9 files changed, 90 insertions, 8 deletions

diff --git a/fs/xfs/linux-2.6/xfs_discard.c b/fs/xfs/linux-2.6/xfs_discard.c
index d61611c88012..244e797dae32 100644
--- a/fs/xfs/linux-2.6/xfs_discard.c
+++ b/fs/xfs/linux-2.6/xfs_discard.c
@@ -191,3 +191,32 @@ xfs_ioc_trim(
                 return -XFS_ERROR(EFAULT);
         return 0;
 }
+
+int
+xfs_discard_extents(
+        struct xfs_mount        *mp,
+        struct list_head        *list)
+{
+        struct xfs_busy_extent  *busyp;
+        int                     error = 0;
+
+        list_for_each_entry(busyp, list, list) {
+                trace_xfs_discard_extent(mp, busyp->agno, busyp->bno,
+                                         busyp->length);
+
+                error = -blkdev_issue_discard(mp->m_ddev_targp->bt_bdev,
+                                XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno),
+                                XFS_FSB_TO_BB(mp, busyp->length),
+                                GFP_NOFS, 0);
+                if (error && error != EOPNOTSUPP) {
+                        xfs_info(mp,
+         "discard failed for extent [0x%llu,%u], error %d",
+                                 (unsigned long long)busyp->bno,
+                                 busyp->length,
+                                 error);
+                        return error;
+                }
+        }
+
+        return 0;
+}
diff --git a/fs/xfs/linux-2.6/xfs_discard.h b/fs/xfs/linux-2.6/xfs_discard.h
index e82b6dd3e127..344879aea646 100644
--- a/fs/xfs/linux-2.6/xfs_discard.h
+++ b/fs/xfs/linux-2.6/xfs_discard.h
@@ -2,7 +2,9 @@
 #define XFS_DISCARD_H 1
 
 struct fstrim_range;
+struct list_head;
 
 extern int      xfs_ioc_trim(struct xfs_mount *, struct fstrim_range __user *);
+extern int      xfs_discard_extents(struct xfs_mount *, struct list_head *);
 
 #endif /* XFS_DISCARD_H */
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index b0aa59e51fd0..98b9c91fcdf1 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -110,8 +110,10 @@ mempool_t *xfs_ioend_pool;
 #define MNTOPT_GQUOTANOENF "gqnoenforce"/* group quota limit enforcement */
 #define MNTOPT_PQUOTANOENF "pqnoenforce"/* project quota limit enforcement */
 #define MNTOPT_QUOTANOENF  "qnoenforce" /* same as uqnoenforce */
-#define MNTOPT_DELAYLOG   "delaylog"    /* Delayed loging enabled */
-#define MNTOPT_NODELAYLOG "nodelaylog"  /* Delayed loging disabled */
+#define MNTOPT_DELAYLOG    "delaylog"   /* Delayed logging enabled */
+#define MNTOPT_NODELAYLOG  "nodelaylog" /* Delayed logging disabled */
+#define MNTOPT_DISCARD     "discard"    /* Discard unused blocks */
+#define MNTOPT_NODISCARD   "nodiscard"  /* Do not discard unused blocks */
 
 /*
  * Table driven mount option parser.
@@ -355,6 +357,10 @@ xfs_parseargs(
                         mp->m_flags |= XFS_MOUNT_DELAYLOG;
                 } else if (!strcmp(this_char, MNTOPT_NODELAYLOG)) {
                         mp->m_flags &= ~XFS_MOUNT_DELAYLOG;
+                } else if (!strcmp(this_char, MNTOPT_DISCARD)) {
+                        mp->m_flags |= XFS_MOUNT_DISCARD;
+                } else if (!strcmp(this_char, MNTOPT_NODISCARD)) {
+                        mp->m_flags &= ~XFS_MOUNT_DISCARD;
                 } else if (!strcmp(this_char, "ihashsize")) {
                         xfs_warn(mp,
         "ihashsize no longer used, option is deprecated.");
@@ -388,6 +394,13 @@ xfs_parseargs(
                 return EINVAL;
         }
 
+        if ((mp->m_flags & XFS_MOUNT_DISCARD) &&
+            !(mp->m_flags & XFS_MOUNT_DELAYLOG)) {
+                xfs_warn(mp,
+        "the discard option is incompatible with the nodelaylog option");
+                return EINVAL;
+        }
+
 #ifndef CONFIG_XFS_QUOTA
         if (XFS_IS_QUOTA_RUNNING(mp)) {
                 xfs_warn(mp, "quota support not available in this kernel.");
@@ -488,6 +501,7 @@ xfs_showargs(
                 { XFS_MOUNT_FILESTREAMS,        "," MNTOPT_FILESTREAM },
                 { XFS_MOUNT_GRPID,              "," MNTOPT_GRPID },
                 { XFS_MOUNT_DELAYLOG,           "," MNTOPT_DELAYLOG },
+                { XFS_MOUNT_DISCARD,            "," MNTOPT_DISCARD },
                 { 0, NULL }
         };
         static struct proc_xfs_info xfs_info_unset[] = {
diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
index da0a561ffba2..8d52ba4c87e5 100644
--- a/fs/xfs/xfs_ag.h
+++ b/fs/xfs/xfs_ag.h
@@ -187,6 +187,8 @@ struct xfs_busy_extent {
         xfs_agnumber_t  agno;
         xfs_agblock_t   bno;
         xfs_extlen_t    length;
+        unsigned int    flags;
+#define XFS_ALLOC_BUSY_DISCARDED        0x01    /* undergoing a discard op. */
 };
 
