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[PATCH 29/58] xfs: disable XFS_IOC_SWAPEXT when rmap btree is enabled

To: david@xxxxxxxxxxxxx, darrick.wong@xxxxxxxxxx
Subject: [PATCH 29/58] xfs: disable XFS_IOC_SWAPEXT when rmap btree is enabled
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Date: Tue, 06 Oct 2015 21:58:19 -0700
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, Dave Chinner <dchinner@xxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20151007045443.30457.47038.stgit@xxxxxxxxxxxxxxxx>
References: <20151007045443.30457.47038.stgit@xxxxxxxxxxxxxxxx>
User-agent: StGit/0.17.1-dirty
>From : Dave Chinner <dchinner@xxxxxxxxxx>

Swapping extents between two inodes requires the owner to be updated
in the rmap tree for all the extents that are swapped. This code
does not yet exist, so switch off the XFS_IOC_SWAPEXT ioctl until
support has been implemented. This will nee dto be done before the
rmap btree code can have the experimental tag removed.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/xfs_bmap_util.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)


diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 8b2e505..f41a6f7 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1685,6 +1685,19 @@ xfs_swap_extents(
        __uint64_t      tmp;
        int             lock_flags;
 
+       /*
+        * We can't swap extents on rmap btree enabled filesystems yet
+        * as there is no mechanism to update the owner of extents in
+        * the rmap tree yet. Hence, for the moment, just reject attempts
+        * to swap extents with EINVAL after emitting a warning once to remind
+        * us this needs fixing.
+        */
+       if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
+               WARN_ONCE(1,
+       "XFS: XFS_IOC_SWAPEXT not supported on RMAP enabled filesystems\n");
+               return -EINVAL;
+       }
+
        tempifp = kmem_alloc(sizeof(xfs_ifork_t), KM_MAYFAIL);
        if (!tempifp) {
                error = -ENOMEM;

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