[PATCH 44/62] xfs: Convert m_perag_tree to XArray

Matthew Wilcox
2017-11-22T21:12:53Z

Getting rid of the m_perag_lock lets us also get rid of the call to
radix_tree_preload(). This is a relatively naive conversion; we could
improve performance over the radix tree implementation by passing around
xa_state pointers instead of indices, possibly at the expense of extending
rcu_read_lock() periods.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
fs/xfs/libxfs/xfs_sb.c | 9 ++++-----
fs/xfs/xfs_icache.c | 35 +++++++++--------------------------
fs/xfs/xfs_icache.h | 6 +++---
fs/xfs/xfs_mount.c | 19 ++++---------------
fs/xfs/xfs_mount.h | 3 +--
5 files changed, 21 insertions(+), 51 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 9b5aae2bcc0b..811fa57007c9 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -59,7 +59,7 @@ xfs_perag_get(
int ref = 0;

rcu_read_lock();
- pag = radix_tree_lookup(&mp->m_perag_tree, agno);
+ pag = xa_load(&mp->m_perag_xa, agno);
if (pag) {
ASSERT(atomic_read(&pag->pag_ref) >= 0);
ref = atomic_inc_return(&pag->pag_ref);
@@ -78,14 +78,13 @@ xfs_perag_get_tag(
xfs_agnumber_t first,
int tag)
{
+ XA_STATE(xas, first);
struct xfs_perag *pag;
- int found;
int ref;

rcu_read_lock();
- found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
- (void **)&pag, first, 1, tag);
- if (found <= 0) {
+ pag = xas_find_tag(&mp->m_perag_xa, &xas, ULONG_MAX, tag);
+ if (!pag) {
rcu_read_unlock();
return NULL;
}
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 43005fbe8b1e..f56e500d89e2 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -156,13 +156,10 @@ static void
xfs_reclaim_work_queue(
struct xfs_mount *mp)
{
-
- rcu_read_lock();
- if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+ if (xa_tagged(&mp->m_perag_xa, XFS_ICI_RECLAIM_TAG)) {
queue_delayed_work(mp->m_reclaim_workqueue, &mp->m_reclaim_work,
msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10));
}
- rcu_read_unlock();
}

/*
@@ -194,10 +191,7 @@ xfs_perag_set_reclaim_tag(
return;

/* propagate the reclaim tag up into the perag radix tree */
- spin_lock(&mp->m_perag_lock);
- radix_tree_tag_set(&mp->m_perag_tree, pag->pag_agno,
- XFS_ICI_RECLAIM_TAG);
- spin_unlock(&mp->m_perag_lock);
+ xa_set_tag(&mp->m_perag_xa, pag->pag_agno, XFS_ICI_RECLAIM_TAG);

/* schedule periodic background inode reclaim */
xfs_reclaim_work_queue(mp);
@@ -216,10 +210,7 @@ xfs_perag_clear_reclaim_tag(
return;

/* clear the reclaim tag from the perag radix tree */
- spin_lock(&mp->m_perag_lock);
- radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno,
- XFS_ICI_RECLAIM_TAG);
- spin_unlock(&mp->m_perag_lock);
+ xa_clear_tag(&mp->m_perag_xa, pag->pag_agno, XFS_ICI_RECLAIM_TAG);
trace_xfs_perag_clear_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
}

@@ -847,12 +838,10 @@ void
xfs_queue_eofblocks(
struct xfs_mount *mp)
{
- rcu_read_lock();
- if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_EOFBLOCKS_TAG))
+ if (xa_tagged(&mp->m_perag_xa, XFS_ICI_EOFBLOCKS_TAG))
queue_delayed_work(mp->m_eofblocks_workqueue,
&mp->m_eofblocks_work,
msecs_to_jiffies(xfs_eofb_secs * 1000));
- rcu_read_unlock();
}

void
@@ -874,12 +863,10 @@ STATIC void
xfs_queue_cowblocks(
struct xfs_mount *mp)
{
- rcu_read_lock();
- if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_COWBLOCKS_TAG))
+ if (xa_tagged(&mp->m_perag_xa, XFS_ICI_COWBLOCKS_TAG))
queue_delayed_work(mp->m_eofblocks_workqueue,
&mp->m_cowblocks_work,
msecs_to_jiffies(xfs_cowb_secs * 1000));
- rcu_read_unlock();
}

void
@@ -1542,7 +1529,7 @@ __xfs_inode_set_eofblocks_tag(
void (*execute)(struct xfs_mount *mp),
void (*set_tp)(struct xfs_mount *mp, xfs_agnumber_t agno,
int error, unsigned long caller_ip),
- int tag)
+ xa_tag_t tag)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_perag *pag;
@@ -1566,11 +1553,9 @@ __xfs_inode_set_eofblocks_tag(
XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino), tag);
if (!tagged) {
/* propagate the eofblocks tag up into the perag radix tree */
- spin_lock(&ip->i_mount->m_perag_lock);
- radix_tree_tag_set(&ip->i_mount->m_perag_tree,
+ xa_set_tag(&ip->i_mount->m_perag_xa,
XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
tag);
- spin_unlock(&ip->i_mount->m_perag_lock);

