[PATCH 16/16] btrfs: btree_writepages lock extents before pages

From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-btrfs@vger.kernel.org
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>,
	Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH 16/16] btrfs: btree_writepages lock extents before pages
Date: Tue, 15 Nov 2022 12:00:34 -0600	[thread overview]
Message-ID: <994c7a74720e3c8589263095704dc7f87cfdb3e7.1668530684.git.rgoldwyn@suse.com> (raw)
In-Reply-To: <cover.1668530684.git.rgoldwyn@suse.com>

Lock extents before pages while performing btree_writepages().

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/btrfs/disk-io.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8ac9612f8f27..b7e7c4c9d404 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -858,8 +858,25 @@ static int btree_migrate_folio(struct address_space *mapping,
 static int btree_writepages(struct address_space *mapping,
 			    struct writeback_control *wbc)
 {
+	u64 start, end;
+	struct btrfs_inode *inode = BTRFS_I(mapping->host);
+        struct extent_state *cached = NULL;
 	struct btrfs_fs_info *fs_info;
 	int ret;
+	u64 isize = round_up(i_size_read(&inode->vfs_inode), PAGE_SIZE) - 1;
+
+	if (wbc->range_cyclic) {
+		start = mapping->writeback_index << PAGE_SHIFT;
+		end = isize;
+	} else {
+		start = round_down(wbc->range_start, PAGE_SIZE);
+		end = round_up(wbc->range_end, PAGE_SIZE) - 1;
+		end = min(isize, end);
+	}
+
+	if (start >= end)
+		return 0;
+
 
 	if (wbc->sync_mode == WB_SYNC_NONE) {
 
@@ -874,7 +891,12 @@ static int btree_writepages(struct address_space *mapping,
 		if (ret < 0)
 			return 0;
 	}
-	return btree_write_cache_pages(mapping, wbc);
+
+	lock_extent(&inode->io_tree, start, end, &cached);
+	ret = btree_write_cache_pages(mapping, wbc);
+	unlock_extent(&inode->io_tree, start, end, &cached);
+
+	return ret;
 }
 
 static bool btree_release_folio(struct folio *folio, gfp_t gfp_flags)
-- 
2.35.3

