udf: Fix deadlock when converting file from in-ICB one to normal one

During BKL removal in 2.6.38, conversion of files from in-ICB format to normal
format got broken. We call ->writepage with i_data_sem held but udf_get_block()
also acquires i_data_sem thus creating A-A deadlock.

We fix the problem by dropping i_data_sem before calling ->writepage() which is
safe since i_mutex still protects us against any changes in the file. Also fix
pagelock - i_data_sem lock inversion in udf_expand_file_adinicb() by dropping
i_data_sem before calling find_or_create_page().

CC: stable@kernel.org
Reported-by: Matthias Matiak <netzpython@mail-on.us>
Tested-by: Matthias Matiak <netzpython@mail-on.us>
Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/udf/file.c b/fs/udf/file.c
index d8ffa7cc661d..dca0c3881e82 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -125,7 +125,6 @@ static ssize_t udf_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
                         err = udf_expand_file_adinicb(inode);
                         if (err) {
                                 udf_debug("udf_expand_adinicb: err=%d\n", err);
-                                up_write(&iinfo->i_data_sem);
                                 return err;
                         }
                 } else {
@@ -133,9 +132,10 @@ static ssize_t udf_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
                                 iinfo->i_lenAlloc = pos + count;
                         else
                                 iinfo->i_lenAlloc = inode->i_size;
+                        up_write(&iinfo->i_data_sem);
                 }
-        }
-        up_write(&iinfo->i_data_sem);
+        } else
+                up_write(&iinfo->i_data_sem);
 
         retval = generic_file_aio_write(iocb, iov, nr_segs, ppos);
         if (retval > 0)