xfs: switch to NOFS allocation under i_lock in xfs_readlink_bmap

xfs_readlink_bmap is called with i_lock held, but i_lock is taken in
reclaim context so all allocations under it must avoid recursions into
the filesystem.

Reported by the new reclaim context tracing in lockdep.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>

diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 1dd7068..ceecafd 100644 (file)
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -538,7 +538,9 @@ xfs_readlink_bmap(
                d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
                byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 
-               bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0);
+               bp = xfs_buf_read_flags(mp->m_ddev_targp, d, BTOBB(byte_cnt),
+                                       XBF_LOCK | XBF_MAPPED |
+                                       XBF_DONT_BLOCK);
                error = XFS_BUF_GETERROR(bp);
                if (error) {
                        xfs_ioerror_alert("xfs_readlink",