xfs: use ->t_firstblock in xattr ops

Similar to the dirops code, the xattr code uses an on-stack
firstblock variable for the various operations. This code rolls the
underlying transaction in various places, however, which means we
cannot simply replace the local firstblock vars with ->t_firstblock.
Doing so (without further changes) would invalidate the memory
pointed to by xfs_da_args.firstblock as soon as the first
transaction rolls.

To avoid this problem, remove xfs_da_args.firstblock and replace all
such accesses with ->t_firstblock at the same time. This ensures
that accesses to the current firstblock always occur through the
current transaction rather than a potentially invalid xfs_da_args
pointer.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

7 files changed, 33 insertions, 38 deletions

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 8a7e2c0308c4..153d2e29f872 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -204,7 +204,6 @@ xfs_attr_set(
         struct xfs_da_args      args;
         struct xfs_defer_ops    dfops;
         struct xfs_trans_res    tres;
-        xfs_fsblock_t           firstblock;
         int                     rsvd = (flags & ATTR_ROOT) != 0;
         int                     error, err2, local;
 
@@ -219,7 +218,6 @@ xfs_attr_set(
 
         args.value = value;
         args.valuelen = valuelen;
-        args.firstblock = &firstblock;
         args.op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
         args.total = xfs_attr_calc_size(&args, &local);
 
@@ -253,7 +251,7 @@ xfs_attr_set(
                         rsvd ? XFS_TRANS_RESERVE : 0, &args.trans);
         if (error)
                 return error;
-        xfs_defer_init(args.trans, &dfops, &firstblock);
+        xfs_defer_init(args.trans, &dfops, &args.trans->t_firstblock);
 
         xfs_ilock(dp, XFS_ILOCK_EXCL);
         error = xfs_trans_reserve_quota_nblks(args.trans, dp, args.total, 0,
@@ -392,7 +390,6 @@ xfs_attr_remove(
         struct xfs_mount        *mp = dp->i_mount;
         struct xfs_da_args      args;
         struct xfs_defer_ops    dfops;
-        xfs_fsblock_t           firstblock;
         int                     error;
 
         XFS_STATS_INC(mp, xs_attr_remove);
@@ -404,8 +401,6 @@ xfs_attr_remove(
         if (error)
                 return error;
 
-        args.firstblock = &firstblock;
-
         /*
          * we have no control over the attribute names that userspace passes us
          * to remove, so we have to allow the name lookup prior to attribute
@@ -427,7 +422,7 @@ xfs_attr_remove(
                         &args.trans);
         if (error)
                 return error;
-        xfs_defer_init(args.trans, &dfops, &firstblock);
+        xfs_defer_init(args.trans, &dfops, &args.trans->t_firstblock);
 
         xfs_ilock(dp, XFS_ILOCK_EXCL);
         /*
@@ -598,7 +593,8 @@ xfs_attr_leaf_addname(
                  * Commit that transaction so that the node_addname() call
                  * can manage its own transactions.
                  */
-                xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+                xfs_defer_init(args->trans, args->trans->t_dfops,
+                               &args->trans->t_firstblock);
                 error = xfs_attr3_leaf_to_node(args);
                 if (error)
                         goto out_defer_cancel;
@@ -687,8 +683,8 @@ xfs_attr_leaf_addname(
                  * If the result is small enough, shrink it all into the inode.
                  */
                 if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
-                        xfs_defer_init(NULL, args->trans->t_dfops,
-                                       args->firstblock);
+                        xfs_defer_init(args->trans, args->trans->t_dfops,
+                                       &args->trans->t_firstblock);
                         error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                         /* bp is gone due to xfs_da_shrink_inode */
                         if (error)
@@ -753,7 +749,8 @@ xfs_attr_leaf_removename(
          * If the result is small enough, shrink it all into the inode.
          */
         if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
-                xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+                xfs_defer_init(args->trans, args->trans->t_dfops,
+                               &args->trans->t_firstblock);
                 error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                 /* bp is gone due to xfs_da_shrink_inode */
                 if (error)
@@ -882,8 +879,8 @@ restart:
                          */
                         xfs_da_state_free(state);
                         state = NULL;
-                        xfs_defer_init(NULL, args->trans->t_dfops,
-                                       args->firstblock);
+                        xfs_defer_init(args->trans, args->trans->t_dfops,
+                                       &args->trans->t_firstblock);
                         error = xfs_attr3_leaf_to_node(args);
                         if (error)
                                 goto out_defer_cancel;
@@ -910,7 +907,8 @@ restart:
                  * in the index/blkno/rmtblkno/rmtblkcnt fields and
                  * in the index2/blkno2/rmtblkno2/rmtblkcnt2 fields.
                  */
-                xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+                xfs_defer_init(args->trans, args->trans->t_dfops,
+                               &args->trans->t_firstblock);
                 error = xfs_da3_split(state);
                 if (error)
                         goto out_defer_cancel;
@@ -1008,8 +1006,8 @@ restart:
                  * Check to see if the tree needs to be collapsed.
                  */
                 if (retval && (state->path.active > 1)) {
-                        xfs_defer_init(NULL, args->trans->t_dfops,
-                                       args->firstblock);
+                        xfs_defer_init(args->trans, args->trans->t_dfops,
+                                       &args->trans->t_firstblock);
                         error = xfs_da3_join(state);
                         if (error)
                                 goto out_defer_cancel;
@@ -1134,7 +1132,8 @@ xfs_attr_node_removename(
          * Check to see if the tree needs to be collapsed.
          */
         if (retval && (state->path.active > 1)) {
-                xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+                xfs_defer_init(args->trans, args->trans->t_dfops,
+                               &args->trans->t_firstblock);
                 error = xfs_da3_join(state);
                 if (error)
                         goto out_defer_cancel;
@@ -1166,8 +1165,8 @@ xfs_attr_node_removename(
                         goto out;
 
