[LogFS] add new flash file system

This is a new flash file system. See
Documentation/filesystems/logfs.txt

Signed-off-by: Joern Engel <joern@logfs.org>

1 files changed, 818 insertions, 0 deletions

diff --git a/fs/logfs/dir.c b/fs/logfs/dir.c
new file mode 100644
index 000000000000..89104e6f81c4
--- /dev/null
+++ b/fs/logfs/dir.c
@@ -0,0 +1,818 @@
+/*
+ * fs/logfs/dir.c       - directory-related code
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
+ */
+#include "logfs.h"
+
+
+/*
+ * Atomic dir operations
+ *
+ * Directory operations are by default not atomic.  Dentries and Inodes are
+ * created/removed/altered in seperate operations.  Therefore we need to do
+ * a small amount of journaling.
+ *
+ * Create, link, mkdir, mknod and symlink all share the same function to do
+ * the work: __logfs_create.  This function works in two atomic steps:
+ * 1. allocate inode (remember in journal)
+ * 2. allocate dentry (clear journal)
+ *
+ * As we can only get interrupted between the two, when the inode we just
+ * created is simply stored in the anchor.  On next mount, if we were
+ * interrupted, we delete the inode.  From a users point of view the
+ * operation never happened.
+ *
+ * Unlink and rmdir also share the same function: unlink.  Again, this
+ * function works in two atomic steps
+ * 1. remove dentry (remember inode in journal)
+ * 2. unlink inode (clear journal)
+ *
+ * And again, on the next mount, if we were interrupted, we delete the inode.
+ * From a users point of view the operation succeeded.
+ *
+ * Rename is the real pain to deal with, harder than all the other methods
+ * combined.  Depending on the circumstances we can run into three cases.
+ * A "target rename" where the target dentry already existed, a "local
+ * rename" where both parent directories are identical or a "cross-directory
+ * rename" in the remaining case.
+ *
+ * Local rename is atomic, as the old dentry is simply rewritten with a new
+ * name.
+ *
+ * Cross-directory rename works in two steps, similar to __logfs_create and
+ * logfs_unlink:
+ * 1. Write new dentry (remember old dentry in journal)
+ * 2. Remove old dentry (clear journal)
+ *
+ * Here we remember a dentry instead of an inode.  On next mount, if we were
+ * interrupted, we delete the dentry.  From a users point of view, the
+ * operation succeeded.
+ *
+ * Target rename works in three atomic steps:
+ * 1. Attach old inode to new dentry (remember old dentry and new inode)
+ * 2. Remove old dentry (still remember the new inode)
+ * 3. Remove victim inode
+ *
+ * Here we remember both an inode an a dentry.  If we get interrupted
+ * between steps 1 and 2, we delete both the dentry and the inode.  If
+ * we get interrupted between steps 2 and 3, we delete just the inode.
+ * In either case, the remaining objects are deleted on next mount.  From
+ * a users point of view, the operation succeeded.
+ */
+
+static int write_dir(struct inode *dir, struct logfs_disk_dentry *dd,
+                loff_t pos)
+{
+        return logfs_inode_write(dir, dd, sizeof(*dd), pos, WF_LOCK, NULL);
+}
+
+static int write_inode(struct inode *inode)
+{
+        return __logfs_write_inode(inode, WF_LOCK);
+}
+
+static s64 dir_seek_data(struct inode *inode, s64 pos)
+{
+        s64 new_pos = logfs_seek_data(inode, pos);
+
+        return max(pos, new_pos - 1);
+}
+
+static int beyond_eof(struct inode *inode, loff_t bix)
+{
+        loff_t pos = bix << inode->i_sb->s_blocksize_bits;
+        return pos >= i_size_read(inode);
+}
+
+/*
+ * Prime value was chosen to be roughly 256 + 26.  r5 hash uses 11,
+ * so short names (len <= 9) don't even occupy the complete 32bit name
+ * space.  A prime >256 ensures short names quickly spread the 32bit
+ * name space.  Add about 26 for the estimated amount of information
+ * of each character and pick a prime nearby, preferrably a bit-sparse
+ * one.
