From a33f13efe05192e7a805018a2ce2b2afddd04057 Mon Sep 17 00:00:00 2001 From: Joel Becker Date: Mon, 16 Aug 2010 12:10:17 -0700 Subject: [PATCH] libfs: Fix shift bug in generic_check_addressable() generic_check_addressable() erroneously shifts pages down by a block factor when it should be shifting up. To prevent overflow, we shift blocks down to pages. Signed-off-by: Joel Becker --- fs/libfs.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index 8debe7b33769..62baa0387d6e 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -925,6 +925,8 @@ EXPORT_SYMBOL(generic_file_fsync); int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) { u64 last_fs_block = num_blocks - 1; + u64 last_fs_page = + last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); if (unlikely(num_blocks == 0)) return 0; @@ -932,10 +934,8 @@ int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) return -EINVAL; - if ((last_fs_block > - (sector_t)(~0ULL) >> (blocksize_bits - 9)) || - (last_fs_block > - (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - blocksize_bits))) { + if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || + (last_fs_page > (pgoff_t)(~0ULL))) { return -EFBIG; } return 0;