aio: fix freeze protection of aio writes

Currently we dropped freeze protection of aio writes just after IO was submitted. Thus aio write could be in flight while the filesystem was frozen and that could result in unexpected situation like aio completion wanting to convert extent type on frozen filesystem. Testcase from Dmitry triggering this is like: for ((i=0;i<60;i++));do fsfreeze -f /mnt ;sleep 1;fsfreeze -u /mnt;done & fio --bs=4k --ioengine=libaio --iodepth=128 --size=1g --direct=1 \ --runtime=60 --filename=/mnt/file --name=rand-write --rw=randwrite Fix the problem by dropping freeze protection only once IO is completed in aio_complete().

Jan Kara committed 10 years ago

Commit 70fe2f41 parent 89319d32 files · +19 −1Browse files

Unified · Split

2 files

fs/aio.c +18 −1
include/linux/fs.h +1 −0

fs/aio.c+18−1

@@ -1078,6 +1078,17 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2) · 1077 unmodified lines
1078	1078	unsigned tail, pos, head;
1079	1079	unsigned long flags;
1080	1080
	1081	+ if (kiocb->ki_flags & IOCB_WRITE) {
	1082	+ struct file *file = kiocb->ki_filp;
	1083	+
	1084	+ /*
	1085	+ * Tell lockdep we inherited freeze protection from submission
	1086	+ * thread.
	1087	+ */
	1088	+ __sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE);
	1089	+ file_end_write(file);
	1090	+ }
	1091	+
1081	1092	/*
1082	1093	* Special case handling for sync iocbs:
1083	1094	* - events go directly into the iocb for fast handling
@@ -1473,9 +1484,15 @@ static ssize_t aio_write(struct kiocb req, struct iocb iocb, bool vectored, · 389 unmodified lines
1473	1484	return ret;
1474	1485	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1475	1486	if (!ret) {
	1487	+ req->ki_flags \|= IOCB_WRITE;
1476	1488	file_start_write(file);
1477	1489	ret = aio_ret(req, file->f_op->write_iter(req, &iter));
1478		− file_end_write(file);
	1490	+ /*
	1491	+ * We release freeze protection in aio_complete(). Fool lockdep
	1492	+ * by telling it the lock got released so that it doesn't
	1493	+ * complain about held lock when we return to userspace.
	1494	+ */
	1495	+ __sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
1479	1496	}
1480	1497	kfree(iovec);
1481	1498	return ret;

include/linux/fs.h+1−0

@@ -321,6 +321,7 @@ struct writeback_control; · 320 unmodified lines
321	321	#define IOCB_HIPRI (1 << 3)
322	322	#define IOCB_DSYNC (1 << 4)
323	323	#define IOCB_SYNC (1 << 5)
	324	+#define IOCB_WRITE (1 << 6)
324	325
325	326	struct kiocb {
326	327	struct file *ki_filp;