Fix unlinked file cannot do xattr operations

Currently, doing things like fsetxattr(2) on an unlinked file will result in
ENODATA. There's two places that cause this: zfs_dirent_lock and zfs_zget.

The fix in zfs_dirent_lock is pretty straightforward. In zfs_zget though, we
need it to not return error when the zp is unlinked. This is a pretty big
change in behavior, but skimming through all the callers, I don't think this
change would cause any problem. Also there's nothing preventing z_unlinked
from being set after the z_lock mutex is dropped before but before zfs_zget
returns anyway.

The rest of the stuff is to make sure we don't log xattr stuff when owner is
unlinked.

Signed-off-by: Chunwei Chen <[email protected]>

1 files changed, 34 insertions, 4 deletions

diff --git a/module/zfs/zfs_log.c b/module/zfs/zfs_log.c
index 69efb3c16..8bb8b0a97 100644
--- a/module/zfs/zfs_log.c
+++ b/module/zfs/zfs_log.c
@@ -212,6 +212,34 @@ zfs_log_fuid_domains(zfs_fuid_info_t *fuidp, void *start)
 }
 
 /*
+ * If zp is an xattr node, check whether the xattr owner is unlinked.
+ * We don't want to log anything if the owner is unlinked.
+ */
+static int
+zfs_xattr_owner_unlinked(znode_t *zp)
+{
+	int unlinked = 0;
+	znode_t *dzp;
+	igrab(ZTOI(zp));
+	/*
+	 * if zp is XATTR node, keep walking up via z_xattr_parent until we
+	 * get the owner
+	 */
+	while (zp->z_pflags & ZFS_XATTR) {
+		ASSERT3U(zp->z_xattr_parent, !=, 0);
+		if (zfs_zget(ZTOZSB(zp), zp->z_xattr_parent, &dzp) != 0) {
+			unlinked = 1;
+			break;
+		}
+		iput(ZTOI(zp));
+		zp = dzp;
+		unlinked = zp->z_unlinked;
+	}
+	iput(ZTOI(zp));
+	return (unlinked);
+}
+
+/*
  * Handles TX_CREATE, TX_CREATE_ATTR, TX_MKDIR, TX_MKDIR_ATTR and
  * TK_MKXATTR transactions.
  *
@@ -247,7 +275,7 @@ zfs_log_create(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
 	size_t namesize = strlen(name) + 1;
 	size_t fuidsz = 0;
 
-	if (zil_replaying(zilog, tx))
+	if (zil_replaying(zilog, tx) || zfs_xattr_owner_unlinked(dzp))
 		return;
 
 	/*
@@ -352,7 +380,7 @@ zfs_log_remove(zilog_t *zilog, dmu_tx_t *tx, uint64_t txtype,
 	lr_remove_t *lr;
 	size_t namesize = strlen(name) + 1;
 
-	if (zil_replaying(zilog, tx))
+	if (zil_replaying(zilog, tx) || zfs_xattr_owner_unlinked(dzp))
 		return;
 
 	itx = zil_itx_create(txtype, sizeof (*lr) + namesize);
@@ -463,7 +491,8 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 	uintptr_t fsync_cnt;
 	ssize_t immediate_write_sz;
 
-	if (zil_replaying(zilog, tx) || zp->z_unlinked) {
+	if (zil_replaying(zilog, tx) || zp->z_unlinked ||
+	    zfs_xattr_owner_unlinked(zp)) {
 		if (callback != NULL)
 			callback(callback_data);
 		return;
@@ -543,7 +572,8 @@ zfs_log_truncate(zilog_t *zilog, dmu_tx_t *tx, int txtype,
 	itx_t *itx;
 	lr_truncate_t *lr;
 
-	if (zil_replaying(zilog, tx) || zp->z_unlinked)
+	if (zil_replaying(zilog, tx) || zp->z_unlinked ||
+	    zfs_xattr_owner_unlinked(zp))
 		return;
 
 	itx = zil_itx_create(txtype, sizeof (*lr));