bcachefs: Inode backpointers

This patch adds two new inode fields, bi_dir and bi_dir_offset, that
point back to the inode's dirent.

Since we're only adding fields for a single backpointer, files that have
been hardlinked won't necessarily have valid backpointers: we also add a
new inode flag, BCH_INODE_BACKPTR_UNTRUSTED, that's set if an inode has
ever had multiple links to it. That's ok, because we only really need
this functionality for directories, which can never have multiple
hardlinks - when we add subvolumes, we'll need a way to enemurate and
print subvolumes, and this will let us reconstruct a path to a subvolume
root given a subvolume root inode.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
index 2172d3cf368092646c8f13e54e68190e15fa906f..f2b5f5c06ee047768084cb508e2c7a324c04b655 100644 (file)
--- a/fs/bcachefs/bcachefs_format.h
+++ b/fs/bcachefs/bcachefs_format.h
@@ -710,7 +710,9 @@ struct bch_inode_generation {
        x(bi_foreground_target,         16)     \
        x(bi_background_target,         16)     \
        x(bi_erasure_code,              16)     \
-       x(bi_fields_set,                16)
+       x(bi_fields_set,                16)     \
+       x(bi_dir,                       64)     \
+       x(bi_dir_offset,                64)
 
 /* subset of BCH_INODE_FIELDS */
 #define BCH_INODE_OPTS()                       \
@@ -746,6 +748,7 @@ enum {
        __BCH_INODE_I_SIZE_DIRTY= 5,
        __BCH_INODE_I_SECTORS_DIRTY= 6,
        __BCH_INODE_UNLINKED    = 7,
+       __BCH_INODE_BACKPTR_UNTRUSTED = 8,
 
        /* bits 20+ reserved for packed fields below: */
 };
@@ -758,6 +761,7 @@ enum {
 #define BCH_INODE_I_SIZE_DIRTY (1 << __BCH_INODE_I_SIZE_DIRTY)
 #define BCH_INODE_I_SECTORS_DIRTY (1 << __BCH_INODE_I_SECTORS_DIRTY)
 #define BCH_INODE_UNLINKED     (1 << __BCH_INODE_UNLINKED)
+#define BCH_INODE_BACKPTR_UNTRUSTED (1 << __BCH_INODE_BACKPTR_UNTRUSTED)
 
 LE32_BITMASK(INODE_STR_HASH,   struct bch_inode, bi_flags, 20, 24);
 LE32_BITMASK(INODE_NR_FIELDS,  struct bch_inode, bi_flags, 24, 31);
@@ -1208,7 +1212,8 @@ enum bcachefs_metadata_version {
        bcachefs_metadata_version_bkey_renumber         = 10,
        bcachefs_metadata_version_inode_btree_change    = 11,
        bcachefs_metadata_version_snapshot              = 12,
-       bcachefs_metadata_version_max                   = 13,
+       bcachefs_metadata_version_inode_backpointers    = 13,
+       bcachefs_metadata_version_max                   = 14,
 };
 
 #define bcachefs_metadata_version_current      (bcachefs_metadata_version_max - 1)

diff --git a/fs/bcachefs/dirent.c b/fs/bcachefs/dirent.c
index 592dd80cf963959f4b23f1ae4f463227bfa655e6..cf4ce2e7f29c1d51cad6c8c14f43822ea26a6079 100644 (file)
--- a/fs/bcachefs/dirent.c
+++ b/fs/bcachefs/dirent.c
@@ -141,7 +141,7 @@ static struct bkey_i_dirent *dirent_create_key(struct btree_trans *trans,
 int bch2_dirent_create(struct btree_trans *trans,
                       u64 dir_inum, const struct bch_hash_info *hash_info,
                       u8 type, const struct qstr *name, u64 dst_inum,
-                      int flags)
+                      u64 *dir_offset, int flags)
 {
        struct bkey_i_dirent *dirent;
        int ret;
@@ -151,8 +151,11 @@ int bch2_dirent_create(struct btree_trans *trans,
        if (ret)
                return ret;
 
