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authorJoel Becker <joel.becker@oracle.com>2010-07-01 15:13:31 -0700
committerJoel Becker <joel.becker@oracle.com>2010-07-08 13:25:35 -0700
commit5693486bad2bc2ac585a2c24f7e2f3964b478df9 (patch)
tree03d61d72c1b73bbf0b049bf0328f8e0c69f35a43 /fs/ocfs2/file.h
parenta4bfb4cf11fd2211b788af59dc8a8b4394bca227 (diff)
ocfs2: Zero the tail cluster when extending past i_size.
ocfs2's allocation unit is the cluster. This can be larger than a block or even a memory page. This means that a file may have many blocks in its last extent that are beyond the block containing i_size. There also may be more unwritten extents after that. When ocfs2 grows a file, it zeros the entire cluster in order to ensure future i_size growth will see cleared blocks. Unfortunately, block_write_full_page() drops the pages past i_size. This means that ocfs2 is actually leaking garbage data into the tail end of that last cluster. This is a bug. We adjust ocfs2_write_begin_nolock() and ocfs2_extend_file() to detect when a write or truncate is past i_size. They will use ocfs2_zero_extend() to ensure the data is properly zeroed. Older versions of ocfs2_zero_extend() simply zeroed every block between i_size and the zeroing position. This presumes three things: 1) There is allocation for all of these blocks. 2) The extents are not unwritten. 3) The extents are not refcounted. (1) and (2) hold true for non-sparse filesystems, which used to be the only users of ocfs2_zero_extend(). (3) is another bug. Since we're now using ocfs2_zero_extend() for sparse filesystems as well, we teach ocfs2_zero_extend() to check every extent between i_size and the zeroing position. If the extent is unwritten, it is ignored. If it is refcounted, it is CoWed. Then it is zeroed. Signed-off-by: Joel Becker <joel.becker@oracle.com> Cc: stable@kernel.org
Diffstat (limited to 'fs/ocfs2/file.h')
-rw-r--r--fs/ocfs2/file.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/ocfs2/file.h b/fs/ocfs2/file.h
index d66cf4f7c70..97bf761c9e7 100644
--- a/fs/ocfs2/file.h
+++ b/fs/ocfs2/file.h
@@ -54,8 +54,10 @@ int ocfs2_add_inode_data(struct ocfs2_super *osb,
int ocfs2_simple_size_update(struct inode *inode,
struct buffer_head *di_bh,
u64 new_i_size);
-int ocfs2_extend_no_holes(struct inode *inode, u64 new_i_size,
- u64 zero_to);
+int ocfs2_extend_no_holes(struct inode *inode, struct buffer_head *di_bh,
+ u64 new_i_size, u64 zero_to);
+int ocfs2_zero_extend(struct inode *inode, struct buffer_head *di_bh,
+ loff_t zero_to);
int ocfs2_setattr(struct dentry *dentry, struct iattr *attr);
int ocfs2_getattr(struct vfsmount *mnt, struct dentry *dentry,
struct kstat *stat);