From: Christoph Hellwig <hch@xxxxxx> Have xfs_vm_bmap return zero for reflinked files. This hack prevents using a file with shared blocks as a swap file, because we don't want to deal with CoW when we're (probably) low on memory. Signed-off-by: Christoph Hellwig <hch@xxxxxx> [darrick.wong@xxxxxxxxxx: add a more descriptive changelog] Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> --- fs/xfs/xfs_aops.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index a85bc62..f564d02 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -1553,6 +1553,17 @@ xfs_vm_bmap( trace_xfs_vm_bmap(XFS_I(inode)); xfs_ilock(ip, XFS_IOLOCK_SHARED); + + /* + * The swap code (ab-)uses ->bmap to get a block mapping and then + * bypasseѕ the file system for actual I/O. We really can't allow + * that on reflinks inodes, so we have to skip out here. And yes, + * 0 is the magic code for a bmap error.. + */ + if (xfs_is_reflink_inode(ip)) { + xfs_iunlock(ip, XFS_IOLOCK_SHARED); + return 0; + } filemap_write_and_wait(mapping); xfs_iunlock(ip, XFS_IOLOCK_SHARED); return generic_block_bmap(mapping, block, xfs_get_blocks); -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html