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Make sure reads on empty files reach PUFFS filesystems

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Sending a read through the page cache will get the operation
short-circuited. This is a problem with some filesystems that
expect to receive the read operation in order to update atime.

We fix that by bypassing the page cache when reading a file
wich a size known to be zero.
This commit is contained in:
manu 2015-01-13 16:39:51 +00:00
parent f91d4e28bb
commit 5fc94787c1
1 changed files with 11 additions and 3 deletions
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14
sys/fs/puffs/puffs_vnops.c
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@ -1,4 +1,4 @@
/* $NetBSD: puffs_vnops.c,v 1.198 2014/11/04 09:14:42 manu Exp $ */
/* $NetBSD: puffs_vnops.c,v 1.199 2015/01/13 16:39:51 manu Exp $ */
/*
* Copyright (c) 2005, 2006, 2007 Antti Kantee. All Rights Reserved.
@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: puffs_vnops.c,v 1.198 2014/11/04 09:14:42 manu Exp $");
__KERNEL_RCSID(0, "$NetBSD: puffs_vnops.c,v 1.199 2015/01/13 16:39:51 manu Exp $");
#include <sys/param.h>
#include <sys/buf.h>
@ -2279,9 +2279,17 @@ puffs_vnop_read(void *v)
if (uio->uio_offset < 0)
return EFBIG;
/*
* On the case of reading empty files and (vp->v_size != 0) below:
* some filesystems (hint: FUSE and distributed filesystems) still
* expect to get the READ in order to update atime. Reading through
* the case filters empty files, therefore we prefer to bypass the
* cache here.
*/
if (vp->v_type == VREG &&
PUFFS_USE_PAGECACHE(pmp) &&
!(pn->pn_stat & PNODE_RDIRECT)) {
!(pn->pn_stat & PNODE_RDIRECT) &&
(vp->v_size != 0)) {
const int advice = IO_ADV_DECODE(ap->a_ioflag);
while (uio->uio_resid > 0) {