Use SA_HDL_PRIVATE for SA xattrs

[zfs.git] / module / zfs / zfs_sa.c

diff --git a/module/zfs/zfs_sa.c b/module/zfs/zfs_sa.c
index 621c5f9..f35f6f6 100644 (file)
--- a/module/zfs/zfs_sa.c
+++ b/module/zfs/zfs_sa.c
@@ -188,6 +188,7 @@ int
 zfs_sa_get_xattr(znode_t *zp)
 {
        zfs_sb_t *zsb = ZTOZSB(zp);
+       sa_handle_t *sa;
        char *obj;
        int size;
        int error;
@@ -196,8 +197,14 @@ zfs_sa_get_xattr(znode_t *zp)
        ASSERT(!zp->z_xattr_cached);
        ASSERT(zp->z_is_sa);
 
-       error = sa_size(zp->z_sa_hdl, SA_ZPL_DXATTR(zsb), &size);
+       error = sa_handle_get(zsb->z_os, zp->z_id, NULL, SA_HDL_PRIVATE, &sa);
+       if (error)
+               return (error);
+
+       error = sa_size(sa, SA_ZPL_DXATTR(zsb), &size);
        if (error) {
+               sa_handle_destroy(sa);
+
                if (error == ENOENT)
                        return nvlist_alloc(&zp->z_xattr_cached,
                            NV_UNIQUE_NAME, KM_SLEEP);
@@ -207,11 +214,12 @@ zfs_sa_get_xattr(znode_t *zp)
 
        obj = sa_spill_alloc(KM_SLEEP);
 
-       error = sa_lookup(zp->z_sa_hdl, SA_ZPL_DXATTR(zsb), obj, size);
+       error = sa_lookup(sa, SA_ZPL_DXATTR(zsb), obj, size);
        if (error == 0)
                error = nvlist_unpack(obj, size, &zp->z_xattr_cached, KM_SLEEP);
 
        sa_spill_free(obj);
+       sa_handle_destroy(sa);
 
        return (error);
 }
@@ -220,6 +228,7 @@ int
 zfs_sa_set_xattr(znode_t *zp)
 {
        zfs_sb_t *zsb = ZTOZSB(zp);
+       sa_handle_t *sa;
        dmu_tx_t *tx;
        char *obj;
        size_t size;
@@ -240,16 +249,30 @@ zfs_sa_set_xattr(znode_t *zp)
        if (error)
                goto out_free;
 
+       /*
+        * A private SA handle must be used to ensure we can drop the hold
+        * on the spill block prior to calling dmu_tx_commit().  If we call
+        * dmu_tx_commit() before sa_handle_destroy(), then our hold will
+        * trigger a copy of the buffer at txg sync time.  This is done to
+        * prevent data from leaking in to the syncing txg.  As a result
+        * the original dirty spill block will be remain dirty in the arc
+        * while the copy is written and laundered.
+        */
+       error = sa_handle_get(zsb->z_os, zp->z_id, NULL, SA_HDL_PRIVATE, &sa);
+       if (error)
+               goto out_free;
+
        tx = dmu_tx_create(zsb->z_os);
        dmu_tx_hold_sa_create(tx, size);
-       dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
+       dmu_tx_hold_sa(tx, sa, B_TRUE);
 
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
+               sa_handle_destroy(sa);
        } else {
-               error = sa_update(zp->z_sa_hdl, SA_ZPL_DXATTR(zsb),
-                   obj, size, tx);
+               error = sa_update(sa, SA_ZPL_DXATTR(zsb), obj, size, tx);
+               sa_handle_destroy(sa);
                if (error)
                        dmu_tx_abort(tx);
                else