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authorAmir Goldstein <amir73il@gmail.com>2018-09-18 16:34:32 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2018-09-24 10:54:01 +0200
commit898cc19d8af2d6a80a9f2804b0db2e83c5dd8863 (patch)
tree771188a58c4632b7615c4bffdffa942b4ed82b22 /fs
parent63e132528032ce937126aba591a7b37ec593a6bb (diff)
downloadlinux-898cc19d8af2d6a80a9f2804b0db2e83c5dd8863.tar.bz2
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 <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/overlayfs/file.c2
1 files changed, 2 insertions, 0 deletions
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 */