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| author | Joel Becker <joel.becker@oracle.com> | 2010-07-02 02:13:31 +0400 |
|---|---|---|
| committer | Joel Becker <joel.becker@oracle.com> | 2010-07-09 00:25:35 +0400 |
| commit | 5693486bad2bc2ac585a2c24f7e2f3964b478df9 (patch) | |
| tree | 03d61d72c1b73bbf0b049bf0328f8e0c69f35a43 /fs/ocfs2/quota_local.c | |
| parent | a4bfb4cf11fd2211b788af59dc8a8b4394bca227 (diff) | |
| download | linux-5693486bad2bc2ac585a2c24f7e2f3964b478df9.tar.xz | |
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/quota_local.c')
| -rw-r--r-- | fs/ocfs2/quota_local.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c index 8bd70d4d184d..dc78764ccc4c 100644 --- a/fs/ocfs2/quota_local.c +++ b/fs/ocfs2/quota_local.c @@ -971,7 +971,7 @@ static struct ocfs2_quota_chunk *ocfs2_local_quota_add_chunk( u64 p_blkno; /* We are protected by dqio_sem so no locking needed */ - status = ocfs2_extend_no_holes(lqinode, + status = ocfs2_extend_no_holes(lqinode, NULL, lqinode->i_size + 2 * sb->s_blocksize, lqinode->i_size); if (status < 0) { @@ -1114,7 +1114,7 @@ static struct ocfs2_quota_chunk *ocfs2_extend_local_quota_file( return ocfs2_local_quota_add_chunk(sb, type, offset); /* We are protected by dqio_sem so no locking needed */ - status = ocfs2_extend_no_holes(lqinode, + status = ocfs2_extend_no_holes(lqinode, NULL, lqinode->i_size + sb->s_blocksize, lqinode->i_size); if (status < 0) { |