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301 lines
7.8 KiB
301 lines
7.8 KiB
/* fs/fat/nfs.c
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <linux/exportfs.h>
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#include "fat.h"
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struct fat_fid {
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u32 i_gen;
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u32 i_pos_low;
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u16 i_pos_hi;
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u16 parent_i_pos_hi;
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u32 parent_i_pos_low;
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u32 parent_i_gen;
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};
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#define FAT_FID_SIZE_WITHOUT_PARENT 3
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#define FAT_FID_SIZE_WITH_PARENT (sizeof(struct fat_fid)/sizeof(u32))
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/**
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* Look up a directory inode given its starting cluster.
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*/
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static struct inode *fat_dget(struct super_block *sb, int i_logstart)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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struct hlist_head *head;
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struct msdos_inode_info *i;
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struct inode *inode = NULL;
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head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
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spin_lock(&sbi->dir_hash_lock);
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hlist_for_each_entry(i, head, i_dir_hash) {
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BUG_ON(i->vfs_inode.i_sb != sb);
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if (i->i_logstart != i_logstart)
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continue;
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inode = igrab(&i->vfs_inode);
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if (inode)
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break;
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}
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spin_unlock(&sbi->dir_hash_lock);
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return inode;
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}
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static struct inode *fat_ilookup(struct super_block *sb, u64 ino, loff_t i_pos)
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{
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if (MSDOS_SB(sb)->options.nfs == FAT_NFS_NOSTALE_RO)
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return fat_iget(sb, i_pos);
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else {
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if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
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return NULL;
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return ilookup(sb, ino);
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}
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}
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static struct inode *__fat_nfs_get_inode(struct super_block *sb,
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u64 ino, u32 generation, loff_t i_pos)
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{
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struct inode *inode = fat_ilookup(sb, ino, i_pos);
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if (inode && generation && (inode->i_generation != generation)) {
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iput(inode);
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inode = NULL;
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}
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if (inode == NULL && MSDOS_SB(sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
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struct buffer_head *bh = NULL;
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struct msdos_dir_entry *de ;
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sector_t blocknr;
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int offset;
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fat_get_blknr_offset(MSDOS_SB(sb), i_pos, &blocknr, &offset);
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bh = sb_bread(sb, blocknr);
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if (!bh) {
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fat_msg(sb, KERN_ERR,
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"unable to read block(%llu) for building NFS inode",
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(llu)blocknr);
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return inode;
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}
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de = (struct msdos_dir_entry *)bh->b_data;
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/* If a file is deleted on server and client is not updated
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* yet, we must not build the inode upon a lookup call.
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*/
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if (IS_FREE(de[offset].name))
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inode = NULL;
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else
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inode = fat_build_inode(sb, &de[offset], i_pos);
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brelse(bh);
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}
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return inode;
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}
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static struct inode *fat_nfs_get_inode(struct super_block *sb,
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u64 ino, u32 generation)
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{
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return __fat_nfs_get_inode(sb, ino, generation, 0);
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}
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static int
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fat_encode_fh_nostale(struct inode *inode, __u32 *fh, int *lenp,
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struct inode *parent)
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{
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int len = *lenp;
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struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
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struct fat_fid *fid = (struct fat_fid *) fh;
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loff_t i_pos;
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int type = FILEID_FAT_WITHOUT_PARENT;
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if (parent) {
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if (len < FAT_FID_SIZE_WITH_PARENT) {
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*lenp = FAT_FID_SIZE_WITH_PARENT;
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return FILEID_INVALID;
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}
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} else {
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if (len < FAT_FID_SIZE_WITHOUT_PARENT) {
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*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
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return FILEID_INVALID;
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}
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}
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i_pos = fat_i_pos_read(sbi, inode);
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*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
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fid->i_gen = inode->i_generation;
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fid->i_pos_low = i_pos & 0xFFFFFFFF;
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fid->i_pos_hi = (i_pos >> 32) & 0xFFFF;
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if (parent) {
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i_pos = fat_i_pos_read(sbi, parent);
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fid->parent_i_pos_hi = (i_pos >> 32) & 0xFFFF;
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fid->parent_i_pos_low = i_pos & 0xFFFFFFFF;
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fid->parent_i_gen = parent->i_generation;
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type = FILEID_FAT_WITH_PARENT;
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*lenp = FAT_FID_SIZE_WITH_PARENT;
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}
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return type;
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}
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/**
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* Map a NFS file handle to a corresponding dentry.
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* The dentry may or may not be connected to the filesystem root.
