WSL2-Linux-Kernel/fs/9p/fid.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * V9FS FID Management
 *
 *  Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
 */
#ifndef FS_9P_FID_H
#define FS_9P_FID_H
#include <linux/list.h>

struct p9_fid *v9fs_fid_lookup(struct dentry *dentry);
static inline struct p9_fid *v9fs_parent_fid(struct dentry *dentry)
{
	return v9fs_fid_lookup(dentry->d_parent);
}
void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid);
struct p9_fid *v9fs_writeback_fid(struct dentry *dentry);
void v9fs_open_fid_add(struct inode *inode, struct p9_fid *fid);
static inline struct p9_fid *clone_fid(struct p9_fid *fid)
{
	return IS_ERR(fid) ? fid :  p9_client_walk(fid, 0, NULL, 1);
}
static inline struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
{
	struct p9_fid *fid, *nfid;

	fid = v9fs_fid_lookup(dentry);
	if (!fid || IS_ERR(fid))
		return fid;

	nfid = clone_fid(fid);
	p9_client_clunk(fid);
	return nfid;
}
#endif
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188 Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to free software foundation 51 franklin street fifth floor boston ma 02111 1301 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 27 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190528170026.981318839@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 2019-05-28 19:57:16 +03:00			`/* SPDX-License-Identifier: GPL-2.0-only */`
[PATCH] v9fs: debug and support routines This part of the patch contains debug and other misc routines. Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> 2005-09-10 00:04:24 +04:00			`/*`
			`* V9FS FID Management`
			`*`
			`* Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>`
			`*/`
fs/9p: Prevent multiple inclusion of same header Add necessary #ifndef #endif blocks to avoid mulitple inclusion of same headers Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> 2011-02-28 14:34:09 +03:00			`#ifndef FS_9P_FID_H`
			`#define FS_9P_FID_H`
[PATCH] v9fs: debug and support routines This part of the patch contains debug and other misc routines. Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> 2005-09-10 00:04:24 +04:00			`#include <linux/list.h>`

9p: Reorganization of 9p file system code This patchset moves non-filesystem interfaces of v9fs from fs/9p to net/9p. It moves the transport, packet marshalling and connection layers to net/9p leaving only the VFS related files in fs/9p. This work is being done in preparation for in-kernel 9p servers as well as alternate 9p clients (other than VFS). Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> 2007-07-11 02:57:28 +04:00			`struct p9_fid v9fs_fid_lookup(struct dentry dentry);`
9p: new helper - v9fs_parent_fid() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 2016-05-29 22:29:26 +03:00			`static inline struct p9_fid v9fs_parent_fid(struct dentry dentry)`
			`{`
			`return v9fs_fid_lookup(dentry->d_parent);`
			`}`
9p: v9fs_fid_add() can't fail now Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 2013-02-28 10:18:14 +04:00			`void v9fs_fid_add(struct dentry dentry, struct p9_fid fid);`
fs/9p: Add fid to inode in cached mode The fid attached to inode will be opened O_RDWR mode and is used for dirty page writeback only. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> 2011-02-28 14:33:57 +03:00			`struct p9_fid v9fs_writeback_fid(struct dentry dentry);`
fs/9p: track open fids This patch adds accounting of open fids in a list hanging off the i_private field of the corresponding inode. This allows faster lookups compared to searching the full 9p client list. The lookup code is modified accordingly. Link: http://lkml.kernel.org/r/20200923141146.90046-3-jianyong.wu@arm.com Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> 2020-09-23 17:11:44 +03:00			`void v9fs_open_fid_add(struct inode inode, struct p9_fid fid);`
9p: fix braino introduced in "9p: new helper - v9fs_parent_fid()" In v9fs_vfs_rename() we need to clone the parents' fids, not just find them. Spotted-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 2016-08-03 18:02:48 +03:00			`static inline struct p9_fid clone_fid(struct p9_fid fid)`
			`{`
			`return IS_ERR(fid) ? fid : p9_client_walk(fid, 0, NULL, 1);`
			`}`
9p: use clone_fid() in a bunch of places it cleans the things up Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 2016-08-03 18:12:12 +03:00			`static inline struct p9_fid v9fs_fid_clone(struct dentry dentry)`
			`{`
9p: add refcount to p9_fid struct Fix race issue in fid contention. Eric's and Greg's patch offer a mechanism to fix open-unlink-fsyscall bug in 9p. But there is race issue in fid parallel accesses. As Greg's patch stores all of fids from opened files into according inode, so all the lookup fid ops can retrieve fid from inode preferentially. But there is no mechanism to handle the fid contention issue. For example, there are two threads get the same fid in the same time and one of them clunk the fid before the other thread ready to discard the fid. In this scenario, it will lead to some fatal problems, even kernel core dump. I introduce a mechanism to fix this race issue. A counter field introduced into p9_fid struct to store the reference counter to the fid. When a fid is allocated from the inode or dentry, the counter will increase, and will decrease at the end of its occupation. It is guaranteed that the fid won't be clunked before the reference counter go down to 0, then we can avoid the clunked fid to be used. tests: race issue test from the old test case: for file in {01..50}; do touch f.${file}; done seq 1 1000 \| xargs -n 1 -P 50 -I{} cat f. > /dev/null open-unlink-fsyscall test: I have tested for fsyscall include: ftruncate fstat fchown fchmod faccessat. Link: http://lkml.kernel.org/r/20200923141146.90046-5-jianyong.wu@arm.com Fixes: 478ba09edc1f ("fs/9p: search open fids first") Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> 2020-09-23 17:11:46 +03:00			`struct p9_fid fid, nfid;`

