From: Gunnar Beutner <gunnar@beutner.name>
Date: Thu, 3 Nov 2011 05:48:13 +0000 (+0100)
Subject: Fix a race condition in zfs_getattr_fast()
X-Git-Tag: zfs-0.6.0-rc7~74
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a7b125e9a577cbf66ddbd7cf9701028ff150ee8e;p=zfs

Fix a race condition in zfs_getattr_fast()

zfs_getattr_fast() was missing a lock on the ZFS superblock which
could result in zfs_znode_dmu_fini() clearing the zp->z_sa_hdl member
while zfs_getattr_fast() was accessing the znode. The result of this
would usually be a panic.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Fixes #431
---

diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 3331a1706..b7f5daaaf 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -2301,6 +2301,9 @@ zfs_getattr_fast(struct inode *ip, struct kstat *sp)
 	znode_t *zp = ITOZ(ip);
 	zfs_sb_t *zsb = ITOZSB(ip);
 
+	ZFS_ENTER(zsb);
+	ZFS_VERIFY_ZP(zp);
+
 	mutex_enter(&zp->z_lock);
 
 	generic_fillattr(ip, sp);
@@ -2316,6 +2319,8 @@ zfs_getattr_fast(struct inode *ip, struct kstat *sp)
 
 	mutex_exit(&zp->z_lock);
 
+	ZFS_EXIT(zsb);
+
 	return (0);
 }
 EXPORT_SYMBOL(zfs_getattr_fast);