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ovl: fix IOCB_DIRECT if underlying fs doesn't support direct IO

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Normally the check at open time suffices, but e.g loop device does set
IOCB_DIRECT after doing its own checks (which are not sufficent for
overlayfs).

Make sure we don't call the underlying filesystem read/write method with
the IOCB_DIRECT if it's not supported.

Reported-by: Huang Jianan <huangjianan@oppo.com>
Fixes: 16914e6fc7 ("ovl: add ovl_read_iter()")
Cc: <stable@vger.kernel.org> # v4.19
Tested-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2021-09-27 11:23:57 +02:00
parent a295aef603
commit 1dc1eed46f
1 changed files with 14 additions and 1 deletions
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15
fs/overlayfs/file.c
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@ -296,6 +296,12 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
if (ret)
return ret;
ret = -EINVAL;
if (iocb->ki_flags & IOCB_DIRECT &&
(!real.file->f_mapping->a_ops ||
!real.file->f_mapping->a_ops->direct_IO))
goto out_fdput;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
if (is_sync_kiocb(iocb)) {
ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
@ -320,7 +326,7 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
out:
revert_creds(old_cred);
ovl_file_accessed(file);
out_fdput:
fdput(real);
return ret;
@ -349,6 +355,12 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
if (ret)
goto out_unlock;
ret = -EINVAL;
if (iocb->ki_flags & IOCB_DIRECT &&
(!real.file->f_mapping->a_ops ||
!real.file->f_mapping->a_ops->direct_IO))
goto out_fdput;
if (!ovl_should_sync(OVL_FS(inode->i_sb)))
ifl &= ~(IOCB_DSYNC | IOCB_SYNC);
@ -384,6 +396,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
}
out:
revert_creds(old_cred);
out_fdput:
fdput(real);
out_unlock: