[PATCH v6 84/99] btrfs: Convert fs_roots_radix to XArray

From: Matthew Wilcox
Date: Wed Jan 17 2018 - 15:32:05 EST

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From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>

Most of the gang lookups being done can be expressed just as efficiently
and somewhat more naturally as xa_for_each() loops. I opted not to
change the one in btrfs_cleanup_fs_roots() as it's using SRCU which is
subtle and quick to anger.

Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
---
fs/btrfs/ctree.h | 3 +-
fs/btrfs/disk-io.c | 65 +++++++++++----------------------
fs/btrfs/tests/btrfs-tests.c | 3 +-
fs/btrfs/transaction.c | 87 ++++++++++++++++++--------------------------
4 files changed, 59 insertions(+), 99 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 13c260b525a1..173d72dfaab6 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -741,8 +741,7 @@ struct btrfs_fs_info {
/* the log root tree is a directory of all the other log roots */
struct btrfs_root *log_root_tree;

- spinlock_t fs_roots_radix_lock;
- struct radix_tree_root fs_roots_radix;
+ struct xarray fs_roots;

/* block group cache stuff */
spinlock_t block_group_cache_lock;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a8ecccfc36de..62995a55d112 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1519,13 +1519,7 @@ int btrfs_init_fs_root(struct btrfs_root *root)
struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
u64 root_id)
{
- struct btrfs_root *root;
-
- spin_lock(&fs_info->fs_roots_radix_lock);
- root = radix_tree_lookup(&fs_info->fs_roots_radix,
- (unsigned long)root_id);
- spin_unlock(&fs_info->fs_roots_radix_lock);
- return root;
+ return xa_load(&fs_info->fs_roots, (unsigned long)root_id);
}

int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info,
@@ -1533,18 +1527,13 @@ int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info,
{
int ret;

- ret = radix_tree_preload(GFP_NOFS);
- if (ret)
- return ret;
-
- spin_lock(&fs_info->fs_roots_radix_lock);
- ret = radix_tree_insert(&fs_info->fs_roots_radix,
+ xa_lock(&fs_info->fs_roots);
+ ret = __xa_insert(&fs_info->fs_roots,
(unsigned long)root->root_key.objectid,
- root);
+ root, GFP_NOFS);
if (ret == 0)
set_bit(BTRFS_ROOT_IN_RADIX, &root->state);
- spin_unlock(&fs_info->fs_roots_radix_lock);
- radix_tree_preload_end();
+ xa_unlock(&fs_info->fs_roots);

return ret;
}
@@ -2079,33 +2068,25 @@ static void free_root_pointers(struct btrfs_fs_info *info, int chunk_root)

void btrfs_free_fs_roots(struct btrfs_fs_info *fs_info)
{
- int ret;
- struct btrfs_root *gang[8];
- int i;
+ struct btrfs_root *root;
+ unsigned long i = 0;

while (!list_empty(&fs_info->dead_roots)) {
- gang[0] = list_entry(fs_info->dead_roots.next,
+ root = list_entry(fs_info->dead_roots.next,
struct btrfs_root, root_list);
- list_del(&gang[0]->root_list);
+ list_del(&root->root_list);

- if (test_bit(BTRFS_ROOT_IN_RADIX, &gang[0]->state)) {
- btrfs_drop_and_free_fs_root(fs_info, gang[0]);
+ if (test_bit(BTRFS_ROOT_IN_RADIX, &root->state)) {
+ btrfs_drop_and_free_fs_root(fs_info, root);
} else {
- free_extent_buffer(gang[0]->node);
- free_extent_buffer(gang[0]->commit_root);
- btrfs_put_fs_root(gang[0]);
+ free_extent_buffer(root->node);
+ free_extent_buffer(root->commit_root);
+ btrfs_put_fs_root(root);
}
}

- while (1) {
- ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
- (void **)gang, 0,
- ARRAY_SIZE(gang));
- if (!ret)
- break;
- for (i = 0; i < ret; i++)
- btrfs_drop_and_free_fs_root(fs_info, gang[i]);
- }
+ xa_for_each(&fs_info->fs_roots, root, i, ULONG_MAX, XA_PRESENT)
+ btrfs_drop_and_free_fs_root(fs_info, root);

if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
btrfs_free_log_root_tree(NULL, fs_info);
@@ -2447,7 +2428,7 @@ int open_ctree(struct super_block *sb,
goto fail_delalloc_bytes;
}

- INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_ATOMIC);
+ xa_init(&fs_info->fs_roots);
INIT_RADIX_TREE(&fs_info->buffer_radix, GFP_ATOMIC);
INIT_LIST_HEAD(&fs_info->trans_list);
INIT_LIST_HEAD(&fs_info->dead_roots);
@@ -2456,7 +2437,6 @@ int open_ctree(struct super_block *sb,
INIT_LIST_HEAD(&fs_info->caching_block_groups);
spin_lock_init(&fs_info->delalloc_root_lock);
spin_lock_init(&fs_info->trans_lock);
- spin_lock_init(&fs_info->fs_roots_radix_lock);
spin_lock_init(&fs_info->delayed_iput_lock);
spin_lock_init(&fs_info->defrag_inodes_lock);
spin_lock_init(&fs_info->tree_mod_seq_lock);
@@ -3573,10 +3553,7 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
struct btrfs_root *root)
{
- spin_lock(&fs_info->fs_roots_radix_lock);
- radix_tree_delete(&fs_info->fs_roots_radix,
- (unsigned long)root->root_key.objectid);
- spin_unlock(&fs_info->fs_roots_radix_lock);
+ xa_erase(&fs_info->fs_roots, (unsigned long)root->root_key.objectid);

if (btrfs_root_refs(&root->root_item) == 0)
synchronize_srcu(&fs_info->subvol_srcu);
@@ -3632,9 +3609,9 @@ int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info)

while (1) {
index = srcu_read_lock(&fs_info->subvol_srcu);
- ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
- (void **)gang, root_objectid,
- ARRAY_SIZE(gang));
+ ret = xa_extract(&fs_info->fs_roots, (void **)gang,
+ root_objectid, ULONG_MAX, ARRAY_SIZE(gang),
+ XA_PRESENT);
if (!ret) {
srcu_read_unlock(&fs_info->subvol_srcu, index);
break;
diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index d3f25376a0f8..570bce31a301 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -114,7 +114,6 @@ struct btrfs_fs_info *btrfs_alloc_dummy_fs_info(u32 nodesize, u32 sectorsize)
spin_lock_init(&fs_info->qgroup_lock);
spin_lock_init(&fs_info->qgroup_op_lock);
spin_lock_init(&fs_info->super_lock);
- spin_lock_init(&fs_info->fs_roots_radix_lock);
spin_lock_init(&fs_info->tree_mod_seq_lock);
mutex_init(&fs_info->qgroup_ioctl_lock);
mutex_init(&fs_info->qgroup_rescan_lock);
@@ -127,7 +126,7 @@ struct btrfs_fs_info *btrfs_alloc_dummy_fs_info(u32 nodesize, u32 sectorsize)
INIT_LIST_HEAD(&fs_info->dead_roots);
INIT_LIST_HEAD(&fs_info->tree_mod_seq_list);
INIT_RADIX_TREE(&fs_info->buffer_radix, GFP_ATOMIC);
- INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_ATOMIC);
+ xa_init(&fs_info->fs_roots);
extent_io_tree_init(&fs_info->freed_extents[0], NULL);
extent_io_tree_init(&fs_info->freed_extents[1], NULL);
fs_info->pinned_extents = &fs_info->freed_extents[0];
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 5a8c2649af2f..2d6606df0fa3 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -33,7 +33,7 @@
#include "dev-replace.h"
#include "qgroup.h"

-#define BTRFS_ROOT_TRANS_TAG 0
+#define BTRFS_ROOT_TRANS_TAG XA_TAG_0

static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
[TRANS_STATE_RUNNING] = 0U,
@@ -333,15 +333,15 @@ static int record_root_in_trans(struct btrfs_trans_handle *trans,
*/
smp_wmb();

