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Subject[PATCH] f2fs: fix to wait IO writeback in __revoke_inmem_pages()
Date
Thread A				Thread B
- f2fs_ioc_commit_atomic_write
- commit_inmem_pages
- f2fs_submit_merged_write_cond
: write data
- write_checkpoint
- do_checkpoint
: commit all node within CP
-> SPO
- f2fs_do_sync_file
- file_write_and_wait_range
: wait data writeback

In above race condition, data/node can be flushed in reversed order when
coming a checkpoint before f2fs_do_sync_file, after SPOR, it results in
atomic written data being corrupted.

This patch adds f2fs_wait_on_page_writeback in __revoke_inmem_pages() to
keep data and node of atomic file being flushed orderly.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/file.c | 4 ++++
fs/f2fs/segment.c | 3 +++
2 files changed, 7 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index be7578774a47..a352804af244 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -217,6 +217,9 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,

trace_f2fs_sync_file_enter(inode);

+ if (atomic)
+ goto write_done;
+
/* if fdatasync is triggered, let's do in-place-update */
if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks)
set_inode_flag(inode, FI_NEED_IPU);
@@ -228,6 +231,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
return ret;
}

+write_done:
/* if the inode is dirty, let's recover all the time */
if (!f2fs_skip_inode_update(inode, datasync)) {
f2fs_write_inode(inode, NULL);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 584483426584..9ca3d0a43d93 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -230,6 +230,8 @@ static int __revoke_inmem_pages(struct inode *inode,

lock_page(page);

+ f2fs_wait_on_page_writeback(page, DATA, true);
+
if (recover) {
struct dnode_of_data dn;
struct node_info ni;
@@ -415,6 +417,7 @@ static int __commit_inmem_pages(struct inode *inode)
/* drop all uncommitted pages */
__revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
} else {
+ /* wait all committed IOs writeback and release them from list */
__revoke_inmem_pages(inode, &revoke_list, false, false);
}

--
2.15.0.55.gc2ece9dc4de6
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