tmpfs: take control of its truncate_range

[sfrench/cifs-2.6.git] / mm / shmem.c

diff --git a/mm/shmem.c b/mm/shmem.c
index 1acfb2687bfa144da8fa9b6b2f6c815663d44145..f1714758ea960f9fc8f7750674a38482ea6136f0 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -539,7 +539,7 @@ static void shmem_free_pages(struct list_head *next)
        } while (next);
 }
 
-static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
+void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
 {
        struct shmem_inode_info *info = SHMEM_I(inode);
        unsigned long idx;
@@ -562,6 +562,8 @@ static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
        spinlock_t *punch_lock;
        unsigned long upper_limit;
 
+       truncate_inode_pages_range(inode->i_mapping, start, end);
+
        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
        idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
        if (idx >= info->next_index)
@@ -738,16 +740,8 @@ done2:
                 * lowered next_index.  Also, though shmem_getpage checks
                 * i_size before adding to cache, no recheck after: so fix the
                 * narrow window there too.
-                *
-                * Recalling truncate_inode_pages_range and unmap_mapping_range
-                * every time for punch_hole (which never got a chance to clear
-                * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
-                * yet hardly ever necessary: try to optimize them out later.
                 */
                truncate_inode_pages_range(inode->i_mapping, start, end);
-               if (punch_hole)
-                       unmap_mapping_range(inode->i_mapping, start,
-                                                       end - start, 1);
        }
 
        spin_lock(&info->lock);
@@ -766,22 +760,23 @@ done2:
                shmem_free_pages(pages_to_free.next);
        }
 }
+EXPORT_SYMBOL_GPL(shmem_truncate_range);
 
-static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
+static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 {
        struct inode *inode = dentry->d_inode;
-       loff_t newsize = attr->ia_size;
        int error;
 
        error = inode_change_ok(inode, attr);
        if (error)
                return error;
 
-       if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)
-                                       && newsize != inode->i_size) {
+       if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
+               loff_t oldsize = inode->i_size;
+               loff_t newsize = attr->ia_size;
                struct page *page = NULL;
 
-               if (newsize < inode->i_size) {
+               if (newsize < oldsize) {
                        /*
                         * If truncating down to a partial page, then
                         * if that page is already allocated, hold it
@@ -810,12 +805,19 @@ static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
                                spin_unlock(&info->lock);
                        }
                }
-
-               /* XXX(truncate): truncate_setsize should be called last */
-               truncate_setsize(inode, newsize);
+               if (newsize != oldsize) {
+                       i_size_write(inode, newsize);
+                       inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+               }
+               if (newsize < oldsize) {
+                       loff_t holebegin = round_up(newsize, PAGE_SIZE);
+                       unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
+                       shmem_truncate_range(inode, newsize, (loff_t)-1);
+                       /* unmap again to remove racily COWed private pages */
+                       unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
+               }
                if (page)
                        page_cache_release(page);
-               shmem_truncate_range(inode, newsize, (loff_t)-1);
        }
 
        setattr_copy(inode, attr);
@@ -832,7 +834,6 @@ static void shmem_evict_inode(struct inode *inode)
        struct shmem_xattr *xattr, *nxattr;
 
        if (inode->i_mapping->a_ops == &shmem_aops) {
-               truncate_inode_pages(inode->i_mapping, 0);
                shmem_unacct_size(info->flags, inode->i_size);
                inode->i_size = 0;
                shmem_truncate_range(inode, 0, (loff_t)-1);
@@ -1114,8 +1115,8 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
                delete_from_page_cache(page);
                shmem_swp_set(info, entry, swap.val);
                shmem_swp_unmap(entry);
-               spin_unlock(&info->lock);
                swap_shmem_alloc(swap);
+               spin_unlock(&info->lock);
                BUG_ON(page_mapped(page));
                swap_writepage(page, wbc);
                return 0;
@@ -2706,7 +2707,7 @@ static const struct file_operations shmem_file_operations = {
 };
 
 static const struct inode_operations shmem_inode_operations = {
-       .setattr        = shmem_notify_change,
+       .setattr        = shmem_setattr,
        .truncate_range = shmem_truncate_range,
 #ifdef CONFIG_TMPFS_XATTR
        .setxattr       = shmem_setxattr,
@@ -2739,7 +2740,7 @@ static const struct inode_operations shmem_dir_inode_operations = {
        .removexattr    = shmem_removexattr,
 #endif
 #ifdef CONFIG_TMPFS_POSIX_ACL
-       .setattr        = shmem_notify_change,
+       .setattr        = shmem_setattr,
        .check_acl      = generic_check_acl,
 #endif
 };
@@ -2752,7 +2753,7 @@ static const struct inode_operations shmem_special_inode_operations = {
        .removexattr    = shmem_removexattr,
 #endif
 #ifdef CONFIG_TMPFS_POSIX_ACL
-       .setattr        = shmem_notify_change,
+       .setattr        = shmem_setattr,
        .check_acl      = generic_check_acl,
 #endif
 };
@@ -2908,6 +2909,12 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user)
        return 0;
 }
 
+void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
+{
+       truncate_inode_pages_range(inode->i_mapping, start, end);
+}
+EXPORT_SYMBOL_GPL(shmem_truncate_range);
+
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 /**
  * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file