[PATCH] add vfs_* helpers for xattr operations

Add vfs_getxattr, vfs_setxattr and vfs_removexattr helpers for common checks
around invocation of the xattr methods.  NFSD already was missing some of the
checks and there will be more soon.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: James Morris <jmorris@namei.org>

(James, I haven't touched selinux yet because it's doing various odd things
and I'm not sure how it would interact with the security attribute fallbacks
you added.  Could you investigate whether it could use vfs_getxattr or if not
add a __vfs_getxattr helper to share the bits it is fine with?)

For NFSv4: instead of just converting it add an nfsd_getxattr helper for the
code shared by NFSv2/3 and NFSv4 ACLs.  In fact that code isn't even
NFS-specific, but I'll wait for more users to pop up first before moving it to
common code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 48 insertions, 77 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index bb36b4304491..eef0576a7785 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -48,8 +48,8 @@
 #include <linux/fsnotify.h>
 #include <linux/posix_acl.h>
 #include <linux/posix_acl_xattr.h>
-#ifdef CONFIG_NFSD_V4
 #include <linux/xattr.h>
+#ifdef CONFIG_NFSD_V4
 #include <linux/nfs4.h>
 #include <linux/nfs4_acl.h>
 #include <linux/nfsd_idmap.h>
@@ -365,8 +365,30 @@ out_nfserr:
         goto out;
 }
 
-#if defined(CONFIG_NFSD_V4)
+#if defined(CONFIG_NFSD_V2_ACL) || \
+    defined(CONFIG_NFSD_V3_ACL) || \
+    defined(CONFIG_NFSD_V4)
+static ssize_t nfsd_getxattr(struct dentry *dentry, char *key, void **buf)
+{
+        ssize_t buflen;
+        int error;
+
+        buflen = vfs_getxattr(dentry, key, NULL, 0);
+        if (buflen <= 0)
+                return buflen;
 
+        *buf = kmalloc(buflen, GFP_KERNEL);
+        if (!*buf)
+                return -ENOMEM;
+
+        error = vfs_getxattr(dentry, key, *buf, buflen);
+        if (error < 0)
+                return error;
+        return buflen;
+}
+#endif
+
+#if defined(CONFIG_NFSD_V4)
 static int
 set_nfsv4_acl_one(struct dentry *dentry, struct posix_acl *pacl, char *key)
 {
@@ -374,7 +396,6 @@ set_nfsv4_acl_one(struct dentry *dentry, struct posix_acl *pacl, char *key)
         size_t buflen;
         char *buf = NULL;
         int error = 0;
-        struct inode *inode = dentry->d_inode;
 
         buflen = posix_acl_xattr_size(pacl->a_count);
         buf = kmalloc(buflen, GFP_KERNEL);
@@ -388,15 +409,7 @@ set_nfsv4_acl_one(struct dentry *dentry, struct posix_acl *pacl, char *key)
                 goto out;
         }
 
-        error = -EOPNOTSUPP;
-        if (inode->i_op && inode->i_op->setxattr) {
-                mutex_lock(&inode->i_mutex);
-                security_inode_setxattr(dentry, key, buf, len, 0);
-                error = inode->i_op->setxattr(dentry, key, buf, len, 0);
-                if (!error)
-                        security_inode_post_setxattr(dentry, key, buf, len, 0);
-                mutex_unlock(&inode->i_mutex);
-        }
+        error = vfs_setxattr(dentry, key, buf, len, 0);
 out:
         kfree(buf);
         return error;
@@ -455,44 +468,19 @@ out_nfserr:
 static struct posix_acl *
 _get_posix_acl(struct dentry *dentry, char *key)
 {
-        struct inode *inode = dentry->d_inode;
-        char *buf = NULL;
-        int buflen, error = 0;
+        void *buf = NULL;
         struct posix_acl *pacl = NULL;
+        int buflen;
 