+ */
+static u32 hash_32(const char *s, int len, u32 seed)
+{
+        u32 hash = seed;
+        int i;
+
+        for (i = 0; i < len; i++)
+                hash = hash * 293 + s[i];
+        return hash;
+}
+
+/*
+ * We have to satisfy several conflicting requirements here.  Small
+ * directories should stay fairly compact and not require too many
+ * indirect blocks.  The number of possible locations for a given hash
+ * should be small to make lookup() fast.  And we should try hard not
+ * to overflow the 32bit name space or nfs and 32bit host systems will
+ * be unhappy.
+ *
+ * So we use the following scheme.  First we reduce the hash to 0..15
+ * and try a direct block.  If that is occupied we reduce the hash to
+ * 16..255 and try an indirect block.  Same for 2x and 3x indirect
+ * blocks.  Lastly we reduce the hash to 0x800_0000 .. 0xffff_ffff,
+ * but use buckets containing eight entries instead of a single one.
+ *
+ * Using 16 entries should allow for a reasonable amount of hash
+ * collisions, so the 32bit name space can be packed fairly tight
+ * before overflowing.  Oh and currently we don't overflow but return
+ * and error.
+ *
+ * How likely are collisions?  Doing the appropriate math is beyond me
+ * and the Bronstein textbook.  But running a test program to brute
+ * force collisions for a couple of days showed that on average the
+ * first collision occurs after 598M entries, with 290M being the
+ * smallest result.  Obviously 21 entries could already cause a
+ * collision if all entries are carefully chosen.
+ */
+static pgoff_t hash_index(u32 hash, int round)
+{
+        switch (round) {
+        case 0:
+                return hash % I0_BLOCKS;
+        case 1:
+                return I0_BLOCKS + hash % (I1_BLOCKS - I0_BLOCKS);
+        case 2:
+                return I1_BLOCKS + hash % (I2_BLOCKS - I1_BLOCKS);
+        case 3:
+                return I2_BLOCKS + hash % (I3_BLOCKS - I2_BLOCKS);
+        case 4 ... 19:
+                return I3_BLOCKS + 16 * (hash % (((1<<31) - I3_BLOCKS) / 16))
+                        + round - 4;
+        }
+        BUG();
+}
+
+static struct page *logfs_get_dd_page(struct inode *dir, struct dentry *dentry)
+{
+        struct qstr *name = &dentry->d_name;
+        struct page *page;
+        struct logfs_disk_dentry *dd;
+        u32 hash = hash_32(name->name, name->len, 0);
+        pgoff_t index;
+        int round;
+
+        if (name->len > LOGFS_MAX_NAMELEN)
+                return ERR_PTR(-ENAMETOOLONG);
+
+        for (round = 0; round < 20; round++) {
+                index = hash_index(hash, round);
+
+                if (beyond_eof(dir, index))
+                        return NULL;
+                if (!logfs_exist_block(dir, index))
+                        continue;
+                page = read_cache_page(dir->i_mapping, index,
+                                (filler_t *)logfs_readpage, NULL);
+                if (IS_ERR(page))
+                        return page;
+                dd = kmap_atomic(page, KM_USER0);
+                BUG_ON(dd->namelen == 0);
+
+                if (name->len != be16_to_cpu(dd->namelen) ||
+                                memcmp(name->name, dd->name, name->len)) {
+                        kunmap_atomic(dd, KM_USER0);
+                        page_cache_release(page);
+                        continue;
+                }
+
+                kunmap_atomic(dd, KM_USER0);
+                return page;
+        }
+        return NULL;
+}
+
+static int logfs_remove_inode(struct inode *inode)
+{
+        int ret;
+
+        inode->i_nlink--;
+        ret = write_inode(inode);
+        LOGFS_BUG_ON(ret, inode->i_sb);
+        return ret;
+}
+
+static void abort_transaction(struct inode *inode, struct logfs_transaction *ta)
+{
+        if (logfs_inode(inode)->li_block)
+                logfs_inode(inode)->li_block->ta = NULL;
+        kfree(ta);
+}
+
+static int logfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+        struct logfs_super *super = logfs_super(dir->i_sb);
+        struct inode *inode = dentry->d_inode;
+        struct logfs_transaction *ta;
+        struct page *page;
+        pgoff_t index;
+        int ret;
+
+        ta = kzalloc(sizeof(*ta), GFP_KERNEL);
