Commit | Line | Data |
---|---|---|
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; | |
7669e8fb SM |
24 | struct msdos_inode_info *i; |
25 | struct inode *inode = NULL; | |
21b6633d | 26 | |
7669e8fb SM |
27 | head = sbi->dir_hashtable + fat_dir_hash(i_logstart); |
28 | spin_lock(&sbi->dir_hash_lock); | |
b67bfe0d | 29 | hlist_for_each_entry(i, head, i_dir_hash) { |
7669e8fb SM |
30 | BUG_ON(i->vfs_inode.i_sb != sb); |
31 | if (i->i_logstart != i_logstart) | |
32 | continue; | |
33 | inode = igrab(&i->vfs_inode); | |
34 | if (inode) | |
35 | break; | |
21b6633d | 36 | } |
7669e8fb SM |
37 | spin_unlock(&sbi->dir_hash_lock); |
38 | return inode; | |
21b6633d SM |
39 | } |
40 | ||
7669e8fb SM |
41 | static struct inode *fat_nfs_get_inode(struct super_block *sb, |
42 | u64 ino, u32 generation) | |
21b6633d | 43 | { |
7669e8fb SM |
44 | struct inode *inode; |
45 | ||
46 | if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO)) | |
47 | return NULL; | |
48 | ||
49 | inode = ilookup(sb, ino); | |
50 | if (inode && generation && (inode->i_generation != generation)) { | |
51 | iput(inode); | |
52 | inode = NULL; | |
53 | } | |
54 | ||
55 | return inode; | |
21b6633d SM |
56 | } |
57 | ||
58 | /** | |
59 | * Map a NFS file handle to a corresponding dentry. | |
60 | * The dentry may or may not be connected to the filesystem root. | |
61 | */ | |
62 | struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid, | |
63 | int fh_len, int fh_type) | |
64 | { | |
7669e8fb SM |
65 | return generic_fh_to_dentry(sb, fid, fh_len, fh_type, |
66 | fat_nfs_get_inode); | |
67 | } | |
21b6633d | 68 | |
7669e8fb SM |
69 | /* |
70 | * Find the parent for a file specified by NFS handle. | |
71 | * This requires that the handle contain the i_ino of the parent. | |
72 | */ | |
73 | struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid, | |
74 | int fh_len, int fh_type) | |
75 | { | |
76 | return generic_fh_to_parent(sb, fid, fh_len, fh_type, | |
77 | fat_nfs_get_inode); | |
21b6633d SM |
78 | } |
79 | ||
80 | /* | |
81 | * Find the parent for a directory that is not currently connected to | |
82 | * the filesystem root. | |
83 | * | |
84 | * On entry, the caller holds child_dir->d_inode->i_mutex. | |
85 | */ | |
86 | struct dentry *fat_get_parent(struct dentry *child_dir) | |
87 | { | |
88 | struct super_block *sb = child_dir->d_sb; | |
89 | struct buffer_head *bh = NULL; | |
90 | struct msdos_dir_entry *de; | |
7669e8fb | 91 | struct inode *parent_inode = NULL; |
21b6633d | 92 | |
7669e8fb SM |
93 | if (!fat_get_dotdot_entry(child_dir->d_inode, &bh, &de)) { |
94 | int parent_logstart = fat_get_start(MSDOS_SB(sb), de); | |
95 | parent_inode = fat_dget(sb, parent_logstart); | |
21b6633d | 96 | } |
21b6633d | 97 | brelse(bh); |
21b6633d | 98 | |
7669e8fb | 99 | return d_obtain_alias(parent_inode); |
21b6633d | 100 | } |