-       return bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
-                            dir_inum, &dirent->k_i, flags);
+       ret = bch2_hash_set(trans, bch2_dirent_hash_desc, hash_info,
+                           dir_inum, &dirent->k_i, flags);
+       *dir_offset = dirent->k.p.offset;
+
+       return ret;
 }
 
 static void dirent_copy_target(struct bkey_i_dirent *dst,
@@ -165,8 +168,8 @@ static void dirent_copy_target(struct bkey_i_dirent *dst,
 int bch2_dirent_rename(struct btree_trans *trans,
                       u64 src_dir, struct bch_hash_info *src_hash,
                       u64 dst_dir, struct bch_hash_info *dst_hash,
-                      const struct qstr *src_name, u64 *src_inum,
-                      const struct qstr *dst_name, u64 *dst_inum,
+                      const struct qstr *src_name, u64 *src_inum, u64 *src_offset,
+                      const struct qstr *dst_name, u64 *dst_inum, u64 *dst_offset,
                       enum bch_rename_mode mode)
 {
        struct btree_iter *src_iter = NULL, *dst_iter = NULL;
@@ -255,7 +258,7 @@ int bch2_dirent_rename(struct btree_trans *trans,
                                new_dst->k.p = src_iter->pos;
                                bch2_trans_update(trans, src_iter,
                                                  &new_dst->k_i, 0);
-                               goto out;
+                               goto out_set_offset;
                        } else {
                                /* If we're overwriting, we can't insert new_dst
                                 * at a different slot because it has to
@@ -278,6 +281,9 @@ int bch2_dirent_rename(struct btree_trans *trans,
 
        bch2_trans_update(trans, src_iter, &new_src->k_i, 0);
        bch2_trans_update(trans, dst_iter, &new_dst->k_i, 0);
+out_set_offset:
+       *src_offset = new_src->k.p.offset;
+       *dst_offset = new_dst->k.p.offset;
 out:
        bch2_trans_iter_put(trans, src_iter);
        bch2_trans_iter_put(trans, dst_iter);

diff --git a/fs/bcachefs/dirent.h b/fs/bcachefs/dirent.h
index 34769371dd13d1725dc96f2c6d01a5fb10d9ecd6..e1d8ce377d43755cd5584edf1afa05d0ba65495e 100644 (file)
--- a/fs/bcachefs/dirent.h
+++ b/fs/bcachefs/dirent.h
@@ -31,7 +31,7 @@ static inline unsigned dirent_val_u64s(unsigned len)
 
 int bch2_dirent_create(struct btree_trans *, u64,
                       const struct bch_hash_info *, u8,
-                      const struct qstr *, u64, int);
+                      const struct qstr *, u64, u64 *, int);
 
 int bch2_dirent_delete_at(struct btree_trans *,
                          const struct bch_hash_info *,
@@ -46,8 +46,8 @@ enum bch_rename_mode {
 int bch2_dirent_rename(struct btree_trans *,
                       u64, struct bch_hash_info *,
                       u64, struct bch_hash_info *,
-                      const struct qstr *, u64 *,
-                      const struct qstr *, u64 *,
+                      const struct qstr *, u64 *, u64 *,
+                      const struct qstr *, u64 *, u64 *,
                       enum bch_rename_mode);
 
 struct btree_iter *

diff --git a/fs/bcachefs/fs-common.c b/fs/bcachefs/fs-common.c
index 503ce1920f395f935a7f3ba57f2cad2afee70bc2..83c2168ce480a92169b68a22c82ea9a64a8a02dd 100644 (file)
--- a/fs/bcachefs/fs-common.c
+++ b/fs/bcachefs/fs-common.c
@@ -20,8 +20,10 @@ int bch2_create_trans(struct btree_trans *trans, u64 dir_inum,
 {
        struct bch_fs *c = trans->c;
        struct btree_iter *dir_iter = NULL;
+       struct btree_iter *inode_iter = NULL;
        struct bch_hash_info hash = bch2_hash_info_init(c, new_inode);
-       u64 now = bch2_current_time(trans->c);
+       u64 now = bch2_current_time(c);
+       u64 dir_offset = 0;
        int ret;
 
        dir_iter = bch2_inode_peek(trans, dir_u, dir_inum, BTREE_ITER_INTENT);
@@ -34,7 +36,8 @@ int bch2_create_trans(struct btree_trans *trans, u64 dir_inum,
        if (!name)
                new_inode->bi_flags |= BCH_INODE_UNLINKED;
 
