path: root/fs
diff options
authorNamjae Jeon <namjae.jeon@samsung.com>2013-01-15 16:45:24 +0900
committerJaegeuk Kim <jaegeuk.kim@samsung.com>2013-01-15 20:18:16 +0900
commitfa9150a84ca333f68127097c4fa1eda4b3913a22 (patch)
tree6c84c6494b03c59f599f07bf28866b54119d30c9 /fs
parent163799872b65b0cbf0091d82971233cc3d2425d3 (diff)
f2fs: remove the blk_plug usage in f2fs_write_data_pages
Let's consider the usage of blk_plug in f2fs_write_data_pages(). We can come up with the two issues: lock contention and task awareness. 1. Merging bios prior to grabing "queue lock" The f2fs merges consecutive IOs in the file system level before submitting any bios, which is similar with the back merge by the plugging mechanism in attempt_plug_merge(). Both of them need to acquire no queue lock. 2. Merging policy with respect to tasks The f2fs merges IOs as much as possible regardless of tasks, while blk-plugging is conducted on a basis of tasks. As we can understand there are trade-offs, f2fs tries to maximize the write performance with well-merged bios. As a result, if f2fs produces many consecutive but separated bios in writepages(), it would be good to use blk-plugging since f2fs would be able to avoid queue lock contention in the block layer by merging them. But, f2fs merges IOs and submit one bio, which means that there are not much chances to merge bios by attempt_plug_merge(). However, f2fs has already been used blk_plug by triggering generic_writepages() in f2fs_write_data_pages(). So to make the overall code consistency, I'd like to remove blk_plug there. Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Diffstat (limited to 'fs')
1 files changed, 10 insertions, 1 deletions
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 3aa5ce7cab8..b1347fc6d68 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -547,6 +547,15 @@ redirty_out:
+static int __f2fs_writepage(struct page *page, struct writeback_control *wbc,
+ void *data)
+ struct address_space *mapping = data;
+ int ret = mapping->a_ops->writepage(page, wbc);
+ mapping_set_error(mapping, ret);
+ return ret;
static int f2fs_write_data_pages(struct address_space *mapping,
struct writeback_control *wbc)
@@ -563,7 +572,7 @@ static int f2fs_write_data_pages(struct address_space *mapping,
if (!S_ISDIR(inode->i_mode))
- ret = generic_writepages(mapping, wbc);
+ ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
if (!S_ISDIR(inode->i_mode))
f2fs_submit_bio(sbi, DATA, (wbc->sync_mode == WB_SYNC_ALL));