Btrfs: kmap_atomic(KM_USER0) is safe for btrfs_readpage_end_io_hook

None of the checksum verification code schedules, so we can use the faster
kmap_atomic

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index cdb701165a05..8adfe059ab41 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1748,7 +1748,7 @@ static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
         } else {
                 ret = get_state_private(io_tree, start, &private);
         }
-        kaddr = kmap(page);
+        kaddr = kmap_atomic(page, KM_USER0);
         if (ret)
                 goto zeroit;
 
@@ -1757,7 +1757,7 @@ static int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
         if (csum != private)
                 goto zeroit;
 
-        kunmap(page);
+        kunmap_atomic(kaddr, KM_USER0);
 good:
         /* if the io failure tree for this inode is non-empty,
          * check to see if we've recovered from a failed IO
@@ -1772,7 +1772,7 @@ zeroit:
                (unsigned long long)private);
         memset(kaddr + offset, 1, end - start + 1);
         flush_dcache_page(page);
-        kunmap(page);
+        kunmap_atomic(kaddr, KM_USER0);
         if (private == 0)
                 return 0;
         return -EIO;