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, 9 insertions, 0 deletions

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index b63d193126db..2220feb2dcc1 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -92,6 +92,15 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
                         flags &= ~EXT4_EXTENTS_FL;
                 }
 
+                if (flags & EXT4_EOFBLOCKS_FL) {
+                        /* we don't support adding EOFBLOCKS flag */
+                        if (!(oldflags & EXT4_EOFBLOCKS_FL)) {
+                                err = -EOPNOTSUPP;
+                                goto flags_out;
+                        }
+                } else if (oldflags & EXT4_EOFBLOCKS_FL)
+                        ext4_truncate(inode);
+
                 handle = ext4_journal_start(inode, 1);
                 if (IS_ERR(handle)) {
                         err = PTR_ERR(handle);