diff options
Diffstat (limited to 'fs/logfs/dir.c')
| -rw-r--r-- | fs/logfs/dir.c | 801 |
1 files changed, 801 insertions, 0 deletions
diff --git a/fs/logfs/dir.c b/fs/logfs/dir.c new file mode 100644 index 000000000..4cf38f118 --- /dev/null +++ b/fs/logfs/dir.c @@ -0,0 +1,801 @@ +/* + * 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" +#include <linux/slab.h> + +/* + * Atomic dir operations + * + * Directory operations are by default not atomic. Dentries and Inodes are + * created/removed/altered in separate 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, NULL, 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, preferably 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) +{ + u32 i0_blocks = I0_BLOCKS; + u32 i1_blocks = I1_BLOCKS; + u32 i2_blocks = I2_BLOCKS; + u32 i3_blocks = I3_BLOCKS; + + 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); + BUG_ON(dd->namelen == 0); + + if (name->len != be16_to_cpu(dd->namelen) || + memcmp(name->name, dd->name, name->len)) { + kunmap_atomic(dd); + page_cache_release(page); + continue; + } + + kunmap_atomic(dd); + return page; + } + return NULL; +} + +static int logfs_remove_inode(struct inode *inode) +{ + int ret; + + drop_nlink(inode); + 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 = d_inode(dentry); + 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) { + kfree(ta); + return -ENOENT; + } + if (IS_ERR(page)) { + kfree(ta); + 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 = d_inode(dentry); + + 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 */ +static int logfs_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *dir = file_inode(file); + loff_t pos; + struct page *page; + struct logfs_disk_dentry *dd; + + if (ctx->pos < 0) + return -EINVAL; + + if (!dir_emit_dots(file, ctx)) + return 0; + + pos = ctx->pos - 2; + BUG_ON(pos < 0); + for (;; pos++, ctx->pos++) { + bool full; + 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(page); + BUG_ON(dd->namelen == 0); + + full = !dir_emit(ctx, (char *)dd->name, + be16_to_cpu(dd->namelen), + be64_to_cpu(dd->ino), dd->type); + kunmap(page); + page_cache_release(page); + if (full) + break; + } + return 0; +} + +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, + unsigned int flags) +{ + 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); + ino = be64_to_cpu(dd->ino); + kunmap_atomic(dd); + 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 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); + 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); + + 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) { + drop_nlink(inode); + iput(inode); + 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 */ + drop_nlink(inode); + 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, umode_t 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, umode_t mode, + bool excl) +{ + 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, umode_t 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_link(struct dentry *old_dentry, struct inode *dir, + struct dentry *dentry) +{ + struct inode *inode = d_inode(old_dentry); + + inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; + ihold(inode); + inc_nlink(inode); + 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); + memcpy(dd, map, sizeof(*dd)); + kunmap_atomic(map); + 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, d_inode(old_dentry)); + 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 = d_inode(old_dentry); + struct inode *new_inode = d_inode(new_dentry); + 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 (d_really_is_positive(new_dentry)) + 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, + .symlink = logfs_symlink, + .unlink = logfs_unlink, +}; +const struct file_operations logfs_dir_fops = { + .fsync = logfs_fsync, + .unlocked_ioctl = logfs_ioctl, + .iterate = logfs_readdir, + .read = generic_read_dir, + .llseek = default_llseek, +}; |