sic] */
+ fh32[4] = parent->i_generation;
+ len = 5;
+ type = 2;
+ }
+ *max_len = len;
+ return type;
+}
+
+struct isofs_fid {
+ u32 block;
+ u16 offset;
+ u16 parent_offset;
+ u32 generation;
+ u32 parent_block;
+ u32 parent_generation;
+};
+
+static struct dentry *isofs_fh_to_dentry(struct super_block *sb,
+ struct fid *fid, int fh_len, int fh_type)
+{
+ struct isofs_fid *ifid = (struct isofs_fid *)fid;
+
+ if (fh_len < 3 || fh_type > 2)
+ return NULL;
+
+ return isofs_export_iget(sb, ifid->block, ifid->offset,
+ ifid->generation);
+}
+
+static struct dentry *isofs_fh_to_parent(struct super_block *sb,
+ struct fid *fid, int fh_len, int fh_type)
+{
+ struct isofs_fid *ifid = (struct isofs_fid *)fid;
+
+ if (fh_len < 2 || fh_type != 2)
+ return NULL;
+
+ return isofs_export_iget(sb,
+ fh_len > 2 ? ifid->parent_block : 0,
+ ifid->parent_offset,
+ fh_len > 4 ? ifid->parent_generation : 0);
+}
+
+const struct export_operations isofs_export_ops = {
+ .encode_fh = isofs_export_encode_fh,
+ .fh_to_dentry = isofs_fh_to_dentry,
+ .fh_to_parent = isofs_fh_to_parent,
+ .get_parent = isofs_export_get_parent,
+};
Code Review / kvmfornfv.git / blobdiff