ext4: only call ext4_truncate when size <= isize

At LSF we decided that if we truncate up from isize we shouldn't trim
fallocated blocks that were fallocated with KEEP_SIZE and are past the
new i_size.  This patch fixes ext4 to do this.

[ Completely reworked patch so that i_disksize would actually get set
  when truncating up.  Also reworked the code for handling truncate so
  that it's easier to handle. -- tytso ]

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>

1 files changed, 18 insertions, 20 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ae93f0bb9485..e057c6fcc227 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4681,8 +4681,10 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
                 ext4_journal_stop(handle);
         }
 
-        if (attr->ia_valid & ATTR_SIZE && attr->ia_size != inode->i_size) {
+        if (attr->ia_valid & ATTR_SIZE) {
                 handle_t *handle;
+                loff_t oldsize = inode->i_size;
+                int shrink = (attr->ia_size <= inode->i_size);
 
                 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
                         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
@@ -4690,24 +4692,26 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
                         if (attr->ia_size > sbi->s_bitmap_maxbytes)
                                 return -EFBIG;
                 }
+                if (!S_ISREG(inode->i_mode))
+                        return -EINVAL;
 
                 if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
                         inode_inc_iversion(inode);
 
-                if (S_ISREG(inode->i_mode) &&
+                if (ext4_should_order_data(inode) &&
                     (attr->ia_size < inode->i_size)) {
-                        if (ext4_should_order_data(inode)) {
-                                error = ext4_begin_ordered_truncate(inode,
+                        error = ext4_begin_ordered_truncate(inode,
                                                             attr->ia_size);
-                                if (error)
-                                        goto err_out;
-                        }
+                        if (error)
+                                goto err_out;
+                }
+                if (attr->ia_size != inode->i_size) {
                         handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
                         if (IS_ERR(handle)) {
                                 error = PTR_ERR(handle);
                                 goto err_out;
                         }
-                        if (ext4_handle_valid(handle)) {
+                        if (ext4_handle_valid(handle) && shrink) {
                                 error = ext4_orphan_add(handle, inode);
                                 orphan = 1;
                         }
@@ -4726,15 +4730,13 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
                         up_write(&EXT4_I(inode)->i_data_sem);
                         ext4_journal_stop(handle);
                         if (error) {
-                                ext4_orphan_del(NULL, inode);
+                                if (orphan)
+                                        ext4_orphan_del(NULL, inode);
                                 goto err_out;
                         }
-                } else {
-                        loff_t oldsize = inode->i_size;
-
-                        i_size_write(inode, attr->ia_size);
-                        pagecache_isize_extended(inode, oldsize, inode->i_size);
                 }
+                if (!shrink)
+                        pagecache_isize_extended(inode, oldsize, inode->i_size);
 
                 /*
                  * Blocks are going to be removed from the inode. Wait
@@ -4754,13 +4756,9 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
                  * in data=journal mode to make pages freeable.
                  */
                 truncate_pagecache(inode, inode->i_size);
+                if (shrink)
+                        ext4_truncate(inode);
         }
-        /*
-         * We want to call ext4_truncate() even if attr->ia_size ==
-         * inode->i_size for cases like truncation of fallocated space
-         */
-        if (attr->ia_valid & ATTR_SIZE)
-                ext4_truncate(inode);
 
         if (!rc) {
                 setattr_copy(inode, attr);