xfs: try any AG when allocating the first btree block when reflinking

When a reflink operation causes the bmap code to allocate a btree block
we're currently doing single-AG allocations due to having ->firstblock
set and then try any higher AG due a little reflink quirk we've put in
when adding the reflink code.  But given that we do not have a minleft
reservation of any kind in this AG we can still not have any space in
the same or higher AG even if the file system has enough free space.
To fix this use a XFS_ALLOCTYPE_FIRST_AG allocation in this fall back
path instead.

[And yes, we need to redo this properly instead of piling hacks over
 hacks.  I'm working on that, but it's not going to be a small series.
 In the meantime this fixes the customer reported issue]

Also add a warning for failing allocations to make it easier to debug.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index bfa59a1a2d0981afc4ab4c4cd0d2f2daaec91aef..9bd104f32908962046af6d2dd4437a045fecdb36 100644 (file)
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -763,8 +763,8 @@ xfs_bmap_extents_to_btree(
                args.type = XFS_ALLOCTYPE_START_BNO;
                args.fsbno = XFS_INO_TO_FSB(mp, ip->i_ino);
        } else if (dfops->dop_low) {
-try_another_ag:
                args.type = XFS_ALLOCTYPE_START_BNO;
+try_another_ag:
                args.fsbno = *firstblock;
        } else {
                args.type = XFS_ALLOCTYPE_NEAR_BNO;
@@ -790,13 +790,17 @@ try_another_ag:
        if (xfs_sb_version_hasreflink(&cur->bc_mp->m_sb) &&
            args.fsbno == NULLFSBLOCK &&
            args.type == XFS_ALLOCTYPE_NEAR_BNO) {
-               dfops->dop_low = true;
+               args.type = XFS_ALLOCTYPE_FIRST_AG;
                goto try_another_ag;
        }
+       if (WARN_ON_ONCE(args.fsbno == NULLFSBLOCK)) {
+               xfs_iroot_realloc(ip, -1, whichfork);
+               xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+               return -ENOSPC;
+       }
        /*
         * Allocation can't fail, the space was reserved.
         */
-       ASSERT(args.fsbno != NULLFSBLOCK);
        ASSERT(*firstblock == NULLFSBLOCK ||
               args.agno >= XFS_FSB_TO_AGNO(mp, *firstblock));
        *firstblock = cur->bc_private.b.firstblock = args.fsbno;

diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c
index f93072b58a58323ae952d55d568a9e53384f88d3..fd55db47938562868d25d4998407ce7650c4da4f 100644 (file)
--- a/fs/xfs/libxfs/xfs_bmap_btree.c
+++ b/fs/xfs/libxfs/xfs_bmap_btree.c
@@ -447,8 +447,8 @@ xfs_bmbt_alloc_block(
 
        if (args.fsbno == NULLFSBLOCK) {
                args.fsbno = be64_to_cpu(start->l);
-try_another_ag:
                args.type = XFS_ALLOCTYPE_START_BNO;
+try_another_ag:
                /*
                 * Make sure there is sufficient room left in the AG to
                 * complete a full tree split for an extent insert.  If
@@ -488,8 +488,8 @@ try_another_ag:
        if (xfs_sb_version_hasreflink(&cur->bc_mp->m_sb) &&
            args.fsbno == NULLFSBLOCK &&
            args.type == XFS_ALLOCTYPE_NEAR_BNO) {
-               cur->bc_private.b.dfops->dop_low = true;
                args.fsbno = cur->bc_private.b.firstblock;
+               args.type = XFS_ALLOCTYPE_FIRST_AG;
                goto try_another_ag;
        }
 
@@ -506,7 +506,7 @@ try_another_ag:
                        goto error0;
                cur->bc_private.b.dfops->dop_low = true;
        }
-       if (args.fsbno == NULLFSBLOCK) {
+       if (WARN_ON_ONCE(args.fsbno == NULLFSBLOCK)) {
                XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                *stat = 0;
                return 0;