-       ret = bch2_inode_create(trans, new_inode);
+       inode_iter = bch2_inode_create(trans, new_inode);
+       ret = PTR_ERR_OR_ZERO(inode_iter);
        if (ret)
                goto err;
 
@@ -66,11 +69,20 @@ int bch2_create_trans(struct btree_trans *trans, u64 dir_inum,
                ret = bch2_dirent_create(trans, dir_inum, &dir_hash,
                                         mode_to_type(new_inode->bi_mode),
                                         name, new_inode->bi_inum,
+                                        &dir_offset,
                                         BCH_HASH_SET_MUST_CREATE);
                if (ret)
                        goto err;
        }
+
+       if (c->sb.version >= bcachefs_metadata_version_inode_backpointers) {
+               new_inode->bi_dir               = dir_u->bi_inum;
+               new_inode->bi_dir_offset        = dir_offset;
+       }
+
+       ret = bch2_inode_write(trans, inode_iter, new_inode);
 err:
+       bch2_trans_iter_put(trans, inode_iter);
        bch2_trans_iter_put(trans, dir_iter);
        return ret;
 }
@@ -79,9 +91,11 @@ int bch2_link_trans(struct btree_trans *trans, u64 dir_inum,
                    u64 inum, struct bch_inode_unpacked *dir_u,
                    struct bch_inode_unpacked *inode_u, const struct qstr *name)
 {
+       struct bch_fs *c = trans->c;
        struct btree_iter *dir_iter = NULL, *inode_iter = NULL;
        struct bch_hash_info dir_hash;
-       u64 now = bch2_current_time(trans->c);
+       u64 now = bch2_current_time(c);
+       u64 dir_offset = 0;
        int ret;
 
        inode_iter = bch2_inode_peek(trans, inode_u, inum, BTREE_ITER_INTENT);
@@ -92,6 +106,8 @@ int bch2_link_trans(struct btree_trans *trans, u64 dir_inum,
        inode_u->bi_ctime = now;
        bch2_inode_nlink_inc(inode_u);
 
+       inode_u->bi_flags |= BCH_INODE_BACKPTR_UNTRUSTED;
+
        dir_iter = bch2_inode_peek(trans, dir_u, dir_inum, 0);
        ret = PTR_ERR_OR_ZERO(dir_iter);
        if (ret)
@@ -99,12 +115,21 @@ int bch2_link_trans(struct btree_trans *trans, u64 dir_inum,
 
        dir_u->bi_mtime = dir_u->bi_ctime = now;
 
-       dir_hash = bch2_hash_info_init(trans->c, dir_u);
+       dir_hash = bch2_hash_info_init(c, dir_u);
 
-       ret =   bch2_dirent_create(trans, dir_inum, &dir_hash,
-                                 mode_to_type(inode_u->bi_mode),
-                                 name, inum, BCH_HASH_SET_MUST_CREATE) ?:
-               bch2_inode_write(trans, dir_iter, dir_u) ?:
+       ret = bch2_dirent_create(trans, dir_inum, &dir_hash,
+                                mode_to_type(inode_u->bi_mode),
+                                name, inum, &dir_offset,
+                                BCH_HASH_SET_MUST_CREATE);
+       if (ret)
+               goto err;
+
+       if (c->sb.version >= bcachefs_metadata_version_inode_backpointers) {
+               inode_u->bi_dir         = dir_inum;
+               inode_u->bi_dir_offset  = dir_offset;
+       }
+
+       ret =   bch2_inode_write(trans, dir_iter, dir_u) ?:
                bch2_inode_write(trans, inode_iter, inode_u);
 err:
        bch2_trans_iter_put(trans, dir_iter);
@@ -117,10 +142,11 @@ int bch2_unlink_trans(struct btree_trans *trans,
                      struct bch_inode_unpacked *inode_u,
                      const struct qstr *name)
 {
+       struct bch_fs *c = trans->c;
        struct btree_iter *dir_iter = NULL, *dirent_iter = NULL,
                          *inode_iter = NULL;
        struct bch_hash_info dir_hash;
-       u64 inum, now = bch2_current_time(trans->c);
+       u64 inum, now = bch2_current_time(c);
        struct bkey_s_c k;
        int ret;
 
@@ -129,7 +155,7 @@ int bch2_unlink_trans(struct btree_trans *trans,
        if (ret)
                goto err;
 
