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freebsd-dev/sys/fs/nullfs/null.h

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/* -> /*- for copyright notices, minor format tweaks as necessary
2005-01-06 18:10:42 +00:00
/*-
sys: further adoption of SPDX licensing ID tags. Mainly focus on files that use BSD 3-Clause license. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts. Special thanks to Wind River for providing access to "The Duke of Highlander" tool: an older (2014) run over FreeBSD tree was useful as a starting point.
2017-11-20 19:43:44 +00:00
* SPDX-License-Identifier: BSD-3-Clause
*
BSD 4.4 Lite Kernel Sources
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* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software donated to Berkeley by
* Jan-Simon Pendry.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
Renumber copyright clause 4 Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
2017-02-28 23:42:47 +00:00
* 3. Neither the name of the University nor the names of its contributors
BSD 4.4 Lite Kernel Sources
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* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
This is the kernel Lite/2 commit. There are some requisite userland changes, so don't expect to be able to run the kernel as-is (very well) without the appropriate Lite/2 userland changes. The system boots and can mount UFS filesystems. Untested: ext2fs, msdosfs, NFS Known problems: Incorrect Berkeley ID strings in some files. Mount_std mounts will not work until the getfsent library routine is changed. Reviewed by: various people Submitted by: Jeffery Hsu <hsu@freebsd.org>
1997-02-10 02:22:35 +00:00
* @(#)null.h 8.3 (Berkeley) 8/20/94
BSD 4.4 Lite Kernel Sources
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*
$Id$ -> $FreeBSD$
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* $FreeBSD$
BSD 4.4 Lite Kernel Sources
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*/
Add the "nocache" nullfs mount option, which disables the caching of the free nullfs vnodes, switching nullfs behaviour to pre-r240285. The option is mostly intended as the last-resort when higher pressure on the vnode cache due to doubling of the vnode counts is not desirable. Note that disabling the cache costs more than 2x wall time in the metadata-hungry scenarious. The default is "cache". Tested and benchmarked by: pho (previous version) MFC after: 2 weeks
2013-01-03 19:17:57 +00:00
#ifndef FS_NULL_H
#define FS_NULL_H
#define NULLM_CACHE 0x0001
BSD 4.4 Lite Kernel Sources
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struct null_mount {
struct mount *nullm_vfs;
Save lower root vnode in nullfs mnt data instead of upper. Nullfs needs to know the root vnode of the lower fs during the operation. Currently it caches the upper vnode of it, which is also the root of the nullfs mount. On unmount, nullfs calls vflush() with rootrefs == 1, and aborts non-forced unmount if there are any more vnodes instantiated during vflush(). This means that the reference to the root vnode after failed non-forced unmount could be lost and nullm_rootvp points to the freed memory. Fix it by storing the reference for lower vnode instead, which is kept intact during vflush(). nullfs_root() now instantiates the upper vnode of lower root. Care about VV_ROOT flag in null_nodeget(). Reported and tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week
2020-01-28 11:29:06 +00:00
struct vnode *nullm_lowerrootvp; /* Ref to lower root vnode */
Add the "nocache" nullfs mount option, which disables the caching of the free nullfs vnodes, switching nullfs behaviour to pre-r240285. The option is mostly intended as the last-resort when higher pressure on the vnode cache due to doubling of the vnode counts is not desirable. Note that disabling the cache costs more than 2x wall time in the metadata-hungry scenarious. The default is "cache". Tested and benchmarked by: pho (previous version) MFC after: 2 weeks
2013-01-03 19:17:57 +00:00
uint64_t nullm_flags;
BSD 4.4 Lite Kernel Sources
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};
Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL" is an application space macro and the applications are supposed to be free to use it as they please (but cannot). This is consistant with the other BSD's who made this change quite some time ago. More commits to come.
