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-rw-r--r--fs/fs-writeback.c139
-rw-r--r--fs/kernfs/dir.c23
2 files changed, 66 insertions, 96 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index ae0f438c2ee6..24489126f8ca 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -53,8 +53,6 @@ struct wb_writeback_work {
unsigned int for_background:1;
unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
unsigned int auto_free:1; /* free on completion */
- unsigned int single_wait:1;
- unsigned int single_done:1;
enum wb_reason reason; /* why was writeback initiated? */
struct list_head list; /* pending work list */
@@ -178,14 +176,11 @@ static void wb_wakeup(struct bdi_writeback *wb)
static void wb_queue_work(struct bdi_writeback *wb,
struct wb_writeback_work *work)
{
- trace_writeback_queue(wb->bdi, work);
+ trace_writeback_queue(wb, work);
spin_lock_bh(&wb->work_lock);
- if (!test_bit(WB_registered, &wb->state)) {
- if (work->single_wait)
- work->single_done = 1;
+ if (!test_bit(WB_registered, &wb->state))
goto out_unlock;
- }
if (work->done)
atomic_inc(&work->done->cnt);
list_add_tail(&work->list, &wb->work_list);
@@ -706,7 +701,7 @@ EXPORT_SYMBOL_GPL(wbc_account_io);
/**
* inode_congested - test whether an inode is congested
- * @inode: inode to test for congestion
+ * @inode: inode to test for congestion (may be NULL)
* @cong_bits: mask of WB_[a]sync_congested bits to test
*
* Tests whether @inode is congested. @cong_bits is the mask of congestion
@@ -716,6 +711,9 @@ EXPORT_SYMBOL_GPL(wbc_account_io);
* determined by whether the cgwb (cgroup bdi_writeback) for the blkcg
* associated with @inode is congested; otherwise, the root wb's congestion
* state is used.
+ *
+ * @inode is allowed to be NULL as this function is often called on
+ * mapping->host which is NULL for the swapper space.
*/
int inode_congested(struct inode *inode, int cong_bits)
{
@@ -738,32 +736,6 @@ int inode_congested(struct inode *inode, int cong_bits)
EXPORT_SYMBOL_GPL(inode_congested);
/**
- * wb_wait_for_single_work - wait for completion of a single bdi_writeback_work
- * @bdi: bdi the work item was issued to
- * @work: work item to wait for
- *
- * Wait for the completion of @work which was issued to one of @bdi's
- * bdi_writeback's. The caller must have set @work->single_wait before
- * issuing it. This wait operates independently fo
- * wb_wait_for_completion() and also disables automatic freeing of @work.
- */
-static void wb_wait_for_single_work(struct backing_dev_info *bdi,
- struct wb_writeback_work *work)
-{
- if (WARN_ON_ONCE(!work->single_wait))
- return;
-
- wait_event(bdi->wb_waitq, work->single_done);
-
- /*
- * Paired with smp_wmb() in wb_do_writeback() and ensures that all
- * modifications to @work prior to assertion of ->single_done is
- * visible to the caller once this function returns.
- */
- smp_rmb();
-}
-
-/**
* wb_split_bdi_pages - split nr_pages to write according to bandwidth
* @wb: target bdi_writeback to split @nr_pages to
* @nr_pages: number of pages to write for the whole bdi
@@ -792,38 +764,6 @@ static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages)
}
/**
- * wb_clone_and_queue_work - clone a wb_writeback_work and issue it to a wb
- * @wb: target bdi_writeback
- * @base_work: source wb_writeback_work
- *
- * Try to make a clone of @base_work and issue it to @wb. If cloning
- * succeeds, %true is returned; otherwise, @base_work is issued directly
- * and %false is returned. In the latter case, the caller is required to
- * wait for @base_work's completion using wb_wait_for_single_work().
- *
- * A clone is auto-freed on completion. @base_work never is.
