Messages in this thread Patch in this message | | | Date | Sun, 12 Apr 2009 15:16:05 +0800 | From | Wu Fengguang <> | Subject | [RFC][PATCH] vfs: check inode size on no_cached_page |
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[This patch may not necessarily be merged, but at least we should be aware of the problem.]
When user space requests past-EOF data, do_generic_file_read() will issue a bonus readpage call, which may be unfavorable.
do_generic_file_read: -> find_page: -> find_get_page() = NULL -> page_cache_sync_readahead() -> find_get_page() = NULL -> no_cached_page: -> readpage: -> nfs_readpage() = error -> readpage_error:
Reported-by: Xu Chenfeng <xcf@ustc.edu.cn> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> --- mm/filemap.c | 5 +++++ 1 file changed, 5 insertions(+)
--- mm.orig/mm/filemap.c +++ mm/mm/filemap.c @@ -1269,6 +1269,11 @@ readpage_error: goto out; no_cached_page: + isize = i_size_read(inode); + end_index = (isize - 1) >> PAGE_CACHE_SHIFT; + if (unlikely(!isize || index > end_index)) + goto out; + /* * Ok, it wasn't cached, so we need to create a new * page..
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