cifs: Avoid calling unlock_page() twice in cifs_readpage() when using fscache

[mirror_ubuntu-artful-kernel.git] / fs / cifs / misc.c

/*
 *   fs/cifs/misc.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2008
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/mempool.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "smberr.h"
#include "nterr.h"
#include "cifs_unicode.h"
#ifdef CONFIG_CIFS_SMB2
#include "smb2pdu.h"
#endif

extern mempool_t *cifs_sm_req_poolp;
extern mempool_t *cifs_req_poolp;

/* The xid serves as a useful identifier for each incoming vfs request,
   in a similar way to the mid which is useful to track each sent smb,
   and CurrentXid can also provide a running counter (although it
   will eventually wrap past zero) of the total vfs operations handled
   since the cifs fs was mounted */

unsigned int
_get_xid(void)
{
	unsigned int xid;

	spin_lock(&GlobalMid_Lock);
	GlobalTotalActiveXid++;

	/* keep high water mark for number of simultaneous ops in filesystem */
	if (GlobalTotalActiveXid > GlobalMaxActiveXid)
		GlobalMaxActiveXid = GlobalTotalActiveXid;
	if (GlobalTotalActiveXid > 65000)
		cifs_dbg(FYI, "warning: more than 65000 requests active\n");
	xid = GlobalCurrentXid++;
	spin_unlock(&GlobalMid_Lock);
	return xid;
}

void
_free_xid(unsigned int xid)
{
	spin_lock(&GlobalMid_Lock);
	/* if (GlobalTotalActiveXid == 0)
		BUG(); */
	GlobalTotalActiveXid--;
	spin_unlock(&GlobalMid_Lock);
}

struct cifs_ses *
sesInfoAlloc(void)
{
	struct cifs_ses *ret_buf;

	ret_buf = kzalloc(sizeof(struct cifs_ses), GFP_KERNEL);
	if (ret_buf) {
		atomic_inc(&sesInfoAllocCount);
		ret_buf->status = CifsNew;
		++ret_buf->ses_count;
		INIT_LIST_HEAD(&ret_buf->smb_ses_list);
		INIT_LIST_HEAD(&ret_buf->tcon_list);
		mutex_init(&ret_buf->session_mutex);
	}
	return ret_buf;
}

void
sesInfoFree(struct cifs_ses *buf_to_free)
{
	if (buf_to_free == NULL) {
		cifs_dbg(FYI, "Null buffer passed to sesInfoFree\n");
		return;
	}

	atomic_dec(&sesInfoAllocCount);
	kfree(buf_to_free->serverOS);
	kfree(buf_to_free->serverDomain);
	kfree(buf_to_free->serverNOS);
	if (buf_to_free->password) {
		memset(buf_to_free->password, 0, strlen(buf_to_free->password));
		kfree(buf_to_free->password);
	}
	kfree(buf_to_free->user_name);
	kfree(buf_to_free->domainName);
	kfree(buf_to_free->auth_key.response);
	kfree(buf_to_free);
}

struct cifs_tcon *
tconInfoAlloc(void)
{
	struct cifs_tcon *ret_buf;
	ret_buf = kzalloc(sizeof(struct cifs_tcon), GFP_KERNEL);
	if (ret_buf) {
		atomic_inc(&tconInfoAllocCount);
		ret_buf->tidStatus = CifsNew;
		++ret_buf->tc_count;
		INIT_LIST_HEAD(&ret_buf->openFileList);
		INIT_LIST_HEAD(&ret_buf->tcon_list);
#ifdef CONFIG_CIFS_STATS
		spin_lock_init(&ret_buf->stat_lock);
#endif
	}
	return ret_buf;
}

void
tconInfoFree(struct cifs_tcon *buf_to_free)
{
	if (buf_to_free == NULL) {
		cifs_dbg(FYI, "Null buffer passed to tconInfoFree\n");
		return;
	}
	atomic_dec(&tconInfoAllocCount);
	kfree(buf_to_free->nativeFileSystem);
	if (buf_to_free->password) {
		memset(buf_to_free->password, 0, strlen(buf_to_free->password));
		kfree(buf_to_free->password);
	}
	kfree(buf_to_free);
}

struct smb_hdr *
cifs_buf_get(void)
{
	struct smb_hdr *ret_buf = NULL;
	size_t buf_size = sizeof(struct smb_hdr);

#ifdef CONFIG_CIFS_SMB2
	/*
	 * SMB2 header is bigger than CIFS one - no problems to clean some
	 * more bytes for CIFS.
	 */
	buf_size = sizeof(struct smb2_hdr);
#endif
	/*
	 * We could use negotiated size instead of max_msgsize -
	 * but it may be more efficient to always alloc same size
	 * albeit slightly larger than necessary and maxbuffersize
	 * defaults to this and can not be bigger.
	 */
	ret_buf = mempool_alloc(cifs_req_poolp, GFP_NOFS);

	/* clear the first few header bytes */
	/* for most paths, more is cleared in header_assemble */
	if (ret_buf) {
		memset(ret_buf, 0, buf_size + 3);
		atomic_inc(&bufAllocCount);
#ifdef CONFIG_CIFS_STATS2
		atomic_inc(&totBufAllocCount);
#endif /* CONFIG_CIFS_STATS2 */
	}

	return ret_buf;
}

void
cifs_buf_release(void *buf_to_free)
{
	if (buf_to_free == NULL) {
		/* cifs_dbg(FYI, "Null buffer passed to cifs_buf_release\n");*/
		return;
	}
	mempool_free(buf_to_free, cifs_req_poolp);

	atomic_dec(&bufAllocCount);
	return;
}

struct smb_hdr *
cifs_small_buf_get(void)
{
	struct smb_hdr *ret_buf = NULL;

/* We could use negotiated size instead of max_msgsize -
   but it may be more efficient to always alloc same size
   albeit slightly larger than necessary and maxbuffersize
   defaults to this and can not be bigger */
	ret_buf = mempool_alloc(cifs_sm_req_poolp, GFP_NOFS);
	if (ret_buf) {
	/* No need to clear memory here, cleared in header assemble */
	/*	memset(ret_buf, 0, sizeof(struct smb_hdr) + 27);*/
		atomic_inc(&smBufAllocCount);
#ifdef CONFIG_CIFS_STATS2
		atomic_inc(&totSmBufAllocCount);
#endif /* CONFIG_CIFS_STATS2 */

	}
	return ret_buf;
}

void
cifs_small_buf_release(void *buf_to_free)
{

	if (buf_to_free == NULL) {
		cifs_dbg(FYI, "Null buffer passed to cifs_small_buf_release\n");
		return;
	}
	mempool_free(buf_to_free, cifs_sm_req_poolp);

	atomic_dec(&smBufAllocCount);
	return;
}

/* NB: MID can not be set if treeCon not passed in, in that
   case it is responsbility of caller to set the mid */
void
header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
		const struct cifs_tcon *treeCon, int word_count
		/* length of fixed section (word count) in two byte units  */)
{
	char *temp = (char *) buffer;

	memset(temp, 0, 256); /* bigger than MAX_CIFS_HDR_SIZE */

	buffer->smb_buf_length = cpu_to_be32(
	    (2 * word_count) + sizeof(struct smb_hdr) -
	    4 /*  RFC 1001 length field does not count */  +
	    2 /* for bcc field itself */) ;

	buffer->Protocol[0] = 0xFF;
	buffer->Protocol[1] = 'S';
	buffer->Protocol[2] = 'M';
	buffer->Protocol[3] = 'B';
	buffer->Command = smb_command;
	buffer->Flags = 0x00;	/* case sensitive */
	buffer->Flags2 = SMBFLG2_KNOWS_LONG_NAMES;
	buffer->Pid = cpu_to_le16((__u16)current->tgid);
	buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
	if (treeCon) {
		buffer->Tid = treeCon->tid;
		if (treeCon->ses) {
			if (treeCon->ses->capabilities & CAP_UNICODE)
				buffer->Flags2 |= SMBFLG2_UNICODE;
			if (treeCon->ses->capabilities & CAP_STATUS32)
				buffer->Flags2 |= SMBFLG2_ERR_STATUS;

