diff options
Diffstat (limited to 'libbcache/dirent.c')
| -rw-r--r-- | libbcache/dirent.c | 449 |
1 files changed, 449 insertions, 0 deletions
diff --git a/libbcache/dirent.c b/libbcache/dirent.c new file mode 100644 index 0000000..920ad2f --- /dev/null +++ b/libbcache/dirent.c @@ -0,0 +1,449 @@ + +#include "bcache.h" +#include "bkey_methods.h" +#include "btree_update.h" +#include "extents.h" +#include "dirent.h" +#include "fs.h" +#include "keylist.h" +#include "str_hash.h" + +#include <linux/dcache.h> + +static unsigned dirent_name_bytes(struct bkey_s_c_dirent d) +{ + unsigned len = bkey_val_bytes(d.k) - sizeof(struct bch_dirent); + + while (len && !d.v->d_name[len - 1]) + --len; + + return len; +} + +static u64 bch_dirent_hash(const struct bch_hash_info *info, + const struct qstr *name) +{ + switch (info->type) { + case BCH_STR_HASH_SHA1: { + SHASH_DESC_ON_STACK(desc, bch_sha1); + u8 digest[SHA1_DIGEST_SIZE]; + u64 ret; + desc->tfm = bch_sha1; + desc->flags = 0; + crypto_shash_init(desc); + + crypto_shash_update(desc, (void *) &info->seed, sizeof(info->seed)); + + crypto_shash_update(desc, (void *) name->name, name->len); + crypto_shash_final(desc, digest); + memcpy(&ret, &digest, sizeof(ret)); + return max_t(u64, ret >> 1, 2); + } + default: { + struct bch_str_hash_ctx ctx; + + bch_str_hash_init(&ctx, info->type); + bch_str_hash_update(&ctx, info->type, &info->seed, sizeof(info->seed)); + + bch_str_hash_update(&ctx, info->type, name->name, name->len); + + /* [0,2) reserved for dots */ + return max_t(u64, bch_str_hash_end(&ctx, info->type), 2); + } + } +} + +static u64 dirent_hash_key(const struct bch_hash_info *info, const void *key) +{ + return bch_dirent_hash(info, key); +} + +static u64 dirent_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k) +{ + struct bkey_s_c_dirent d = bkey_s_c_to_dirent(k); + struct qstr name = QSTR_INIT(d.v->d_name, dirent_name_bytes(d)); + + return bch_dirent_hash(info, &name); +} + +static bool dirent_cmp_key(struct bkey_s_c _l, const void *_r) +{ + struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l); + int len = dirent_name_bytes(l); + const struct qstr *r = _r; + + return len - r->len ?: memcmp(l.v->d_name, r->name, len); +} + +static bool dirent_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r) +{ + struct bkey_s_c_dirent l = bkey_s_c_to_dirent(_l); + struct bkey_s_c_dirent r = bkey_s_c_to_dirent(_r); + int l_len = dirent_name_bytes(l); + int r_len = dirent_name_bytes(r); + + return l_len - r_len ?: memcmp(l.v->d_name, r.v->d_name, l_len); +} + +static const struct bch_hash_desc dirent_hash_desc = { + .btree_id = BTREE_ID_DIRENTS, + .key_type = BCH_DIRENT, + .whiteout_type = BCH_DIRENT_WHITEOUT, + .hash_key = dirent_hash_key, + .hash_bkey = dirent_hash_bkey, + .cmp_key = dirent_cmp_key, + .cmp_bkey = dirent_cmp_bkey, +}; + +static const char *bch_dirent_invalid(const struct cache_set *c, + struct bkey_s_c k) +{ + switch (k.k->type) { + case BCH_DIRENT: + return bkey_val_bytes(k.k) < sizeof(struct bch_dirent) + ? "value too small" + : NULL; + + case BCH_DIRENT_WHITEOUT: + return bkey_val_bytes(k.k) != 0 + ? "value size should be zero" + : NULL; + + default: + return "invalid type"; + } +} + +static void bch_dirent_to_text(struct cache_set *c, char *buf, + size_t size, struct bkey_s_c k) +{ + struct bkey_s_c_dirent d; + + switch (k.k->type) { + case BCH_DIRENT: + d = bkey_s_c_to_dirent(k); + + if (size) { + unsigned n = min_t(unsigned, size, + dirent_name_bytes(d)); + memcpy(buf, d.v->d_name, n); + buf[size - 1] = '\0'; + buf += n; + size -= n; + } + + scnprintf(buf, size, " -> %llu", d.v->d_inum); + break; + case BCH_DIRENT_WHITEOUT: + scnprintf(buf, size, "whiteout"); + break; + } +} + +const struct bkey_ops bch_bkey_dirent_ops = { + .key_invalid = bch_dirent_invalid, + .val_to_text = bch_dirent_to_text, +}; + +static struct bkey_i_dirent *dirent_create_key(u8 type, + const struct qstr *name, u64 