xfs: add online discard support

Now that we have reliably tracking of deleted extents in a
transaction we can easily implement "online" discard support
which calls blkdev_issue_discard once a transaction commits.

The actual discard is a two stage operation as we first have
to mark the busy extent as not available for reuse before we
can start the actual discard.  Note that we don't bother
supporting discard for the non-delaylog mode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 7d56e88a3f0e..c7755d5a5fbe 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -29,6 +29,7 @@
 #include "xfs_mount.h"
 #include "xfs_error.h"
 #include "xfs_alloc.h"
+#include "xfs_discard.h"
 
 /*
  * Perform initial CIL structure initialisation. If the CIL is not
@@ -361,18 +362,28 @@ xlog_cil_committed(
         int     abort)
 {
         struct xfs_cil_ctx      *ctx = args;
+        struct xfs_mount        *mp = ctx->cil->xc_log->l_mp;
 
         xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain,
                                         ctx->start_lsn, abort);
 
         xfs_alloc_busy_sort(&ctx->busy_extents);
-        xfs_alloc_busy_clear(ctx->cil->xc_log->l_mp, &ctx->busy_extents);
+        xfs_alloc_busy_clear(mp, &ctx->busy_extents,
+                             (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
 
         spin_lock(&ctx->cil->xc_cil_lock);
         list_del(&ctx->committing);
         spin_unlock(&ctx->cil->xc_cil_lock);
 
         xlog_cil_free_logvec(ctx->lv_chain);
+
+        if (!list_empty(&ctx->busy_extents)) {
+                ASSERT(mp->m_flags & XFS_MOUNT_DISCARD);
+
+                xfs_discard_extents(mp, &ctx->busy_extents);
+                xfs_alloc_busy_clear(mp, &ctx->busy_extents, false);
+        }
+
         kmem_free(ctx);
 }