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[-V2] Fix sub-block zeroing for buffered writes into unwritten extents.

Message ID 1240892027-6481-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com
State Superseded, archived
Headers show

Commit Message

Aneesh Kumar K.V April 28, 2009, 4:13 a.m. UTC 
We need to mark the  buffer_head mapping prealloc space
as new during write_begin. Otherwise we don't zero out the
page cache content properly for a partial write. This will
cause file corruption with preallocation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

---
 fs/ext4/inode.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
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Patch

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c6bd6ce..8dfa97a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2323,6 +2323,14 @@  static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
 		set_buffer_delay(bh_result);
 	} else if (ret > 0) {
 		bh_result->b_size = (ret << inode->i_blkbits);
+		bh_result->b_bdev = inode->i_sb->s_bdev;
+		/*
+		 * With sub-block writes into unwritten extents
+		 * we also need to mark the buffer as new so that
+		 * the unwritten parts of the buffer gets correctly zeroed.
+		 */
+		if (buffer_unwritten(bh_result))
+			set_buffer_new(bh_result);
 		ret = 0;
 	}