--- /dev/null
+/*
+ * OMFS (as used by RIO Karma) directory operations.
+ * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
+ * Released under GPL v2.
+ */
+
+#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);
+
+ dir->i_ctime = CURRENT_TIME_SEC;
+
+ /* 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 inode *dir, struct dentry *dentry, umode_t mode)
+{
+ return omfs_add_node(dir, dentry, mode | S_IFDIR);
+}
+
+static int omfs_create(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);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+ }
+ d_add(dentry, inode);
+ return NULL;
+}
+
+/* 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 inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ struct inode *new_inode = d_inode(new_dentry);
+ struct inode *old_inode = d_inode(old_dentry);
+ int err;
+
+ 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;
+
+ old_inode->i_ctime = CURRENT_TIME_SEC;
+ 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 = omfs_readdir,
+ .llseek = generic_file_llseek,
+};
Code Review / kvmfornfv.git / blobdiff