+        if (!ta)
+                return -ENOMEM;
+
+        ta->state = UNLINK_1;
+        ta->ino = inode->i_ino;
+
+        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+
+        page = logfs_get_dd_page(dir, dentry);
+        if (!page)
+                return -ENOENT;
+        if (IS_ERR(page))
+                return PTR_ERR(page);
+        index = page->index;
+        page_cache_release(page);
+
+        mutex_lock(&super->s_dirop_mutex);
+        logfs_add_transaction(dir, ta);
+
+        ret = logfs_delete(dir, index, NULL);
+        if (!ret)
+                ret = write_inode(dir);
+
+        if (ret) {
+                abort_transaction(dir, ta);
+                printk(KERN_ERR"LOGFS: unable to delete inode\n");
+                goto out;
+        }
+
+        ta->state = UNLINK_2;
+        logfs_add_transaction(inode, ta);
+        ret = logfs_remove_inode(inode);
+out:
+        mutex_unlock(&super->s_dirop_mutex);
+        return ret;
+}
+
+static inline int logfs_empty_dir(struct inode *dir)
+{
+        u64 data;
+
+        data = logfs_seek_data(dir, 0) << dir->i_sb->s_blocksize_bits;
+        return data >= i_size_read(dir);
+}
+
+static int logfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+        struct inode *inode = dentry->d_inode;
+
+        if (!logfs_empty_dir(inode))
+                return -ENOTEMPTY;
+
+        return logfs_unlink(dir, dentry);
+}
+
+/* FIXME: readdir currently has it's own dir_walk code.  I don't see a good
+ * way to combine the two copies */
+#define IMPLICIT_NODES 2
+static int __logfs_readdir(struct file *file, void *buf, filldir_t filldir)
+{
+        struct inode *dir = file->f_dentry->d_inode;
+        loff_t pos = file->f_pos - IMPLICIT_NODES;
+        struct page *page;
+        struct logfs_disk_dentry *dd;
+        int full;
+
+        BUG_ON(pos < 0);
+        for (;; pos++) {
+                if (beyond_eof(dir, pos))
+                        break;
+                if (!logfs_exist_block(dir, pos)) {
+                        /* deleted dentry */
+                        pos = dir_seek_data(dir, pos);
+                        continue;
+                }
+                page = read_cache_page(dir->i_mapping, pos,
+                                (filler_t *)logfs_readpage, NULL);
+                if (IS_ERR(page))
+                        return PTR_ERR(page);
+                dd = kmap_atomic(page, KM_USER0);
+                BUG_ON(dd->namelen == 0);
+
+                full = filldir(buf, (char *)dd->name, be16_to_cpu(dd->namelen),
+                                pos, be64_to_cpu(dd->ino), dd->type);
+                kunmap_atomic(dd, KM_USER0);
+                page_cache_release(page);
+                if (full)
+                        break;
+        }
+
+        file->f_pos = pos + IMPLICIT_NODES;
+        return 0;
+}
+
+static int logfs_readdir(struct file *file, void *buf, filldir_t filldir)
+{
+        struct inode *inode = file->f_dentry->d_inode;
+        ino_t pino = parent_ino(file->f_dentry);
+        int err;
+
+        if (file->f_pos < 0)
+                return -EINVAL;
+
+        if (file->f_pos == 0) {
+                if (filldir(buf, ".", 1, 1, inode->i_ino, DT_DIR) < 0)
+                        return 0;
+                file->f_pos++;
+        }
+        if (file->f_pos == 1) {
+                if (filldir(buf, "..", 2, 2, pino, DT_DIR) < 0)
+                        return 0;
+                file->f_pos++;
+        }
+
+        err = __logfs_readdir(file, buf, filldir);
+        return err;
+}
+
+static void logfs_set_name(struct logfs_disk_dentry *dd, struct qstr *name)
+{
+        dd->namelen = cpu_to_be16(name->len);
+        memcpy(dd->name, name->name, name->len);
+}
+
+static struct dentry *logfs_lookup(struct inode *dir, struct dentry *dentry,
+                struct nameidata *nd)
+{
+        struct page *page;
+        struct logfs_disk_dentry *dd;
+        pgoff_t index;
+        u64 ino = 0;
+        struct inode *inode;
+
+        page = logfs_get_dd_page(dir, dentry);
+        if (IS_ERR(page))
+                return ERR_CAST(page);
+        if (!page) {
+                d_add(dentry, NULL);
+                return NULL;
+        }
