From c75e839414d3610e6487ae3145199c500d55f7f7 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 14 Feb 2020 16:11:47 -0500 Subject: btrfs: kill the subvol_srcu Now that we have proper root ref counting everywhere we can kill the subvol_srcu. * removal of fs_info::subvol_srcu reduces size of fs_info by 1176 bytes * the refcount_t used for the references checks for accidental 0->1 in cases where the root lifetime would not be properly protected * there's a leak detector for roots to catch unfreed roots at umount time * SRCU served us well over the years but is was not a proper synchronization mechanism for some cases Signed-off-by: Josef Bacik Reviewed-by: David Sterba [ update changelog ] Signed-off-by: David Sterba --- fs/btrfs/backref.c | 12 +----------- fs/btrfs/ctree.h | 1 - fs/btrfs/disk-io.c | 37 +++++++++---------------------------- fs/btrfs/export.c | 21 ++++----------------- fs/btrfs/file.c | 5 ----- fs/btrfs/inode.c | 3 --- fs/btrfs/send.c | 14 -------------- fs/btrfs/tests/btrfs-tests.c | 9 --------- 8 files changed, 14 insertions(+), 88 deletions(-) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index f2728fb3ee8f..cd2d39b60be0 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -542,24 +542,19 @@ static int resolve_indirect_ref(struct btrfs_fs_info *fs_info, int ret = 0; int root_level; int level = ref->level; - int index; struct btrfs_key search_key = ref->key_for_search; root_key.objectid = ref->root_id; root_key.type = BTRFS_ROOT_ITEM_KEY; root_key.offset = (u64)-1; - index = srcu_read_lock(&fs_info->subvol_srcu); - root = btrfs_get_fs_root(fs_info, &root_key, false); if (IS_ERR(root)) { - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = PTR_ERR(root); goto out_free; } if (btrfs_is_testing(fs_info)) { - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -ENOENT; goto out; } @@ -571,10 +566,8 @@ static int resolve_indirect_ref(struct btrfs_fs_info *fs_info, else root_level = btrfs_old_root_level(root, time_seq); - if (root_level + 1 == level) { - srcu_read_unlock(&fs_info->subvol_srcu, index); + if (root_level + 1 == level) goto out; - } /* * We can often find data backrefs with an offset that is too large @@ -604,9 +597,6 @@ static int resolve_indirect_ref(struct btrfs_fs_info *fs_info, else ret = btrfs_search_old_slot(root, &search_key, path, time_seq); - /* root node has been locked, we can release @subvol_srcu safely here */ - srcu_read_unlock(&fs_info->subvol_srcu, index); - btrfs_debug(fs_info, "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)", ref->root_id, level, ref->count, ret, diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f1eef81aaa49..8aa7b9dac405 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -697,7 +697,6 @@ struct btrfs_fs_info { struct rw_semaphore cleanup_work_sem; struct rw_semaphore subvol_sem; - struct srcu_struct subvol_srcu; spinlock_t trans_lock; /* diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 4d3eba909664..a6cb5cbbdb9f 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2757,46 +2757,33 @@ static int init_mount_fs_info(struct btrfs_fs_info *fs_info, struct super_block sb->s_blocksize = BTRFS_BDEV_BLOCKSIZE; sb->s_blocksize_bits = blksize_bits(BTRFS_BDEV_BLOCKSIZE); - ret = init_srcu_struct(&fs_info->subvol_srcu); - if (ret) - return ret; - ret = percpu_counter_init(&fs_info->dio_bytes, 0, GFP_KERNEL); if (ret) - goto fail; + return ret; ret = percpu_counter_init(&fs_info->dirty_metadata_bytes, 0, GFP_KERNEL); if (ret) - goto fail; + return ret; fs_info->dirty_metadata_batch = PAGE_SIZE * (1 + ilog2(nr_cpu_ids)); ret = percpu_counter_init(&fs_info->delalloc_bytes, 0, GFP_KERNEL); if (ret) - goto fail; + return ret; ret = percpu_counter_init(&fs_info->dev_replace.bio_counter, 0, GFP_KERNEL); if (ret) - goto fail; + return ret; fs_info->delayed_root = kmalloc(sizeof(struct btrfs_delayed_root), GFP_KERNEL); - if (!fs_info->delayed_root) { - ret = -ENOMEM; - goto fail; - } + if (!fs_info->delayed_root) + return -ENOMEM; btrfs_init_delayed_root(fs_info->delayed_root); - ret = btrfs_alloc_stripe_hash_table(fs_info); - if (ret) - goto fail; - - return 0; -fail: - cleanup_srcu_struct(&fs_info->subvol_srcu); - return ret; + return btrfs_alloc_stripe_hash_table(fs_info); } static int btrfs_uuid_rescan_kthread(void *data) @@ -2870,13 +2857,13 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device fs_info->chunk_root = chunk_root; if (!tree_root || !chunk_root) { err = -ENOMEM; - goto fail_srcu; + goto fail; } fs_info->btree_inode = new_inode(sb); if (!fs_info->btree_inode) { err = -ENOMEM; - goto fail_srcu; + goto fail; } mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS); btrfs_init_btree_inode(fs_info); @@ -3398,8 +3385,6 @@ fail_alloc: btrfs_mapping_tree_free(&fs_info->mapping_tree); iput(fs_info->btree_inode); -fail_srcu: - cleanup_srcu_struct(&fs_info->subvol_srcu); fail: btrfs_close_devices(fs_info->fs_devices); return err; @@ -3902,9 +3887,6 @@ void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info, drop_ref = true; spin_unlock(&fs_info->fs_roots_radix_lock); - if (btrfs_root_refs(&root->root_item) == 0) - synchronize_srcu(&fs_info->subvol_srcu); - if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) { btrfs_free_log(NULL, root); if (root->reloc_root) { @@ -4116,7 +4098,6 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info) btrfs_mapping_tree_free(&fs_info->mapping_tree); btrfs_close_devices(fs_info->fs_devices); - cleanup_srcu_struct(&fs_info->subvol_srcu); } int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid, diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c index 25bd4317bf5a..2bb25d2dc44b 100644 --- a/fs/btrfs/export.c +++ b/fs/btrfs/export.c @@ -65,8 +65,6 @@ struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, struct btrfs_root *root; struct inode *inode; struct btrfs_key key; - int index; - int err = 0; if (objectid < BTRFS_FIRST_FREE_OBJECTID) return ERR_PTR(-ESTALE); @@ -75,13 +73,9 @@ struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, key.type = BTRFS_ROOT_ITEM_KEY; key.offset = (u64)-1; - index = srcu_read_lock(&fs_info->subvol_srcu); - root = btrfs_get_fs_root(fs_info, &key, true); - if (IS_ERR(root)) { - err = PTR_ERR(root); - goto fail; - } + if (IS_ERR(root)) + return ERR_CAST(root); key.objectid = objectid; key.type = BTRFS_INODE_ITEM_KEY; @@ -89,12 +83,8 @@ struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, inode = btrfs_iget(sb, &key, root); btrfs_put_root(root); - if (IS_ERR(inode)) { - err = PTR_ERR(inode); - goto fail; - } - - srcu_read_unlock(&fs_info->subvol_srcu, index); + if (IS_ERR(inode)) + return ERR_CAST(inode); if (check_generation && generation != inode->i_generation) { iput(inode); @@ -102,9 +92,6 @@ struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, } return d_obtain_alias(inode); -fail: - srcu_read_unlock(&fs_info->subvol_srcu, index); - return ERR_PTR(err); } static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 18c88f514a0d..20107f42a766 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -278,7 +278,6 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info, struct btrfs_key key; struct btrfs_ioctl_defrag_range_args range; int num_defrag; - int index; int ret; /* get the inode */ @@ -286,8 +285,6 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info, key.type = BTRFS_ROOT_ITEM_KEY; key.offset = (u64)-1; - index = srcu_read_lock(&fs_info->subvol_srcu); - inode_root = btrfs_get_fs_root(fs_info, &key, true); if (IS_ERR(inode_root)) { ret = PTR_ERR(inode_root); @@ -303,7 +300,6 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info, ret = PTR_ERR(inode); goto cleanup; } - srcu_read_unlock(&fs_info->subvol_srcu, index); /* do a chunk of defrag */ clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags); @@ -339,7 +335,6 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info, iput(inode); return 0; cleanup: - srcu_read_unlock(&fs_info->subvol_srcu, index); kmem_cache_free(btrfs_inode_defrag_cachep, defrag); return ret; } diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 683bb20c1d0f..320d1062068d 