- spin_lock(&fs_info->fs_roots_radix_lock);
+ xa_lock(&fs_info->fs_roots);
if (root->last_trans == trans->transid && !force) {
- spin_unlock(&fs_info->fs_roots_radix_lock);
+ xa_unlock(&fs_info->fs_roots);
return 0;
}
- radix_tree_tag_set(&fs_info->fs_roots_radix,
+ __xa_set_tag(&fs_info->fs_roots,
(unsigned long)root->root_key.objectid,
BTRFS_ROOT_TRANS_TAG);
- spin_unlock(&fs_info->fs_roots_radix_lock);
+ xa_unlock(&fs_info->fs_roots);
root->last_trans = trans->transid;

/* this is pretty tricky. We don't want to
@@ -383,11 +383,8 @@ void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
spin_unlock(&cur_trans->dropped_roots_lock);

/* Make sure we don't try to update the root at commit time */
- spin_lock(&fs_info->fs_roots_radix_lock);
- radix_tree_tag_clear(&fs_info->fs_roots_radix,
- (unsigned long)root->root_key.objectid,
+ xa_clear_tag(&fs_info->fs_roots, (unsigned long)root->root_key.objectid,
BTRFS_ROOT_TRANS_TAG);
- spin_unlock(&fs_info->fs_roots_radix_lock);
}

int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
@@ -1255,53 +1252,41 @@ void btrfs_add_dead_root(struct btrfs_root *root)
static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info)
{
- struct btrfs_root *gang[8];
- int i;
- int ret;
+ struct btrfs_root *root;
+ unsigned long index = 0;
int err = 0;

- spin_lock(&fs_info->fs_roots_radix_lock);
- while (1) {
- ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
- (void **)gang, 0,
- ARRAY_SIZE(gang),
- BTRFS_ROOT_TRANS_TAG);
- if (ret == 0)
- break;
- for (i = 0; i < ret; i++) {
- struct btrfs_root *root = gang[i];
- radix_tree_tag_clear(&fs_info->fs_roots_radix,
- (unsigned long)root->root_key.objectid,
- BTRFS_ROOT_TRANS_TAG);
- spin_unlock(&fs_info->fs_roots_radix_lock);
-
- btrfs_free_log(trans, root);
- btrfs_update_reloc_root(trans, root);
- btrfs_orphan_commit_root(trans, root);
-
- btrfs_save_ino_cache(root, trans);
-
- /* see comments in should_cow_block() */
- clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
- smp_mb__after_atomic();
-
- if (root->commit_root != root->node) {
- list_add_tail(&root->dirty_list,
- &trans->transaction->switch_commits);
- btrfs_set_root_node(&root->root_item,
- root->node);
- }
+ xa_lock(&fs_info->fs_roots);
+ xa_for_each(&fs_info->fs_roots, root, index, ULONG_MAX,
+ BTRFS_ROOT_TRANS_TAG) {
+ __xa_clear_tag(&fs_info->fs_roots, index, BTRFS_ROOT_TRANS_TAG);
+ xa_unlock(&fs_info->fs_roots);

- err = btrfs_update_root(trans, fs_info->tree_root,
- &root->root_key,
- &root->root_item);
- spin_lock(&fs_info->fs_roots_radix_lock);
- if (err)
- break;
- btrfs_qgroup_free_meta_all(root);
+ btrfs_free_log(trans, root);
+ btrfs_update_reloc_root(trans, root);
+ btrfs_orphan_commit_root(trans, root);
+
+ btrfs_save_ino_cache(root, trans);
+
+ /* see comments in should_cow_block() */
+ clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
+ smp_mb__after_atomic();
+
+ if (root->commit_root != root->node) {
+ list_add_tail(&root->dirty_list,
+ &trans->transaction->switch_commits);
+ btrfs_set_root_node(&root->root_item, root->node);
}
+
+ err = btrfs_update_root(trans, fs_info->tree_root,
+ &root->root_key, &root->root_item);
+ xa_lock(&fs_info->fs_roots);
+ if (err)
+ break;
+ btrfs_qgroup_free_meta_all(root);
+ index = 0;
}
- spin_unlock(&fs_info->fs_roots_radix_lock);
+ xa_unlock(&fs_info->fs_roots);
return err;
}

--
2.15.1

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