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21b6633d SM |
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 | ||
7669e8fb SM |
17 | /** |
18 | * Look up a directory inode given its starting cluster. | |
21b6633d | 19 | */ |
7669e8fb | 20 | static struct inode *fat_dget(struct super_block *sb, int i_logstart) |
21b6633d | 21 | { |
7669e8fb SM |
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; | |
21b6633d | 27 | |
7669e8fb SM |
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; | |
21b6633d | 37 | } |
7669e8fb SM |
38 | spin_unlock(&sbi->dir_hash_lock); |
39 | return inode; | |
21b6633d SM |
40 | } |
41 | ||
7669e8fb SM |
42 | static struct inode *fat_nfs_get_inode(struct super_block *sb, |
43 | u64 ino, u32 generation) | |
21b6633d | 44 | { |
7669e8fb SM |
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; | |
21b6633d SM |
57 | } |
58 | ||
59 | /** | |
60 | * Map a NFS file handle to a corresponding dentry. | |
61 | * The dentry may or may not be connected to the filesystem root. | |
62 | */ | |
63 | struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid, | |
64 | int fh_len, int fh_type) | |
65 | { | |
7669e8fb SM |
66 | return generic_fh_to_dentry(sb, fid, fh_len, fh_type, |
67 | fat_nfs_get_inode); | |
68 | } | |
21b6633d | 69 | |
7669e8fb SM |
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); | |
21b6633d SM |
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; | |
7669e8fb | 92 | struct inode *parent_inode = NULL; |
21b6633d | 93 | |
7669e8fb SM |
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); | |
21b6633d | 97 | } |
21b6633d | 98 | brelse(bh); |
21b6633d | 99 | |
7669e8fb | 100 | return d_obtain_alias(parent_inode); |
21b6633d | 101 | } |