-       dir_hash = bch2_hash_info_init(trans->c, dir_u);
+       dir_hash = bch2_hash_info_init(c, dir_u);
 
        dirent_iter = __bch2_dirent_lookup_trans(trans, dir_inum, &dir_hash,
                                                 name, BTREE_ITER_INTENT);
@@ -195,10 +221,12 @@ int bch2_rename_trans(struct btree_trans *trans,
                      const struct qstr *dst_name,
                      enum bch_rename_mode mode)
 {
+       struct bch_fs *c = trans->c;
        struct btree_iter *src_dir_iter = NULL, *dst_dir_iter = NULL;
        struct btree_iter *src_inode_iter = NULL, *dst_inode_iter = NULL;
        struct bch_hash_info src_hash, dst_hash;
-       u64 src_inode, dst_inode, now = bch2_current_time(trans->c);
+       u64 src_inode, src_offset, dst_inode, dst_offset;
+       u64 now = bch2_current_time(c);
        int ret;
 
        src_dir_iter = bch2_inode_peek(trans, src_dir_u, src_dir,
@@ -207,7 +235,7 @@ int bch2_rename_trans(struct btree_trans *trans,
        if (ret)
                goto err;
 
-       src_hash = bch2_hash_info_init(trans->c, src_dir_u);
+       src_hash = bch2_hash_info_init(c, src_dir_u);
 
        if (dst_dir != src_dir) {
                dst_dir_iter = bch2_inode_peek(trans, dst_dir_u, dst_dir,
@@ -216,7 +244,7 @@ int bch2_rename_trans(struct btree_trans *trans,
                if (ret)
                        goto err;
 
-               dst_hash = bch2_hash_info_init(trans->c, dst_dir_u);
+               dst_hash = bch2_hash_info_init(c, dst_dir_u);
        } else {
                dst_dir_u = src_dir_u;
                dst_hash = src_hash;
@@ -225,8 +253,8 @@ int bch2_rename_trans(struct btree_trans *trans,
        ret = bch2_dirent_rename(trans,
                                 src_dir, &src_hash,
                                 dst_dir, &dst_hash,
-                                src_name, &src_inode,
-                                dst_name, &dst_inode,
+                                src_name, &src_inode, &src_offset,
+                                dst_name, &dst_inode, &dst_offset,
                                 mode);
        if (ret)
                goto err;
@@ -245,6 +273,16 @@ int bch2_rename_trans(struct btree_trans *trans,
                        goto err;
        }
 
+       if (c->sb.version >= bcachefs_metadata_version_inode_backpointers) {
+               src_inode_u->bi_dir             = dst_dir_u->bi_inum;
+               src_inode_u->bi_dir_offset      = dst_offset;
+
+               if (mode == BCH_RENAME_EXCHANGE) {
+                       dst_inode_u->bi_dir             = src_dir_u->bi_inum;
+                       dst_inode_u->bi_dir_offset      = src_offset;
+               }
+       }
+
        if (mode == BCH_RENAME_OVERWRITE) {
                if (S_ISDIR(src_inode_u->bi_mode) !=
                    S_ISDIR(dst_inode_u->bi_mode)) {

diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index a3acae0ddfa905c3e0bde336c1edaa34d957ab39..d65b3e100f78bbb05b59088980652feda4df3c9b 100644 (file)
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -675,6 +675,39 @@ retry:
                        continue;
                }
 
+               if (!target.bi_nlink &&
+                   !(target.bi_flags & BCH_INODE_BACKPTR_UNTRUSTED) &&
+                   (target.bi_dir != k.k->p.inode ||
+                    target.bi_dir_offset != k.k->p.offset) &&
+                   (fsck_err_on(c->sb.version >= bcachefs_metadata_version_inode_backpointers, c,
+                                "inode %llu has wrong backpointer:\n"
+                                "got       %llu:%llu\n"
+                                "should be %llu:%llu",
+                                d_inum,
+                                target.bi_dir,
+                                target.bi_dir_offset,
+                                k.k->p.inode,
+                                k.k->p.offset) ||
+                    c->opts.version_upgrade)) {
+                       struct bkey_inode_buf p;
+
+                       target.bi_dir           = k.k->p.inode;
+                       target.bi_dir_offset    = k.k->p.offset;
+                       bch2_trans_unlock(&trans);
+
+                       bch2_inode_pack(c, &p, &target);
+
+                       ret = bch2_btree_insert(c, BTREE_ID_inodes,
+                                               &p.inode.k_i, NULL, NULL,
+                                               BTREE_INSERT_NOFAIL|
+                                               BTREE_INSERT_LAZY_RW);
+                       if (ret) {
+                               bch_err(c, "error in fsck: error %i updating inode", ret);
+                               goto err;
+                       }
+                       continue;
+               }
+
                if (fsck_err_on(have_target &&
                                d.v->d_type !=
                                mode_to_type(target.bi_mode), c,
@@ -1314,6 +1347,16 @@ static int check_inode(struct btree_trans *trans,
                do_update = true;
        }
 