+        index = page->index;
+        dd = kmap_atomic(page, KM_USER0);
+        ino = be64_to_cpu(dd->ino);
+        kunmap_atomic(dd, KM_USER0);
+        page_cache_release(page);
+
+        inode = logfs_iget(dir->i_sb, ino);
+        if (IS_ERR(inode)) {
+                printk(KERN_ERR"LogFS: Cannot read inode #%llx for dentry (%lx, %lx)n",
+                                ino, dir->i_ino, index);
+                return ERR_CAST(inode);
+        }
+        return d_splice_alias(inode, dentry);
+}
+
+static void grow_dir(struct inode *dir, loff_t index)
+{
+        index = (index + 1) << dir->i_sb->s_blocksize_bits;
+        if (i_size_read(dir) < index)
+                i_size_write(dir, index);
+}
+
+static int logfs_write_dir(struct inode *dir, struct dentry *dentry,
+                struct inode *inode)
+{
+        struct page *page;
+        struct logfs_disk_dentry *dd;
+        u32 hash = hash_32(dentry->d_name.name, dentry->d_name.len, 0);
+        pgoff_t index;
+        int round, err;
+
+        for (round = 0; round < 20; round++) {
+                index = hash_index(hash, round);
+
+                if (logfs_exist_block(dir, index))
+                        continue;
+                page = find_or_create_page(dir->i_mapping, index, GFP_KERNEL);
+                if (!page)
+                        return -ENOMEM;
+
+                dd = kmap_atomic(page, KM_USER0);
+                memset(dd, 0, sizeof(*dd));
+                dd->ino = cpu_to_be64(inode->i_ino);
+                dd->type = logfs_type(inode);
+                logfs_set_name(dd, &dentry->d_name);
+                kunmap_atomic(dd, KM_USER0);
+
+                err = logfs_write_buf(dir, page, WF_LOCK);
+                unlock_page(page);
+                page_cache_release(page);
+                if (!err)
+                        grow_dir(dir, index);
+                return err;
+        }
+        /* FIXME: Is there a better return value?  In most cases neither
+         * the filesystem nor the directory are full.  But we have had
+         * too many collisions for this particular hash and no fallback.
+         */
+        return -ENOSPC;
+}
+
+static int __logfs_create(struct inode *dir, struct dentry *dentry,
+                struct inode *inode, const char *dest, long destlen)
+{
+        struct logfs_super *super = logfs_super(dir->i_sb);
+        struct logfs_inode *li = logfs_inode(inode);
+        struct logfs_transaction *ta;
+        int ret;
+
+        ta = kzalloc(sizeof(*ta), GFP_KERNEL);
+        if (!ta)
+                return -ENOMEM;
+
+        ta->state = CREATE_1;
+        ta->ino = inode->i_ino;
+        mutex_lock(&super->s_dirop_mutex);
+        logfs_add_transaction(inode, ta);
+
+        if (dest) {
+                /* symlink */
+                ret = logfs_inode_write(inode, dest, destlen, 0, WF_LOCK, NULL);
+                if (!ret)
+                        ret = write_inode(inode);
+        } else {
+                /* creat/mkdir/mknod */
+                ret = write_inode(inode);
+        }
+        if (ret) {
+                abort_transaction(inode, ta);
+                li->li_flags |= LOGFS_IF_STILLBORN;
+                /* FIXME: truncate symlink */
+                inode->i_nlink--;
+                iput(inode);
+                goto out;
+        }
+
+        ta->state = CREATE_2;
+        logfs_add_transaction(dir, ta);
+        ret = logfs_write_dir(dir, dentry, inode);
+        /* sync directory */
+        if (!ret)
+                ret = write_inode(dir);
+
+        if (ret) {
+                logfs_del_transaction(dir, ta);
+                ta->state = CREATE_2;
+                logfs_add_transaction(inode, ta);
+                logfs_remove_inode(inode);
+                iput(inode);
+                goto out;
+        }
+        d_instantiate(dentry, inode);
+out:
+        mutex_unlock(&super->s_dirop_mutex);
+        return ret;
+}
+
+static int logfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+        struct inode *inode;
+
+        /*
+         * FIXME: why do we have to fill in S_IFDIR, while the mode is
+         * correct for mknod, creat, etc.?  Smells like the vfs *should*
+         * do it for us but for some reason fails to do so.
+         */
+        inode = logfs_new_inode(dir, S_IFDIR | mode);
+        if (IS_ERR(inode))
+                return PTR_ERR(inode);
+
+        inode->i_op = &logfs_dir_iops;
+        inode->i_fop = &logfs_dir_fops;
+
+        return __logfs_create(dir, dentry, inode, NULL, 0);
+}
+
+static int logfs_create(struct inode *dir, struct dentry *dentry, int mode,
+                struct nameidata *nd)
+{
+        struct inode *inode;
+
+        inode = logfs_new_inode(dir, mode);
+        if (IS_ERR(inode))
+                return PTR_ERR(inode);
+
+        inode->i_op = &logfs_reg_iops;
+        inode->i_fop = &logfs_reg_fops;
+        inode->i_mapping->a_ops = &logfs_reg_aops;
+
+        return __logfs_create(dir, dentry, inode, NULL, 0);
+}
+
+static int logfs_mknod(struct inode *dir, struct dentry *dentry, int mode,
+                dev_t rdev)
+{
+        struct inode *inode;
+
+        if (dentry->d_name.len > LOGFS_MAX_NAMELEN)
+                return -ENAMETOOLONG;
+
+        inode = logfs_new_inode(dir, mode);
+        if (IS_ERR(inode))
+                return PTR_ERR(inode);
+
+        init_special_inode(inode, mode, rdev);
+
+        return __logfs_create(dir, dentry, inode, NULL, 0);
+}
+
+static int logfs_symlink(struct inode *dir, struct dentry *dentry,
+                const char *target)
+{
+        struct inode *inode;
+        size_t destlen = strlen(target) + 1;
+
+        if (destlen > dir->i_sb->s_blocksize)
+                return -ENAMETOOLONG;
+
+        inode = logfs_new_inode(dir, S_IFLNK | 0777);
+        if (IS_ERR(inode))
+                return PTR_ERR(inode);
+
+        inode->i_op = &logfs_symlink_iops;
+        inode->i_mapping->a_ops = &logfs_reg_aops;
+
+        return __logfs_create(dir, dentry, inode, target, destlen);
+}
+
+static int logfs_permission(struct inode *inode, int mask)
+{
+        return generic_permission(inode, mask, NULL);
+}
+
+static int logfs_link(struct dentry *old_dentry, struct inode *dir,
+                struct dentry *dentry)
+{
+        struct inode *inode = old_dentry->d_inode;
+
+        if (inode->i_nlink >= LOGFS_LINK_MAX)
+                return -EMLINK;
+
+        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+        atomic_inc(&inode->i_count);
+        inode->i_nlink++;
+        mark_inode_dirty_sync(inode);
+
+        return __logfs_create(dir, dentry, inode, NULL, 0);
+}
+
+static int logfs_get_dd(struct inode *dir, struct dentry *dentry,
+                struct logfs_disk_dentry *dd, loff_t *pos)
+{
+        struct page *page;
+        void *map;
+
+        page = logfs_get_dd_page(dir, dentry);
+        if (IS_ERR(page))
+                return PTR_ERR(page);
+        *pos = page->index;
+        map = kmap_atomic(page, KM_USER0);
+        memcpy(dd, map, sizeof(*dd));
+        kunmap_atomic(map, KM_USER0);
+        page_cache_release(page);
+        return 0;
+}
+
+static int logfs_delete_dd(struct inode *dir, loff_t pos)
+{
+        /*
+         * Getting called with pos somewhere beyond eof is either a goofup
+         * within this file or means someone maliciously edited the
+         * (crc-protected) journal.
