ext4: Add flag to files with blocks intentionally past EOF

fallocate() may potentially instantiate blocks past EOF, depending
on the flags used when it is called.

e2fsck currently has a test for blocks past i_size, and it
sometimes trips up - noticeably on xfstests 013 which runs fsstress.

This patch from Jiayang does fix it up - it (along with
e2fsprogs updates and other patches recently from Aneesh) has
survived many fsstress runs in a row.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ecac8c5a6f5c..edb7edc99f71 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4456,6 +4456,8 @@ void ext4_truncate(struct inode *inode)
         if (!ext4_can_truncate(inode))
                 return;
 
+        EXT4_I(inode)->i_flags &= ~EXT4_EOFBLOCKS_FL;
+
         if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
                 ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 
@@ -5305,7 +5307,9 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
         }
 
         if (S_ISREG(inode->i_mode) &&
-            attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
+            attr->ia_valid & ATTR_SIZE &&
+            (attr->ia_size < inode->i_size ||
+             (EXT4_I(inode)->i_flags & EXT4_EOFBLOCKS_FL))) {
                 handle_t *handle;
 
                 handle = ext4_journal_start(inode, 3);
@@ -5336,6 +5340,9 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
                                 goto err_out;
                         }
                 }
+                /* ext4_truncate will clear the flag */
+                if ((EXT4_I(inode)->i_flags & EXT4_EOFBLOCKS_FL))
+                        ext4_truncate(inode);
         }
 
         rc = inode_setattr(inode, attr);