+       if (!S_ISDIR(u.bi_mode) &&
+           u.bi_nlink &&
+           !(u.bi_flags & BCH_INODE_BACKPTR_UNTRUSTED) &&
+           (fsck_err_on(c->sb.version >= bcachefs_metadata_version_inode_backpointers, c,
+                        "inode missing BCH_INODE_BACKPTR_UNTRUSTED flags") ||
+            c->opts.version_upgrade)) {
+               u.bi_flags |= BCH_INODE_BACKPTR_UNTRUSTED;
+               do_update = true;
+       }
+
        if (do_update) {
                struct bkey_inode_buf p;
 

diff --git a/fs/bcachefs/inode.c b/fs/bcachefs/inode.c
index 7044ab73831cd18836fdfb9b132768d7ece4149b..b72b3578bbe259bdd1ab8cd3e8c7c14e354c626f 100644 (file)
--- a/fs/bcachefs/inode.c
+++ b/fs/bcachefs/inode.c
@@ -470,11 +470,10 @@ static inline u32 bkey_generation(struct bkey_s_c k)
        }
 }
 
-int bch2_inode_create(struct btree_trans *trans,
-                     struct bch_inode_unpacked *inode_u)
+struct btree_iter *bch2_inode_create(struct btree_trans *trans,
+                                    struct bch_inode_unpacked *inode_u)
 {
        struct bch_fs *c = trans->c;
-       struct bkey_inode_buf *inode_p;
        struct btree_iter *iter = NULL;
        struct bkey_s_c k;
        u64 min, max, start, *hint;
@@ -494,10 +493,6 @@ int bch2_inode_create(struct btree_trans *trans,
 
        if (start >= max || start < min)
                start = min;
-
-       inode_p = bch2_trans_kmalloc(trans, sizeof(*inode_p));
-       if (IS_ERR(inode_p))
-               return PTR_ERR(inode_p);
 again:
        for_each_btree_key(trans, iter, BTREE_ID_inodes, POS(0, start),
                           BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
@@ -521,7 +516,7 @@ again:
        bch2_trans_iter_put(trans, iter);
 
        if (ret)
-               return ret;
+               return ERR_PTR(ret);
 
        if (start != min) {
                /* Retry from start */
@@ -529,15 +524,12 @@ again:
                goto again;
        }
 
-       return -ENOSPC;
+       return ERR_PTR(-ENOSPC);
 found_slot:
        *hint                   = k.k->p.offset;
        inode_u->bi_inum        = k.k->p.offset;
        inode_u->bi_generation  = bkey_generation(k);
-
-       ret = bch2_inode_write(trans, iter, inode_u);
-       bch2_trans_iter_put(trans, iter);
-       return ret;
+       return iter;
 }
 
 int bch2_inode_rm(struct bch_fs *c, u64 inode_nr, bool cached)

diff --git a/fs/bcachefs/inode.h b/fs/bcachefs/inode.h
index 1caf036ae928fe822a8426fe952ac50774c891b6..6bad6dfb79891ccf941ded70f125bb4d33b61bfb 100644 (file)
--- a/fs/bcachefs/inode.h
+++ b/fs/bcachefs/inode.h
@@ -69,7 +69,8 @@ void bch2_inode_init(struct bch_fs *, struct bch_inode_unpacked *,
                     uid_t, gid_t, umode_t, dev_t,
                     struct bch_inode_unpacked *);
 
-int bch2_inode_create(struct btree_trans *, struct bch_inode_unpacked *);
+struct btree_iter *bch2_inode_create(struct btree_trans *,
+                                    struct bch_inode_unpacked *);
 
 int bch2_inode_rm(struct bch_fs *, u64, bool);