Re: [PATCH 3/9] xfs: increase number of ACL entries for V5 superblocks

From: Brian Foster <bfoster@redhat.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 3/9] xfs: increase number of ACL entries for V5 superblocks
Date: Wed, 29 May 2013 12:40:50 -0400	[thread overview]
Message-ID: <51A62F92.8060506@redhat.com> (raw)
In-Reply-To: <1369636707-15150-4-git-send-email-david@fromorbit.com>

On 05/27/2013 02:38 AM, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> The limit of 25 ACL entries is arbitrary, but baked into the on-disk
> format.  For version 5 superblocks, increase it to the maximum nuber
> of ACLs that can fit into a single xattr.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  fs/xfs/xfs_acl.c |   31 ++++++++++++++++++-------------
>  fs/xfs/xfs_acl.h |   30 +++++++++++++++++++++++-------
>  2 files changed, 41 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
> index 1d32f1d..b6bed9b 100644
> --- a/fs/xfs/xfs_acl.c
> +++ b/fs/xfs/xfs_acl.c
> @@ -21,6 +21,8 @@
>  #include "xfs_bmap_btree.h"
>  #include "xfs_inode.h"
>  #include "xfs_vnodeops.h"
> +#include "xfs_sb.h"
> +#include "xfs_mount.h"
>  #include "xfs_trace.h"
>  #include <linux/slab.h>
>  #include <linux/xattr.h>
> @@ -34,7 +36,9 @@
>   */
>  
>  STATIC struct posix_acl *
> -xfs_acl_from_disk(struct xfs_acl *aclp)
> +xfs_acl_from_disk(
> +	struct xfs_acl	*aclp,
> +	int		max_entries)
>  {
>  	struct posix_acl_entry *acl_e;
>  	struct posix_acl *acl;
> @@ -42,7 +46,7 @@ xfs_acl_from_disk(struct xfs_acl *aclp)
>  	unsigned int count, i;
>  
>  	count = be32_to_cpu(aclp->acl_cnt);
> -	if (count > XFS_ACL_MAX_ENTRIES)
> +	if (count > max_entries)
>  		return ERR_PTR(-EFSCORRUPTED);
>  
>  	acl = posix_acl_alloc(count, GFP_KERNEL);
> @@ -108,7 +112,7 @@ xfs_get_acl(struct inode *inode, int type)
>  	struct xfs_inode *ip = XFS_I(inode);
>  	struct posix_acl *acl;
>  	struct xfs_acl *xfs_acl;
> -	int len = sizeof(struct xfs_acl);
> +	int len = XFS_ACL_SIZE(ip->i_mount);
>  	unsigned char *ea_name;
>  	int error;
>  
> @@ -133,8 +137,8 @@ xfs_get_acl(struct inode *inode, int type)
>  	 * If we have a cached ACLs value just return it, not need to
>  	 * go out to the disk.
>  	 */
> -
> -	xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
> +	len = XFS_ACL_SIZE(ip->i_mount);

Duplicate initialization of len. Harmless (perhaps Ben can drop it) and
the parens in XFS_ACL_MAX_ENTRIES() are fixed, so:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> +	xfs_acl = kzalloc(len, GFP_KERNEL);
>  	if (!xfs_acl)
>  		return ERR_PTR(-ENOMEM);
>  
> @@ -153,7 +157,7 @@ xfs_get_acl(struct inode *inode, int type)
>  		goto out;
>  	}
>  
> -	acl = xfs_acl_from_disk(xfs_acl);
> +	acl = xfs_acl_from_disk(xfs_acl, XFS_ACL_MAX_ENTRIES(ip->i_mount));
>  	if (IS_ERR(acl))
>  		goto out;
>  
> @@ -189,16 +193,17 @@ xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
>  
>  	if (acl) {
>  		struct xfs_acl *xfs_acl;
> -		int len;
> +		int len = XFS_ACL_SIZE(ip->i_mount);
>  
> -		xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
> +		xfs_acl = kzalloc(len, GFP_KERNEL);
>  		if (!xfs_acl)
>  			return -ENOMEM;
>  
>  		xfs_acl_to_disk(xfs_acl, acl);
> -		len = sizeof(struct xfs_acl) -
> -			(sizeof(struct xfs_acl_entry) *
> -			 (XFS_ACL_MAX_ENTRIES - acl->a_count));
> +
> +		/* subtract away the unused acl entries */
> +		len -= sizeof(struct xfs_acl_entry) *
> +			 (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
>  
>  		error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
>  				len, ATTR_ROOT);
> @@ -243,7 +248,7 @@ xfs_set_mode(struct inode *inode, umode_t mode)
>  static int
>  xfs_acl_exists(struct inode *inode, unsigned char *name)
>  {
> -	int len = sizeof(struct xfs_acl);
> +	int len = XFS_ACL_SIZE(XFS_M(inode->i_sb));
>  
>  	return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
>  			    ATTR_ROOT|ATTR_KERNOVAL) == 0);
> @@ -379,7 +384,7 @@ xfs_xattr_acl_set(struct dentry *dentry, const char *name,
>  		goto out_release;
>  
>  	error = -EINVAL;
> -	if (acl->a_count > XFS_ACL_MAX_ENTRIES)
> +	if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
>  		goto out_release;
>  
>  	if (type == ACL_TYPE_ACCESS) {
> diff --git a/fs/xfs/xfs_acl.h b/fs/xfs/xfs_acl.h
> index 39632d9..0da8725 100644
> --- a/fs/xfs/xfs_acl.h
> +++ b/fs/xfs/xfs_acl.h
> @@ -22,19 +22,35 @@ struct inode;
>  struct posix_acl;
>  struct xfs_inode;
>  
> -#define XFS_ACL_MAX_ENTRIES 25
>  #define XFS_ACL_NOT_PRESENT (-1)
>  
>  /* On-disk XFS access control list structure */
> +struct xfs_acl_entry {
> +	__be32	ae_tag;
> +	__be32	ae_id;
> +	__be16	ae_perm;
> +	__be16	ae_pad;		/* fill the implicit hole in the structure */
> +};
> +
>  struct xfs_acl {
> -	__be32		acl_cnt;
> -	struct xfs_acl_entry {
> -		__be32	ae_tag;
> -		__be32	ae_id;
> -		__be16	ae_perm;
> -	} acl_entry[XFS_ACL_MAX_ENTRIES];
> +	__be32			acl_cnt;
> +	struct xfs_acl_entry	acl_entry[0];
>  };
>  
> +/*
> + * The number of ACL entries allowed is defined by the on-disk format.
> + * For v4 superblocks, that is limited to 25 entries. For v5 superblocks, it is
> + * limited only by the maximum size of the xattr that stores the information.
> + */
> +#define XFS_ACL_MAX_ENTRIES(mp)	\
> +	(xfs_sb_version_hascrc(&mp->m_sb) \
> +	   ?  (XATTR_SIZE_MAX - sizeof(__be32)) / sizeof(struct xfs_acl_entry) \
> +	   : 25)
> +
> +#define XFS_ACL_SIZE(mp) \
> +	(sizeof(struct xfs_acl) + \
> +		sizeof(struct xfs_acl_entry) * XFS_ACL_MAX_ENTRIES((mp)))
> +
>  /* On-disk XFS extended attribute names */
>  #define SGI_ACL_FILE		(unsigned char *)"SGI_ACL_FILE"
>  #define SGI_ACL_DEFAULT		(unsigned char *)"SGI_ACL_DEFAULT"
> 

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