The fill_zero() from fallocate() calls get_new_data_page() in which calls
reserve_new_block().
The reserve_new_block() should be covered by *DATA_NEW*, one of global locks.
And also, before getting the lock, we should check free sections by calling
f2fs_balance_fs().
If we break this rule, f2fs is able to face with out-of-control free space
management and fall into infinite loop like the following scenario as well.
[f2fs_sync_fs()] [fallocate()]
- write_checkpoint() - fill_zero()
- block_operations() - get_new_data_page()
: grab NODE_NEW - get_dnode_of_data()
: get locked dirty node page
- sync_node_pages()
: try to grab NODE_NEW for data allocation
: trylock and skip the dirty node page
: call sync_node_pages() repeatedly in order to flush all the dirty node
pages!
In order to avoid this, we should grab another global lock such as DATA_NEW
before calling get_new_data_page() in fill_zero().
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
---
fs/f2fs/file.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 3191b52..6cdab2c 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -387,12 +387,17 @@ const struct inode_operations f2fs_file_inode_operations = {
static void fill_zero(struct inode *inode, pgoff_t index,
loff_t start, loff_t len)
{
+ struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
struct page *page;
if (!len)
return;
+ f2fs_balance_fs(sbi);
+
+ mutex_lock_op(sbi, DATA_NEW);
page = get_new_data_page(inode, index, false);
+ mutex_unlock_op(sbi, DATA_NEW);
if (!IS_ERR(page)) {
wait_on_page_writeback(page);
--
1.8.0.1.250.gb7973fb
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