From cb7ab02156e4ba999df90e9fa8e96107683586fd Mon Sep 17 00:00:00 2001
From: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Date: Wed, 4 Dec 2013 21:16:53 +0800
Subject: [PATCH] Btrfs: wrap repeated code into scrub_blocked_if_needed()
Just wrap same code into one function scrub_blocked_if_needed().
This make a change that we will move waiting (@workers_pending = 0)
before we can wake up commiting transaction(atomic_inc(@scrub_paused)),
we must take carefully to not deadlock here.
Thread 1 Thread 2
|->btrfs_commit_transaction()
|->set trans type(COMMIT_DOING)
|->btrfs_scrub_paused()(blocked)
|->join_transaction(blocked)
Move btrfs_scrub_paused() before setting trans type which means we can
still join a transaction when commiting_transaction is blocked.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Suggested-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
---
fs/btrfs/scrub.c | 43 +++++++++++++++++-------------------------
fs/btrfs/transaction.c | 3 ++-
2 files changed, 19 insertions(+), 27 deletions(-)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 6acb573e7d6b..adebe12e497e 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -256,6 +256,7 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
int mirror_num, u64 physical_for_dev_replace);
static void copy_nocow_pages_worker(struct btrfs_work *work);
+static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info);
@@ -270,7 +271,7 @@ static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
wake_up(&sctx->list_wait);
}
-static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
+static void __scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
{
while (atomic_read(&fs_info->scrub_pause_req)) {
mutex_unlock(&fs_info->scrub_lock);
@@ -280,6 +281,19 @@ static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
}
}
+static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
+{
+ atomic_inc(&fs_info->scrubs_paused);
+ wake_up(&fs_info->scrub_pause_wait);
+
+ mutex_lock(&fs_info->scrub_lock);
+ __scrub_blocked_if_needed(fs_info);
+ atomic_dec(&fs_info->scrubs_paused);
+ mutex_unlock(&fs_info->scrub_lock);
+
+ wake_up(&fs_info->scrub_pause_wait);
+}
+
/*
* used for workers that require transaction commits (i.e., for the
* NOCOW case)
@@ -2295,8 +2309,7 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
wait_event(sctx->list_wait,
atomic_read(&sctx->bios_in_flight) == 0);
- atomic_inc(&fs_info->scrubs_paused);
- wake_up(&fs_info->scrub_pause_wait);
+ scrub_blocked_if_needed(fs_info);
/* FIXME it might be better to start readahead at commit root */
key_start.objectid = logical;
@@ -2320,12 +2333,6 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
if (!IS_ERR(reada2))
btrfs_reada_wait(reada2);
- mutex_lock(&fs_info->scrub_lock);
- scrub_blocked_if_needed(fs_info);
- atomic_dec(&fs_info->scrubs_paused);
- mutex_unlock(&fs_info->scrub_lock);
-
- wake_up(&fs_info->scrub_pause_wait);
/*
* collect all data csums for the stripe to avoid seeking during
@@ -2362,15 +2369,7 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
wait_event(sctx->list_wait,
atomic_read(&sctx->bios_in_flight) == 0);
atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
- atomic_inc(&fs_info->scrubs_paused);
- wake_up(&fs_info->scrub_pause_wait);
-
- mutex_lock(&fs_info->scrub_lock);
scrub_blocked_if_needed(fs_info);
- atomic_dec(&fs_info->scrubs_paused);
- mutex_unlock(&fs_info->scrub_lock);
-
- wake_up(&fs_info->scrub_pause_wait);
}
key.objectid = logical;
@@ -2685,17 +2684,9 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
wait_event(sctx->list_wait,
atomic_read(&sctx->bios_in_flight) == 0);
atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
- atomic_inc(&fs_info->scrubs_paused);
- wake_up(&fs_info->scrub_pause_wait);
wait_event(sctx->list_wait,
atomic_read(&sctx->workers_pending) == 0);
-
- mutex_lock(&fs_info->scrub_lock);
scrub_blocked_if_needed(fs_info);
- atomic_dec(&fs_info->scrubs_paused);
- mutex_unlock(&fs_info->scrub_lock);
-
- wake_up(&fs_info->scrub_pause_wait);
btrfs_put_block_group(cache);
if (ret)
@@ -2912,7 +2903,7 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
* checking @scrub_pause_req here, we can avoid
* race between committing transaction and scrubbing.
*/
- scrub_blocked_if_needed(fs_info);
+ __scrub_blocked_if_needed(fs_info);
atomic_inc(&fs_info->scrubs_running);
mutex_unlock(&fs_info->scrub_lock);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 14516375777e..026f1fea963e 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1748,6 +1748,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
goto cleanup_transaction;
btrfs_wait_delalloc_flush(root->fs_info);
+
+ btrfs_scrub_pause(root);
/*
* Ok now we need to make sure to block out any other joins while we
* commit the transaction. We could have started a join before setting
@@ -1812,7 +1814,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
WARN_ON(cur_trans != trans->transaction);
- btrfs_scrub_pause(root);
/* btrfs_commit_tree_roots is responsible for getting the
* various roots consistent with each other. Every pointer
* in the tree of tree roots has to point to the most up to date
--
2.42.0