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FAILED: patch "[PATCH] ovl: fix IOCB_DIRECT if underlying fs doesn't support direct" failed to apply to 5.4-stable tree

PATCH [email protected] 1 participant 1 message Oct 9, 2021

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Stable branch Overlay filesystem
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#0 lore raw

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1dc1eed46f9fa4cb8a07baa24fb44c96d6dd35c9 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <[email protected]>
Date: Mon, 27 Sep 2021 11:23:57 +0200
Subject: [PATCH] ovl: fix IOCB_DIRECT if underlying fs doesn't support direct
IO

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 <[email protected]>
Fixes 16914e6fc7e1 ("ovl: add ovl_read_iter()")
Cc <[email protected]> # v4.19
Tested-by Huang Jianan <[email protected]>
Signed-off-by Miklos Szeredi <[email protected]>
fs/overlayfs/file.c +14 -1
index d081faa55e83..c88ac571593d 100644
@@ -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: