[PATCH] xfs: perag may be null in xfs_imap()

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

Dan Carpenter's static checker reported:

The patch 7b13c5155182: "xfs: use perag for ialloc btree cursors"
from Jun 2, 2021, leads to the following Smatch complaint:

    fs/xfs/libxfs/xfs_ialloc.c:2403 xfs_imap()
    error: we previously assumed 'pag' could be null (see line 2294)

And it's right. Fix it.

Fixes: 7b13c5155182 ("xfs: use perag for ialloc btree cursors")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/libxfs/xfs_ialloc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 654a8d9681e1..57d9cb632983 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -2398,7 +2398,8 @@ xfs_imap(
 	}
 	error = 0;
 out_drop:
-	xfs_perag_put(pag);
+	if (pag)
+		xfs_perag_put(pag);
 	return error;
 }