[PATCH] vfs: inode_change_ok have to perform all necessery checks

[Dmitry Monakhov]

Usually this is the only function which called before inode
attributes manipulation. In fact inode_change_ok performs only
posix checks. But it new_size check is also important. Otherwise
we mail fail in very late stage.

Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
---
 fs/attr.c          |   20 ++++++++++++++++++--
 fs/libfs.c         |   26 +++++++++++++++++++-------
 include/linux/fs.h |    5 +++--
 3 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/fs/attr.c b/fs/attr.c
index 1bca479..007c706 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -18,7 +18,7 @@
 /* Taken over from the old code... */
 
 /* POSIX UID/GID verification for setting inode attributes. */
-int inode_change_ok(const struct inode *inode, struct iattr *attr)
+int inode_change_posix_ok(const struct inode *inode, struct iattr *attr)
 {
 	int retval = -EPERM;
 	unsigned int ia_valid = attr->ia_valid;
@@ -60,7 +60,7 @@ fine:
 error:
 	return retval;
 }
-EXPORT_SYMBOL(inode_change_ok);
+EXPORT_SYMBOL(inode_change_posix_ok);
 
 /**
  * inode_newsize_ok - may this inode be truncated to a given size
@@ -105,6 +105,22 @@ out_big:
 }
 EXPORT_SYMBOL(inode_newsize_ok);
 
+/*
+ * General verification for setting inode attributes.
+ */
+int inode_change_ok(const struct inode *inode, struct iattr *attr)
+{
+	int ret;
+	ret = inode_change_posix_ok(inode, attr);
+	if (ret)
+		return ret;
+	if (attr->ia_valid & ATTR_SIZE)
+		ret = inode_newsize_ok(inode, attr->ia_size);
+	return ret;
+}
+EXPORT_SYMBOL(inode_change_ok);
+
+
 /**
  * generic_setattr - copy simple metadata updates into the generic inode
  * @inode:	the inode to be updated
diff --git a/fs/libfs.c b/fs/libfs.c
index 338575b..2aa89d7 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -329,6 +329,23 @@ int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 	return 0;
 }
+/**
+ * simple_setsize_nocheck - handle core mm and vfs requirements for file
+ * size change
+ * @inode: inode
+ * @newsize: new file size
+ * simple_setsize_nocheck must be called with inode_mutex held.
+ *
+ * Caller is responsible for all appropriate checks
+ */
+void simple_setsize_nocheck(struct inode *inode, loff_t newsize)
+{
+	loff_t oldsize;
+	oldsize = inode->i_size;
+	i_size_write(inode, newsize);
+	truncate_pagecache(inode, oldsize, newsize);
+}
+EXPORT_SYMBOL(simple_setsize_nocheck);
 
 /**
  * simple_setsize - handle core mm and vfs requirements for file size change
@@ -358,18 +375,13 @@ int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
  */
 int simple_setsize(struct inode *inode, loff_t newsize)
 {
-	loff_t oldsize;
 	int error;
 
 	error = inode_newsize_ok(inode, newsize);
 	if (error)
 		return error;
-
-	oldsize = inode->i_size;
-	i_size_write(inode, newsize);
-	truncate_pagecache(inode, oldsize, newsize);
-
-	return error;
+	simple_setsize_nocheck(inode, newsize);
+	return 0;
 }
 EXPORT_SYMBOL(simple_setsize);
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f5638e5..1097e28 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2361,6 +2361,7 @@ extern int simple_unlink(struct inode *, struct dentry *);
 extern int simple_rmdir(struct inode *, struct dentry *);
 extern int simple_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
 extern int simple_setsize(struct inode *inode, loff_t newsize);
+extern void simple_setsize_nocheck(struct inode *inode, loff_t newsize);
 extern int simple_sync_file(struct file *, struct dentry *, int);
 extern int simple_empty(struct dentry *);
 extern int simple_readpage(struct file *file, struct page *page);
@@ -2395,11 +2396,11 @@ extern int buffer_migrate_page(struct address_space *,
 #define buffer_migrate_page NULL
 #endif
 
-extern int inode_change_ok(const struct inode *, struct iattr *);
+extern int inode_change_posix_ok(const struct inode *, struct iattr *);
 extern int inode_newsize_ok(const struct inode *, loff_t offset);
+extern int inode_change_ok(const struct inode *, struct iattr *);
 extern int __must_check inode_setattr(struct inode *, const struct iattr *);
 extern void generic_setattr(struct inode *inode, const struct iattr *attr);
-
 extern void file_update_time(struct file *file);
 
 extern int generic_show_options(struct seq_file *m, struct vfsmount *mnt);
-- 
1.6.6


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