                 if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
-                        xfs_defer_init(NULL, args->trans->t_dfops,
-                                       args->firstblock);
+                        xfs_defer_init(args->trans, args->trans->t_dfops,
+                                       &args->trans->t_firstblock);
                         error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
                         /* bp is gone due to xfs_da_shrink_inode */
                         if (error)
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index c131469db0f1..251304f3bc5d 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -802,7 +802,6 @@ xfs_attr_shortform_to_leaf(
         memset((char *)&nargs, 0, sizeof(nargs));
         nargs.dp = dp;
         nargs.geo = args->geo;
-        nargs.firstblock = args->firstblock;
         nargs.total = args->total;
         nargs.whichfork = XFS_ATTR_FORK;
         nargs.trans = args->trans;
@@ -1005,7 +1004,6 @@ xfs_attr3_leaf_to_shortform(
         memset((char *)&nargs, 0, sizeof(nargs));
         nargs.geo = args->geo;
         nargs.dp = dp;
-        nargs.firstblock = args->firstblock;
         nargs.total = args->total;
         nargs.whichfork = XFS_ATTR_FORK;
         nargs.trans = args->trans;
diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
index ab7c2755ad8c..205098aeb4bc 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.c
+++ b/fs/xfs/libxfs/xfs_attr_remote.c
@@ -480,11 +480,13 @@ xfs_attr_rmtval_set(
                  * extent and then crash then the block may not contain the
                  * correct metadata after log recovery occurs.
                  */
-                xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+                xfs_defer_init(args->trans, args->trans->t_dfops,
+                               &args->trans->t_firstblock);
                 nmap = 1;
                 error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
-                                  blkcnt, XFS_BMAPI_ATTRFORK, args->firstblock,
-                                  args->total, &map, &nmap);
+                                  blkcnt, XFS_BMAPI_ATTRFORK,
+                                  &args->trans->t_firstblock, args->total, &map,
+                                  &nmap);
                 if (error)
                         goto out_defer_cancel;
                 xfs_defer_ijoin(args->trans->t_dfops, dp);
@@ -522,7 +524,8 @@ xfs_attr_rmtval_set(
 
                 ASSERT(blkcnt > 0);
 