1999-12-29 05:07:58 +00:00
#ifdef _KERNEL
BSD 4.4 Lite Kernel Sources
1994-05-24 10:09:53 +00:00
/*
* A cache of vnode references
*/
struct null_node {
Back out the previous change to the queue(3) interface. It was not discussed and should probably not happen. Requested by: msmith and others
2000-05-26 02:09:24 +00:00
LIST_ENTRY(null_node) null_hash; /* Hash list */
BSD 4.4 Lite Kernel Sources
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struct vnode *null_lowervp; /* VREFed once */
struct vnode *null_vnode; /* Back pointer */
- Fix nullfs vnode reference leak in nullfs_reclaim_lowervp(). The null_hashget() obtains the reference on the nullfs vnode, which must be dropped. - Fix a wart which existed from the introduction of the nullfs caching, do not unlock lower vnode in the nullfs_reclaim_lowervp(). It should be innocent, but now it is also formally safe. Inform the nullfs_reclaim() about this using the NULLV_NOUNLOCK flag set on nullfs inode. - Add a callback to the upper filesystems for the lower vnode unlinking. When inactivating a nullfs vnode, check if the lower vnode was unlinked, indicated by nullfs flag NULLV_DROP or VV_NOSYNC on the lower vnode, and reclaim upper vnode if so. This allows nullfs to purge cached vnodes for the unlinked lower vnode, avoiding excessive caching. Reported by: G??ran L??wkrantz <goran.lowkrantz@ismobile.com> Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks
2013-05-11 11:17:44 +00:00
u_int null_flags;
BSD 4.4 Lite Kernel Sources
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};
- Fix nullfs vnode reference leak in nullfs_reclaim_lowervp(). The null_hashget() obtains the reference on the nullfs vnode, which must be dropped. - Fix a wart which existed from the introduction of the nullfs caching, do not unlock lower vnode in the nullfs_reclaim_lowervp(). It should be innocent, but now it is also formally safe. Inform the nullfs_reclaim() about this using the NULLV_NOUNLOCK flag set on nullfs inode. - Add a callback to the upper filesystems for the lower vnode unlinking. When inactivating a nullfs vnode, check if the lower vnode was unlinked, indicated by nullfs flag NULLV_DROP or VV_NOSYNC on the lower vnode, and reclaim upper vnode if so. This allows nullfs to purge cached vnodes for the unlinked lower vnode, avoiding excessive caching. Reported by: G??ran L??wkrantz <goran.lowkrantz@ismobile.com> Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks
2013-05-11 11:17:44 +00:00
#define NULLV_NOUNLOCK 0x0001
#define NULLV_DROP 0x0002
BSD 4.4 Lite Kernel Sources
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#define MOUNTTONULLMOUNT(mp) ((struct null_mount *)((mp)->mnt_data))
#define VTONULL(vp) ((struct null_node *)(vp)->v_data)
#define NULLTOV(xp) ((xp)->null_vnode)
Get rid from the __P() macros. Encouraged by: peter
2000-09-05 07:54:39 +00:00
int nullfs_init(struct vfsconf *vfsp);
Various cleanups towards make nullfs functional (it is still broken at this point): Replace all '#ifdef DEBUG' with '#ifdef NULLFS_DEBUG' and add NULLFSDEBUG macro. Protect nullfs hash table with lockmgr. Use proper order of operations when freeing mnt_data. Return correct fsid in the null_getattr(). Add null_open() function to catch MNT_NODEV (obtained from NetBSD). Add null_rename() to catch cross-fs rename operations (submitted by Ustimenko Semen <semen@iclub.nsu.ru>) Remove duplicate $FreeBSD$ tags.
2000-09-05 09:02:07 +00:00
int nullfs_uninit(struct vfsconf *vfsp);
Fix a race during null node creation between relookuping the hash and adding vnode to hash. The fix is to use atomic hash-lookup-and-add-if- not-found operation. The odd thing is that this race can't happen actually because the lowervp vnode is locked exclusively now during the whole process of null node creation. This must be thought as a step toward shared lookups. Also remove vp->v_mount checks when looking for a match in the hash, as this is the vestige. Also add comments and cosmetic changes.
2002-06-13 21:49:09 +00:00
int null_nodeget(struct mount *mp, struct vnode *target, struct vnode **vpp);
Allow shared lookups for nullfs mounts, if lower filesystem supports it. There are two problems which shall be addressed for shared lookups use to have measurable effect on nullfs scalability: 1. When vfs_lookup() calls VOP_LOOKUP() for nullfs, which passes lookup operation to lower fs, resulting vnode is often only shared-locked. Then null_nodeget() cannot instantiate covering vnode for lower vnode, since insmntque1() and null_hashins() require exclusive lock on the lower. Change the assert that lower vnode is exclusively locked to only require any lock. If null hash failed to find pre-existing nullfs vnode for lower vnode and the vnode is shared-locked, the lower vnode lock is upgraded. 2. Nullfs reclaims its vnodes on deactivation. This is due to nullfs inability to detect reclamation of the lower vnode. Reclamation of a nullfs vnode at deactivation time prevents a reference to the lower vnode to become stale. Change nullfs VOP_INACTIVE to not reclaim the vnode, instead use the VFS_RECLAIM_LOWERVP to get notification and reclaim upper vnode together with the reclamation of the lower vnode. Note that nullfs reclamation procedure calls vput() on the lowervp vnode, temporary unlocking the vnode being reclaimed. This seems to be fine for MPSAFE filesystems, but not-MPSAFE code often put partially initialized vnode on some globally visible list, and later can decide that half-constructed vnode is not needed. If nullfs mount is created above such filesystem, then other threads might catch such not properly initialized vnode. Instead of trying to overcome this case, e.g. by recursing the lower vnode lock in null_reclaim_lowervp(), I decided to rely on nearby removal of the support for non-MPSAFE filesystems. In collaboration with: pho MFC after: 3 weeks
2012-09-09 19:20:23 +00:00
struct vnode *null_hashget(struct mount *mp, struct vnode *lowervp);
Fix the "error" path (when dropping not fully initialized vnode). Also move hash operations out of null_vnops.c and explicitly initialize v_lock in null_node_alloc (to set wmesg). Reviewed by: bp MFC after: 2 weeks
2002-06-13 18:25:06 +00:00
void null_hashrem(struct null_node *xp);
Get rid from the __P() macros. Encouraged by: peter
2000-09-05 07:54:39 +00:00
int null_bypass(struct vop_generic_args *ap);
Get rid of the NULLFS_DIAGNOSTIC option. This option was as useful as the other XXXFS_DIAGNOSTIC options (not very) and mostly controlled tracing of normal operation. Use `#ifdef DEBUG' for non-diagnostics and `#ifdef DIAGNOSTIC' for diagnostics.
