xfs
[Top] [All Lists]

[PATCH] xfs: add discard support (at transaction commit)

To: xfs@xxxxxxxxxxx
Subject: [PATCH] xfs: add discard support (at transaction commit)
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Sun, 9 May 2010 13:50:48 -0400
User-agent: Mutt/1.5.19 (2009-01-05)
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.  We simply have to
walk the list of busy extents after transaction commit, but before deleting
it from the rbtree tracking these busy extents.

This does not replace by background discard support patch which is probably
better for thin provisioned arrays - I will updated it to apply ontop of
this patch when I'm ready to re-submit it.

[Note: this patch needs Dave's delayed-logging series any patch titled
 "xfs: simplify log item descriptor tracking" applied]

Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: xfs/fs/xfs/xfs_alloc.c
===================================================================
--- xfs.orig/fs/xfs/xfs_alloc.c 2010-05-09 19:08:34.544262404 +0200
+++ xfs/fs/xfs/xfs_alloc.c      2010-05-09 19:09:24.975032203 +0200
@@ -2761,3 +2761,25 @@ xfs_alloc_busy_clear(
 
        kmem_free(busyp);
 }
+
+int
+xfs_discard_extent(
+       struct xfs_mount        *mp,
+       struct xfs_busy_extent  *busyp)
+{
+       int                     error = 0;
+       xfs_daddr_t             bno;
+       __int64_t               len;
+
+       if ((mp->m_flags & XFS_MOUNT_DISCARD) == 0)
+               return 0;
+
+       bno = XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno);
+       len = XFS_FSB_TO_BB(mp, busyp->length);
+
+       error = -blkdev_issue_discard(mp->m_ddev_targp->bt_bdev, bno, len,
+                                     GFP_NOFS, DISCARD_FL_BARRIER);
+       if (error && error != EOPNOTSUPP)
+               xfs_fs_cmn_err(CE_NOTE, mp, "discard failed, error %d", error);
+       return error;
+}
Index: xfs/fs/xfs/xfs_alloc.h
===================================================================
--- xfs.orig/fs/xfs/xfs_alloc.h 2010-05-09 19:08:34.551265756 +0200
+++ xfs/fs/xfs/xfs_alloc.h      2010-05-09 19:09:16.213023263 +0200
@@ -128,6 +128,9 @@ xfs_alloc_busy_insert(xfs_trans_t *tp,
 void
 xfs_alloc_busy_clear(struct xfs_mount *mp, struct xfs_busy_extent *busyp);
 
+int
+xfs_discard_extent(struct xfs_mount *mp, struct xfs_busy_extent *busyp);
+
 #endif /* __KERNEL__ */
 
 /*
Index: xfs/fs/xfs/linux-2.6/xfs_super.c
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_super.c       2010-05-09 19:08:34.562254302 
+0200
+++ xfs/fs/xfs/linux-2.6/xfs_super.c    2010-05-09 19:09:16.223693748 +0200
@@ -120,6 +120,8 @@ mempool_t *xfs_ioend_pool;
 #define MNTOPT_DMI     "dmi"           /* DMI enabled (DMAPI / XDSM) */
 #define MNTOPT_DELAYLOG   "delaylog"   /* Delayed loging enabled */
 #define MNTOPT_NODELAYLOG "nodelaylog" /* Delayed loging disabled */
+#define MNTOPT_DISCARD "discard"       /* Discard unused blocks */
+#define MNTOPT_NODISCARD "nodiscard"   /* Do not discard unused blocks */
 
 /*
  * Table driven mount option parser.
@@ -382,6 +384,10 @@ xfs_parseargs(
                                "- use at your own risk.\n");
                } 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")) {
                        cmn_err(CE_WARN,
        "XFS: ihashsize no longer used, option is deprecated.");
Index: xfs/fs/xfs/xfs_mount.h
===================================================================
--- xfs.orig/fs/xfs/xfs_mount.h 2010-05-09 19:08:34.571254232 +0200
+++ xfs/fs/xfs/xfs_mount.h      2010-05-09 19:09:16.231005734 +0200
@@ -274,6 +274,7 @@ 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
Index: xfs/fs/xfs/xfs_log_cil.c
===================================================================
--- xfs.orig/fs/xfs/xfs_log_cil.c       2010-05-09 19:08:34.580004407 +0200
+++ xfs/fs/xfs/xfs_log_cil.c    2010-05-09 19:09:16.241255699 +0200
@@ -415,6 +415,7 @@ xlog_cil_committed(
        int     abort)
 {
        struct xfs_cil_ctx      *ctx = args;
+       struct xfs_mount        *mp = ctx->cil->xc_log->l_mp;
        struct xfs_log_vec      *lv;
        int                     abortflag = abort ? XFS_LI_ABORTED : 0;
        struct xfs_busy_extent  *busyp, *n;
@@ -425,8 +426,10 @@ xlog_cil_committed(
                                                        abortflag);
        }
 
-       list_for_each_entry_safe(busyp, n, &ctx->busy_extents, list)
-               xfs_alloc_busy_clear(ctx->cil->xc_log->l_mp, busyp);
+       list_for_each_entry_safe(busyp, n, &ctx->busy_extents, list) {
+               xfs_discard_extent(mp, busyp);
+               xfs_alloc_busy_clear(mp, busyp);
+       }
 
        spin_lock(&ctx->cil->xc_cil_lock);
        list_del(&ctx->committing);
Index: xfs/fs/xfs/xfs_trans.c
===================================================================
--- xfs.orig/fs/xfs/xfs_trans.c 2010-05-09 19:08:34.596025010 +0200
+++ xfs/fs/xfs/xfs_trans.c      2010-05-09 19:09:16.252005804 +0200
@@ -1398,6 +1398,7 @@ xfs_trans_committed(
        int                     abortflag)
 {
        struct xfs_log_item_desc *lidp, *next;
+       struct xfs_busy_extent  *busyp;
 
        /* Call the transaction's completion callback if there is one. */
        if (tp->t_callback != NULL)
@@ -1408,6 +1409,9 @@ xfs_trans_committed(
                xfs_trans_free_item_desc(lidp);
        }
 
+       list_for_each_entry(busyp, &tp->t_busy, list)
+               xfs_discard_extent(tp->t_mountp, busyp);
+
        xfs_trans_free(tp);
 }
 

<Prev in Thread] Current Thread [Next in Thread>