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[PATCH 11/11] xfs: increase number of ACL entries for V5 superblocks

To: xfs@xxxxxxxxxxx
Subject: [PATCH 11/11] xfs: increase number of ACL entries for V5 superblocks
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 21 May 2013 18:02:10 +1000
Cc: bpm@xxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1369123330-9579-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1369123330-9579-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

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@xxxxxxxxxx>
---
 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);
+       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..5310a52 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"
-- 
1.7.10.4

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