			/* Uid is not converted */
			buffer->Uid = treeCon->ses->Suid;
			buffer->Mid = get_next_mid(treeCon->ses->server);
		}
		if (treeCon->Flags & SMB_SHARE_IS_IN_DFS)
			buffer->Flags2 |= SMBFLG2_DFS;
		if (treeCon->nocase)
			buffer->Flags  |= SMBFLG_CASELESS;
		if ((treeCon->ses) && (treeCon->ses->server))
			if (treeCon->ses->server->sign)
				buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
	}

/*  endian conversion of flags is now done just before sending */
	buffer->WordCount = (char) word_count;
	return;
}

static int
check_smb_hdr(struct smb_hdr *smb, __u16 mid)
{
	/* does it have the right SMB "signature" ? */
	if (*(__le32 *) smb->Protocol != cpu_to_le32(0x424d53ff)) {
		cifs_dbg(VFS, "Bad protocol string signature header 0x%x\n",
			 *(unsigned int *)smb->Protocol);
		return 1;
	}

	/* Make sure that message ids match */
	if (mid != smb->Mid) {
		cifs_dbg(VFS, "Mids do not match. received=%u expected=%u\n",
			 smb->Mid, mid);
		return 1;
	}

	/* if it's a response then accept */
	if (smb->Flags & SMBFLG_RESPONSE)
		return 0;

	/* only one valid case where server sends us request */
	if (smb->Command == SMB_COM_LOCKING_ANDX)
		return 0;

	cifs_dbg(VFS, "Server sent request, not response. mid=%u\n", smb->Mid);
	return 1;
}

int
checkSMB(char *buf, unsigned int total_read)
{
	struct smb_hdr *smb = (struct smb_hdr *)buf;
	__u16 mid = smb->Mid;
	__u32 rfclen = be32_to_cpu(smb->smb_buf_length);
	__u32 clc_len;  /* calculated length */
	cifs_dbg(FYI, "checkSMB Length: 0x%x, smb_buf_length: 0x%x\n",
		 total_read, rfclen);

	/* is this frame too small to even get to a BCC? */
	if (total_read < 2 + sizeof(struct smb_hdr)) {
		if ((total_read >= sizeof(struct smb_hdr) - 1)
			    && (smb->Status.CifsError != 0)) {
			/* it's an error return */
			smb->WordCount = 0;
			/* some error cases do not return wct and bcc */
			return 0;
		} else if ((total_read == sizeof(struct smb_hdr) + 1) &&
				(smb->WordCount == 0)) {
			char *tmp = (char *)smb;
			/* Need to work around a bug in two servers here */
			/* First, check if the part of bcc they sent was zero */
			if (tmp[sizeof(struct smb_hdr)] == 0) {
				/* some servers return only half of bcc
				 * on simple responses (wct, bcc both zero)
				 * in particular have seen this on
				 * ulogoffX and FindClose. This leaves
				 * one byte of bcc potentially unitialized
				 */
				/* zero rest of bcc */
				tmp[sizeof(struct smb_hdr)+1] = 0;
				return 0;
			}
			cifs_dbg(VFS, "rcvd invalid byte count (bcc)\n");
		} else {
			cifs_dbg(VFS, "Length less than smb header size\n");
		}
		return -EIO;
	}