dst) +{ + struct bkey_i_dirent *dirent; + unsigned u64s = BKEY_U64s + + DIV_ROUND_UP(sizeof(struct bch_dirent) + name->len, + sizeof(u64)); + + dirent = kmalloc(u64s * sizeof(u64), GFP_NOFS); + if (!dirent) + return NULL; + + bkey_dirent_init(&dirent->k_i); + dirent->k.u64s = u64s; + dirent->v.d_inum = cpu_to_le64(dst); + dirent->v.d_type = type; + + memcpy(dirent->v.d_name, name->name, name->len); + memset(dirent->v.d_name + name->len, 0, + bkey_val_bytes(&dirent->k) - + (sizeof(struct bch_dirent) + name->len)); + + EBUG_ON(dirent_name_bytes(dirent_i_to_s_c(dirent)) != name->len); + + return dirent; +} + +int bch_dirent_create(struct cache_set *c, struct inode *dir, u8 type, + const struct qstr *name, u64 dst_inum) +{ + struct bch_inode_info *ei = to_bch_ei(dir); + struct bkey_i_dirent *dirent; + int ret; + + dirent = dirent_create_key(type, name, dst_inum); + if (!dirent) + return -ENOMEM; + + ret = bch_hash_set(dirent_hash_desc, &ei->str_hash, c, + ei->vfs_inode.i_ino, &ei->journal_seq, + &dirent->k_i, BCH_HASH_SET_MUST_CREATE); + kfree(dirent); + + return ret; +} + +static void dirent_copy_target(struct bkey_i_dirent *dst, + struct bkey_s_c_dirent src) +{ + dst->v.d_inum = src.v->d_inum; + dst->v.d_type = src.v->d_type; +} + +static struct bpos bch_dirent_pos(struct bch_inode_info *ei, + const struct qstr *name) +{ + return POS(ei->vfs_inode.i_ino, bch_dirent_hash(&ei->str_hash, name)); +} + +int bch_dirent_rename(struct cache_set *c, + struct inode *src_dir, const struct qstr *src_name, + struct inode *dst_dir, const struct qstr *dst_name, + u64 *journal_seq, enum bch_rename_mode mode) +{ + struct bch_inode_info *src_ei = to_bch_ei(src_dir); + struct bch_inode_info *dst_ei = to_bch_ei(dst_dir); + struct btree_iter src_iter, dst_iter, whiteout_iter; + struct bkey_s_c old_src, old_dst; + struct bkey delete; + struct bkey_i_dirent *new_src = NULL, *new_dst = NULL; + struct bpos src_pos = bch_dirent_pos(src_ei, src_name); + struct bpos dst_pos = bch_dirent_pos(dst_ei, dst_name); + bool need_whiteout; + int ret = -ENOMEM; + + bch_btree_iter_init_intent(&src_iter, c, BTREE_ID_DIRENTS, src_pos); + bch_btree_iter_init_intent(&dst_iter, c, BTREE_ID_DIRENTS, dst_pos); + bch_btree_iter_link(&src_iter, &dst_iter); + + bch_btree_iter_init(&whiteout_iter, c, BTREE_ID_DIRENTS, src_pos); + bch_btree_iter_link(&src_iter, &whiteout_iter); + + if (mode == BCH_RENAME_EXCHANGE) { + new_src = dirent_create_key(0, src_name, 0); + if (!new_src) + goto err; + } else { + new_src = (void *) &delete; + } + + new_dst = dirent_create_key(0, dst_name, 0); + if (!new_dst) + goto err; +retry: + /* + * Note that on -EINTR/dropped locks we're not restarting the lookup + * from the original hashed position (like we do when creating dirents, + * in bch_hash_set) - we never move existing dirents to different slot: + */ + old_src = bch_hash_lookup_at(dirent_hash_desc, + &src_ei->str_hash, + &src_iter, src_name); + if ((ret = btree_iter_err(old_src))) + goto err; + + ret = bch_hash_needs_whiteout(dirent_hash_desc, + &src_ei->str_hash, + &whiteout_iter, &src_iter); + if (ret < 0) + goto err; + need_whiteout = ret; + + /* + * Note that in BCH_RENAME mode, we're _not_ checking if + * the target already exists - we're relying on the VFS + * to do that check for us for correctness: + */ + old_dst = mode == BCH_RENAME + ? bch_hash_hole_at(dirent_hash_desc, &dst_iter) + : bch_hash_lookup_at(dirent_hash_desc, + &dst_ei->str_hash, + &dst_iter, dst_name); + if ((ret = btree_iter_err(old_dst))) + goto err; + + switch (mode) { + case BCH_RENAME: + bkey_init(&new_src->k); + dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src)); + + if (bkey_cmp(dst_pos, src_iter.pos) <= 0 && + bkey_cmp(src_iter.pos, dst_iter.pos) < 0) { + /* + * If we couldn't insert new_dst at its hashed + * position (dst_pos) due to a hash collision, + * and we're going to be deleting in + * between the hashed position