ext4: truncate the file properly if we fail to copy data from userspace

In generic_perform_write if we fail to copy the user data we don't
update the inode->i_size.  We should truncate the file in the above
case so that we don't have blocks allocated outside inode->i_size.  Add
the inode to orphan list in the same transaction as block allocation
This ensures that if we crash in between the recovery would do the
truncate.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
CC:  Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 102 insertions, 26 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8d215881172f..2c10d346f7a3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1549,6 +1549,52 @@ static int write_end_fn(handle_t *handle, struct buffer_head *bh)
         return ext4_handle_dirty_metadata(handle, NULL, bh);
 }
 
+static int ext4_generic_write_end(struct file *file,
+                                struct address_space *mapping,
+                                loff_t pos, unsigned len, unsigned copied,
+                                struct page *page, void *fsdata)
+{
+        int i_size_changed = 0;
+        struct inode *inode = mapping->host;
+        handle_t *handle = ext4_journal_current_handle();
+
+        copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+        /*
+         * No need to use i_size_read() here, the i_size
+         * cannot change under us because we hold i_mutex.
+         *
+         * But it's important to update i_size while still holding page lock:
+         * page writeout could otherwise come in and zero beyond i_size.
+         */
+        if (pos + copied > inode->i_size) {
+                i_size_write(inode, pos + copied);
+                i_size_changed = 1;
+        }
+
+        if (pos + copied >  EXT4_I(inode)->i_disksize) {
+                /* We need to mark inode dirty even if
+                 * new_i_size is less that inode->i_size
+                 * bu greater than i_disksize.(hint delalloc)
+                 */
+                ext4_update_i_disksize(inode, (pos + copied));
+                i_size_changed = 1;
+        }
+        unlock_page(page);
+        page_cache_release(page);
+
+        /*
+         * Don't mark the inode dirty under page lock. First, it unnecessarily
+         * makes the holding time of page lock longer. Second, it forces lock
+         * ordering of page lock and transaction start for journaling
+         * filesystems.
+         */
+        if (i_size_changed)
+                ext4_mark_inode_dirty(handle, inode);
+
+        return copied;
+}
+
 /*
  * We need to pick up the new inode size which generic_commit_write gave us
  * `file' can be NULL - eg, when called from page_symlink().
@@ -1572,21 +1618,15 @@ static int ext4_ordered_write_end(struct file *file,
         ret = ext4_jbd2_file_inode(handle, inode);
 
         if (ret == 0) {
-                loff_t new_i_size;
-
-                new_i_size = pos + copied;
-                if (new_i_size > EXT4_I(inode)->i_disksize) {
-                        ext4_update_i_disksize(inode, new_i_size);
-                        /* We need to mark inode dirty even if
-                         * new_i_size is less that inode->i_size
-                         * bu greater than i_disksize.(hint delalloc)
-                         */
-                        ext4_mark_inode_dirty(handle, inode);
-                }
-
-                ret2 = generic_write_end(file, mapping, pos, len, copied,
+                ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
                                                         page, fsdata);
                 copied = ret2;
+                if (pos + len > inode->i_size)
+                        /* if we have allocated more blocks and copied
+                         * less. We will have blocks allocated outside
+                         * inode->i_size. So truncate them
+                         */
+                        ext4_orphan_add(handle, inode);
                 if (ret2 < 0)
                         ret = ret2;
         }
@@ -1594,6 +1634,18 @@ static int ext4_ordered_write_end(struct file *file,
         if (!ret)
                 ret = ret2;
 
+        if (pos + len > inode->i_size) {
+                vmtruncate(inode, inode->i_size);
+                /* 
+                 * If vmtruncate failed early the inode might still be
+                 * on the orphan list; we need to make sure the inode
+                 * is removed from the orphan list in that case.
+                 */
+                if (inode->i_nlink)
+                        ext4_orphan_del(NULL, inode);
+        }
+
+
         return ret ? ret : copied;
 }
 
@@ -1605,25 +1657,21 @@ static int ext4_writeback_write_end(struct file *file,
         handle_t *handle = ext4_journal_current_handle();
         struct inode *inode = mapping->host;
         int ret = 0, ret2;
-        loff_t new_i_size;
 
         trace_mark(ext4_writeback_write_end,
                    "dev %s ino %lu pos %llu len %u copied %u",
                    inode->i_sb->s_id, inode->i_ino,
                    (unsigned long long) pos, len, copied);
-        new_i_size = pos + copied;
-        if (new_i_size > EXT4_I(inode)->i_disksize) {
-                ext4_update_i_disksize(inode, new_i_size);
-                /* We need to mark inode dirty even if
-                 * new_i_size is less that inode->i_size
-                 * bu greater than i_disksize.(hint delalloc)
-                 */
-                ext4_mark_inode_dirty(handle, inode);
-        }
-
-        ret2 = generic_write_end(file, mapping, pos, len, copied,
+        ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
                                                         page, fsdata);
         copied = ret2;
+        if (pos + len > inode->i_size)
+                /* if we have allocated more blocks and copied
+                 * less. We will have blocks allocated outside
+                 * inode->i_size. So truncate them
+                 */
+                ext4_orphan_add(handle, inode);
+
         if (ret2 < 0)
                 ret = ret2;
 
@@ -1631,6 +1679,17 @@ static int ext4_writeback_write_end(struct file *file,
         if (!ret)
                 ret = ret2;
 
+        if (pos + len > inode->i_size) {
+                vmtruncate(inode, inode->i_size);
+                /* 
+                 * If vmtruncate failed early the inode might still be
+                 * on the orphan list; we need to make sure the inode
+                 * is removed from the orphan list in that case.
+                 */
+                if (inode->i_nlink)
+                        ext4_orphan_del(NULL, inode);
+        }
+
         return ret ? ret : copied;
 }
 
@@ -1675,10 +1734,27 @@ static int ext4_journalled_write_end(struct file *file,
         }
 
         unlock_page(page);
+        page_cache_release(page);
+        if (pos + len > inode->i_size)
+                /* if we have allocated more blocks and copied
+                 * less. We will have blocks allocated outside
+                 * inode->i_size. So truncate them
+                 */
+                ext4_orphan_add(handle, inode);
+
         ret2 = ext4_journal_stop(handle);
         if (!ret)
                 ret = ret2;
-        page_cache_release(page);
+        if (pos + len > inode->i_size) {
+                vmtruncate(inode, inode->i_size);
+                /* 
+                 * If vmtruncate failed early the inode might still be
+                 * on the orphan list; we need to make sure the inode
+                 * is removed from the orphan list in that case.
+                 */
+                if (inode->i_nlink)
+                        ext4_orphan_del(NULL, inode);
+        }
 
         return ret ? ret : copied;
 }