[PATCH] fat: support a truncate() for expanding size (generic_cont_expand)

[GitHub/MotorolaMobilityLLC/kernel-slsi.git] / fs / fat / file.c

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 15229fe569c3cbf22da7043c31e51b06787cd7e3..9b07c328a6fca012ea16b192966ae8a2d409cda2 100644 (file)
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -11,6 +11,7 @@
 #include <linux/msdos_fs.h>
 #include <linux/smp_lock.h>
 #include <linux/buffer_head.h>
+#include <linux/writeback.h>
 
 int fat_generic_ioctl(struct inode *inode, struct file *filp,
                      unsigned int cmd, unsigned long arg)
@@ -124,6 +125,24 @@ struct file_operations fat_file_operations = {
        .sendfile       = generic_file_sendfile,
 };
 
+static int fat_cont_expand(struct inode *inode, loff_t size)
+{
+       struct address_space *mapping = inode->i_mapping;
+       loff_t start = inode->i_size, count = size - inode->i_size;
+       int err;
+
+       err = generic_cont_expand_simple(inode, size);
+       if (err)
+               goto out;
+
+       inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
+       mark_inode_dirty(inode);
+       if (IS_SYNC(inode))
+               err = sync_page_range_nolock(inode, mapping, start, count);
+out:
+       return err;
+}
+
 int fat_notify_change(struct dentry *dentry, struct iattr *attr)
 {
        struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
@@ -132,11 +151,17 @@ int fat_notify_change(struct dentry *dentry, struct iattr *attr)
 
        lock_kernel();
 
-       /* FAT cannot truncate to a longer file */
+       /*
+        * Expand the file. Since inode_setattr() updates ->i_size
+        * before calling the ->truncate(), but FAT needs to fill the
+        * hole before it.
+        */
        if (attr->ia_valid & ATTR_SIZE) {
                if (attr->ia_size > inode->i_size) {
-                       error = -EPERM;
-                       goto out;
+                       error = fat_cont_expand(inode, attr->ia_size);
+                       if (error || attr->ia_valid == ATTR_SIZE)
+                               goto out;
+                       attr->ia_valid &= ~ATTR_SIZE;
                }
        }