From: Nikolay Borisov <nborisov@suse.com>
To: linux-btrfs@vger.kernel.org
Cc: Nikolay Borisov <nborisov@suse.com>
Subject: [PATCH 7/7] btrfs: Refactor shrink_delalloc
Date: Thu, 3 Jan 2019 10:50:05 +0200 [thread overview]
Message-ID: <20190103085005.32053-8-nborisov@suse.com> (raw)
In-Reply-To: <20190103085005.32053-1-nborisov@suse.com>
Add a couple of comments regarding the logic flow in shrink_delalloc.
Then, cease using max_reclaim as a temporary variable when calculating
nr_pages. Finally give max_reclaim a more becoming name, which
uneqivocally shows at what this variable really holds. No functional
changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
fs/btrfs/extent-tree.c | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b15afeae16df..615441f4d458 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4743,7 +4743,7 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info, u64 to_reclaim,
struct btrfs_space_info *space_info;
struct btrfs_trans_handle *trans;
u64 delalloc_bytes;
- u64 max_reclaim;
+ u64 async_pages;
u64 items;
long time_left;
unsigned long nr_pages;
@@ -4768,25 +4768,36 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info, u64 to_reclaim,
loops = 0;
while (delalloc_bytes && loops < 3) {
- max_reclaim = min(delalloc_bytes, to_reclaim);
- nr_pages = max_reclaim >> PAGE_SHIFT;
+ nr_pages = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
+
+ /*
+ * Triggers inode writeback for up to nr_pages. This will invoke
+ * ->writepages callback and trigger delalloc filling
+ * (btrfs_run_delalloc_range()).
+ */
btrfs_writeback_inodes_sb_nr(fs_info, nr_pages, items);
+
/*
- * We need to wait for the async pages to actually start before
- * we do anything.
+ * We need to wait for the compressed pages to start before
+ * we continue.
*/
- max_reclaim = atomic_read(&fs_info->async_delalloc_pages);
- if (!max_reclaim)
+ async_pages = atomic_read(&fs_info->async_delalloc_pages);
+ if (!async_pages)
goto skip_async;
- if (max_reclaim <= nr_pages)
- max_reclaim = 0;
+ /*
+ * Calculate how many compressed pages we want to be written
+ * before we continue. I.e if there are more async pages than we
+ * require wait_event will wait until nr_pages are written.
+ */
+ if (async_pages <= nr_pages)
+ async_pages = 0;
else
- max_reclaim -= nr_pages;
+ async_pages -= nr_pages;
wait_event(fs_info->async_submit_wait,
atomic_read(&fs_info->async_delalloc_pages) <=
- (int)max_reclaim);
+ (int)async_pages);
skip_async:
spin_lock(&space_info->lock);
if (list_empty(&space_info->tickets) &&
--
2.17.1
next prev parent reply other threads:[~2019-01-03 8:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-03 8:49 [PATCH 0/7] More misc fixes Nikolay Borisov
2019-01-03 8:49 ` [PATCH 1/7] btrfs: Remove inode argument from async_cow_submit Nikolay Borisov
2019-01-05 6:02 ` Anand Jain
2019-01-07 10:12 ` Johannes Thumshirn
2019-01-03 8:50 ` [PATCH 2/7] btrfs: Remove isize local variable in compress_file_range Nikolay Borisov
2019-01-05 6:17 ` Anand Jain
2019-01-07 10:17 ` Johannes Thumshirn
2019-01-07 17:41 ` David Sterba
2019-01-03 8:50 ` [PATCH 3/7] btrfs: Use ihold instead of igrab in cow_file_range_async Nikolay Borisov
2019-01-04 15:29 ` David Sterba
2019-01-03 8:50 ` [PATCH 4/7] btrfs: Remove WARN_ON in btrfs_alloc_delalloc_work Nikolay Borisov
2019-01-04 15:30 ` David Sterba
2019-01-07 10:19 ` Johannes Thumshirn
2019-01-03 8:50 ` [PATCH 5/7] btrfs: Document logic in async_cow_submit Nikolay Borisov
2019-01-03 8:50 ` [PATCH 6/7] btrfs: Replace open-coded maths with DIV_ROUND_UP Nikolay Borisov
2019-01-03 14:44 ` David Sterba
2019-01-03 15:33 ` Nikolay Borisov
2019-01-07 15:29 ` David Sterba
2019-01-03 8:50 ` Nikolay Borisov [this message]
2019-01-04 15:35 ` [PATCH 7/7] btrfs: Refactor shrink_delalloc David Sterba
2019-01-07 17:58 ` David Sterba
2019-01-07 17:59 ` [PATCH 0/7] More misc fixes David Sterba
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