vfs: Add IOP_XATTR inode operations flag

The IOP_XATTR inode operations flag in inode->i_opflags indicates that
the inode has xattr support.  The flag is automatically set by
new_inode() on filesystems with xattr support (where sb->s_xattr is
defined), and cleared otherwise.  Filesystems can explicitly clear it
for inodes that should not have xattr support.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 11 insertions, 4 deletions

diff --git a/fs/inode.c b/fs/inode.c
index 7e3ef3af3db9..705f8609fdb8 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -140,6 +140,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
         inode->i_fop = &no_open_fops;
         inode->__i_nlink = 1;
         inode->i_opflags = 0;
+        if (sb->s_xattr)
+                inode->i_opflags |= IOP_XATTR;
         i_uid_write(inode, 0);
         i_gid_write(inode, 0);
         atomic_set(&inode->i_writecount, 0);
diff --git a/fs/xattr.c b/fs/xattr.c
index bb3cbbfd982d..38b52a356d1b 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -53,10 +53,13 @@ strcmp_prefix(const char *a, const char *a_prefix)
  * Find the xattr_handler with the matching prefix.
  */
 static const struct xattr_handler *
-xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
+xattr_resolve_name(struct inode *inode, const char **name)
 {
+        const struct xattr_handler **handlers = inode->i_sb->s_xattr;
         const struct xattr_handler *handler;
 
+        if (!(inode->i_opflags & IOP_XATTR))
+                return ERR_PTR(-EOPNOTSUPP);
         for_each_xattr_handler(handlers, handler) {
                 const char *n;
 
@@ -298,6 +301,7 @@ nolsm:
                 error = -EOPNOTSUPP;
 
         return error;
+
 }
 EXPORT_SYMBOL_GPL(vfs_getxattr);
 
@@ -700,7 +704,7 @@ generic_getxattr(struct dentry *dentry, struct inode *inode,
 {
         const struct xattr_handler *handler;
 
-        handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
+        handler = xattr_resolve_name(inode, &name);
         if (IS_ERR(handler))
                 return PTR_ERR(handler);
         return handler->get(handler, dentry, inode,
@@ -755,7 +759,7 @@ generic_setxattr(struct dentry *dentry, struct inode *inode, const char *name,
 
         if (size == 0)
                 value = "";  /* empty EA, do not remove */
-        handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
+        handler = xattr_resolve_name(inode, &name);
         if (IS_ERR(handler))
                 return PTR_ERR(handler);
         return handler->set(handler, dentry, inode, name, value, size, flags);
@@ -770,7 +774,7 @@ generic_removexattr(struct dentry *dentry, const char *name)
 {
         const struct xattr_handler *handler;
 
-        handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
+        handler = xattr_resolve_name(d_inode(dentry), &name);
         if (IS_ERR(handler))
                 return PTR_ERR(handler);
         return handler->set(handler, dentry, d_inode(dentry), name, NULL,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7540e872591a..91a7245e58c7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -591,6 +591,7 @@ is_uncached_acl(struct posix_acl *acl)
 #define IOP_FASTPERM    0x0001
 #define IOP_LOOKUP      0x0002
 #define IOP_NOFOLLOW    0x0004
+#define IOP_XATTR       0x0008
 
 /*
  * Keep mostly read-only and often accessed (especially for