1 files changed, 51 insertions, 33 deletions

diff --git a/fs/attr.c b/fs/attr.c
index 0815e93bb487..7ca41811afa1 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -14,35 +14,53 @@
 #include <linux/fcntl.h>
 #include <linux/security.h>
 
-/* Taken over from the old code... */
-
-/* POSIX UID/GID verification for setting inode attributes. */
+/**
+ * inode_change_ok - check if attribute changes to an inode are allowed
+ * @inode:      inode to check
+ * @attr:       attributes to change
+ *
+ * Check if we are allowed to change the attributes contained in @attr
+ * in the given inode.  This includes the normal unix access permission
+ * checks, as well as checks for rlimits and others.
+ *
+ * Should be called as the first thing in ->setattr implementations,
+ * possibly after taking additional locks.
+ */
 int inode_change_ok(const struct inode *inode, struct iattr *attr)
 {
-        int retval = -EPERM;
         unsigned int ia_valid = attr->ia_valid;
 
+        /*
+         * First check size constraints.  These can't be overriden using
+         * ATTR_FORCE.
+         */
+        if (ia_valid & ATTR_SIZE) {
+                int error = inode_newsize_ok(inode, attr->ia_size);
+                if (error)
+                        return error;
+        }
+
         /* If force is set do it anyway. */
         if (ia_valid & ATTR_FORCE)
-                goto fine;
+                return 0;
 
         /* Make sure a caller can chown. */
         if ((ia_valid & ATTR_UID) &&
             (current_fsuid() != inode->i_uid ||
              attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
-                goto error;
+                return -EPERM;
 
         /* Make sure caller can chgrp. */
         if ((ia_valid & ATTR_GID) &&
             (current_fsuid() != inode->i_uid ||
             (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
             !capable(CAP_CHOWN))
-                goto error;
+                return -EPERM;
 
         /* Make sure a caller can chmod. */
         if (ia_valid & ATTR_MODE) {
                 if (!is_owner_or_cap(inode))
-                        goto error;
+                        return -EPERM;
                 /* Also check the setgid bit! */
                 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
                                 inode->i_gid) && !capable(CAP_FSETID))
@@ -52,12 +70,10 @@ int inode_change_ok(const struct inode *inode, struct iattr *attr)
         /* Check for setting the inode time. */
         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
                 if (!is_owner_or_cap(inode))
-                        goto error;
+                        return -EPERM;
         }
-fine:
-        retval = 0;
-error:
-        return retval;
+
+        return 0;
 }
 EXPORT_SYMBOL(inode_change_ok);
 
@@ -67,14 +83,14 @@ EXPORT_SYMBOL(inode_change_ok);
  * @offset:     the new size to assign to the inode
  * @Returns:    0 on success, -ve errno on failure
  *
+ * inode_newsize_ok must be called with i_mutex held.
+ *
  * inode_newsize_ok will check filesystem limits and ulimits to check that the
  * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
  * when necessary. Caller must not proceed with inode size change if failure is
  * returned. @inode must be a file (not directory), with appropriate
  * permissions to allow truncate (inode_newsize_ok does NOT check these
  * conditions).
- *
- * inode_newsize_ok must be called with i_mutex held.
  */
 int inode_newsize_ok(const struct inode *inode, loff_t offset)
 {
@@ -104,17 +120,25 @@ out_big:
 }
 EXPORT_SYMBOL(inode_newsize_ok);
 
-int inode_setattr(struct inode * inode, struct iattr * attr)
+/**
+ * setattr_copy - copy simple metadata updates into the generic inode
+ * @inode:      the inode to be updated
+ * @attr:       the new attributes
+ *
+ * setattr_copy must be called with i_mutex held.
+ *
+ * setattr_copy updates the inode's metadata with that specified
+ * in attr. Noticably missing is inode size update, which is more complex
+ * as it requires pagecache updates.
+ *
+ * The inode is not marked as dirty after this operation. The rationale is
+ * that for "simple" filesystems, the struct inode is the inode storage.
+ * The caller is free to mark the inode dirty afterwards if needed.
+ */
+void setattr_copy(struct inode *inode, const struct iattr *attr)
 {
         unsigned int ia_valid = attr->ia_valid;
 
-        if (ia_valid & ATTR_SIZE &&
-            attr->ia_size != i_size_read(inode)) {
-                int error = vmtruncate(inode, attr->ia_size);
-                if (error)
-                        return error;
-        }
-
         if (ia_valid & ATTR_UID)
                 inode->i_uid = attr->ia_uid;
         if (ia_valid & ATTR_GID)
@@ -135,11 +159,8 @@ int inode_setattr(struct inode * inode, struct iattr * attr)
                         mode &= ~S_ISGID;
                 inode->i_mode = mode;
         }
-        mark_inode_dirty(inode);
-
-        return 0;
 }
-EXPORT_SYMBOL(inode_setattr);
+EXPORT_SYMBOL(setattr_copy);
 
 int notify_change(struct dentry * dentry, struct iattr * attr)
 {
@@ -207,13 +228,10 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
         if (ia_valid & ATTR_SIZE)
                 down_write(&dentry->d_inode->i_alloc_sem);
 
-        if (inode->i_op && inode->i_op->setattr) {
+        if (inode->i_op->setattr)
                 error = inode->i_op->setattr(dentry, attr);
-        } else {
-                error = inode_change_ok(inode, attr);
-                if (!error)
-                        error = inode_setattr(inode, attr);
-        }
+        else
+                error = simple_setattr(dentry, attr);
 
         if (ia_valid & ATTR_SIZE)
                 up_write(&dentry->d_inode->i_alloc_sem);