[PATCH 15/14] xfs: capture inode generation numbers in the ondisk exchmaps log item

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

Per some very late review comments, capture the generation numbers of
both inodes involved in a file content exchange operation so that we
don't accidentally target files with have been reallocated.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
I'm throwing this one on the pile since I guess it's not so hard to add
the generation number to a brand new log item.
---
 fs/xfs/libxfs/xfs_log_format.h |    2 ++
 fs/xfs/xfs_exchmaps_item.c     |   12 ++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
index 8dbe1f997dfd5..accba2acd623d 100644
--- a/fs/xfs/libxfs/xfs_log_format.h
+++ b/fs/xfs/libxfs/xfs_log_format.h
@@ -896,6 +896,8 @@ struct xfs_xmi_log_format {
 
 	uint64_t		xmi_inode1;	/* inumber of first file */
 	uint64_t		xmi_inode2;	/* inumber of second file */
+	uint32_t		xmi_igen1;	/* generation of first file */
+	uint32_t		xmi_igen2;	/* generation of second file */
 	uint64_t		xmi_startoff1;	/* block offset into file1 */
 	uint64_t		xmi_startoff2;	/* block offset into file2 */
 	uint64_t		xmi_blockcount;	/* number of blocks */
diff --git a/fs/xfs/xfs_exchmaps_item.c b/fs/xfs/xfs_exchmaps_item.c
index a40216f33214c..3c4bb9601c3e0 100644
--- a/fs/xfs/xfs_exchmaps_item.c
+++ b/fs/xfs/xfs_exchmaps_item.c
@@ -231,7 +231,9 @@ xfs_exchmaps_create_intent(
 	xlf = &xmi_lip->xmi_format;
 
 	xlf->xmi_inode1 = xmi->xmi_ip1->i_ino;
+	xlf->xmi_igen1 = VFS_I(xmi->xmi_ip1)->i_generation;
 	xlf->xmi_inode2 = xmi->xmi_ip2->i_ino;
+	xlf->xmi_igen2 = VFS_I(xmi->xmi_ip2)->i_generation;
 	xlf->xmi_startoff1 = xmi->xmi_startoff1;
 	xlf->xmi_startoff2 = xmi->xmi_startoff2;
 	xlf->xmi_blockcount = xmi->xmi_blockcount;
@@ -377,6 +379,14 @@ xfs_xmi_item_recover_intent(
 	if (error)
 		goto err_rele1;
 
+	if (VFS_I(ip1)->i_generation != xlf->xmi_igen1 ||
+	    VFS_I(ip2)->i_generation != xlf->xmi_igen2) {
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+				xlf, sizeof(*xlf));
+		error = -EFSCORRUPTED;
+		goto err_rele2;
+	}
+
 	req->ip1 = ip1;
 	req->ip2 = ip2;
 	req->startoff1 = xlf->xmi_startoff1;
@@ -485,6 +495,8 @@ xfs_exchmaps_relog_intent(
 
 	new_xlf->xmi_inode1	= old_xlf->xmi_inode1;
 	new_xlf->xmi_inode2	= old_xlf->xmi_inode2;
+	new_xlf->xmi_igen1	= old_xlf->xmi_igen1;
+	new_xlf->xmi_igen2	= old_xlf->xmi_igen2;
 	new_xlf->xmi_startoff1	= old_xlf->xmi_startoff1;
 	new_xlf->xmi_startoff2	= old_xlf->xmi_startoff2;
 	new_xlf->xmi_blockcount	= old_xlf->xmi_blockcount;