From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH 2/4] ovl: fix freeze protection bypass in ovl_write_iter()
Date: Tue, 18 Sep 2018 16:34:32 +0300 [thread overview]
Message-ID: <20180918133434.27437-3-amir73il@gmail.com> (raw)
In-Reply-To: <20180918133434.27437-1-amir73il@gmail.com>
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 <amir73il@gmail.com>
---
fs/overlayfs/file.c | 2 ++
1 file changed, 2 insertions(+)
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 */
--
2.17.1
next prev parent reply other threads:[~2018-09-18 19:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-18 13:34 [PATCH 0/4] Assorted overlayfs fixes for 4.19-rc5 Amir Goldstein
2018-09-18 13:34 ` [PATCH 1/4] ovl: fix memory leak on unlink of indexed file Amir Goldstein
2018-09-18 13:59 ` Greg KH
2018-09-18 15:14 ` Amir Goldstein
2018-09-18 13:34 ` Amir Goldstein [this message]
2018-09-18 13:34 ` [PATCH 3/4] ovl: fix freeze protection bypass in ovl_clone_file_range() Amir Goldstein
2018-09-18 13:34 ` [PATCH 4/4] vfs: swap names of {do,vfs}_clone_file_range() Amir Goldstein
2018-09-24 8:25 ` [PATCH 0/4] Assorted overlayfs fixes for 4.19-rc5 Amir Goldstein
2018-09-24 8:56 ` Miklos Szeredi
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