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5364,7 +5364,6 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) struct btrfs_root *sub_root = root; struct btrfs_key location; u8 di_type = 0; - int index; int ret = 0; if (dentry->d_name.len > BTRFS_NAME_LEN) @@ -5391,7 +5390,6 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) return inode; } - index = srcu_read_lock(&fs_info->subvol_srcu); ret = fixup_tree_root_location(fs_info, dir, dentry, &location, &sub_root); if (ret < 0) { @@ -5404,7 +5402,6 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) } if (root != sub_root) btrfs_put_root(sub_root); - srcu_read_unlock(&fs_info->subvol_srcu, index); if (!IS_ERR(inode) && root != sub_root) { down_read(&fs_info->cleanup_work_sem); diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index e47f768cec3d..c5f41bd86765 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -7028,7 +7028,6 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) int clone_sources_to_rollback = 0; unsigned alloc_size; int sort_clone_roots = 0; - int index; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -7155,11 +7154,8 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) key.type = BTRFS_ROOT_ITEM_KEY; key.offset = (u64)-1; - index = srcu_read_lock(&fs_info->subvol_srcu); - clone_root = btrfs_get_fs_root(fs_info, &key, true); if (IS_ERR(clone_root)) { - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = PTR_ERR(clone_root); goto out; } @@ -7168,7 +7164,6 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) btrfs_root_dead(clone_root)) { spin_unlock(&clone_root->root_item_lock); btrfs_put_root(clone_root); - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -EPERM; goto out; } @@ -7176,13 +7171,11 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) dedupe_in_progress_warn(clone_root); spin_unlock(&clone_root->root_item_lock); btrfs_put_root(clone_root); - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -EAGAIN; goto out; } clone_root->send_in_progress++; spin_unlock(&clone_root->root_item_lock); - srcu_read_unlock(&fs_info->subvol_srcu, index); sctx->clone_roots[i].root = clone_root; clone_sources_to_rollback = i + 1; @@ -7196,11 +7189,8 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) key.type = BTRFS_ROOT_ITEM_KEY; key.offset = (u64)-1; - index = srcu_read_lock(&fs_info->subvol_srcu); - sctx->parent_root = btrfs_get_fs_root(fs_info, &key, true); if (IS_ERR(sctx->parent_root)) { - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = PTR_ERR(sctx->parent_root); goto out; } @@ -7210,20 +7200,16 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg) if (!btrfs_root_readonly(sctx->parent_root) || btrfs_root_dead(sctx->parent_root)) { spin_unlock(&sctx->parent_root->root_item_lock); - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -EPERM; goto out; } if (sctx->parent_root->dedupe_in_progress) { dedupe_in_progress_warn(sctx->parent_root); spin_unlock(&sctx->parent_root->root_item_lock); - srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -EAGAIN; goto out; } spin_unlock(&sctx->parent_root->root_item_lock); - - srcu_read_unlock(&fs_info->subvol_srcu, index); } /* diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c index 42e62fd2809c..999c14e5d0bd 100644 --- a/fs/btrfs/tests/btrfs-tests.c +++ b/fs/btrfs/tests/btrfs-tests.c @@ -134,14 +134,6 @@ struct btrfs_fs_info *btrfs_alloc_dummy_fs_info(u32 nodesize, u32 sectorsize) fs_info->nodesize = nodesize; fs_info->sectorsize = sectorsize; - - if (init_srcu_struct(&fs_info->subvol_srcu)) { - kfree(fs_info->fs_devices); - kfree(fs_info->super_copy); - kfree(fs_info); - return NULL; - } - set_bit(BTRFS_FS_STATE_DUMMY_FS_INFO, &fs_info->fs_state); test_mnt->mnt_sb->s_fs_info = fs_info; @@ -191,7 +183,6 @@ void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info) } btrfs_free_qgroup_config(fs_info); btrfs_free_fs_roots(fs_info); - cleanup_srcu_struct(&fs_info->subvol_srcu); kfree(fs_info->super_copy); btrfs_check_leaked_roots(fs_info); btrfs_extent_buffer_leak_debug_check(fs_info); -- cgit v1.2.3