[PATCH 2/2] ext4: Fix truncation of symlinks after failed write

[Jan Kara <jack@suse.cz>]

Contents of long symlinks is written via standard write methods. So when the
write fails, we add inode to orphan list. But symlinks don't have .truncate
method defined so nobody properly removes them from the on disk orphan list.

Fix this by calling ext4_truncate() directly instead of calling vmtruncate()
(which is saner anyway since we don't need anything vmtruncate() does except
from calling .truncate in these paths).  We also add inode to orphan list only
if ext4_can_truncate() is true (currently, it can be false for symlinks when
there are no blocks allocated) - otherwise orphan list processing will complain
and ext4_truncate() will not remove inode from on-disk orphan list.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/inode.c |   26 +++++++++++++-------------
 1 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 60a26f3..88552ef 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1513,14 +1513,14 @@ retry:
 		 * Add inode to orphan list in case we crash before
 		 * truncate finishes
 		 */
-		if (pos + len > inode->i_size)
+		if (pos + len > inode->i_size && ext4_can_truncate(inode))
 			ext4_orphan_add(handle, inode);
 
 		ext4_journal_stop(handle);
 		if (pos + len > inode->i_size) {
-			vmtruncate(inode, inode->i_size);
+			ext4_truncate(inode);
 			/*
-			 * If vmtruncate failed early the inode might
+			 * If truncate 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.
@@ -1614,7 +1614,7 @@ static int ext4_ordered_write_end(struct file *file,
 		ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
 							page, fsdata);
 		copied = ret2;
-		if (pos + len > inode->i_size)
+		if (pos + len > inode->i_size && ext4_can_truncate(inode))
 			/* if we have allocated more blocks and copied
 			 * less. We will have blocks allocated outside
 			 * inode->i_size. So truncate them
@@ -1628,9 +1628,9 @@ static int ext4_ordered_write_end(struct file *file,
 		ret = ret2;
 
 	if (pos + len > inode->i_size) {
-		vmtruncate(inode, inode->i_size);
+		ext4_truncate(inode);
 		/*
-		 * If vmtruncate failed early the inode might still be
+		 * If truncate 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.
 		 */
@@ -1655,7 +1655,7 @@ static int ext4_writeback_write_end(struct file *file,
 	ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
 							page, fsdata);
 	copied = ret2;
-	if (pos + len > inode->i_size)
+	if (pos + len > inode->i_size && ext4_can_truncate(inode))
 		/* if we have allocated more blocks and copied
 		 * less. We will have blocks allocated outside
 		 * inode->i_size. So truncate them
@@ -1670,9 +1670,9 @@ static int ext4_writeback_write_end(struct file *file,
 		ret = ret2;
 
 	if (pos + len > inode->i_size) {
-		vmtruncate(inode, inode->i_size);
+		ext4_truncate(inode);
 		/*
-		 * If vmtruncate failed early the inode might still be
+		 * If truncate 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.
 		 */
@@ -1722,7 +1722,7 @@ static int ext4_journalled_write_end(struct file *file,
 
 	unlock_page(page);
 	page_cache_release(page);
-	if (pos + len > inode->i_size)
+	if (pos + len > inode->i_size && ext4_can_truncate(inode))
 		/* if we have allocated more blocks and copied
 		 * less. We will have blocks allocated outside
 		 * inode->i_size. So truncate them
@@ -1733,9 +1733,9 @@ static int ext4_journalled_write_end(struct file *file,
 	if (!ret)
 		ret = ret2;
 	if (pos + len > inode->i_size) {
-		vmtruncate(inode, inode->i_size);
+		ext4_truncate(inode);
 		/*
-		 * If vmtruncate failed early the inode might still be
+		 * If truncate 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.
 		 */
@@ -2907,7 +2907,7 @@ retry:
 		 * i_size_read because we hold i_mutex.
 		 */
 		if (pos + len > inode->i_size)
-			vmtruncate(inode, inode->i_size);
+			ext4_truncate(inode);
 	}
 
 	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
-- 
1.6.0.2