[PATCH] tightening hugetlb strict accounting

Current hugetlb strict accounting for shared mapping always assume mapping
starts at zero file offset and reserves pages between zero and size of the
file.  This assumption often reserves (or lock down) a lot more pages then
necessary if application maps at none zero file offset.  libhugetlbfs is
one example that requires proper reservation on shared mapping starts at
none zero offset.

This patch extends the reservation and hugetlb strict accounting to support
any arbitrary pair of (offset, len), resulting a much more robust and
accurate scheme.  More importantly, it won't lock down any hugetlb pages
outside file mapping.

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 12 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 678fc72c3646..e6410d8edd0e 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -59,7 +59,6 @@ static void huge_pagevec_release(struct pagevec *pvec)
 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
         struct inode *inode = file->f_dentry->d_inode;
-        struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
         loff_t len, vma_len;
         int ret;
 
@@ -87,9 +86,10 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
         if (!(vma->vm_flags & VM_WRITE) && len > inode->i_size)
                 goto out;
 
-        if (vma->vm_flags & VM_MAYSHARE)
-                if (hugetlb_extend_reservation(info, len >> HPAGE_SHIFT) != 0)
-                        goto out;
+        if (vma->vm_flags & VM_MAYSHARE &&
+            hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
+                                  len >> HPAGE_SHIFT))
+                goto out;
 
         ret = 0;
         hugetlb_prefault_arch_hook(vma->vm_mm);
@@ -195,12 +195,8 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart)
         const pgoff_t start = lstart >> HPAGE_SHIFT;
         struct pagevec pvec;
         pgoff_t next;
-        int i;
+        int i, freed = 0;
 
-        hugetlb_truncate_reservation(HUGETLBFS_I(inode),
-                                     lstart >> HPAGE_SHIFT);
-        if (!mapping->nrpages)
-                return;
         pagevec_init(&pvec, 0);
         next = start;
         while (1) {
@@ -221,10 +217,12 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart)
                         truncate_huge_page(page);
                         unlock_page(page);
                         hugetlb_put_quota(mapping);
+                        freed++;
                 }
                 huge_pagevec_release(&pvec);
         }
         BUG_ON(!lstart && mapping->nrpages);
+        hugetlb_unreserve_pages(inode, start, freed);
 }
 
 static void hugetlbfs_delete_inode(struct inode *inode)
@@ -366,6 +364,7 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid,
                 inode->i_mapping->a_ops = &hugetlbfs_aops;
                 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+                INIT_LIST_HEAD(&inode->i_mapping->private_list);
                 info = HUGETLBFS_I(inode);
                 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, NULL);
                 switch (mode & S_IFMT) {
@@ -538,7 +537,6 @@ static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
                 hugetlbfs_inc_free_inodes(sbinfo);
                 return NULL;
         }
-        p->prereserved_hpages = 0;
         return &p->vfs_inode;
 }
 
@@ -781,8 +779,7 @@ struct file *hugetlb_zero_setup(size_t size)
                 goto out_file;
 
         error = -ENOMEM;
-        if (hugetlb_extend_reservation(HUGETLBFS_I(inode),
-                                       size >> HPAGE_SHIFT) != 0)
+        if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
                 goto out_inode;
 
         d_instantiate(dentry, inode);