			`fid = v9fs_fid_lookup(dentry);`
			`if (!fid \|\| IS_ERR(fid))`
			`return fid;`

9p: apply review requests for fid refcounting Fix style issues in parent commit ("apply review requests for fid refcounting"), no functional change. Link: http://lkml.kernel.org/r/1605802012-31133-2-git-send-email-asmadeus@codewreck.org Fixes: 6636b6dcc3db ("9p: add refcount to p9_fid struct") Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> 2020-11-03 11:35:57 +03:00			`nfid = clone_fid(fid);`
9p: add refcount to p9_fid struct Fix race issue in fid contention. Eric's and Greg's patch offer a mechanism to fix open-unlink-fsyscall bug in 9p. But there is race issue in fid parallel accesses. As Greg's patch stores all of fids from opened files into according inode, so all the lookup fid ops can retrieve fid from inode preferentially. But there is no mechanism to handle the fid contention issue. For example, there are two threads get the same fid in the same time and one of them clunk the fid before the other thread ready to discard the fid. In this scenario, it will lead to some fatal problems, even kernel core dump. I introduce a mechanism to fix this race issue. A counter field introduced into p9_fid struct to store the reference counter to the fid. When a fid is allocated from the inode or dentry, the counter will increase, and will decrease at the end of its occupation. It is guaranteed that the fid won't be clunked before the reference counter go down to 0, then we can avoid the clunked fid to be used. tests: race issue test from the old test case: for file in {01..50}; do touch f.${file}; done seq 1 1000 \| xargs -n 1 -P 50 -I{} cat f. > /dev/null open-unlink-fsyscall test: I have tested for fsyscall include: ftruncate fstat fchown fchmod faccessat. Link: http://lkml.kernel.org/r/20200923141146.90046-5-jianyong.wu@arm.com Fixes: 478ba09edc1f ("fs/9p: search open fids first") Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> 2020-09-23 17:11:46 +03:00			`p9_client_clunk(fid);`
			`return nfid;`
9p: use clone_fid() in a bunch of places it cleans the things up Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 2016-08-03 18:12:12 +03:00			`}`
fs/9p: Prevent multiple inclusion of same header Add necessary #ifndef #endif blocks to avoid mulitple inclusion of same headers Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> 2011-02-28 14:34:09 +03:00			`#endif`