diff options
Diffstat (limited to 'fs/omfs/dir.c')
-rw-r--r-- | fs/omfs/dir.c | 461 |
1 files changed, 461 insertions, 0 deletions
diff --git a/fs/omfs/dir.c b/fs/omfs/dir.c new file mode 100644 index 0000000000..6bda275826 --- /dev/null +++ b/fs/omfs/dir.c @@ -0,0 +1,461 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * OMFS (as used by RIO Karma) directory operations. + * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com> + */ + +#include <linux/fs.h> +#include <linux/ctype.h> +#include <linux/buffer_head.h> +#include "omfs.h" + +static int omfs_hash(const char *name, int namelen, int mod) +{ + int i, hash = 0; + for (i = 0; i < namelen; i++) + hash ^= tolower(name[i]) << (i % 24); + return hash % mod; +} + +/* + * Finds the bucket for a given name and reads the containing block; + * *ofs is set to the offset of the first list entry. + */ +static struct buffer_head *omfs_get_bucket(struct inode *dir, + const char *name, int namelen, int *ofs) +{ + int nbuckets = (dir->i_size - OMFS_DIR_START)/8; + int bucket = omfs_hash(name, namelen, nbuckets); + + *ofs = OMFS_DIR_START + bucket * 8; + return omfs_bread(dir->i_sb, dir->i_ino); +} + +static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block, + const char *name, int namelen, + u64 *prev_block) +{ + struct buffer_head *bh; + struct omfs_inode *oi; + int err = -ENOENT; + *prev_block = ~0; + + while (block != ~0) { + bh = omfs_bread(dir->i_sb, block); + if (!bh) { + err = -EIO; + goto err; + } + + oi = (struct omfs_inode *) bh->b_data; + if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) { + brelse(bh); + goto err; + } + + if (strncmp(oi->i_name, name, namelen) == 0) + return bh; + + *prev_block = block; + block = be64_to_cpu(oi->i_sibling); + brelse(bh); + } +err: + return ERR_PTR(err); +} + +static struct buffer_head *omfs_find_entry(struct inode *dir, + const char *name, int namelen) +{ + struct buffer_head *bh; + int ofs; + u64 block, dummy; + + bh = omfs_get_bucket(dir, name, namelen, &ofs); + if (!bh) + return ERR_PTR(-EIO); + + block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs])); + brelse(bh); + + return omfs_scan_list(dir, block, name, namelen, &dummy); +} + +int omfs_make_empty(struct inode *inode, struct super_block *sb) +{ + struct omfs_sb_info *sbi = OMFS_SB(sb); + struct buffer_head *bh; + struct omfs_inode *oi; + + bh = omfs_bread(sb, inode->i_ino); + if (!bh) + return -ENOMEM; + + memset(bh->b_data, 0, sizeof(struct omfs_inode)); + + if (S_ISDIR(inode->i_mode)) { + memset(&bh->b_data[OMFS_DIR_START], 0xff, + sbi->s_sys_blocksize - OMFS_DIR_START); + } else + omfs_make_empty_table(bh, OMFS_EXTENT_START); + + oi = (struct omfs_inode *) bh->b_data; + oi->i_head.h_self = cpu_to_be64(inode->i_ino); + oi->i_sibling = ~cpu_to_be64(0ULL); + + mark_buffer_dirty(bh); + brelse(bh); + return 0; +} + +static int omfs_add_link(struct dentry *dentry, struct inode *inode) +{ + struct inode *dir = d_inode(dentry->d_parent); + const char *name = dentry->d_name.name; + int namelen = dentry->d_name.len; + struct omfs_inode *oi; + struct buffer_head *bh; + u64 block; + __be64 *entry; + int ofs; + + /* just prepend to head of queue in proper bucket */ + bh = omfs_get_bucket(dir, name, namelen, &ofs); + if (!bh) + goto out; + + entry = (__be64 *) &bh->b_data[ofs]; + block = be64_to_cpu(*entry); + *entry = cpu_to_be64(inode->i_ino); + mark_buffer_dirty(bh); + brelse(bh); + + /* now set the sibling and parent pointers on the new inode */ + bh = omfs_bread(dir->i_sb, inode->i_ino); + if (!bh) + goto out; + + oi = (struct omfs_inode *) bh->b_data; + memcpy(oi->i_name, name, namelen); + memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen); + oi->i_sibling = cpu_to_be64(block); + oi->i_parent = cpu_to_be64(dir->i_ino); + mark_buffer_dirty(bh); + brelse(bh); + + inode_set_ctime_current(dir); + + /* mark affected inodes dirty to rebuild checksums */ + mark_inode_dirty(dir); + mark_inode_dirty(inode); + return 0; +out: + return -ENOMEM; +} + +static int omfs_delete_entry(struct dentry *dentry) +{ + struct inode *dir = d_inode(dentry->d_parent); + struct inode *dirty; + const char *name = dentry->d_name.name; + int namelen = dentry->d_name.len; + struct omfs_inode *oi; + struct buffer_head *bh, *bh2; + __be64 *entry, next; + u64 block, prev; + int ofs; + int err = -ENOMEM; + + /* delete the proper node in the bucket's linked list */ + bh = omfs_get_bucket(dir, name, namelen, &ofs); + if (!bh) + goto out; + + entry = (__be64 *) &bh->b_data[ofs]; + block = be64_to_cpu(*entry); + + bh2 = omfs_scan_list(dir, block, name, namelen, &prev); + if (IS_ERR(bh2)) { + err = PTR_ERR(bh2); + goto out_free_bh; + } + + oi = (struct omfs_inode *) bh2->b_data; + next = oi->i_sibling; + brelse(bh2); + + if (prev != ~0) { + /* found in middle of list, get list ptr */ + brelse(bh); + bh = omfs_bread(dir->i_sb, prev); + if (!bh) + goto out; + + oi = (struct omfs_inode *) bh->b_data; + entry = &oi->i_sibling; + } + + *entry = next; + mark_buffer_dirty(bh); + + if (prev != ~0) { + dirty = omfs_iget(dir->i_sb, prev); + if (!IS_ERR(dirty)) { + mark_inode_dirty(dirty); + iput(dirty); + } + } + + err = 0; +out_free_bh: + brelse(bh); +out: + return err; +} + +static int omfs_dir_is_empty(struct inode *inode) +{ + int nbuckets = (inode->i_size - OMFS_DIR_START) / 8; + struct buffer_head *bh; + u64 *ptr; + int i; + + bh = omfs_bread(inode->i_sb, inode->i_ino); + + if (!bh) + return 0; + + ptr = (u64 *) &bh->b_data[OMFS_DIR_START]; + + for (i = 0; i < nbuckets; i++, ptr++) + if (*ptr != ~0) + break; + + brelse(bh); + return *ptr != ~0; +} + +static int omfs_remove(struct inode *dir, struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + int ret; + + + if (S_ISDIR(inode->i_mode) && + !omfs_dir_is_empty(inode)) + return -ENOTEMPTY; + + ret = omfs_delete_entry(dentry); + if (ret) + return ret; + + clear_nlink(inode); + mark_inode_dirty(inode); + mark_inode_dirty(dir); + return 0; +} + +static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode) +{ + int err; + struct inode *inode = omfs_new_inode(dir, mode); + + if (IS_ERR(inode)) + return PTR_ERR(inode); + + err = omfs_make_empty(inode, dir->i_sb); + if (err) + goto out_free_inode; + + err = omfs_add_link(dentry, inode); + if (err) + goto out_free_inode; + + d_instantiate(dentry, inode); + return 0; + +out_free_inode: + iput(inode); + return err; +} + +static int omfs_mkdir(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, umode_t mode) +{ + return omfs_add_node(dir, dentry, mode | S_IFDIR); +} + +static int omfs_create(struct mnt_idmap *idmap, struct inode *dir, + struct dentry *dentry, umode_t mode, bool excl) +{ + return omfs_add_node(dir, dentry, mode | S_IFREG); +} + +static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry, + unsigned int flags) +{ + struct buffer_head *bh; + struct inode *inode = NULL; + + if (dentry->d_name.len > OMFS_NAMELEN) + return ERR_PTR(-ENAMETOOLONG); + + bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len); + if (!IS_ERR(bh)) { + struct omfs_inode *oi = (struct omfs_inode *)bh->b_data; + ino_t ino = be64_to_cpu(oi->i_head.h_self); + brelse(bh); + inode = omfs_iget(dir->i_sb, ino); + } else if (bh != ERR_PTR(-ENOENT)) { + inode = ERR_CAST(bh); + } + return d_splice_alias(inode, dentry); +} + +/* sanity check block's self pointer */ +int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header, + u64 fsblock) +{ + int is_bad; + u64 ino = be64_to_cpu(header->h_self); + is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) || + (ino > sbi->s_num_blocks)); + + if (is_bad) + printk(KERN_WARNING "omfs: bad hash chain detected\n"); + + return is_bad; +} + +static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx, + u64 fsblock, int hindex) +{ + /* follow chain in this bucket */ + while (fsblock != ~0) { + struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock); + struct omfs_inode *oi; + u64 self; + unsigned char d_type; + + if (!bh) + return true; + + oi = (struct omfs_inode *) bh->b_data; + if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) { + brelse(bh); + return true; + } + + self = fsblock; + fsblock = be64_to_cpu(oi->i_sibling); + + /* skip visited nodes */ + if (hindex) { + hindex--; + brelse(bh); + continue; + } + + d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG; + + if (!dir_emit(ctx, oi->i_name, + strnlen(oi->i_name, OMFS_NAMELEN), + self, d_type)) { + brelse(bh); + return false; + } + brelse(bh); + ctx->pos++; + } + return true; +} + +static int omfs_rename(struct mnt_idmap *idmap, struct inode *old_dir, + struct dentry *old_dentry, struct inode *new_dir, + struct dentry *new_dentry, unsigned int flags) +{ + struct inode *new_inode = d_inode(new_dentry); + struct inode *old_inode = d_inode(old_dentry); + int err; + + if (flags & ~RENAME_NOREPLACE) + return -EINVAL; + + if (new_inode) { + /* overwriting existing file/dir */ + err = omfs_remove(new_dir, new_dentry); + if (err) + goto out; + } + + /* since omfs locates files by name, we need to unlink _before_ + * adding the new link or we won't find the old one */ + err = omfs_delete_entry(old_dentry); + if (err) + goto out; + + mark_inode_dirty(old_dir); + err = omfs_add_link(new_dentry, old_inode); + if (err) + goto out; + + inode_set_ctime_current(old_inode); + mark_inode_dirty(old_inode); +out: + return err; +} + +static int omfs_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *dir = file_inode(file); + struct buffer_head *bh; + __be64 *p; + unsigned int hchain, hindex; + int nbuckets; + + if (ctx->pos >> 32) + return -EINVAL; + + if (ctx->pos < 1 << 20) { + if (!dir_emit_dots(file, ctx)) + return 0; + ctx->pos = 1 << 20; + } + + nbuckets = (dir->i_size - OMFS_DIR_START) / 8; + + /* high 12 bits store bucket + 1 and low 20 bits store hash index */ + hchain = (ctx->pos >> 20) - 1; + hindex = ctx->pos & 0xfffff; + + bh = omfs_bread(dir->i_sb, dir->i_ino); + if (!bh) + return -EINVAL; + + p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain; + + for (; hchain < nbuckets; hchain++) { + __u64 fsblock = be64_to_cpu(*p++); + if (!omfs_fill_chain(dir, ctx, fsblock, hindex)) + break; + hindex = 0; + ctx->pos = (hchain+2) << 20; + } + brelse(bh); + return 0; +} + +const struct inode_operations omfs_dir_inops = { + .lookup = omfs_lookup, + .mkdir = omfs_mkdir, + .rename = omfs_rename, + .create = omfs_create, + .unlink = omfs_remove, + .rmdir = omfs_remove, +}; + +const struct file_operations omfs_dir_operations = { + .read = generic_read_dir, + .iterate_shared = omfs_readdir, + .llseek = generic_file_llseek, +}; |