linux-kernel - [PATCH] ROMFS 0 byte file read error

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Message-ID: <20080730161051.GA3133@kaboom.dhcp.chi.wms.com>
Date:	Wed, 30 Jul 2008 11:10:52 -0500
From:	Chris Fester <cfester@....com>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Matt Waddel <matt.waddel@...escale.com>,
	Greg Ungerer <gerg@...pgear.com>
Subject: [PATCH] ROMFS 0 byte file read error

I've verified that the git tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

also has the zero byte file problem for romfs.  This patch
fixes the problem.  Avoids calling romfs_copyfrom when in 
the 0 size case.

Thanks!
Chris Fester

Signed-off-by: Chris Fester <cfester@....com>
---

diff --git a/fs/romfs/inode.c b/fs/romfs/inode.c
index 8e51a2a..5d24113 100644
--- a/fs/romfs/inode.c
+++ b/fs/romfs/inode.c
@@ -430,10 +430,10 @@ romfs_readpage(struct file *file, struct page * page)
 
        /* 32 bit warning -- but not for us :) */
        offset = page_offset(page);
-       if (offset < i_size_read(inode)) {
+       if (offset <= i_size_read(inode)) {
                avail = inode->i_size-offset;
                readlen = min_t(unsigned long, avail, PAGE_SIZE);
-               if (romfs_copyfrom(inode, buf, ROMFS_I(inode)->i_dataoffset+offset, readlen) == readlen) {
+               if (!readlen || romfs_copyfrom(inode, buf, ROMFS_I(inode)->i_dataoffset+offset, readlen) == readlen) {
                        if (readlen < PAGE_SIZE) {
                                memset(buf + readlen,0,PAGE_SIZE-readlen);
                        }

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