Linux Kernel  3.7.1
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nfs.c
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1 /* fs/fat/nfs.c
2  *
3  * This software is licensed under the terms of the GNU General Public
4  * License version 2, as published by the Free Software Foundation, and
5  * may be copied, distributed, and modified under those terms.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10  * GNU General Public License for more details.
11  *
12  */
13 
14 #include <linux/exportfs.h>
15 #include "fat.h"
16 
20 static struct inode *fat_dget(struct super_block *sb, int i_logstart)
21 {
22  struct msdos_sb_info *sbi = MSDOS_SB(sb);
23  struct hlist_head *head;
24  struct hlist_node *_p;
25  struct msdos_inode_info *i;
26  struct inode *inode = NULL;
27 
28  head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
29  spin_lock(&sbi->dir_hash_lock);
30  hlist_for_each_entry(i, _p, head, i_dir_hash) {
31  BUG_ON(i->vfs_inode.i_sb != sb);
32  if (i->i_logstart != i_logstart)
33  continue;
34  inode = igrab(&i->vfs_inode);
35  if (inode)
36  break;
37  }
38  spin_unlock(&sbi->dir_hash_lock);
39  return inode;
40 }
41 
42 static struct inode *fat_nfs_get_inode(struct super_block *sb,
44 {
45  struct inode *inode;
46 
47  if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
48  return NULL;
49 
50  inode = ilookup(sb, ino);
51  if (inode && generation && (inode->i_generation != generation)) {
52  iput(inode);
53  inode = NULL;
54  }
55 
56  return inode;
57 }
58 
63 struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
64  int fh_len, int fh_type)
65 {
66  return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
67  fat_nfs_get_inode);
68 }
69 
70 /*
71  * Find the parent for a file specified by NFS handle.
72  * This requires that the handle contain the i_ino of the parent.
73  */
74 struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
75  int fh_len, int fh_type)
76 {
77  return generic_fh_to_parent(sb, fid, fh_len, fh_type,
78  fat_nfs_get_inode);
79 }
80 
81 /*
82  * Find the parent for a directory that is not currently connected to
83  * the filesystem root.
84  *
85  * On entry, the caller holds child_dir->d_inode->i_mutex.
86  */
87 struct dentry *fat_get_parent(struct dentry *child_dir)
88 {
89  struct super_block *sb = child_dir->d_sb;
90  struct buffer_head *bh = NULL;
91  struct msdos_dir_entry *de;
92  struct inode *parent_inode = NULL;
93 
94  if (!fat_get_dotdot_entry(child_dir->d_inode, &bh, &de)) {
95  int parent_logstart = fat_get_start(MSDOS_SB(sb), de);
96  parent_inode = fat_dget(sb, parent_logstart);
97  }
98  brelse(bh);
99 
100  return d_obtain_alias(parent_inode);
101 }