ext4: truncate block allocated on a failed ext4_write_begin

For blocksize < pagesize we need to remove blocks that got allocated in
block_write_begin() if we fail with ENOSPC for later blocks.
block_write_begin() internally does this if it allocated pages locally.
This makes sure we don't have blocks outside inode.i_size during ENOSPC.

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

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f97b347..634f0bc 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1391,6 +1391,13 @@ retry:
                unlock_page(page);
                ext4_journal_stop(handle);
                page_cache_release(page);
+               /*
+                * block_write_begin may have instantiated a few blocks
+                * outside i_size.  Trim these off again. Don't need
+                * i_size_read because we hold i_mutex.
+                */
+               if (pos + len > inode->i_size)
+                       vmtruncate(inode, inode->i_size);
        }
 
        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
@@ -2560,6 +2567,13 @@ retry:
                unlock_page(page);
                ext4_journal_stop(handle);
                page_cache_release(page);
+               /*
+                * block_write_begin may have instantiated a few blocks
+                * outside i_size.  Trim these off again. Don't need
+                * i_size_read because we hold i_mutex.
+                */
+               if (pos + len > inode->i_size)
+                       vmtruncate(inode, inode->i_size);
        }
 
        if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))