[v3,4/4] nfs/super: check NFS_CAP_ACLS instead of the NFS version
diff mbox series

Message ID 20200407142243.2032-4-mk@cm4all.com
State New
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Series
  • [v3,1/4] fs/posix_acl: apply umask if superblock disables ACL support
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Commit Message

Max Kellermann April 7, 2020, 2:22 p.m. UTC
This sets SB_POSIXACL only if ACL support is really enabled, instead
of always setting SB_POSIXACL if the NFS protocol version
theoretically supports ACL.

The code comment says "We will [apply the umask] ourselves", but that
happens in posix_acl_create() only if the kernel has POSIX ACL
support.  Without it, posix_acl_create() is an empty dummy function.

So let's not pretend we will apply the umask if we can already know
that we will never.

This fixes a problem where the umask is always ignored in the NFS
client when compiled without CONFIG_FS_POSIX_ACL.  This is a 4 year
old regression caused by commit 013cdf1088d723 which itself was not
completely wrong, but failed to consider all the side effects by
misdesigned VFS code.

Signed-off-by: Max Kellermann <mk@cm4all.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Cc: stable@vger.kernel.org
---
 fs/nfs/super.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Christoph Hellwig April 17, 2020, 7:53 a.m. UTC | #1
On Tue, Apr 07, 2020 at 04:22:43PM +0200, Max Kellermann wrote:
> This sets SB_POSIXACL only if ACL support is really enabled, instead
> of always setting SB_POSIXACL if the NFS protocol version
> theoretically supports ACL.
> 
> The code comment says "We will [apply the umask] ourselves", but that
> happens in posix_acl_create() only if the kernel has POSIX ACL
> support.  Without it, posix_acl_create() is an empty dummy function.
> 
> So let's not pretend we will apply the umask if we can already know
> that we will never.
> 
> This fixes a problem where the umask is always ignored in the NFS
> client when compiled without CONFIG_FS_POSIX_ACL.  This is a 4 year
> old regression caused by commit 013cdf1088d723 which itself was not
> completely wrong, but failed to consider all the side effects by
> misdesigned VFS code.
> 
> Signed-off-by: Max Kellermann <mk@cm4all.com>
> Reviewed-by: J. Bruce Fields <bfields@redhat.com>
> Cc: stable@vger.kernel.org
> ---
>  fs/nfs/super.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index dada09b391c6..dab79193f641 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -977,11 +977,14 @@ static void nfs_fill_super(struct super_block *sb, struct nfs_fs_context *ctx)
>  	if (ctx && ctx->bsize)
>  		sb->s_blocksize = nfs_block_size(ctx->bsize, &sb->s_blocksize_bits);
>  
> -	if (server->nfs_client->rpc_ops->version != 2) {
> +	if (NFS_SB(sb)->caps & NFS_CAP_ACLS) {
>  		/* The VFS shouldn't apply the umask to mode bits. We will do
>  		 * so ourselves when necessary.
>  		 */
>  		sb->s_flags |= SB_POSIXACL;
> +	}

Looks good, but I'd use the opportunity to also fix up the commen to be
a little less cryptic:

	/*
	 * If the server supports ACLs, the VFS shouldn't apply the umask to
	 * the mode bits as we'll do it ourselves when necessary.
	 */
	if (NFS_SB(sb)->caps & NFS_CAP_ACLS)
		sb->s_flags |= SB_POSIXACL;

Patch
diff mbox series

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index dada09b391c6..dab79193f641 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -977,11 +977,14 @@  static void nfs_fill_super(struct super_block *sb, struct nfs_fs_context *ctx)
 	if (ctx && ctx->bsize)
 		sb->s_blocksize = nfs_block_size(ctx->bsize, &sb->s_blocksize_bits);
 
-	if (server->nfs_client->rpc_ops->version != 2) {
+	if (NFS_SB(sb)->caps & NFS_CAP_ACLS) {
 		/* The VFS shouldn't apply the umask to mode bits. We will do
 		 * so ourselves when necessary.
 		 */
 		sb->s_flags |= SB_POSIXACL;
+	}
+
+	if (server->nfs_client->rpc_ops->version != 2) {
 		sb->s_time_gran = 1;
 		sb->s_export_op = &nfs_export_ops;
 	} else