在 2024/8/13 22:36, Mateusz Guzik 写道:
Most commonly neither I_LRU_ISOLATING nor I_SYNC are set, but the stock
kernel takes a back-to-back relock trip to check for them.
It probably can be avoided altogether, but for now massage things back
to just one lock acquire.
Signed-off-by: Mateusz Guzik <mjguzik@xxxxxxxxx>
---
Reviewed-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
there are smp_mb's in the area I'm going to look at removing at some
point(tm), in the meantime I think this is an easy cleanup
has a side effect of whacking a inode_wait_for_writeback which was only
there to deal with not holding the lock
fs/fs-writeback.c | 17 +++--------------
fs/inode.c | 5 +++--
2 files changed, 6 insertions(+), 16 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 4451ecff37c4..1a5006329f6f 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1510,13 +1510,12 @@ static int write_inode(struct inode *inode, struct writeback_control *wbc)
* Wait for writeback on an inode to complete. Called with i_lock held.
* Caller must make sure inode cannot go away when we drop i_lock.
*/
-static void __inode_wait_for_writeback(struct inode *inode)
- __releases(inode->i_lock)
- __acquires(inode->i_lock)
+void inode_wait_for_writeback(struct inode *inode)
{
DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
wait_queue_head_t *wqh;
+ lockdep_assert_held(&inode->i_lock);
wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
while (inode->i_state & I_SYNC) {
spin_unlock(&inode->i_lock);
@@ -1526,16 +1525,6 @@ static void __inode_wait_for_writeback(struct inode *inode)
}
}
-/*
- * Wait for writeback on an inode to complete. Caller must have inode pinned.
- */
-void inode_wait_for_writeback(struct inode *inode)
-{
- spin_lock(&inode->i_lock);
- __inode_wait_for_writeback(inode);
- spin_unlock(&inode->i_lock);
-}
-
/*
* Sleep until I_SYNC is cleared. This function must be called with i_lock
* held and drops it. It is aimed for callers not holding any inode reference
@@ -1757,7 +1746,7 @@ static int writeback_single_inode(struct inode *inode,
*/
if (wbc->sync_mode != WB_SYNC_ALL)
goto out;
- __inode_wait_for_writeback(inode);
+ inode_wait_for_writeback(inode);
}
WARN_ON(inode->i_state & I_SYNC);
/*
diff --git a/fs/inode.c b/fs/inode.c
index 73183a499b1c..d48d29d39cd2 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -582,7 +582,7 @@ static void inode_unpin_lru_isolating(struct inode *inode)
static void inode_wait_for_lru_isolating(struct inode *inode)
{
- spin_lock(&inode->i_lock);
+ lockdep_assert_held(&inode->i_lock);
if (inode->i_state & I_LRU_ISOLATING) {
DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LRU_ISOLATING);
wait_queue_head_t *wqh;
@@ -593,7 +593,6 @@ static void inode_wait_for_lru_isolating(struct inode *inode)
spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_LRU_ISOLATING);
}
- spin_unlock(&inode->i_lock);
}
/**
@@ -765,6 +764,7 @@ static void evict(struct inode *inode)
inode_sb_list_del(inode);
+ spin_lock(&inode->i_lock);
inode_wait_for_lru_isolating(inode);
/*
@@ -774,6 +774,7 @@ static void evict(struct inode *inode)
* the inode. We just have to wait for running writeback to finish.
*/
inode_wait_for_writeback(inode);
+ spin_unlock(&inode->i_lock);
if (op->evict_inode) {
op->evict_inode(inode);
