Messages in this thread Patch in this message | | | Date | Tue, 09 Jun 2009 17:14:25 -0700 | From | Greg KH <> | Subject | [patch 57/60] ext4: Fix sub-block zeroing for writes into preallocated extents |
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-stable review patch. If anyone has any objections, please let us know.
------------------ From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
(cherry picked from commit 9c1ee184a30394e54165fa4c15923cabd952c106)
We need to mark the buffer_head mapping preallocated 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.
Now that we mark the buffer_head new we also need to have a valid buffer_head blocknr so that unmap_underlying_metadata() unmaps the correct block.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- fs/ext4/extents.c | 2 ++ fs/ext4/inode.c | 7 +++++++ 2 files changed, 9 insertions(+)
--- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -2670,6 +2670,8 @@ int ext4_ext_get_blocks(handle_t *handle if (allocated > max_blocks) allocated = max_blocks; set_buffer_unwritten(bh_result); + bh_result->b_bdev = inode->i_sb->s_bdev; + bh_result->b_blocknr = newblock; goto out2; } --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2131,6 +2131,13 @@ static int ext4_da_get_block_prep(struct set_buffer_delay(bh_result); } else if (ret > 0) { bh_result->b_size = (ret << inode->i_blkbits); + /* + * 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; }
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