[PATCH 1/6] mmap: don't assume f_op->mmap() doesn't change vma->vm_file

[Tejun Heo]

mmap_region() assumes that vma->vm_file isn't changed by f_op->mmap()
and continues to use cache file after f_op->mmap() returns.  Don't
assume that.  This will be used by FUSE to redirect mmap to
shmem_file.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
---
 mm/mmap.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index d4855a6..2e4e0b5 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1177,6 +1177,7 @@ munmap_back:
 		vma->vm_file = file;
 		get_file(file);
 		error = file->f_op->mmap(file, vma);
+		file = vma->vm_file;
 		if (error)
 			goto unmap_and_free_vma;
 		if (vm_flags & VM_EXECUTABLE)
-- 
1.5.6

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