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f2fs: don't give partially written atomic data from process crash

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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>
This commit is contained in:
Jaegeuk Kim 2017-07-24 19:46:29 -07:00
parent 640cc18982
commit 7a10f0177e
2 changed files with 19 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
fs/f2fs/f2fs.h
View file

@ -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 */

18
fs/f2fs/file.c
View file

@ -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,