[PATCH -v2] ext4: move ext4_update_i_disksize() into mpage_map_and_submit_extent()

[Theodore Ts'o <tytso@mit.edu>]

The function ext4_update_i_disksize() is used in only one place, in
the function mpage_map_and_submit_extent().  Move there to simplify
the code paths, and also move the call to ext4_mark_inode_dirty() into
the i_data_sem's critical region, to be consistent with all of the
other places where we update i_disksize.  That way, we also keep the
raw_inode's i_disksize protected.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
---

Oops, the first version was missing the commit description

 fs/ext4/ext4.h  | 17 -----------------
 fs/ext4/inode.c | 16 +++++++++++++---
 2 files changed, 13 insertions(+), 20 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f1c65dc..66946aa 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2466,23 +2466,6 @@ static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)
 	up_write(&EXT4_I(inode)->i_data_sem);
 }
 
-/*
- * Update i_disksize after writeback has been started. Races with truncate
- * are avoided by checking i_size under i_data_sem.
- */
-static inline void ext4_wb_update_i_disksize(struct inode *inode, loff_t newsize)
-{
-	loff_t i_size;
-
-	down_write(&EXT4_I(inode)->i_data_sem);
-	i_size = i_size_read(inode);
-	if (newsize > i_size)
-		newsize = i_size;
-	if (newsize > EXT4_I(inode)->i_disksize)
-		EXT4_I(inode)->i_disksize = newsize;
-	up_write(&EXT4_I(inode)->i_data_sem);
-}
-
 struct ext4_group_info {
 	unsigned long   bb_state;
 	struct rb_root  bb_free_root;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7b93df9..f023f0c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2247,13 +2247,23 @@ static int mpage_map_and_submit_extent(handle_t *handle,
 			return err;
 	} while (map->m_len);
 
-	/* Update on-disk size after IO is submitted */
+	/*
+	 * Update on-disk size after IO is submitted.  Races with
+	 * truncate are avoided by checking i_size under i_data_sem.
+	 */
 	disksize = ((loff_t)mpd->first_page) << PAGE_CACHE_SHIFT;
 	if (disksize > EXT4_I(inode)->i_disksize) {
 		int err2;