xfs: use EFI refcount consistently in log recovery

The EFI is initialized with a reference count of 2. One for the EFI to
ensure the item makes it to the AIL and one for the subsequently created
EFD to release the EFI once the EFD is committed. Log recovery uses the
EFI in a similar manner, but implements a hack to remove both references
in one call once the EFD is handled.

Update log recovery to use EFI reference counting in a manner consistent
with the log. When an EFI is encountered during recovery, an EFI item is
allocated and inserted to the AIL directly. Since the EFI reference is
typically dropped when the EFI is unpinned and this is analogous with
AIL insertion, drop the EFI reference at this point.

When a corresponding EFD is encountered in the log, this indicates that
the extents were freed, no processing is required and the EFI can be
dropped. Update xlog_recover_efd_pass2() to simply drop the EFD
reference at this point rather than open code the AIL removal and EFI
free.

Remaining EFIs (i.e., with no corresponding EFD) are processed in
xlog_recover_finish(). An EFD transaction is allocated and the extents
are freed, which transfers ownership of the EFI reference to the EFD
item in the log.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 23 insertions, 20 deletions

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 434ba2cdf6e8..05c0cc83f9a4 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2928,16 +2928,16 @@ xlog_recover_efi_pass2(
         struct xlog_recover_item        *item,
         xfs_lsn_t                       lsn)
 {
-        int                     error;
-        xfs_mount_t             *mp = log->l_mp;
-        xfs_efi_log_item_t      *efip;
-        xfs_efi_log_format_t    *efi_formatp;
+        int                             error;
+        struct xfs_mount                *mp = log->l_mp;
+        struct xfs_efi_log_item         *efip;
+        struct xfs_efi_log_format       *efi_formatp;
 
         efi_formatp = item->ri_buf[0].i_addr;
 
         efip = xfs_efi_init(mp, efi_formatp->efi_nextents);
-        if ((error = xfs_efi_copy_format(&(item->ri_buf[0]),
-                                         &(efip->efi_format)))) {
+        error = xfs_efi_copy_format(&item->ri_buf[0], &efip->efi_format);
+        if (error) {
                 xfs_efi_item_free(efip);
                 return error;
         }
@@ -2945,20 +2945,23 @@ xlog_recover_efi_pass2(
 
         spin_lock(&log->l_ailp->xa_lock);
         /*
-         * xfs_trans_ail_update() drops the AIL lock.
+         * The EFI has two references. One for the EFD and one for EFI to ensure
+         * it makes it into the AIL. Insert the EFI into the AIL directly and
+         * drop the EFI reference. Note that xfs_trans_ail_update() drops the
+         * AIL lock.
          */
         xfs_trans_ail_update(log->l_ailp, &efip->efi_item, lsn);
+        xfs_efi_release(efip);
         return 0;
 }
 
 
 /*
- * This routine is called when an efd format structure is found in
- * a committed transaction in the log.  It's purpose is to cancel
- * the corresponding efi if it was still in the log.  To do this
- * it searches the AIL for the efi with an id equal to that in the
- * efd format structure.  If we find it, we remove the efi from the
- * AIL and free it.
+ * This routine is called when an EFD format structure is found in a committed
+ * transaction in the log. Its purpose is to cancel the corresponding EFI if it
+ * was still in the log. To do this it searches the AIL for the EFI with an id
+ * equal to that in the EFD format structure. If we find it we drop the EFD
+ * reference, which removes the EFI from the AIL and frees it.
  */
 STATIC int
 xlog_recover_efd_pass2(
@@ -2980,8 +2983,8 @@ xlog_recover_efd_pass2(
         efi_id = efd_formatp->efd_efi_id;
 
         /*
-         * Search for the efi with the id in the efd format structure
-         * in the AIL.
+         * Search for the EFI with the id in the EFD format structure in the
+         * AIL.
          */
         spin_lock(&ailp->xa_lock);
         lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
@@ -2990,18 +2993,18 @@ xlog_recover_efd_pass2(
                         efip = (xfs_efi_log_item_t *)lip;
                         if (efip->efi_format.efi_id == efi_id) {
                                 /*
-                                 * xfs_trans_ail_delete() drops the
-                                 * AIL lock.
+                                 * Drop the EFD reference to the EFI. This
+                                 * removes the EFI from the AIL and frees it.
                                  */
-                                xfs_trans_ail_delete(ailp, lip,
-                                                     SHUTDOWN_CORRUPT_INCORE);
-                                xfs_efi_item_free(efip);
+                                spin_unlock(&ailp->xa_lock);
+                                xfs_efi_release(efip);
                                 spin_lock(&ailp->xa_lock);
                                 break;
                         }
                 }
                 lip = xfs_trans_ail_cursor_next(ailp, &cur);
         }
+
         xfs_trans_ail_cursor_done(&cur);
         spin_unlock(&ailp->xa_lock);