Btrfs: KM_IRQ0 usage in end_io handling

endio handling is typically called with interrupts disabled, but can
also be called with it enabled. So save interrupts before using KM_IRQ0
to be completely safe.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0e1ca423e22d..02d802cdd59b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -168,8 +168,10 @@ int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end)
         int ret;
         struct btrfs_root *root = BTRFS_I(inode)->root;
         u32 csum = ~(u32)0;
+        unsigned long flags;
 
         ret = get_state_private(em_tree, start, &private);
+        local_irq_save(flags);
         kaddr = kmap_atomic(page, KM_IRQ0);
         if (ret) {
                 goto zeroit;
@@ -180,6 +182,7 @@ int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end)
                 goto zeroit;
         }
         kunmap_atomic(kaddr, KM_IRQ0);
+        local_irq_restore(flags);
         return 0;
 
 zeroit:
@@ -188,6 +191,7 @@ zeroit:
         memset(kaddr + offset, 1, end - start + 1);
         flush_dcache_page(page);
         kunmap_atomic(kaddr, KM_IRQ0);
+        local_irq_restore(flags);
         return 0;
 }