From 6fa164b865e44ac1d1ffc9a24ccd442f17acc4f6 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 3 Oct 2016 09:11:45 -0700 Subject: [PATCH] xfs: don't allow reflink when the AG is low on space If the AG free space is down to the reserves, refuse to reflink our way out of space. Hopefully userspace will make a real copy and/or go elsewhere. Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_reflink.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 8e894118295f..e92ccd316391 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -54,6 +54,8 @@ #include "xfs_reflink.h" #include "xfs_iomap.h" #include "xfs_rmap_btree.h" +#include "xfs_sb.h" +#include "xfs_ag_resv.h" /* * Copy on Write of Shared Blocks @@ -977,6 +979,31 @@ out_error: return error; } +/* + * Do we have enough reserve in this AG to handle a reflink? The refcount + * btree already reserved all the space it needs, but the rmap btree can grow + * infinitely, so we won't allow more reflinks when the AG is down to the + * btree reserves. + */ +static int +xfs_reflink_ag_has_free_space( + struct xfs_mount *mp, + xfs_agnumber_t agno) +{ + struct xfs_perag *pag; + int error = 0; + + if (!xfs_sb_version_hasrmapbt(&mp->m_sb)) + return 0; + + pag = xfs_perag_get(mp, agno); + if (xfs_ag_resv_critical(pag, XFS_AG_RESV_AGFL) || + xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA)) + error = -ENOSPC; + xfs_perag_put(pag); + return error; +} + /* * Unmap a range of blocks from a file, then map other blocks into the hole. * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount). @@ -1009,6 +1036,14 @@ xfs_reflink_remap_extent( irec->br_startblock != DELAYSTARTBLOCK && !ISUNWRITTEN(irec)); + /* No reflinking if we're low on space */ + if (real_extent) { + error = xfs_reflink_ag_has_free_space(mp, + XFS_FSB_TO_AGNO(mp, irec->br_startblock)); + if (error) + goto out; + } + /* Start a rolling transaction to switch the mappings */ resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK); error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp); -- 2.20.1