From 898cc19d8af2d6a80a9f2804b0db2e83c5dd8863 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Tue, 18 Sep 2018 16:34:32 +0300 Subject: ovl: fix freeze protection bypass in ovl_write_iter() Tested by re-writing to an open overlayfs file while upper ext4 is frozen: xfs_io -f /ovl/x xfs_io> pwrite 0 4096 fsfreeze -f /ext4 xfs_io> pwrite 0 4096 WARNING: CPU: 0 PID: 1492 at fs/ext4/ext4_jbd2.c:53 \ ext4_journal_check_start+0x48/0x82 After the fix, the second write blocks in ovl_write_iter() and avoids hitting WARN_ON(sb->s_writers.frozen == SB_FREEZE_COMPLETE) in ext4_journal_check_start(). Fixes: 2a92e07edc5e ("ovl: add ovl_write_iter()") Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/file.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/overlayfs') diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index aeaefd2a551b..986313da0c88 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -240,8 +240,10 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) goto out_unlock; old_cred = ovl_override_creds(file_inode(file)->i_sb); + file_start_write(real.file); ret = vfs_iter_write(real.file, iter, &iocb->ki_pos, ovl_iocb_to_rwf(iocb)); + file_end_write(real.file); revert_creds(old_cred); /* Update size */ -- cgit v1.2.3