From 70fe2f48152e60664809e2fed76bbb50c9fa2aa3 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Sun, 30 Oct 2016 11:42:04 -0500 Subject: [PATCH] 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(). Reported-by: Dmitry Monakhov Signed-off-by: Jan Kara [hch: forward ported on top of various VFS and aio changes] Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- fs/aio.c | 19 ++++++++++++++++++- include/linux/fs.h | 1 + 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/fs/aio.c b/fs/aio.c index c19755187ca5..428484f2f841 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1078,6 +1078,17 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2) unsigned tail, pos, head; unsigned long flags; + if (kiocb->ki_flags & IOCB_WRITE) { + struct file *file = kiocb->ki_filp; + + /* + * Tell lockdep we inherited freeze protection from submission + * thread. + */ + __sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE); + file_end_write(file); + } + /* * Special case handling for sync iocbs: * - 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, return ret; ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter)); if (!ret) { + req->ki_flags |= IOCB_WRITE; file_start_write(file); ret = aio_ret(req, file->f_op->write_iter(req, &iter)); - file_end_write(file); + /* + * We release freeze protection in aio_complete(). Fool lockdep + * by telling it the lock got released so that it doesn't + * complain about held lock when we return to userspace. + */ + __sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE); } kfree(iovec); return ret; diff --git a/include/linux/fs.h b/include/linux/fs.h index ff7bcd9e8398..dc0478c07b2a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -321,6 +321,7 @@ struct writeback_control; #define IOCB_HIPRI (1 << 3) #define IOCB_DSYNC (1 << 4) #define IOCB_SYNC (1 << 5) +#define IOCB_WRITE (1 << 6) struct kiocb { struct file *ki_filp;