reada create 2 works for each level of tree in recursion.
In case of a tree having many levels, the number of created works
is 2^level_of_tree.
Actually we don't need so many works in parallel, this patch limit
max works to BTRFS_MAX_MIRRORS * 2.
The works_counter will also used for btrfs_reada_wait() to check
is there exist background workers.
Changelog v1->v2:
Move works_counter from global lobal variable to btrfs_fs_info's
member variable, to avoid too small workers when more than
one FS mounted, noticed by: Chris Mason <clm@xxxxxx>
Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
---
fs/btrfs/ctree.h | 3 +++
fs/btrfs/disk-io.c | 1 +
fs/btrfs/reada.c | 9 ++++++++-
3 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index c5592b1..904ed5c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1822,6 +1822,9 @@ struct btrfs_fs_info {
spinlock_t reada_lock;
struct radix_tree_root reada_tree;
+ /* readahead works cnt */
+ atomic_t reada_works_cnt;
+
/* Extent buffer radix tree */
spinlock_t buffer_lock;
struct radix_tree_root buffer_radix;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1e0693b..4656425 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2602,6 +2602,7 @@ int open_ctree(struct super_block *sb,
atomic_set(&fs_info->nr_async_bios, 0);
atomic_set(&fs_info->defrag_running, 0);
atomic_set(&fs_info->qgroup_op_seq, 0);
+ atomic_set(&fs_info->reada_works_cnt, 0);
atomic64_set(&fs_info->tree_mod_seq, 0);
fs_info->sb = sb;
fs_info->max_inline = BTRFS_DEFAULT_MAX_INLINE;
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 13818d8..245a961 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -748,6 +748,8 @@ static void reada_start_machine_worker(struct btrfs_work *work)
set_task_ioprio(current, BTRFS_IOPRIO_READA);
__reada_start_machine(fs_info);
set_task_ioprio(current, old_ioprio);
+
+ atomic_dec(&fs_info->reada_works_cnt);
}
static void __reada_start_machine(struct btrfs_fs_info *fs_info)
@@ -779,8 +781,12 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info)
* enqueue to workers to finish it. This will distribute the load to
* the cores.
*/
- for (i = 0; i < 2; ++i)
+ for (i = 0; i < 2; ++i) {
reada_start_machine(fs_info);
+ if (atomic_read(&fs_info->reada_works_cnt) >
+ BTRFS_MAX_MIRRORS * 2)
+ break;
+ }
}
static void reada_start_machine(struct btrfs_fs_info *fs_info)
@@ -797,6 +803,7 @@ static void reada_start_machine(struct btrfs_fs_info *fs_info)
rmw->fs_info = fs_info;
btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
+ atomic_inc(&fs_info->reada_works_cnt);
}
#ifdef DEBUG
--
1.8.5.1
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