 /*
diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index acdced86413c..721db22c6ec9 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -2609,6 +2609,18 @@ xfs_alloc_busy_update_extent(
         xfs_agblock_t           bend = bbno + busyp->length;
 
         /*
+         * This extent is currently being discarded.  Give the thread
+         * performing the discard a chance to mark the extent unbusy
+         * and retry.
+         */
+        if (busyp->flags & XFS_ALLOC_BUSY_DISCARDED) {
+                spin_unlock(&pag->pagb_lock);
+                delay(1);
+                spin_lock(&pag->pagb_lock);
+                return false;
+        }
+
+        /*
          * If there is a busy extent overlapping a user allocation, we have
          * no choice but to force the log and retry the search.
          *
@@ -2813,7 +2825,8 @@ restart:
                  * If this is a metadata allocation, try to reuse the busy
                  * extent instead of trimming the allocation.
                  */
-                if (!args->userdata) {
+                if (!args->userdata &&
+                    !(busyp->flags & XFS_ALLOC_BUSY_DISCARDED)) {
                         if (!xfs_alloc_busy_update_extent(args->mp, args->pag,
                                                           busyp, fbno, flen,
                                                           false))
@@ -2979,10 +2992,16 @@ xfs_alloc_busy_clear_one(
         kmem_free(busyp);
 }
 
+/*
+ * Remove all extents on the passed in list from the busy extents tree.
+ * If do_discard is set skip extents that need to be discarded, and mark
+ * these as undergoing a discard operation instead.
+ */
 void
 xfs_alloc_busy_clear(
         struct xfs_mount        *mp,
-        struct list_head        *list)
+        struct list_head        *list,
+        bool                    do_discard)
 {
         struct xfs_busy_extent  *busyp, *n;
         struct xfs_perag        *pag = NULL;
@@ -2999,7 +3018,10 @@ xfs_alloc_busy_clear(
                         agno = busyp->agno;
                 }
 
-                xfs_alloc_busy_clear_one(mp, pag, busyp);
+                if (do_discard && busyp->length)
+                        busyp->flags = XFS_ALLOC_BUSY_DISCARDED;
+                else
+                        xfs_alloc_busy_clear_one(mp, pag, busyp);
         }
 
         if (pag) {
diff --git a/fs/xfs/xfs_alloc.h b/fs/xfs/xfs_alloc.h
index 240ad288f2f9..06aa8217452b 100644
--- a/fs/xfs/xfs_alloc.h
+++ b/fs/xfs/xfs_alloc.h
@@ -140,7 +140,8 @@ xfs_alloc_busy_insert(struct xfs_trans *tp, xfs_agnumber_t agno,
         xfs_agblock_t bno, xfs_extlen_t len);
 
 void
-xfs_alloc_busy_clear(struct xfs_mount *mp, struct list_head *list);
+xfs_alloc_busy_clear(struct xfs_mount *mp, struct list_head *list,
+        bool do_discard);
 
 int
 xfs_alloc_busy_search(struct xfs_mount *mp, xfs_agnumber_t agno,
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);
 }
 
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 19af0ab0d0c6..3d68bb267c5f 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -224,6 +224,7 @@ typedef struct xfs_mount {
 #define XFS_MOUNT_FS_SHUTDOWN   (1ULL << 4)     /* atomic stop of all filesystem
                                                    operations, typically for
                                                    disk errors in metadata */
+#define XFS_MOUNT_DISCARD       (1ULL << 5)     /* discard unused blocks */
 #define XFS_MOUNT_RETERR        (1ULL << 6)     /* return alignment errors to
                                                    user */
 #define XFS_MOUNT_NOALIGN       (1ULL << 7)     /* turn off stripe alignment
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index d1f24858ccc4..7c7bc2b786bd 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -609,7 +609,7 @@ xfs_trans_free(
         struct xfs_trans        *tp)
 {
         xfs_alloc_busy_sort(&tp->t_busy);
-        xfs_alloc_busy_clear(tp->t_mountp, &tp->t_busy);
+        xfs_alloc_busy_clear(tp->t_mountp, &tp->t_busy, false);
 
         atomic_dec(&tp->t_mountp->m_active_trans);
         xfs_trans_free_dqinfo(tp);