Re: [PATCH] f2fs: provide f2fs_balance_fs to __write_data_page for dentry pages

From: Yunlong Song
Date: Tue Aug 01 2017 - 02:10:54 EST

Hi Jay,
The SBI_BLOCK_OPS can not cover all the case, once SBI_BLOCK_OPS is set, all the normal writeback
(before the SBI_BLOCK_OPS is clear) of dentry pages which do not come from write_checkpoint flow will
totally miss all the f2fs_balance_fs check.

On 2017/8/1 8:44, Jaegeuk Kim wrote:
Hi Yunlong,

On 07/29, Yunlong Song wrote:
f2fs_balance_fs of dentry pages is skipped in __write_data_page due to deadlock
of gc_mutex in write_checkpoint flow. This patch enables f2fs_balance_fs for
normal dentry page writeback to ensure there are always enough free segments.
So, how about adding SBI_BLOCK_OPS

/* For s_flag in struct f2fs_sb_info */
enum {
SBI_IS_DIRTY, /* dirty flag for checkpoint */
SBI_IS_CLOSE, /* specify unmounting */
SBI_NEED_FSCK, /* need fsck.f2fs to fix */
SBI_POR_DOING, /* recovery is doing or not */
SBI_NEED_SB_WRITE, /* need to recover superblock */
SBI_NEED_CP, /* need to checkpoint */
===
SBI_BLOCK_OPS, /* doing block_operations */
===
};

How aboud avoiding f2fs_balance_fs() in __write_data_page() by:

if (!is_sbi_flag_set(sbi, SBI_BLOCK_OPS) || !S_ISDIR(inode->i_mode))
f2fs_balance_fs();

In block_operations(),
set_sbi_flag(sbi, SBI_BLOCK_OPS);
...
clear_sbi_flag(sbi, SBI_BLOCK_OPS);

Thanks,

Reported-by: Chao Yu <yuchao0@xxxxxxxxxx>
Signed-off-by: Yunlong Song <yunlong.song@xxxxxxxxxx>
---
fs/f2fs/checkpoint.c | 2 +-
fs/f2fs/data.c | 67 +++++++++++++++++++++++++++++++++++++++++++++-------
fs/f2fs/f2fs.h | 1 +
3 files changed, 61 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 3c84a25..2882878 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -904,7 +904,7 @@ int sync_dirty_inodes(struct f2fs_sb_info *sbi, enum inode_type type)
if (inode) {
unsigned long cur_ino = inode->i_ino;
- filemap_fdatawrite(inode->i_mapping);
+ f2fs_filemap_fdatawrite(inode->i_mapping, is_dir);
iput(inode);
/* We need to give cpu to another writers. */
if (ino == cur_ino) {
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index aefc2a5..ed7efa5 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1475,7 +1475,7 @@ int do_write_data_page(struct f2fs_io_info *fio)
}
static int __write_data_page(struct page *page, bool *submitted,
- struct writeback_control *wbc)
+ struct writeback_control *wbc, bool do_balance)
{
struct inode *inode = page->mapping->host;
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
@@ -1578,7 +1578,7 @@ static int __write_data_page(struct page *page, bool *submitted,
}
unlock_page(page);
- if (!S_ISDIR(inode->i_mode))
+ if (do_balance)
f2fs_balance_fs(sbi, need_balance_fs);
if (unlikely(f2fs_cp_error(sbi))) {
@@ -1602,7 +1602,7 @@ static int __write_data_page(struct page *page, bool *submitted,
static int f2fs_write_data_page(struct page *page,
struct writeback_control *wbc)
{
- return __write_data_page(page, NULL, wbc);
+ return __write_data_page(page, NULL, wbc, true);
}
/*
@@ -1611,7 +1611,7 @@ static int f2fs_write_data_page(struct page *page,
* warm/hot data page.
*/
static int f2fs_write_cache_pages(struct address_space *mapping,
- struct writeback_control *wbc)
+ struct writeback_control *wbc, bool do_balance)
{
int ret = 0;
int done = 0;
@@ -1701,7 +1701,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
if (!clear_page_dirty_for_io(page))
goto continue_unlock;
- ret = __write_data_page(page, &submitted, wbc);
+ ret = __write_data_page(page, &submitted, wbc, do_balance);
if (unlikely(ret)) {
/*
* keep nr_to_write, since vfs uses this to
@@ -1756,8 +1756,8 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
return ret;
}
-static int f2fs_write_data_pages(struct address_space *mapping,
- struct writeback_control *wbc)
+static int _f2fs_write_data_pages(struct address_space *mapping,
+ struct writeback_control *wbc, bool do_balance)
{
struct inode *inode = mapping->host;
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
@@ -1794,7 +1794,7 @@ static int f2fs_write_data_pages(struct address_space *mapping,
goto skip_write;
blk_start_plug(&plug);
- ret = f2fs_write_cache_pages(mapping, wbc);
+ ret = f2fs_write_cache_pages(mapping, wbc, do_balance);
blk_finish_plug(&plug);
if (wbc->sync_mode == WB_SYNC_ALL)
@@ -1813,6 +1813,57 @@ static int f2fs_write_data_pages(struct address_space *mapping,
return 0;
}
+static int f2fs_write_data_pages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ return _f2fs_write_data_pages(mapping, wbc, true);
+}
+
+/*
+ * This function was copied from do_writepages from mm/page-writeback.c.
+ * The major change is changing writepages to _f2fs_write_data_pages.
+ */
+static int f2fs_do_writepages(struct address_space *mapping,
+ struct writeback_control *wbc, bool is_dir)
+{
+ int ret;
+
+ if (wbc->nr_to_write <= 0)
+ return 0;
+ while (1) {
+ ret = _f2fs_write_data_pages(mapping, wbc, !is_dir);
+ if ((ret != -ENOMEM) || (wbc->sync_mode != WB_SYNC_ALL))
+ break;
+ cond_resched();
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
+ }
+ return ret;
+}
+
+/*
+ * This function was copied from __filemap_fdatawrite_range from
+ * mm/filemap.c. The major change is changing do_writepages to
+ * f2fs_do_writepages.
+ */
+int f2fs_filemap_fdatawrite(struct address_space *mapping, bool is_dir)
+{
+ int ret;
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_ALL,
+ .nr_to_write = LONG_MAX,
+ .range_start = 0,
+ .range_end = LLONG_MAX,
+ };
+
+ if (!mapping_cap_writeback_dirty(mapping))
+ return 0;
+
+ wbc_attach_fdatawrite_inode(&wbc, mapping->host);
+ ret = f2fs_do_writepages(mapping, &wbc, is_dir);
+ wbc_detach_inode(&wbc);
+ return ret;
+}
+
static void f2fs_write_failed(struct address_space *mapping, loff_t to)
{
struct inode *inode = mapping->host;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9280283..ea9bebb 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2572,6 +2572,7 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset,
int f2fs_migrate_page(struct address_space *mapping, struct page *newpage,
struct page *page, enum migrate_mode mode);
#endif
+int f2fs_filemap_fdatawrite(struct address_space *mapping, bool is_dir);
/*
* gc.c
--
1.8.5.2
.


--
Thanks,
Yunlong Song