	/* otherwise, there is enough to get to the BCC */
	if (check_smb_hdr(smb, mid))
		return -EIO;
	clc_len = smbCalcSize(smb);

	if (4 + rfclen != total_read) {
		cifs_dbg(VFS, "Length read does not match RFC1001 length %d\n",
			 rfclen);
		return -EIO;
	}

	if (4 + rfclen != clc_len) {
		/* check if bcc wrapped around for large read responses */
		if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {
			/* check if lengths match mod 64K */
			if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))
				return 0; /* bcc wrapped */
		}
		cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n",
			 clc_len, 4 + rfclen, smb->Mid);

		if (4 + rfclen < clc_len) {
			cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
				 rfclen, smb->Mid);
			return -EIO;
		} else if (rfclen > clc_len + 512) {
			/*
			 * Some servers (Windows XP in particular) send more
			 * data than the lengths in the SMB packet would
			 * indicate on certain calls (byte range locks and
			 * trans2 find first calls in particular). While the
			 * client can handle such a frame by ignoring the
			 * trailing data, we choose limit the amount of extra
			 * data to 512 bytes.
			 */
			cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n",
				 rfclen, smb->Mid);
			return -EIO;
		}
	}
	return 0;
}

bool
is_valid_oplock_break(char *buffer, struct TCP_Server_Info *srv)
{
	struct smb_hdr *buf = (struct smb_hdr *)buffer;
	struct smb_com_lock_req *pSMB = (struct smb_com_lock_req *)buf;
	struct list_head *tmp, *tmp1, *tmp2;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;
	struct cifsInodeInfo *pCifsInode;
	struct cifsFileInfo *netfile;

	cifs_dbg(FYI, "Checking for oplock break or dnotify response\n");
	if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
	   (pSMB->hdr.Flags & SMBFLG_RESPONSE)) {
		struct smb_com_transaction_change_notify_rsp *pSMBr =
			(struct smb_com_transaction_change_notify_rsp *)buf;
		struct file_notify_information *pnotify;
		__u32 data_offset = 0;
		if (get_bcc(buf) > sizeof(struct file_notify_information)) {
			data_offset = le32_to_cpu(pSMBr->DataOffset);

			pnotify = (struct file_notify_information *)
				((char *)&pSMBr->hdr.Protocol + data_offset);
			cifs_dbg(FYI, "dnotify on %s Action: 0x%x\n",
				 pnotify->FileName, pnotify->Action);
			/*   cifs_dump_mem("Rcvd notify Data: ",buf,
				sizeof(struct smb_hdr)+60); */
			return true;
		}
		if (pSMBr->hdr.Status.CifsError) {
			cifs_dbg(FYI, "notify err 0x%d\n",
				 pSMBr->hdr.Status.CifsError);
			return true;
		}
		return false;
	}
	if (pSMB->hdr.Command != SMB_COM_LOCKING_ANDX)
		return false;
	if (pSMB->hdr.Flags & SMBFLG_RESPONSE) {
		/* no sense logging error on invalid handle on oplock
		   break - harmless race between close request and oplock
		   break response is expected from time to time writing out
		   large dirty files cached on the client */
		if ((NT_STATUS_INVALID_HANDLE) ==
		   le32_to_cpu(pSMB->hdr.Status.CifsError)) {
			cifs_dbg(FYI, "invalid handle on oplock break\n");
			return true;
		} else if (ERRbadfid ==
		   le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
			return true;
		} else {
			return false; /* on valid oplock brk we get "request" */
		}
	}
	if (pSMB->hdr.WordCount != 8)
		return false;

	cifs_dbg(FYI, "oplock type 0x%d level 0x%d\n",
		 pSMB->LockType, pSMB->OplockLevel);
	if (!(pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE))
		return false;

	/* look up tcon based on tid & uid */
	spin_lock(&cifs_tcp_ses_lock);
	list_for_each(tmp, &srv->smb_ses_list) {
		ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
		list_for_each(tmp1, &ses->tcon_list) {
			tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
			if (tcon->tid != buf->Tid)
				continue;

			cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
			spin_lock(&cifs_file_list_lock);
			list_for_each(tmp2, &tcon->openFileList) {
				netfile = list_entry(tmp2, struct cifsFileInfo,
						     tlist);
				if (pSMB->Fid != netfile->fid.netfid)
					continue;

				cifs_dbg(FYI, "file id match, oplock break\n");
				pCifsInode = CIFS_I(netfile->dentry->d_inode);

