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2b0143b5c9
that's the bulk of filesystem drivers dealing with inodes of their own Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
193 lines
5.1 KiB
C
193 lines
5.1 KiB
C
/*
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* fs/isofs/export.c
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*
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* (C) 2004 Paul Serice - The new inode scheme requires switching
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* from iget() to iget5_locked() which means
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* the NFS export operations have to be hand
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* coded because the default routines rely on
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* iget().
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*
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* The following files are helpful:
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*
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* Documentation/filesystems/nfs/Exporting
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* fs/exportfs/expfs.c.
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*/
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#include "isofs.h"
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static struct dentry *
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isofs_export_iget(struct super_block *sb,
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unsigned long block,
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unsigned long offset,
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__u32 generation)
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{
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struct inode *inode;
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if (block == 0)
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return ERR_PTR(-ESTALE);
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inode = isofs_iget(sb, block, offset);
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if (IS_ERR(inode))
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return ERR_CAST(inode);
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if (generation && inode->i_generation != generation) {
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iput(inode);
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return ERR_PTR(-ESTALE);
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}
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return d_obtain_alias(inode);
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}
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/* This function is surprisingly simple. The trick is understanding
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* that "child" is always a directory. So, to find its parent, you
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* simply need to find its ".." entry, normalize its block and offset,
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* and return the underlying inode. See the comments for
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* isofs_normalize_block_and_offset(). */
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static struct dentry *isofs_export_get_parent(struct dentry *child)
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{
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unsigned long parent_block = 0;
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unsigned long parent_offset = 0;
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struct inode *child_inode = d_inode(child);
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struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);
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struct iso_directory_record *de = NULL;
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struct buffer_head * bh = NULL;
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struct dentry *rv = NULL;
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/* "child" must always be a directory. */
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if (!S_ISDIR(child_inode->i_mode)) {
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printk(KERN_ERR "isofs: isofs_export_get_parent(): "
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"child is not a directory!\n");
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rv = ERR_PTR(-EACCES);
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goto out;
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}
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/* It is an invariant that the directory offset is zero. If
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* it is not zero, it means the directory failed to be
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* normalized for some reason. */
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if (e_child_inode->i_iget5_offset != 0) {
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printk(KERN_ERR "isofs: isofs_export_get_parent(): "
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"child directory not normalized!\n");
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rv = ERR_PTR(-EACCES);
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goto out;
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}
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/* The child inode has been normalized such that its
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* i_iget5_block value points to the "." entry. Fortunately,
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* the ".." entry is located in the same block. */
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parent_block = e_child_inode->i_iget5_block;
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/* Get the block in question. */
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bh = sb_bread(child_inode->i_sb, parent_block);
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if (bh == NULL) {
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rv = ERR_PTR(-EACCES);
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goto out;
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}
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/* This is the "." entry. */
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de = (struct iso_directory_record*)bh->b_data;
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/* The ".." entry is always the second entry. */
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parent_offset = (unsigned long)isonum_711(de->length);
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de = (struct iso_directory_record*)(bh->b_data + parent_offset);
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/* Verify it is in fact the ".." entry. */
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if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) {
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printk(KERN_ERR "isofs: Unable to find the \"..\" "
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"directory for NFS.\n");
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rv = ERR_PTR(-EACCES);
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goto out;
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}
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/* Normalize */
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isofs_normalize_block_and_offset(de, &parent_block, &parent_offset);
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rv = d_obtain_alias(isofs_iget(child_inode->i_sb, parent_block,
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parent_offset));
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out:
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if (bh)
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brelse(bh);
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return rv;
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}
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static int
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isofs_export_encode_fh(struct inode *inode,
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__u32 *fh32,
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int *max_len,
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struct inode *parent)
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{
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struct iso_inode_info * ei = ISOFS_I(inode);
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int len = *max_len;
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int type = 1;
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__u16 *fh16 = (__u16*)fh32;
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/*
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* WARNING: max_len is 5 for NFSv2. Because of this
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* limitation, we use the lower 16 bits of fh32[1] to hold the
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* offset of the inode and the upper 16 bits of fh32[1] to
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* hold the offset of the parent.
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*/
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if (parent && (len < 5)) {
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*max_len = 5;
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return FILEID_INVALID;
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} else if (len < 3) {
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*max_len = 3;
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return FILEID_INVALID;
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}
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len = 3;
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fh32[0] = ei->i_iget5_block;
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fh16[2] = (__u16)ei->i_iget5_offset; /* fh16 [sic] */
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fh16[3] = 0; /* avoid leaking uninitialized data */
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fh32[2] = inode->i_generation;
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if (parent) {
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struct iso_inode_info *eparent;
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eparent = ISOFS_I(parent);
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fh32[3] = eparent->i_iget5_block;
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fh16[3] = (__u16)eparent->i_iget5_offset; /* fh16 [sic] */
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fh32[4] = parent->i_generation;
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len = 5;
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type = 2;
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}
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*max_len = len;
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return type;
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}
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struct isofs_fid {
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u32 block;
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u16 offset;
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u16 parent_offset;
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u32 generation;
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u32 parent_block;
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u32 parent_generation;
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};
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static struct dentry *isofs_fh_to_dentry(struct super_block *sb,
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struct fid *fid, int fh_len, int fh_type)
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{
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struct isofs_fid *ifid = (struct isofs_fid *)fid;
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if (fh_len < 3 || fh_type > 2)
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return NULL;
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return isofs_export_iget(sb, ifid->block, ifid->offset,
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ifid->generation);
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}
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static struct dentry *isofs_fh_to_parent(struct super_block *sb,
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struct fid *fid, int fh_len, int fh_type)
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{
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struct isofs_fid *ifid = (struct isofs_fid *)fid;
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if (fh_len < 2 || fh_type != 2)
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return NULL;
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return isofs_export_iget(sb,
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fh_len > 2 ? ifid->parent_block : 0,
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ifid->parent_offset,
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fh_len > 4 ? ifid->parent_generation : 0);
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}
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const struct export_operations isofs_export_ops = {
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.encode_fh = isofs_export_encode_fh,
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.fh_to_dentry = isofs_fh_to_dentry,
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.fh_to_parent = isofs_fh_to_parent,
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.get_parent = isofs_export_get_parent,
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};
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