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path: root/drivers/scsi/libiscsi_tcp.c
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#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/ns_common.h>
#include <linux/fs_pin.h>

struct mnt_namespace {
	atomic_t		count;
	struct ns_common	ns;
	struct mount *	root;
	struct list_head	list;
	struct user_namespace	*user_ns;
	u64			seq;	/* Sequence number to prevent loops */
	wait_queue_head_t poll;
	u64 event;
};

struct mnt_pcp {
	int mnt_count;
	int mnt_writers;
};

struct mountpoint {
	struct hlist_node m_hash;
	struct dentry *m_dentry;
	struct hlist_head m_list;
	int m_count;
};

struct mount {
	struct hlist_node mnt_hash;
	struct mount *mnt_parent;
	struct dentry *mnt_mountpoint;
	struct vfsmount mnt;
	union {
		struct rcu_head mnt_rcu;
		struct llist_node mnt_llist;
	};
#ifdef CONFIG_SMP
	struct mnt_pcp __percpu *mnt_pcp;
#else
	int mnt_count;
	int mnt_writers;
#endif
	struct list_head mnt_mounts;	/* list of children, anchored here */
	struct list_head mnt_child;	/* and going through their mnt_child */
	struct list_head mnt_instance;	/* mount instance on sb->s_mounts */
	const char *mnt_devname;	/* Name of device e.g. /dev/dsk/hda1 */
	struct list_head mnt_list;
	struct list_head mnt_expire;	/* link in fs-specific expiry list */
	struct list_head mnt_share;	/* circular list of shared mounts */
	struct list_head mnt_slave_list;/* list of slave mounts */
	struct list_head mnt_slave;	/* slave list entry */
	struct mount *mnt_master;	/* slave is on master->mnt_slave_list */
	struct mnt_namespace *mnt_ns;	/* containing namespace */
	struct mountpoint *mnt_mp;	/* where is it mounted */
	struct hlist_node mnt_mp_list;	/* list mounts with the same mountpoint */
#ifdef CONFIG_FSNOTIFY
	struct hlist_head mnt_fsnotify_marks;
	__u32 mnt_fsnotify_mask;
#endif
	int mnt_id;			/* mount identifier */
	int mnt_group_id;		/* peer group identifier */
	int mnt_expiry_mark;		/* true if marked for expiry */
	struct hlist_head mnt_pins;
	struct fs_pin mnt_umount;
	struct dentry *mnt_ex_mountpoint;
};

#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */

static inline struct mount *real_mount(struct vfsmount *mnt)
{
	return container_of(mnt, struct mount, mnt);
}

static inline int mnt_has_parent(struct mount *mnt)
{
	return mnt != mnt->mnt_parent;
}

static inline int is_mounted(struct vfsmount *mnt)
{
	/* neither detached nor internal? */
	return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
}

extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
extern struct mount *__lookup_mnt_last(struct vfsmount *, struct dentry *);

extern bool legitimize_mnt(struct vfsmount *, unsigned);

extern void __detach_mounts(struct dentry *dentry);

static inline void detach_mounts(struct dentry *dentry)
{
	if (!d_mountpoint(dentry))
		return;
	__detach_mounts(dentry);
}

static inline void get_mnt_ns(struct mnt_namespace *ns)
{
	atomic_inc(&ns->count);
}

extern seqlock_t mount_lock;

static inline void lock_mount_hash(void)
{
	write_seqlock(&mount_lock);
}

static inline void unlock_mount_hash(void)
{
	write_sequnlock(&mount_lock);
}

struct proc_mounts {
	struct seq_file m;
	struct mnt_namespace *ns;
	struct path root;
	int (*show)(struct seq_file *, struct vfsmount *);
	void *cached_mount;
	u64 cached_event;
	loff_t cached_index;
};

#define proc_mounts(p) (container_of((p), struct proc_mounts, m))

extern const struct seq_operations mounts_op;

extern bool __is_local_mountpoint(struct dentry *dentry);
static inline bool is_local_mountpoint(struct dentry *dentry)
{
	if (!d_mountpoint(dentry))
		return false;

	return __is_local_mountpoint(dentry);
}
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/*
 * iSCSI over TCP/IP Data-Path lib
 *
 * Copyright (C) 2004 Dmitry Yusupov
 * Copyright (C) 2004 Alex Aizman
 * Copyright (C) 2005 - 2006 Mike Christie
 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
 * maintained by open-iscsi@googlegroups.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * See the file COPYING included with this distribution for more details.
 *
 * Credits:
 *	Christoph Hellwig
 *	FUJITA Tomonori
 *	Arne Redlich
 *	Zhenyu Wang
 */

#include <linux/types.h>
#include <linux/list.h>
#include <linux/inet.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/crypto.h>
#include <linux/delay.h>
#include <linux/kfifo.h>
#include <linux/scatterlist.h>
#include <linux/module.h>
#include <net/tcp.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi.h>
#include <scsi/scsi_transport_iscsi.h>

#include "iscsi_tcp.h"

MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
	      "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
	      "Alex Aizman <itn780@yahoo.com>");
MODULE_DESCRIPTION("iSCSI/TCP data-path");
MODULE_LICENSE("GPL");

static int iscsi_dbg_libtcp;
module_param_named(debug_libiscsi_tcp, iscsi_dbg_libtcp, int,
		   S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug_libiscsi_tcp, "Turn on debugging for libiscsi_tcp "
		 "module. Set to 1 to turn on, and zero to turn off. Default "
		 "is off.");

#define ISCSI_DBG_TCP(_conn, dbg_fmt, arg...)			\
	do {							\
		if (iscsi_dbg_libtcp)				\
			iscsi_conn_printk(KERN_INFO, _conn,	\
					     "%s " dbg_fmt,	\
					     __func__, ##arg);	\
	} while (0);

static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
				   struct iscsi_segment *segment);

/*
 * Scatterlist handling: inside the iscsi_segment, we
 * remember an index into the scatterlist, and set data/size
 * to the current scatterlist entry. For highmem pages, we
 * kmap as needed.
 *
 * Note that the page is unmapped when we return from
 * TCP's data_ready handler, so we may end up mapping and
 * unmapping the same page repeatedly. The whole reason
 * for this is that we shouldn't keep the page mapped
 * outside the softirq.
 */

/**
 * iscsi_tcp_segment_init_sg - init indicated scatterlist entry
 * @segment: the buffer object
 * @sg: scatterlist
 * @offset: byte offset into that sg entry
 *
 * This function sets up the segment so that subsequent
 * data is copied to the indicated sg entry, at the given
 * offset.
 */
static inline void
iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
			  struct scatterlist *sg, unsigned int offset)
{
	segment->sg = sg;
	segment->sg_offset = offset;
	segment->size = min(sg->length - offset,
			    segment->total_size - segment->total_copied);
	segment->data = NULL;
}

/**
 * iscsi_tcp_segment_map - map the current S/G page
 * @segment: iscsi_segment
 * @recv: 1 if called from recv path
 *
 * We only need to possibly kmap data if scatter lists are being used,
 * because the iscsi passthrough and internal IO paths will never use high
 * mem pages.
 */
static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
{
	struct scatterlist *sg;

	if (segment->data != NULL || !segment->sg)
		return;

	sg = segment->sg;
	BUG_ON(segment->sg_mapped);
	BUG_ON(sg->length == 0);

	/*
	 * If the page count is greater than one it is ok to send
	 * to the network layer's zero copy send path. If not we
	 * have to go the slow sendmsg path. We always map for the
	 * recv path.
	 */
	if (page_count(sg_page(sg)) >= 1 && !recv)
		return;

	if (recv) {
		segment->atomic_mapped = true;
		segment->sg_mapped = kmap_atomic(sg_page(sg));
	} else {
		segment->atomic_mapped = false;
		/* the xmit path can sleep with the page mapped so use kmap */
		segment->sg_mapped = kmap(sg_page(sg));
	}

	segment->data =