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193 lines
5.2 KiB
193 lines
5.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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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.rst |
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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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