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Merge -r1.45 of ufs_extattr.c:

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Fix UFS1 extended attribute backend autocreation deadlock
This commit is contained in:
dholland 2016-06-20 01:47:58 +00:00
parent 87c7b3f519
commit 762a526551
1 changed files with 45 additions and 16 deletions
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61
sys/ufs/lfs/ulfs_extattr.c
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@ -1,5 +1,5 @@
/* $NetBSD: ulfs_extattr.c,v 1.10 2016/06/20 01:44:05 dholland Exp $ */
/* from NetBSD: ufs_extattr.c,v 1.44 2014/11/14 10:09:50 manu */
/* $NetBSD: ulfs_extattr.c,v 1.11 2016/06/20 01:47:58 dholland Exp $ */
/* from NetBSD: ufs_extattr.c,v 1.45 2014/11/15 05:03:55 manu Exp */
/*-
* Copyright (c) 1999-2002 Robert N. M. Watson
@ -49,7 +49,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ulfs_extattr.c,v 1.10 2016/06/20 01:44:05 dholland Exp $");
__KERNEL_RCSID(0, "$NetBSD: ulfs_extattr.c,v 1.11 2016/06/20 01:47:58 dholland Exp $");
#ifdef _KERNEL_OPT
#include "opt_lfs.h"
@ -210,9 +210,9 @@ ulfs_extattr_valid_attrname(int attrnamespace, const char *attrname)
/*
* Autocreate an attribute storage
*/
static struct ulfs_extattr_list_entry *
static int
ulfs_extattr_autocreate_attr(struct vnode *vp, int attrnamespace,
const char *attrname, struct lwp *l)
const char *attrname, struct lwp *l, struct ulfs_extattr_list_entry **uelep)
{
struct mount *mp = vp->v_mount;
struct ulfsmount *ump = VFSTOULFS(mp);
@ -246,10 +246,20 @@ ulfs_extattr_autocreate_attr(struct vnode *vp, int attrnamespace,
break;
default:
PNBUF_PUT(path);
return NULL;
*uelep = NULL;
return EINVAL;
break;
}
/*
* Release extended attribute mount lock, otherwise
* we can deadlock with another thread that would lock
* vp after we unlock it below, and call
* ulfs_extattr_uepm_lock(ump), for instance
* in ulfs_getextattr().
*/
ulfs_extattr_uepm_unlock(ump);
/*
* XXX unlock/lock should only be done when setting extattr
* on backing store or one of its parent directory
@ -261,7 +271,12 @@ ulfs_extattr_autocreate_attr(struct vnode *vp, int attrnamespace,
pb = pathbuf_create(path);
NDINIT(&nd, CREATE, LOCKPARENT, pb);
error = vn_open(&nd, O_CREAT|O_RDWR, 0600);
/*
* Since we do not hold ulfs_extattr_uepm_lock anymore,
* another thread may race with us for backend creation,
* but only one can succeed here thanks to O_EXCL
*/
error = vn_open(&nd, O_CREAT|O_EXCL|O_RDWR, 0600);
/*
* Reacquire the lock on the vnode
@ -269,10 +284,13 @@ ulfs_extattr_autocreate_attr(struct vnode *vp, int attrnamespace,
KASSERT(VOP_ISLOCKED(vp) == 0);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
ulfs_extattr_uepm_lock(ump);
if (error != 0) {
pathbuf_destroy(pb);
PNBUF_PUT(path);
return NULL;
*uelep = NULL;
return error;
}
KASSERT(nd.ni_vp != NULL);
@ -300,7 +318,8 @@ ulfs_extattr_autocreate_attr(struct vnode *vp, int attrnamespace,
printf("%s: write uef header failed for %s, error = %d\n",
__func__, attrname, error);
vn_close(backing_vp, FREAD|FWRITE, l->l_cred);
return NULL;
*uelep = NULL;
return error;
}
/*
@ -313,7 +332,8 @@ ulfs_extattr_autocreate_attr(struct vnode *vp, int attrnamespace,
printf("%s: enable %s failed, error %d\n",
__func__, attrname, error);
vn_close(backing_vp, FREAD|FWRITE, l->l_cred);
return NULL;
*uelep = NULL;
return error;
}
uele = ulfs_extattr_find_attr(ump, attrnamespace, attrname);
@ -321,13 +341,15 @@ ulfs_extattr_autocreate_attr(struct vnode *vp, int attrnamespace,
printf("%s: atttribute %s created but not found!\n",
__func__, attrname);
vn_close(backing_vp, FREAD|FWRITE, l->l_cred);
return NULL;
*uelep = NULL;
return ESRCH; /* really internal error */
}
printf("%s: EA backing store autocreated for %s\n",
mp->mnt_stat.f_mntonname, attrname);
return uele;
*uelep = uele;
return 0;
}
/*
@ -1405,10 +1427,17 @@ ulfs_extattr_set(struct vnode *vp, int attrnamespace, const char *name,
attribute = ulfs_extattr_find_attr(ump, attrnamespace, name);
if (!attribute) {
attribute = ulfs_extattr_autocreate_attr(vp, attrnamespace,
name, l);
if (!attribute)
return (ENODATA);
error = ulfs_extattr_autocreate_attr(vp, attrnamespace,
name, l, &attribute);
if (error == EEXIST) {
/* Another thread raced us for backend creation */
error = 0;
attribute =
ulfs_extattr_find_attr(ump, attrnamespace, name);
}
if (error || !attribute)
return ENODATA;
}
/*