-                xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+                xfs_defer_init(args->trans, args->trans->t_dfops,
+                               &args->trans->t_firstblock);
                 nmap = 1;
                 error = xfs_bmapi_read(dp, (xfs_fileoff_t)lblkno,
                                        blkcnt, &map, &nmap,
@@ -626,10 +629,11 @@ xfs_attr_rmtval_remove(
         blkcnt = args->rmtblkcnt;
         done = 0;
         while (!done) {
-                xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+                xfs_defer_init(args->trans, args->trans->t_dfops,
+                               &args->trans->t_firstblock);
                 error = xfs_bunmapi(args->trans, args->dp, lblkno, blkcnt,
-                                    XFS_BMAPI_ATTRFORK, 1, args->firstblock,
-                                    &done);
+                                    XFS_BMAPI_ATTRFORK, 1,
+                                    &args->trans->t_firstblock, &done);
                 if (error)
                         goto out_defer_cancel;
                 xfs_defer_ijoin(args->trans->t_dfops, args->dp);
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index da73c1a011d3..6f9b2cddb933 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1000,7 +1000,6 @@ xfs_bmap_add_attrfork_local(
                 memset(&dargs, 0, sizeof(dargs));
                 dargs.geo = ip->i_mount->m_dir_geo;
                 dargs.dp = ip;
-                dargs.firstblock = &tp->t_firstblock;
                 dargs.total = dargs.geo->fsbcount;
                 dargs.whichfork = XFS_DATA_FORK;
                 dargs.trans = tp;
diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 68a72e3d9f53..2f2be86c10dc 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -2059,10 +2059,9 @@ xfs_da_grow_inode_int(
          * Try mapping it in one filesystem block.
          */
         nmap = 1;
-        ASSERT(args->firstblock != NULL);
         error = xfs_bmapi_write(tp, dp, *bno, count,
                         xfs_bmapi_aflag(w)|XFS_BMAPI_METADATA|XFS_BMAPI_CONTIG,
-                        args->firstblock, args->total, &map, &nmap);
+                        &tp->t_firstblock, args->total, &map, &nmap);
         if (error)
                 return error;
 
@@ -2084,7 +2083,7 @@ xfs_da_grow_inode_int(
                         c = (int)(*bno + count - b);
                         error = xfs_bmapi_write(tp, dp, b, c,
                                         xfs_bmapi_aflag(w)|XFS_BMAPI_METADATA,
-                                        args->firstblock, args->total,
+                                        &tp->t_firstblock, args->total,
                                         &mapp[mapi], &nmap);
                         if (error)
                                 goto out_free_map;
@@ -2394,7 +2393,7 @@ xfs_da_shrink_inode(
                  * the last block to the place we want to kill.
                  */
                 error = xfs_bunmapi(tp, dp, dead_blkno, count,
-                                    xfs_bmapi_aflag(w), 0, args->firstblock,
+                                    xfs_bmapi_aflag(w), 0, &tp->t_firstblock,
                                     &done);
                 if (error == -ENOSPC) {
                         if (w != XFS_DATA_FORK)
diff --git a/fs/xfs/libxfs/xfs_da_btree.h b/fs/xfs/libxfs/xfs_da_btree.h
index 6b8a04f3f162..59e290ef334f 100644
--- a/fs/xfs/libxfs/xfs_da_btree.h
+++ b/fs/xfs/libxfs/xfs_da_btree.h
@@ -57,7 +57,6 @@ typedef struct xfs_da_args {
         xfs_dahash_t    hashval;        /* hash value of name */
         xfs_ino_t       inumber;        /* input/output inode number */
         struct xfs_inode *dp;           /* directory inode to manipulate */
-        xfs_fsblock_t   *firstblock;    /* ptr to firstblock for bmap calls */
         struct xfs_trans *trans;        /* current trans (changes over time) */
         xfs_extlen_t    total;          /* total blocks needed, for 1st bmap */
         int             whichfork;      /* data or attribute fork */
diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index a3983e3eb64a..5db73d96b99e 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -272,7 +272,6 @@ xfs_dir_createname(
         args->total = total;
         args->whichfork = XFS_DATA_FORK;
         args->trans = tp;
-        args->firstblock = &tp->t_firstblock;
         args->op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
         if (!inum)
                 args->op_flags |= XFS_DA_OP_JUSTCHECK;
@@ -439,7 +438,6 @@ xfs_dir_removename(
         args->hashval = dp->i_mount->m_dirnameops->hashname(name);
         args->inumber = ino;
         args->dp = dp;
-        args->firstblock = &tp->t_firstblock;
         args->total = total;
         args->whichfork = XFS_DATA_FORK;
         args->trans = tp;
@@ -502,7 +500,6 @@ xfs_dir_replace(
         args->hashval = dp->i_mount->m_dirnameops->hashname(name);
         args->inumber = inum;
         args->dp = dp;
-        args->firstblock = &tp->t_firstblock;
         args->total = total;
         args->whichfork = XFS_DATA_FORK;
         args->trans = tp;
@@ -660,7 +657,7 @@ xfs_dir2_shrink_inode(
 
         /* Unmap the fsblock(s). */
         error = xfs_bunmapi(tp, dp, da, args->geo->fsbcount, 0, 0,
-                            args->firstblock, &done);
+                            &tp->t_firstblock, &done);
         if (error) {
                 /*
                  * ENOSPC actually can happen if we're in a removename with no