+         */
+        BUG_ON(beyond_eof(dir, pos));
+        dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+        log_dir(" Delete dentry (%lx, %llx)\n", dir->i_ino, pos);
+        return logfs_delete(dir, pos, NULL);
+}
+
+/*
+ * Cross-directory rename, target does not exist.  Just a little nasty.
+ * Create a new dentry in the target dir, then remove the old dentry,
+ * all the while taking care to remember our operation in the journal.
+ */
+static int logfs_rename_cross(struct inode *old_dir, struct dentry *old_dentry,
+                              struct inode *new_dir, struct dentry *new_dentry)
+{
+        struct logfs_super *super = logfs_super(old_dir->i_sb);
+        struct logfs_disk_dentry dd;
+        struct logfs_transaction *ta;
+        loff_t pos;
+        int err;
+
+        /* 1. locate source dd */
+        err = logfs_get_dd(old_dir, old_dentry, &dd, &pos);
+        if (err)
+                return err;
+
+        ta = kzalloc(sizeof(*ta), GFP_KERNEL);
+        if (!ta)
+                return -ENOMEM;
+
+        ta->state = CROSS_RENAME_1;
+        ta->dir = old_dir->i_ino;
+        ta->pos = pos;
+
+        /* 2. write target dd */
+        mutex_lock(&super->s_dirop_mutex);
+        logfs_add_transaction(new_dir, ta);
+        err = logfs_write_dir(new_dir, new_dentry, old_dentry->d_inode);
+        if (!err)
+                err = write_inode(new_dir);
+
+        if (err) {
+                super->s_rename_dir = 0;
+                super->s_rename_pos = 0;
+                abort_transaction(new_dir, ta);
+                goto out;
+        }
+
+        /* 3. remove source dd */
+        ta->state = CROSS_RENAME_2;
+        logfs_add_transaction(old_dir, ta);
+        err = logfs_delete_dd(old_dir, pos);
+        if (!err)
+                err = write_inode(old_dir);
+        LOGFS_BUG_ON(err, old_dir->i_sb);
+out:
+        mutex_unlock(&super->s_dirop_mutex);
+        return err;
+}
+
+static int logfs_replace_inode(struct inode *dir, struct dentry *dentry,
+                struct logfs_disk_dentry *dd, struct inode *inode)
+{
+        loff_t pos;
+        int err;
+
+        err = logfs_get_dd(dir, dentry, dd, &pos);
+        if (err)
+                return err;
+        dd->ino = cpu_to_be64(inode->i_ino);
+        dd->type = logfs_type(inode);
+
+        err = write_dir(dir, dd, pos);
+        if (err)
+                return err;
+        log_dir("Replace dentry (%lx, %llx) %s -> %llx\n", dir->i_ino, pos,
+                        dd->name, be64_to_cpu(dd->ino));
+        return write_inode(dir);
+}
+
+/* Target dentry exists - the worst case.  We need to attach the source
+ * inode to the target dentry, then remove the orphaned target inode and
+ * source dentry.
