1 files changed, 90 insertions, 16 deletions

diff --git a/fs/xfs/xfs_dfrag.c b/fs/xfs/xfs_dfrag.c
index d1483a4f71b8..84ca1cf16a1e 100644
--- a/fs/xfs/xfs_dfrag.c
+++ b/fs/xfs/xfs_dfrag.c
@@ -114,10 +114,82 @@ xfs_swapext(
         return error;
 }
 
+/*
+ * We need to check that the format of the data fork in the temporary inode is
+ * valid for the target inode before doing the swap. This is not a problem with
+ * attr1 because of the fixed fork offset, but attr2 has a dynamically sized
+ * data fork depending on the space the attribute fork is taking so we can get
+ * invalid formats on the target inode.
+ *
+ * E.g. target has space for 7 extents in extent format, temp inode only has
+ * space for 6.  If we defragment down to 7 extents, then the tmp format is a
+ * btree, but when swapped it needs to be in extent format. Hence we can't just
+ * blindly swap data forks on attr2 filesystems.
+ *
+ * Note that we check the swap in both directions so that we don't end up with
+ * a corrupt temporary inode, either.
+ *
+ * Note that fixing the way xfs_fsr sets up the attribute fork in the source
+ * inode will prevent this situation from occurring, so all we do here is
+ * reject and log the attempt. basically we are putting the responsibility on
+ * userspace to get this right.
+ */
+static int
+xfs_swap_extents_check_format(
+        xfs_inode_t     *ip,    /* target inode */
+        xfs_inode_t     *tip)   /* tmp inode */
+{
+
+        /* Should never get a local format */
+        if (ip->i_d.di_format == XFS_DINODE_FMT_LOCAL ||
+            tip->i_d.di_format == XFS_DINODE_FMT_LOCAL)
+                return EINVAL;
+
+        /*
+         * if the target inode has less extents that then temporary inode then
+         * why did userspace call us?
+         */
+        if (ip->i_d.di_nextents < tip->i_d.di_nextents)
+                return EINVAL;
+
+        /*
+         * if the target inode is in extent form and the temp inode is in btree
+         * form then we will end up with the target inode in the wrong format
+         * as we already know there are less extents in the temp inode.
+         */
+        if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
+            tip->i_d.di_format == XFS_DINODE_FMT_BTREE)
+                return EINVAL;
+
+        /* Check temp in extent form to max in target */
+        if (tip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
+            XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK) > ip->i_df.if_ext_max)
+                return EINVAL;
+
+        /* Check target in extent form to max in temp */
+        if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
+            XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK) > tip->i_df.if_ext_max)
+                return EINVAL;
+
+        /* Check root block of temp in btree form to max in target */
+        if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE &&
+            XFS_IFORK_BOFF(ip) &&
+            tip->i_df.if_broot_bytes > XFS_IFORK_BOFF(ip))
+                return EINVAL;
+
+        /* Check root block of target in btree form to max in temp */
+        if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE &&
+            XFS_IFORK_BOFF(tip) &&
+            ip->i_df.if_broot_bytes > XFS_IFORK_BOFF(tip))
+                return EINVAL;
+
+        return 0;
+}
+
 int
 xfs_swap_extents(
-        xfs_inode_t     *ip,
-        xfs_inode_t     *tip,
+        xfs_inode_t     *ip,    /* target inode */
+        xfs_inode_t     *tip,   /* tmp inode */
         xfs_swapext_t   *sxp)
 {
         xfs_mount_t     *mp;
@@ -161,13 +233,6 @@ xfs_swap_extents(
                 goto out_unlock;
         }
 
-        /* Should never get a local format */
-        if (ip->i_d.di_format == XFS_DINODE_FMT_LOCAL ||
-            tip->i_d.di_format == XFS_DINODE_FMT_LOCAL) {
-                error = XFS_ERROR(EINVAL);
-                goto out_unlock;
-        }
-
         if (VN_CACHED(VFS_I(tip)) != 0) {
                 error = xfs_flushinval_pages(tip, 0, -1,
                                 FI_REMAPF_LOCKED);
@@ -189,13 +254,12 @@ xfs_swap_extents(
                 goto out_unlock;
         }
 
-        /*
-         * If the target has extended attributes, the tmp file
-         * must also in order to ensure the correct data fork
-         * format.
-         */
-        if ( XFS_IFORK_Q(ip) != XFS_IFORK_Q(tip) ) {
-                error = XFS_ERROR(EINVAL);
+        /* check inode formats now that data is flushed */
+        error = xfs_swap_extents_check_format(ip, tip);
+        if (error) {
+                xfs_fs_cmn_err(CE_NOTE, mp,
+                    "%s: inode 0x%llx format is incompatible for exchanging.",
+                                __FILE__, ip->i_ino);
                 goto out_unlock;
         }
 
@@ -276,6 +340,16 @@ xfs_swap_extents(
         *tifp = *tempifp;       /* struct copy */
 
         /*
+         * Fix the in-memory data fork values that are dependent on the fork
+         * offset in the inode. We can't assume they remain the same as attr2
+         * has dynamic fork offsets.
+         */
+        ifp->if_ext_max = XFS_IFORK_SIZE(ip, XFS_DATA_FORK) /
+                                        (uint)sizeof(xfs_bmbt_rec_t);
+        tifp->if_ext_max = XFS_IFORK_SIZE(tip, XFS_DATA_FORK) /
+                                        (uint)sizeof(xfs_bmbt_rec_t);
+
+        /*
          * Fix the on-disk inode values
          */
         tmp = (__uint64_t)ip->i_d.di_nblocks;