From patchwork Mon May 9 16:41:30 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [RFC,12/30] ext4: snapshot file - store on disk Date: Mon, 09 May 2011 06:41:30 -0000 From: "Amir G." X-Patchwork-Id: 94804 Message-Id: <1304959308-11122-13-git-send-email-amir73il@users.sourceforge.net> To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, Amir Goldstein , Yongqiang Yang From: Amir Goldstein Snapshot inode is stored differently in memory and on disk. During store and load of snapshot inode, some of the inode flags and fields are converted. Signed-off-by: Amir Goldstein Signed-off-by: Yongqiang Yang --- fs/ext4/inode.c | 33 +++++++++++++++++++++++++++------ 1 files changed, 27 insertions(+), 6 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c3af773..db1706f 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5201,6 +5201,17 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) */ for (block = 0; block < EXT4_N_BLOCKS; block++) ei->i_data[block] = raw_inode->i_block[block]; + /* snapshot on-disk list is stored in snapshot inode on-disk version */ + if (ext4_snapshot_file(inode)) { + ei->i_next_snapshot_ino = + le32_to_cpu(raw_inode->i_disk_version); + /* + * snapshot volume size is stored in i_disksize. + * in-memory i_size of snapshot files is set to 0 (disabled). + * enabling a snapshot is setting i_size to i_disksize. + */ + inode->i_size = 0; + } INIT_LIST_HEAD(&ei->i_orphan); /* @@ -5465,12 +5476,22 @@ static int ext4_do_update_inode(handle_t *handle, for (block = 0; block < EXT4_N_BLOCKS; block++) raw_inode->i_block[block] = ei->i_data[block]; - raw_inode->i_disk_version = cpu_to_le32(inode->i_version); - if (ei->i_extra_isize) { - if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi)) - raw_inode->i_version_hi = - cpu_to_le32(inode->i_version >> 32); - raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize); + if (ext4_snapshot_file(inode)) { + /* + * Snapshot on-disk list overrides snapshot on-disk version. + * Snapshot files are not writable and have a fixed version. + */ + raw_inode->i_disk_version = + cpu_to_le32(ei->i_next_snapshot_ino); + } else { + raw_inode->i_disk_version = cpu_to_le32(inode->i_version); + if (ei->i_extra_isize) { + if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi)) + raw_inode->i_version_hi = + cpu_to_le32(inode->i_version >> 32); + raw_inode->i_extra_isize = + cpu_to_le16(ei->i_extra_isize); + } } BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");