1999-09-04 12:35:09 +00:00
#ifdef DIAGNOSTIC
Get rid from the __P() macros. Encouraged by: peter
2000-09-05 07:54:39 +00:00
struct vnode *null_checkvp(struct vnode *vp, char *fil, int lno);
BSD 4.4 Lite Kernel Sources
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#define NULLVPTOLOWERVP(vp) null_checkvp((vp), __FILE__, __LINE__)
#else
#define NULLVPTOLOWERVP(vp) (VTONULL(vp)->null_lowervp)
#endif
Back when VOP_* was introduced, we did not have new-style struct initializations but we did have lofty goals and big ideals. Adjust to more contemporary circumstances and gain type checking. Replace the entire vop_t frobbing thing with properly typed structures. The only casualty is that we can not add a new VOP_ method with a loadable module. History has not given us reason to belive this would ever be feasible in the the first place. Eliminate in toto VOCALL(), vop_t, VNODEOP_SET() etc. Give coda correct prototypes and function definitions for all vop_()s. Generate a bit more data from the vnode_if.src file: a struct vop_vector and protype typedefs for all vop methods. Add a new vop_bypass() and make vop_default be a pointer to another struct vop_vector. Remove a lot of vfs_init since vop_vector is ready to use from the compiler. Cast various vop_mumble() to void * with uppercase name, for instance VOP_PANIC, VOP_NULL etc. Implement VCALL() by making vdesc_offset the offsetof() the relevant function pointer in vop_vector. This is disgusting but since the code is generated by a script comparatively safe. The alternative for nullfs etc. would be much worse. Fix up all vnode method vectors to remove casts so they become typesafe. (The bulk of this is generated by scripts)
2004-12-01 23:16:38 +00:00
extern struct vop_vector null_vnodeops;
Various cleanups towards make nullfs functional (it is still broken at this point): Replace all '#ifdef DEBUG' with '#ifdef NULLFS_DEBUG' and add NULLFSDEBUG macro. Protect nullfs hash table with lockmgr. Use proper order of operations when freeing mnt_data. Return correct fsid in the null_getattr(). Add null_open() function to catch MNT_NODEV (obtained from NetBSD). Add null_rename() to catch cross-fs rename operations (submitted by Ustimenko Semen <semen@iclub.nsu.ru>) Remove duplicate $FreeBSD$ tags.
2000-09-05 09:02:07 +00:00
#ifdef MALLOC_DECLARE
MALLOC_DECLARE(M_NULLFSNODE);
#endif
#ifdef NULLFS_DEBUG
#define NULLFSDEBUG(format, args...) printf(format ,## args)
#else
#define NULLFSDEBUG(format, args...)
#endif /* NULLFS_DEBUG */
Get rid from the __P() macros. Encouraged by: peter
2000-09-05 07:54:39 +00:00
Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL" is an application space macro and the applications are supposed to be free to use it as they please (but cannot). This is consistant with the other BSD's who made this change quite some time ago. More commits to come.
1999-12-29 05:07:58 +00:00
#endif /* _KERNEL */
Add the "nocache" nullfs mount option, which disables the caching of the free nullfs vnodes, switching nullfs behaviour to pre-r240285. The option is mostly intended as the last-resort when higher pressure on the vnode cache due to doubling of the vnode counts is not desirable. Note that disabling the cache costs more than 2x wall time in the metadata-hungry scenarious. The default is "cache". Tested and benchmarked by: pho (previous version) MFC after: 2 weeks
2013-01-03 19:17:57 +00:00
#endif
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