xfs: Pull EFI/EFD handling out from under the AIL lock

EFI/EFD interactions are protected from races by the AIL lock. They
are the only type of log items that require the the AIL lock to
serialise internal state, so they need to be separated from the AIL
lock before we can do bulk insert operations on the AIL.

To acheive this, convert the counter of the number of extents in the
EFI to an atomic so it can be safely manipulated by EFD processing
without locks. Also, convert the EFI state flag manipulations to use
atomic bit operations so no locks are needed to record state
changes. Finally, use the state bits to determine when it is safe to
free the EFI and clean up the code to do this neatly.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/xfs/xfs_extfree_item.h b/fs/xfs/xfs_extfree_item.h
index f7834ec8efad..375f68e42531 100644
--- a/fs/xfs/xfs_extfree_item.h
+++ b/fs/xfs/xfs_extfree_item.h
@@ -111,10 +111,10 @@ typedef struct xfs_efd_log_format_64 {
 #define	XFS_EFI_MAX_FAST_EXTENTS	16
 
 /*
- * Define EFI flags.
+ * Define EFI flag bits. Manipulated by set/clear/test_bit operators.
  */
-#define	XFS_EFI_RECOVERED	0x1
-#define	XFS_EFI_COMMITTED	0x2
+#define	XFS_EFI_RECOVERED	1
+#define	XFS_EFI_COMMITTED	2
 
 /*
  * This is the "extent free intention" log item.  It is used
@@ -124,8 +124,8 @@ typedef struct xfs_efd_log_format_64 {
  */
 typedef struct xfs_efi_log_item {
 	xfs_log_item_t		efi_item;
-	uint			efi_flags;	/* misc flags */
-	uint			efi_next_extent;
+	atomic_t		efi_next_extent;
+	unsigned long		efi_flags;	/* misc flags */
 	xfs_efi_log_format_t	efi_format;
 } xfs_efi_log_item_t;