Commit 7a10f017 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

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: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 640cc189

fs/f2fs/f2fs.h

+1 −0
Original line number Diff line number Diff line
@@ -536,6 +536,7 @@ struct f2fs_inode_info { 
	struct list_head dirty_list;	/* dirty list for dirs and files */

	struct list_head gdirty_list;	/* linked in global dirty list */

	struct list_head inmem_pages;	/* inmemory pages managed by f2fs */

	struct task_struct *inmem_task;	/* store inmemory task */

	struct mutex inmem_lock;	/* lock for inmemory pages */

	struct extent_tree *extent_tree;	/* cached extent_tree entry */

	struct rw_semaphore dio_rwsem[2];/* avoid racing between dio and gc */

fs/f2fs/file.c

+18 −0
Original line number Diff line number Diff line
@@ -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,

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