f2fs: don't give partially written atomic data from process crash
This patch resolves the below scenario.
== Process 1 == == Process 2 ==
open(w) open(rw)
begin
write(new_#1)
process_crash
f_op->flush
locks_remove_posix
f_op>release
read (new_#1)
In order to avoid corrupted database caused by new_#1, we must do roll-back
at process_crash time. In order to check that, this patch keeps task which
triggers transaction begin, and does roll-back in f_op->flush before removing
file locks.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 2706130..75b3fda 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1495,6 +1495,22 @@ static int f2fs_release_file(struct inode *inode, struct file *filp)
return 0;
}
+static int f2fs_file_flush(struct file *file, fl_owner_t id)
+{
+ struct inode *inode = file_inode(file);
+
+ /*
+ * If the process doing a transaction is crashed, we should do
+ * roll-back. Otherwise, other reader/write can see corrupted database
+ * until all the writers close its file. Since this should be done
+ * before dropping file lock, it needs to do in ->flush.
+ */
+ if (f2fs_is_atomic_file(inode) &&
+ F2FS_I(inode)->inmem_task == current)
+ drop_inmem_pages(inode);
+ return 0;
+}
+
#define F2FS_REG_FLMASK (~(FS_DIRSYNC_FL | FS_TOPDIR_FL))
#define F2FS_OTHER_FLMASK (FS_NODUMP_FL | FS_NOATIME_FL)
@@ -1614,6 +1630,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
}
inc_stat:
+ F2FS_I(inode)->inmem_task = current;
stat_inc_atomic_write(inode);
stat_update_max_atomic_write(inode);
out:
@@ -2506,6 +2523,7 @@ const struct file_operations f2fs_file_operations = {
.open = f2fs_file_open,
.release = f2fs_release_file,
.mmap = f2fs_file_mmap,
+ .flush = f2fs_file_flush,
.fsync = f2fs_sync_file,
.fallocate = f2fs_fallocate,
.unlocked_ioctl = f2fs_ioctl,