Message ID | 1258885259.1127.80.camel@macbook.infradead.org |
---|---|
State | New, archived |
Headers | show |
On Sun, Nov 22, 2009 at 10:20:59AM +0000, David Woodhouse wrote: > On Fri, 2009-11-20 at 12:45 -0700, Anton Vorontsov wrote: > > + if (pg->index > ((i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT)) { > > + ret = 0; > > + memset(pg_buf, 0, PAGE_CACHE_SIZE); > > + } else { > > + ret = jffs2_read_inode_range(c, f, pg_buf, > > + pg->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE); > > + } > > Thank you for the excellent diagnosis and the patch. > > I think I'd prefer to fix it a little differently though -- I would be > happier to make jffs2_read_inode_range() cope with out-of-file reads, > rather than adding this special case where we don't call it. > > That way we aren't at all susceptible to potential races between the > VFS-maintained i_size and our own internal fragtree handling. And > jffs2_read_inode_range() already handles the memset to zero for various > other reasons anyway. > > Does this patch look OK to you? It seems to work on the test cases I've > tried. Yep, it looks good (and works). Thanks David!
diff --git a/fs/jffs2/read.c b/fs/jffs2/read.c index cfe05c1..9640175 100644 --- a/fs/jffs2/read.c +++ b/fs/jffs2/read.c @@ -164,12 +164,14 @@ int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f, /* XXX FIXME: Where a single physical node actually shows up in two frags, we read it twice. Don't do that. */ - /* Now we're pointing at the first frag which overlaps our page */ + /* Now we're pointing at the first frag which overlaps our page + * (or perhaps is before it, if we've been asked to read off the + * end of the file). */ while(offset < end) { D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end)); - if (unlikely(!frag || frag->ofs > offset)) { + if (unlikely(!frag || frag->ofs > offset || frag->ofs + frag->size <= offset)) { uint32_t holesize = end - offset; - if (frag) { + if (frag && frag->ofs > offset) { D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset)); holesize = min(holesize, frag->ofs - offset); }