and first empty + * slot we found - just overwrite the pos we + * were going to delete: + * + * Note: this is a correctness issue, in this + * situation bch_hash_needs_whiteout() could + * return false when the whiteout would have + * been needed if we inserted at the pos + * __dirent_find_hole() found + */ + new_dst->k.p = src_iter.pos; + ret = bch_btree_insert_at(c, NULL, NULL, + journal_seq, + BTREE_INSERT_ATOMIC, + BTREE_INSERT_ENTRY(&src_iter, + &new_dst->k_i)); + goto err; + } + + if (need_whiteout) + new_src->k.type = BCH_DIRENT_WHITEOUT; + break; + case BCH_RENAME_OVERWRITE: + bkey_init(&new_src->k); + dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src)); + + if (bkey_cmp(dst_pos, src_iter.pos) <= 0 && + bkey_cmp(src_iter.pos, dst_iter.pos) < 0) { + /* + * Same case described above - + * bch_hash_needs_whiteout could spuriously + * return false, but we have to insert at + * dst_iter.pos because we're overwriting + * another dirent: + */ + new_src->k.type = BCH_DIRENT_WHITEOUT; + } else if (need_whiteout) + new_src->k.type = BCH_DIRENT_WHITEOUT; + break; + case BCH_RENAME_EXCHANGE: + dirent_copy_target(new_src, bkey_s_c_to_dirent(old_dst)); + dirent_copy_target(new_dst, bkey_s_c_to_dirent(old_src)); + break; + } + + new_src->k.p = src_iter.pos; + new_dst->k.p = dst_iter.pos; + ret = bch_btree_insert_at(c, NULL, NULL, journal_seq, + BTREE_INSERT_ATOMIC, + BTREE_INSERT_ENTRY(&src_iter, &new_src->k_i), + BTREE_INSERT_ENTRY(&dst_iter, &new_dst->k_i)); +err: + if (ret == -EINTR) + goto retry; + + bch_btree_iter_unlock(&whiteout_iter); + bch_btree_iter_unlock(&dst_iter); + bch_btree_iter_unlock(&src_iter); + + if (new_src != (void *) &delete) + kfree(new_src); + kfree(new_dst); + return ret; +} + +int bch_dirent_delete(struct cache_set *c, struct inode *dir, + const struct qstr *name) +{ + struct bch_inode_info *ei = to_bch_ei(dir); + + return bch_hash_delete(dirent_hash_desc, &ei->str_hash, + c, ei->vfs_inode.i_ino, + &ei->journal_seq, name); +} + +u64 bch_dirent_lookup(struct cache_set *c, struct inode *dir, + const struct qstr *name) +{ + struct bch_inode_info *ei = to_bch_ei(dir); + struct btree_iter iter; + struct bkey_s_c k; + u64 inum; + + k = bch_hash_lookup(dirent_hash_desc, &ei->str_hash, c, + ei->vfs_inode.i_ino, &iter, name); + if (IS_ERR(k.k)) { + bch_btree_iter_unlock(&iter); + return 0; + } + + inum = le64_to_cpu(bkey_s_c_to_dirent(k).v->d_inum); + bch_btree_iter_unlock(&iter); + + return inum; +} + +int bch_empty_dir(struct cache_set *c, u64 dir_inum) +{ + struct btree_iter iter; + struct bkey_s_c k; + int ret = 0; + + for_each_btree_key(&iter, c, BTREE_ID_DIRENTS, POS(dir_inum, 0), k) { + if (k.k->p.inode > dir_inum) + break; + + if (k.k->type == BCH_DIRENT) { + ret = -ENOTEMPTY; + break; + } + } + bch_btree_iter_unlock(&iter); + + return ret; +} + +int bch_readdir(struct cache_set *c, struct file *file, + struct dir_context *ctx) +{ + struct inode *inode = file_inode(file); + struct btree_iter iter; + struct bkey_s_c k; + struct bkey_s_c_dirent dirent; + unsigned len; + + if (!dir_emit_dots(file, ctx)) + return 0; + + pr_debug("listing for %lu from %llu", inode->i_ino, ctx->pos); + + for_each_btree_key(&iter, c, BTREE_ID_DIRENTS, + POS(inode->i_ino, ctx->pos), k) { + if (k.k->type != BCH_DIRENT) + continue; + + dirent = bkey_s_c_to_dirent(k); + + pr_debug("saw %llu:%llu (%s) -> %llu", + k.k->p.inode, k.k->p.offset, + dirent.v->d_name, dirent.v->d_inum); + + if (bkey_cmp(k.k->p, POS(inode->i_ino, ctx->pos)) < 0) + continue; + + if (k.k->p.inode > inode->i_ino) + break; + + len = dirent_name_bytes(dirent); + + pr_debug("emitting %s", dirent.v->d_name); + + /* + * XXX: dir_emit() can fault and block, while we're holding + * locks + */ + if (!dir_emit(ctx, dirent.v->d_name, len, + le64_to_cpu(dirent.v->d_inum), + dirent.v->d_type)) + break; + + ctx->pos = k.k->p.offset + 1; + } + bch_btree_iter_unlock(&iter); + + return 0; +} |