- */
-static bool wb_clone_and_queue_work(struct bdi_writeback *wb,
- struct wb_writeback_work *base_work)
-{
- struct wb_writeback_work *work;
-
- work = kmalloc(sizeof(*work), GFP_ATOMIC);
- if (work) {
- *work = *base_work;
- work->auto_free = 1;
- work->single_wait = 0;
- } else {
- work = base_work;
- work->auto_free = 0;
- work->single_wait = 1;
- }
- work->single_done = 0;
- wb_queue_work(wb, work);
- return work != base_work;
-}
-
-/**
* bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi
* @bdi: target backing_dev_info
* @base_work: wb_writeback_work to issue
@@ -838,15 +778,19 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
struct wb_writeback_work *base_work,
bool skip_if_busy)
{
- long nr_pages = base_work->nr_pages;
- int next_blkcg_id = 0;
+ int next_memcg_id = 0;
struct bdi_writeback *wb;
struct wb_iter iter;
might_sleep();
restart:
rcu_read_lock();
- bdi_for_each_wb(wb, bdi, &iter, next_blkcg_id) {
+ bdi_for_each_wb(wb, bdi, &iter, next_memcg_id) {
+ DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done);
+ struct wb_writeback_work fallback_work;
+ struct wb_writeback_work *work;
+ long nr_pages;
+
/* SYNC_ALL writes out I_DIRTY_TIME too */
if (!wb_has_dirty_io(wb) &&
(base_work->sync_mode == WB_SYNC_NONE ||
@@ -855,13 +799,30 @@ restart:
if (skip_if_busy && writeback_in_progress(wb))
continue;
- base_work->nr_pages = wb_split_bdi_pages(wb, nr_pages);
- if (!wb_clone_and_queue_work(wb, base_work)) {
- next_blkcg_id = wb->blkcg_css->id + 1;
- rcu_read_unlock();
- wb_wait_for_single_work(bdi, base_work);
- goto restart;
+ nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages);
+
+ work = kmalloc(sizeof(*work), GFP_ATOMIC);
+ if (work) {
+ *work = *base_work;
+ work->nr_pages = nr_pages;
+ work->auto_free = 1;
+ wb_queue_work(wb, work);
+ continue;
}
+
+ /* alloc failed, execute synchronously using on-stack fallback */
+ work = &fallback_work;
+ *work = *base_work;
+ work->nr_pages = nr_pages;
+ work->auto_free = 0;
+ work->done = &fallback_work_done;
+
+ wb_queue_work(wb, work);
+
+ next_memcg_id = wb->memcg_css->id + 1;
+ rcu_read_unlock();
+ wb_wait_for_completion(bdi, &fallback_work_done);
+ goto restart;
}
rcu_read_unlock();
}
@@ -902,8 +863,6 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) {
base_work->auto_free = 0;
- base_work->single_wait = 0;
- base_work->single_done = 0;
wb_queue_work(&bdi->wb, base_work);
}
}
@@ -924,7 +883,7 @@ void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
*/
work = kzalloc(sizeof(*work), GFP_ATOMIC);
if (!work) {
- trace_writeback_nowork(wb->bdi);
+ trace_writeback_nowork(wb);
wb_wakeup(wb);
return;
}
@@ -954,7 +913,7 @@ void wb_start_background_writeback(struct bdi_writeback *wb)
* We just wake up the flusher thread. It will perform background
* writeback as soon as there is no other work to do.
*/
- trace_writeback_wake_background(wb->bdi);
+ trace_writeback_wake_background(wb);
wb_wakeup(wb);
}
@@ -1660,14 +1619,14 @@ static long wb_writeback(struct bdi_writeback *wb,
} else if (work->for_background)
oldest_jif = jiffies;
- trace_writeback_start(wb->bdi, work);
+ trace_writeback_start(wb, work);
if (list_empty(&wb->b_io))
queue_io(wb, work);
if (work->sb)
progress = writeback_sb_inodes(work->sb, wb, work);
else
progress = __writeback_inodes_wb(wb, work);
- trace_writeback_written(wb->bdi, work);
+ trace_writeback_written(wb, work);
wb_update_bandwidth(wb, wb_start);
@@ -1692,7 +1651,7 @@ static long wb_writeback(struct bdi_writeback *wb,
* we'll just busyloop.
*/
if (!list_empty(&wb->b_more_io)) {
- trace_writeback_wait(wb->bdi, work);
+ trace_writeback_wait(wb, work);
inode = wb_inode(wb->b_more_io.prev);
spin_lock(&inode->i_lock);
spin_unlock(&wb->list_lock);
@@ -1797,26 +1756,14 @@ static long wb_do_writeback(struct bdi_writeback *wb)
set_bit(WB_writeback_running, &wb->state);
while ((work = get_next_work_item(wb)) != NULL) {
struct wb_completion *done = work->done;
- bool need_wake_up = false;
- trace_writeback_exec(wb->bdi, work);
+ trace_writeback_exec(wb, work);
wrote += wb_writeback(wb, work);
- if (work->single_wait) {
- WARN_ON_ONCE(work->auto_free);
- /* paired w/ rmb in wb_wait_for_single_work() */
- smp_wmb();
- work->single_done = 1;
- need_wake_up = true;
- } else if (work->auto_free) {
+ if (work->auto_free)
kfree(work);
- }
-
if (done && atomic_dec_and_test(&done->cnt))
- need_wake_up = true;
-
- if (need_wake_up)
wake_up_all(&wb->bdi->wb_waitq);
}
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 2d48d28e1640..91e004518237 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -92,6 +92,29 @@ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
}
/**
+ * kernfs_path_len - determine the length of the full path of a given node
+ * @kn: kernfs_node of interest
+ *
+ * The returned length doesn't include the space for the terminating '\0'.
+ */
+size_t kernfs_path_len(struct kernfs_node *kn)
+{
+ size_t len = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&kernfs_rename_lock, flags);
+
+ do {
+ len += strlen(kn->name) + 1;
+ kn = kn->parent;
+ } while (kn && kn->parent);
+
+ spin_unlock_irqrestore(&kernfs_rename_lock, flags);
+
+ return len;
+}
+
+/**
* kernfs_path - build full path of a given node
* @kn: kernfs_node of interest
* @buf: buffer to copy @kn's name into
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.