/* kick off background trimming */
execute(ip->i_mount);
@@ -1597,7 +1582,7 @@ __xfs_inode_clear_eofblocks_tag(
xfs_inode_t *ip,
void (*clear_tp)(struct xfs_mount *mp, xfs_agnumber_t agno,
int error, unsigned long caller_ip),
- int tag)
+ xa_tag_t tag)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_perag *pag;
@@ -1613,11 +1598,9 @@ __xfs_inode_clear_eofblocks_tag(
XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino), tag);
if (!radix_tree_tagged(&pag->pag_ici_root, tag)) {
/* clear the eofblocks tag from the perag radix tree */
- spin_lock(&ip->i_mount->m_perag_lock);
- radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
+ xa_clear_tag(&ip->i_mount->m_perag_xa,
XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
tag);
- spin_unlock(&ip->i_mount->m_perag_lock);
clear_tp(ip->i_mount, pag->pag_agno, -1, _RET_IP_);
}

diff --git a/fs/xfs/xfs_icache.h b/fs/xfs/xfs_icache.h
index bff4d85e5498..bd04d5adadfe 100644
--- a/fs/xfs/xfs_icache.h
+++ b/fs/xfs/xfs_icache.h
@@ -37,9 +37,9 @@ struct xfs_eofblocks {
*/
#define XFS_ICI_NO_TAG (-1) /* special flag for an untagged lookup
in xfs_inode_ag_iterator */
-#define XFS_ICI_RECLAIM_TAG 0 /* inode is to be reclaimed */
-#define XFS_ICI_EOFBLOCKS_TAG 1 /* inode has blocks beyond EOF */
-#define XFS_ICI_COWBLOCKS_TAG 2 /* inode can have cow blocks to gc */
+#define XFS_ICI_RECLAIM_TAG XA_TAG_0 /* inode is to be reclaimed */
+#define XFS_ICI_EOFBLOCKS_TAG XA_TAG_1 /* inode has blocks beyond EOF */
+#define XFS_ICI_COWBLOCKS_TAG XA_TAG_2 /* inode can have cow blocks to gc */

/*
* Flags for xfs_iget()
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index c879b517cc94..ae90f6f8fa5c 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -156,9 +156,7 @@ xfs_free_perag(
struct xfs_perag *pag;

for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
- spin_lock(&mp->m_perag_lock);
- pag = radix_tree_delete(&mp->m_perag_tree, agno);
- spin_unlock(&mp->m_perag_lock);
+ pag = xa_store(&mp->m_perag_xa, agno, NULL, GFP_NOWAIT);
ASSERT(pag);
ASSERT(atomic_read(&pag->pag_ref) == 0);
xfs_buf_hash_destroy(pag);
@@ -219,19 +217,11 @@ xfs_initialize_perag(
goto out_free_pag;
init_waitqueue_head(&pag->pagb_wait);

- if (radix_tree_preload(GFP_NOFS))
- goto out_hash_destroy;
-
- spin_lock(&mp->m_perag_lock);
- if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
+ if (xa_store(&mp->m_perag_xa, index, pag, GFP_NOFS)) {
BUG();
- spin_unlock(&mp->m_perag_lock);
- radix_tree_preload_end();
error = -EEXIST;
goto out_hash_destroy;
}
- spin_unlock(&mp->m_perag_lock);
- radix_tree_preload_end();
/* first new pag is fully initialized */
if (first_initialised == NULLAGNUMBER)
first_initialised = index;
@@ -252,7 +242,7 @@ xfs_initialize_perag(
out_unwind_new_pags:
/* unwind any prior newly initialized pags */
for (index = first_initialised; index < agcount; index++) {
- pag = radix_tree_delete(&mp->m_perag_tree, index);
+ pag = xa_store(&mp->m_perag_xa, index, NULL, GFP_NOWAIT);
if (!pag)
break;
xfs_buf_hash_destroy(pag);
@@ -816,8 +806,7 @@ xfs_mountfs(
/*
* Allocate and initialize the per-ag data.
*/
- spin_lock_init(&mp->m_perag_lock);
- INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
+ xa_init(&mp->m_perag_xa);
error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
if (error) {
xfs_warn(mp, "Failed per-ag init: %d", error);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index e0792d036be2..6e5ad7b26f46 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -134,8 +134,7 @@ typedef struct xfs_mount {
xfs_extlen_t m_ag_prealloc_blocks; /* reserved ag blocks */
uint m_alloc_set_aside; /* space we can't use */
uint m_ag_max_usable; /* max space per AG */
- struct radix_tree_root m_perag_tree; /* per-ag accounting info */
- spinlock_t m_perag_lock; /* lock for m_perag_tree */
+ struct xarray m_perag_xa; /* per-ag accounting info */
struct mutex m_growlock; /* growfs mutex */
int m_fixedfsid[2]; /* unchanged for life of FS */
uint m_dmevmask; /* DMI events for this FS */
--
2.15.0