zisofs: fix readpage() outside i_size

A read request outside i_size will be handled in do_generic_file_read().  So
we just return 0 to avoid getting -EIO as normal reading, let
do_generic_file_read do the rest.

At the same time we need unlock the page to avoid system stuck.

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=10227

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Report-by: Christian Perle <chris@linuxinfotag.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/isofs/compress.c b/fs/isofs/compress.c
index 37dbd6404787..defb932eee9a 100644
--- a/fs/isofs/compress.c
+++ b/fs/isofs/compress.c
@@ -72,6 +72,17 @@ static int zisofs_readpage(struct file *file, struct page *page)
         offset = index & ~zisofs_block_page_mask;
         blockindex = offset >> zisofs_block_page_shift;
         maxpage = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
+        /*
+         * If this page is wholly outside i_size we just return zero;
+         * do_generic_file_read() will handle this for us
+         */
+        if (page->index >= maxpage) {
+                SetPageUptodate(page);
+                unlock_page(page);
+                return 0;
+        }
+
         maxpage = min(zisofs_block_pages, maxpage-offset);
 
         for ( i = 0 ; i < maxpage ; i++, offset++ ) {