				cifs_set_oplock_level(pCifsInode,
					pSMB->OplockLevel ? OPLOCK_READ : 0);
				queue_work(cifsiod_wq,
					   &netfile->oplock_break);
				netfile->oplock_break_cancelled = false;

				spin_unlock(&cifs_file_list_lock);
				spin_unlock(&cifs_tcp_ses_lock);
				return true;
			}
			spin_unlock(&cifs_file_list_lock);
			spin_unlock(&cifs_tcp_ses_lock);
			cifs_dbg(FYI, "No matching file for oplock break\n");
			return true;
		}
	}
	spin_unlock(&cifs_tcp_ses_lock);
	cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
	return true;
}

void
dump_smb(void *buf, int smb_buf_length)
{
	int i, j;
	char debug_line[17];
	unsigned char *buffer = buf;

	if (traceSMB == 0)
		return;

	for (i = 0, j = 0; i < smb_buf_length; i++, j++) {
		if (i % 8 == 0) {
			/* have reached the beginning of line */
			printk(KERN_DEBUG "| ");
			j = 0;
		}
		printk("%0#4x ", buffer[i]);
		debug_line[2 * j] = ' ';
		if (isprint(buffer[i]))
			debug_line[1 + (2 * j)] = buffer[i];
		else
			debug_line[1 + (2 * j)] = '_';

		if (i % 8 == 7) {
			/* reached end of line, time to print ascii */
			debug_line[16] = 0;
			printk(" | %s\n", debug_line);
		}
	}
	for (; j < 8; j++) {
		printk("     ");
		debug_line[2 * j] = ' ';
		debug_line[1 + (2 * j)] = ' ';
	}
	printk(" | %s\n", debug_line);
	return;
}

void
cifs_autodisable_serverino(struct cifs_sb_info *cifs_sb)
{
	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
		cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
		cifs_dbg(VFS, "Autodisabling the use of server inode numbers on %s. This server doesn't seem to support them properly. Hardlinks will not be recognized on this mount. Consider mounting with the \"noserverino\" option to silence this message.\n",
			 cifs_sb_master_tcon(cifs_sb)->treeName);
	}
}

void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
{
	oplock &= 0xF;

	if (oplock == OPLOCK_EXCLUSIVE) {
		cinode->oplock = CIFS_CACHE_WRITE_FLG | CIFS_CACHE_READ_FLG;
		cifs_dbg(FYI, "Exclusive Oplock granted on inode %p\n",
			 &cinode->vfs_inode);
	} else if (oplock == OPLOCK_READ) {
		cinode->oplock = CIFS_CACHE_READ_FLG;
		cifs_dbg(FYI, "Level II Oplock granted on inode %p\n",
			 &cinode->vfs_inode);
	} else
		cinode->oplock = 0;
}

bool
backup_cred(struct cifs_sb_info *cifs_sb)
{
	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
		if (uid_eq(cifs_sb->mnt_backupuid, current_fsuid()))
			return true;
	}
	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
		if (in_group_p(cifs_sb->mnt_backupgid))
			return true;
	}

	return false;
}

void
cifs_del_pending_open(struct cifs_pending_open *open)
{
	spin_lock(&cifs_file_list_lock);
	list_del(&open->olist);
	spin_unlock(&cifs_file_list_lock);
}

void
cifs_add_pending_open_locked(struct cifs_fid *fid, struct tcon_link *tlink,
			     struct cifs_pending_open *open)
{
#ifdef CONFIG_CIFS_SMB2
	memcpy(open->lease_key, fid->lease_key, SMB2_LEASE_KEY_SIZE);
#endif
	open->oplock = CIFS_OPLOCK_NO_CHANGE;
	open->tlink = tlink;
	fid->pending_open = open;
	list_add_tail(&open->olist, &tlink_tcon(tlink)->pending_opens);
}

void
cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
		      struct cifs_pending_open *open)
{
	spin_lock(&cifs_file_list_lock);
	cifs_add_pending_open_locked(fid, tlink, open);
	spin_unlock(&cifs_file_list_lock);
}