bcachefs: Fix lockdep splat in bch2_readdir

dir_emit() can fault (taking mmap_lock); thus we can't be holding btree
locks.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/dirent.c b/fs/bcachefs/dirent.c
index 1544fc56974f213d51c978756033482bd205c512..610dd7425fb477e2ff9cf0fba1b7f5abd4a50181 100644 (file)
--- a/fs/bcachefs/dirent.c
+++ b/fs/bcachefs/dirent.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include "bcachefs.h"
+#include "bkey_buf.h"
 #include "bkey_methods.h"
 #include "btree_update.h"
 #include "extents.h"
@@ -504,8 +505,10 @@ int bch2_readdir(struct bch_fs *c, subvol_inum inum, struct dir_context *ctx)
        struct bkey_s_c_dirent dirent;
        subvol_inum target;
        u32 snapshot;
+       struct bkey_buf sk;
        int ret;
 
+       bch2_bkey_buf_init(&sk);
        bch2_trans_init(&trans, c, 0, 0);
 retry:
        bch2_trans_begin(&trans);
@@ -528,10 +531,11 @@ retry:
                if (ret)
                        continue;
 
-               /*
-                * XXX: dir_emit() can fault and block, while we're holding
-                * locks
-                */
+               /* dir_emit() can fault and block: */
+               bch2_bkey_buf_reassemble(&sk, c, k);
+               dirent = bkey_i_to_s_c_dirent(sk.k);
+               bch2_trans_unlock(&trans);
+
                ctx->pos = dirent.k->p.offset;
                if (!dir_emit(ctx, dirent.v->d_name,
                              bch2_dirent_name_bytes(dirent),
@@ -554,6 +558,7 @@ err:
                goto retry;
 
        bch2_trans_exit(&trans);
+       bch2_bkey_buf_exit(&sk, c);
 
        return ret;
 }