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*/
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static struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
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int fh_len, int fh_type)
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{
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return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
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fat_nfs_get_inode);
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}
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static struct dentry *fat_fh_to_dentry_nostale(struct super_block *sb,
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struct fid *fh, int fh_len,
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int fh_type)
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{
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struct inode *inode = NULL;
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struct fat_fid *fid = (struct fat_fid *)fh;
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loff_t i_pos;
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switch (fh_type) {
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case FILEID_FAT_WITHOUT_PARENT:
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if (fh_len < FAT_FID_SIZE_WITHOUT_PARENT)
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return NULL;
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break;
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case FILEID_FAT_WITH_PARENT:
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if (fh_len < FAT_FID_SIZE_WITH_PARENT)
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return NULL;
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break;
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default:
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return NULL;
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}
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i_pos = fid->i_pos_hi;
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i_pos = (i_pos << 32) | (fid->i_pos_low);
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inode = __fat_nfs_get_inode(sb, 0, fid->i_gen, i_pos);
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return d_obtain_alias(inode);
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}
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/*
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* Find the parent for a file specified by NFS handle.
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* This requires that the handle contain the i_ino of the parent.
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*/
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static struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
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int fh_len, int fh_type)
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{
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return generic_fh_to_parent(sb, fid, fh_len, fh_type,
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fat_nfs_get_inode);
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}
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static struct dentry *fat_fh_to_parent_nostale(struct super_block *sb,
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struct fid *fh, int fh_len,
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int fh_type)
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{
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struct inode *inode = NULL;
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struct fat_fid *fid = (struct fat_fid *)fh;
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loff_t i_pos;
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if (fh_len < FAT_FID_SIZE_WITH_PARENT)
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return NULL;
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switch (fh_type) {
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case FILEID_FAT_WITH_PARENT:
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i_pos = fid->parent_i_pos_hi;
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i_pos = (i_pos << 32) | (fid->parent_i_pos_low);
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inode = __fat_nfs_get_inode(sb, 0, fid->parent_i_gen, i_pos);
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break;
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}
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return d_obtain_alias(inode);
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}
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/*
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* Rebuild the parent for a directory that is not connected
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* to the filesystem root
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*/
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static
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struct inode *fat_rebuild_parent(struct super_block *sb, int parent_logstart)
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{
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int search_clus, clus_to_match;
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struct msdos_dir_entry *de;
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struct inode *parent = NULL;
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struct inode *dummy_grand_parent = NULL;
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struct fat_slot_info sinfo;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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sector_t blknr = fat_clus_to_blknr(sbi, parent_logstart);
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struct buffer_head *parent_bh = sb_bread(sb, blknr);
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if (!parent_bh) {
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fat_msg(sb, KERN_ERR,
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"unable to read cluster of parent directory");
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return NULL;
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}
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de = (struct msdos_dir_entry *) parent_bh->b_data;
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clus_to_match = fat_get_start(sbi, &de[0]);
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search_clus = fat_get_start(sbi, &de[1]);
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dummy_grand_parent = fat_dget(sb, search_clus);
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if (!dummy_grand_parent) {
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dummy_grand_parent = new_inode(sb);
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if (!dummy_grand_parent) {
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brelse(parent_bh);
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return parent;
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}
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dummy_grand_parent->i_ino = iunique(sb, MSDOS_ROOT_INO);
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fat_fill_inode(dummy_grand_parent, &de[1]);
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MSDOS_I(dummy_grand_parent)->i_pos = -1;
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}
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if (!fat_scan_logstart(dummy_grand_parent, clus_to_match, &sinfo))
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parent = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
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brelse(parent_bh);
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iput(dummy_grand_parent);
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return parent;
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}
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/*
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* Find the parent for a directory that is not currently connected to
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* the filesystem root.
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*
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* On entry, the caller holds d_inode(child_dir)->i_mutex.
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*/
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static struct dentry *fat_get_parent(struct dentry *child_dir)
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{
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struct super_block *sb = child_dir->d_sb;
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struct buffer_head *bh = NULL;
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struct msdos_dir_entry *de;
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struct inode *parent_inode = NULL;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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if (!fat_get_dotdot_entry(d_inode(child_dir), &bh, &de)) {
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int parent_logstart = fat_get_start(sbi, de);
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parent_inode = fat_dget(sb, parent_logstart);
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if (!parent_inode && sbi->options.nfs == FAT_NFS_NOSTALE_RO)
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parent_inode = fat_rebuild_parent(sb, parent_logstart);
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}
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brelse(bh);
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return d_obtain_alias(parent_inode);
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}
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const struct export_operations fat_export_ops = {
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.fh_to_dentry = fat_fh_to_dentry,
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.fh_to_parent = fat_fh_to_parent,
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.get_parent = fat_get_parent,
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};
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const struct export_operations fat_export_ops_nostale = {
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.encode_fh = fat_encode_fh_nostale,
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.fh_to_dentry = fat_fh_to_dentry_nostale,
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.fh_to_parent = fat_fh_to_parent_nostale,
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.get_parent = fat_get_parent,
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};
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