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