iomap: Make sure iomap_end is called after iomap_begin

Make sure iomap_end is always called when iomap_begin succeeds.

Without this fix, iomap_end won't be called when a filesystem's
iomap_begin operation returns an invalid mapping, bypassing any
unlocking done in iomap_end.  With this fix, the unlocking will still
happen.

This bug was found by Bob Peterson during code review.  It's unlikely
that such iomap_begin bugs will survive to affect users, so backporting
this fix seems unnecessary.

Fixes: ae259a9c8593 ("fs: introduce iomap infrastructure")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
index 76925b40b5fd25aaa72cbaba466a33857af7bcdb..26ab6563181fc63491ec7f744c1ec0eadce056ab 100644 (file)
--- a/fs/iomap/apply.c
+++ b/fs/iomap/apply.c
@@ -46,10 +46,14 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
        ret = ops->iomap_begin(inode, pos, length, flags, &iomap, &srcmap);
        if (ret)
                return ret;
-       if (WARN_ON(iomap.offset > pos))
-               return -EIO;
-       if (WARN_ON(iomap.length == 0))
-               return -EIO;
+       if (WARN_ON(iomap.offset > pos)) {
+               written = -EIO;
+               goto out;
+       }
+       if (WARN_ON(iomap.length == 0)) {
+               written = -EIO;
+               goto out;
+       }
 
        trace_iomap_apply_dstmap(inode, &iomap);
        if (srcmap.type != IOMAP_HOLE)
@@ -80,6 +84,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
        written = actor(inode, pos, length, data, &iomap,
                        srcmap.type != IOMAP_HOLE ? &srcmap : &iomap);
 
+out:
        /*
         * Now the data has been copied, commit the range we've copied.  This
         * should not fail unless the filesystem has had a fatal error.