7669e8fb09
Maintain an index of directory inodes by starting cluster, so that fat_get_parent() can return the proper cached inode rather than inventing one that cannot be traced back to the filesystem root. Add a new msdos/vfat binary mount option "nfs" so that FAT filesystems that are _not_ exported via NFS are not saddled with maintenance of an index they will never use. Finally, simplify NFS file handle generation and lookups. An ext2-congruent implementation is adequate for FAT needs. Signed-off-by: Steven J. Magnani <steve@digidescorp.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
101 lines
2.6 KiB
C
101 lines
2.6 KiB
C
/* 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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/**
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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 hlist_node *_p;
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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, _p, 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_nfs_get_inode(struct super_block *sb,
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u64 ino, u32 generation)
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{
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struct inode *inode;
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if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
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return NULL;
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inode = ilookup(sb, ino);
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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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return inode;
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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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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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/*
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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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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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/*
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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 child_dir->d_inode->i_mutex.
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*/
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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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if (!fat_get_dotdot_entry(child_dir->d_inode, &bh, &de)) {
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int parent_logstart = fat_get_start(MSDOS_SB(sb), de);
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parent_inode = fat_dget(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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