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authorJosef Bacik <josef@toxicpanda.com>2020-02-15 00:11:47 +0300
committerDavid Sterba <dsterba@suse.com>2020-03-23 19:02:00 +0300
commitc75e839414d3610e6487ae3145199c500d55f7f7 (patch)
tree68e609a6362c4f259afc2e107fffac94e743a126
parentefc3453494af78180ac00d9dd8391fd52c4a921e (diff)
downloadlinux-c75e839414d3610e6487ae3145199c500d55f7f7.tar.xz
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 <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/backref.c12
-rw-r--r--fs/btrfs/ctree.h1
-rw-r--r--fs/btrfs/disk-io.c37
-rw-r--r--fs/btrfs/export.c21
-rw-r--r--fs/btrfs/file.c5
-rw-r--r--fs/btrfs/inode.c3
-rw-r--r--fs/btrfs/send.c14
-rw-r--r--fs/btrfs/tests/btrfs-tests.c9
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);