[PATCH] ftruncate on huge page couldn't extend hugetlb file

["Zhang, Yanmin" <yanmin_zhang@linux.intel.com>]

From: Zhang Yanmin <yanmin.zhang@intel.com>

Currently, ftruncate on hugetlb files couldn't extend them. My patch enables it.

This patch is against 2.6.16-rc5-mm3 and on the top of the patch which
implements mmap on zero-length hugetlb files with PROT_NONE.

Thanks for Ken's good idea.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>

---

diff -Nraup linux-2.6.16-rc5-mm3_huge_check/fs/hugetlbfs/inode.c linux-2.6.16-rc5-mm3_truncate/fs/hugetlbfs/inode.c
--- linux-2.6.16-rc5-mm3_huge_check/fs/hugetlbfs/inode.c	2006-03-08 18:17:15.000000000 +0800
+++ linux-2.6.16-rc5-mm3_truncate/fs/hugetlbfs/inode.c	2006-03-08 18:50:40.000000000 +0800
@@ -308,18 +308,22 @@ static int hugetlb_vmtruncate(struct ino
 	unsigned long pgoff;
 	struct address_space *mapping = inode->i_mapping;
 
-	if (offset > inode->i_size)
-		return -EINVAL;
-
 	BUG_ON(offset & ~HPAGE_MASK);
 	pgoff = offset >> HPAGE_SHIFT;
-
-	inode->i_size = offset;
-	spin_lock(&mapping->i_mmap_lock);
-	if (!prio_tree_empty(&mapping->i_mmap))
-		hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
-	spin_unlock(&mapping->i_mmap_lock);
-	truncate_hugepages(inode, offset);
+        if (offset > inode->i_size) {
+        	if (hugetlb_extend_reservation(HUGETLBFS_I(inode), pgoff) != 0)
+			return -ENOMEM;
+		inode->i_size = offset;
+	}
+	else {
+
+		inode->i_size = offset;
+		spin_lock(&mapping->i_mmap_lock);
+		if (!prio_tree_empty(&mapping->i_mmap))
+			hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
+		spin_unlock(&mapping->i_mmap_lock);
+		truncate_hugepages(inode, offset);
+	}
 	return 0;
 }
 


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