+ */
+static int logfs_rename_target(struct inode *old_dir, struct dentry *old_dentry,
+                               struct inode *new_dir, struct dentry *new_dentry)
+{
+        struct logfs_super *super = logfs_super(old_dir->i_sb);
+        struct inode *old_inode = old_dentry->d_inode;
+        struct inode *new_inode = new_dentry->d_inode;
+        int isdir = S_ISDIR(old_inode->i_mode);
+        struct logfs_disk_dentry dd;
+        struct logfs_transaction *ta;
+        loff_t pos;
+        int err;
+
+        BUG_ON(isdir != S_ISDIR(new_inode->i_mode));
+        if (isdir) {
+                if (!logfs_empty_dir(new_inode))
+                        return -ENOTEMPTY;
+        }
+
+        /* 1. locate source dd */
+        err = logfs_get_dd(old_dir, old_dentry, &dd, &pos);
+        if (err)
+                return err;
+
+        ta = kzalloc(sizeof(*ta), GFP_KERNEL);
+        if (!ta)
+                return -ENOMEM;
+
+        ta->state = TARGET_RENAME_1;
+        ta->dir = old_dir->i_ino;
+        ta->pos = pos;
+        ta->ino = new_inode->i_ino;
+
+        /* 2. attach source inode to target dd */
+        mutex_lock(&super->s_dirop_mutex);
+        logfs_add_transaction(new_dir, ta);
+        err = logfs_replace_inode(new_dir, new_dentry, &dd, old_inode);
+        if (err) {
+                super->s_rename_dir = 0;
+                super->s_rename_pos = 0;
+                super->s_victim_ino = 0;
+                abort_transaction(new_dir, ta);
+                goto out;
+        }
+
+        /* 3. remove source dd */
+        ta->state = TARGET_RENAME_2;
+        logfs_add_transaction(old_dir, ta);
+        err = logfs_delete_dd(old_dir, pos);
+        if (!err)
+                err = write_inode(old_dir);
+        LOGFS_BUG_ON(err, old_dir->i_sb);
+
+        /* 4. remove target inode */
+        ta->state = TARGET_RENAME_3;
+        logfs_add_transaction(new_inode, ta);
+        err = logfs_remove_inode(new_inode);
+
+out:
+        mutex_unlock(&super->s_dirop_mutex);
+        return err;
+}
+
+static int logfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+                        struct inode *new_dir, struct dentry *new_dentry)
+{
+        if (new_dentry->d_inode)
+                return logfs_rename_target(old_dir, old_dentry,
+                                           new_dir, new_dentry);
+        return logfs_rename_cross(old_dir, old_dentry, new_dir, new_dentry);
+}
+
+/* No locking done here, as this is called before .get_sb() returns. */
+int logfs_replay_journal(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct inode *inode;
+        u64 ino, pos;
+        int err;
+
+        if (super->s_victim_ino) {
+                /* delete victim inode */
+                ino = super->s_victim_ino;
+                printk(KERN_INFO"LogFS: delete unmapped inode #%llx\n", ino);
+                inode = logfs_iget(sb, ino);
+                if (IS_ERR(inode))
+                        goto fail;
+
+                LOGFS_BUG_ON(i_size_read(inode) > 0, sb);
+                super->s_victim_ino = 0;
+                err = logfs_remove_inode(inode);
+                iput(inode);
+                if (err) {
+                        super->s_victim_ino = ino;
+                        goto fail;
+                }
+        }
+        if (super->s_rename_dir) {
+                /* delete old dd from rename */
+                ino = super->s_rename_dir;
+                pos = super->s_rename_pos;
+                printk(KERN_INFO"LogFS: delete unbacked dentry (%llx, %llx)\n",
+                                ino, pos);
+                inode = logfs_iget(sb, ino);
+                if (IS_ERR(inode))
+                        goto fail;
+
+                super->s_rename_dir = 0;
+                super->s_rename_pos = 0;
+                err = logfs_delete_dd(inode, pos);
+                iput(inode);
+                if (err) {
+                        super->s_rename_dir = ino;
+                        super->s_rename_pos = pos;
+                        goto fail;
+                }
+        }
+        return 0;
+fail:
+        LOGFS_BUG(sb);
+        return -EIO;
+}
+
+const struct inode_operations logfs_symlink_iops = {
+        .readlink       = generic_readlink,
+        .follow_link    = page_follow_link_light,
+};
+
+const struct inode_operations logfs_dir_iops = {
+        .create         = logfs_create,
+        .link           = logfs_link,
+        .lookup         = logfs_lookup,
+        .mkdir          = logfs_mkdir,
+        .mknod          = logfs_mknod,
+        .rename         = logfs_rename,
+        .rmdir          = logfs_rmdir,
+        .permission     = logfs_permission,
+        .symlink        = logfs_symlink,
+        .unlink         = logfs_unlink,
+};
+const struct file_operations logfs_dir_fops = {
+        .fsync          = logfs_fsync,
+        .ioctl          = logfs_ioctl,
+        .readdir        = logfs_readdir,
+        .read           = generic_read_dir,
+};