-        error = -EOPNOTSUPP;
-        if (inode->i_op == NULL)
-                goto out_err;
-        if (inode->i_op->getxattr == NULL)
-                goto out_err;
-
-        error = security_inode_getxattr(dentry, key);
-        if (error)
-                goto out_err;
-
-        buflen = inode->i_op->getxattr(dentry, key, NULL, 0);
-        if (buflen <= 0) {
-                error = buflen < 0 ? buflen : -ENODATA;
-                goto out_err;
-        }
-
-        buf = kmalloc(buflen, GFP_KERNEL);
-        if (buf == NULL) {
-                error = -ENOMEM;
-                goto out_err;
-        }
-
-        error = inode->i_op->getxattr(dentry, key, buf, buflen);
-        if (error < 0)
-                goto out_err;
+        buflen = nfsd_getxattr(dentry, key, &buf);
+        if (!buflen)
+                buflen = -ENODATA;
+        if (buflen <= 0)
+                return ERR_PTR(buflen);
 
         pacl = posix_acl_from_xattr(buf, buflen);
- out:
         kfree(buf);
         return pacl;
- out_err:
-        pacl = ERR_PTR(error);
-        goto out;
 }
 
 int
@@ -1884,39 +1872,25 @@ nfsd_get_posix_acl(struct svc_fh *fhp, int type)
         ssize_t size;
         struct posix_acl *acl;
 
-        if (!IS_POSIXACL(inode) || !inode->i_op || !inode->i_op->getxattr)
+        if (!IS_POSIXACL(inode))
+                return ERR_PTR(-EOPNOTSUPP);
+
+        switch (type) {
+        case ACL_TYPE_ACCESS:
+                name = POSIX_ACL_XATTR_ACCESS;
+                break;
+        case ACL_TYPE_DEFAULT:
+                name = POSIX_ACL_XATTR_DEFAULT;
+                break;
+        default:
                 return ERR_PTR(-EOPNOTSUPP);
-        switch(type) {
-                case ACL_TYPE_ACCESS:
-                        name = POSIX_ACL_XATTR_ACCESS;
-                        break;
-                case ACL_TYPE_DEFAULT:
-                        name = POSIX_ACL_XATTR_DEFAULT;
-                        break;
-                default:
-                        return ERR_PTR(-EOPNOTSUPP);
         }
 
-        size = inode->i_op->getxattr(fhp->fh_dentry, name, NULL, 0);
+        size = nfsd_getxattr(fhp->fh_dentry, name, &value);
+        if (size < 0)
+                return ERR_PTR(size);
 
-        if (size < 0) {
-                acl = ERR_PTR(size);
-                goto getout;
-        } else if (size > 0) {
-                value = kmalloc(size, GFP_KERNEL);
-                if (!value) {
-                        acl = ERR_PTR(-ENOMEM);
-                        goto getout;
-                }
-                size = inode->i_op->getxattr(fhp->fh_dentry, name, value, size);
-                if (size < 0) {
-                        acl = ERR_PTR(size);
-                        goto getout;
-                }
-        }
         acl = posix_acl_from_xattr(value, size);
-
-getout:
         kfree(value);
         return acl;
 }
@@ -1957,16 +1931,13 @@ nfsd_set_posix_acl(struct svc_fh *fhp, int type, struct posix_acl *acl)
         } else
                 size = 0;
 
-        if (!fhp->fh_locked)
-                fh_lock(fhp);  /* unlocking is done automatically */
         if (size)
-                error = inode->i_op->setxattr(fhp->fh_dentry, name,
-                                              value, size, 0);
+                error = vfs_setxattr(fhp->fh_dentry, name, value, size, 0);
         else {
                 if (!S_ISDIR(inode->i_mode) && type == ACL_TYPE_DEFAULT)
                         error = 0;
                 else {
-                        error = inode->i_op->removexattr(fhp->fh_dentry, name);
+                        error = vfs_removexattr(fhp->fh_dentry, name);
                         if (error == -ENODATA)
                                 error = 0;
                 }