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linux-next/fs/cifs/misc.c
Sachin Prabhu c11f1df500 cifs: Wait for writebacks to complete before attempting write. 
Problem reported in Red Hat bz 1040329 for strict writes where we cache
only when we hold oplock and write direct to the server when we don't.

When we receive an oplock break, we first change the oplock value for
the inode in cifsInodeInfo->oplock to indicate that we no longer hold
the oplock before we enqueue a task to flush changes to the backing
device. Once we have completed flushing the changes, we return the
oplock to the server.

There are 2 ways here where we can have data corruption
1) While we flush changes to the backing device as part of the oplock
break, we can have processes write to the file. These writes check for
the oplock, find none and attempt to write directly to the server.
These direct writes made while we are flushing from cache could be
overwritten by data being flushed from the cache causing data
corruption.
2) While a thread runs in cifs_strict_writev, the machine could receive
and process an oplock break after the thread has checked the oplock and
found that it allows us to cache and before we have made changes to the
cache. In that case, we end up with a dirty page in cache when we
shouldn't have any. This will be flushed later and will overwrite all
subsequent writes to the part of the file represented by this page.

Before making any writes to the server, we need to confirm that we are
not in the process of flushing data to the server and if we are, we
should wait until the process is complete before we attempt the write.
We should also wait for existing writes to complete before we process
an oplock break request which changes oplock values.

We add a version specific  downgrade_oplock() operation to allow for
differences in the oplock values set for the different smb versions.

Cc: stable@vger.kernel.org
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>
2014-04-16 13:51:46 -05:00

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/*
* 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)
{
/* 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;
}
/* 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",
get_mid(smb));
return 1;
}
int
checkSMB(char *buf, unsigned int total_read)
{
struct smb_hdr *smb = (struct smb_hdr *)buf;
__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))
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) {
__u16 mid = get_mid(smb);
/* 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, mid);
if (4 + rfclen < clc_len) {
cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n",
rfclen, 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, 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);
set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
&pCifsInode->flags);
/*
* Set flag if the server downgrades the oplock
* to L2 else clear.
*/
if (pSMB->OplockLevel)
set_bit(
CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
&pCifsInode->flags);
else
clear_bit(
CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
&pCifsInode->flags);
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;
}
static int
cifs_oplock_break_wait(void *unused)
{
schedule();
return signal_pending(current) ? -ERESTARTSYS : 0;
}
/*
* We wait for oplock breaks to be processed before we attempt to perform
* writes.
*/
int cifs_get_writer(struct cifsInodeInfo *cinode)
{
int rc;
start:
rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
cifs_oplock_break_wait, TASK_KILLABLE);
if (rc)
return rc;
spin_lock(&cinode->writers_lock);
if (!cinode->writers)
set_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
cinode->writers++;
/* Check to see if we have started servicing an oplock break */
if (test_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags)) {
cinode->writers--;
if (cinode->writers == 0) {
clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
}
spin_unlock(&cinode->writers_lock);
goto start;
}
spin_unlock(&cinode->writers_lock);
return 0;
}
void cifs_put_writer(struct cifsInodeInfo *cinode)
{
spin_lock(&cinode->writers_lock);
cinode->writers--;
if (cinode->writers == 0) {
clear_bit(CIFS_INODE_PENDING_WRITERS, &cinode->flags);
wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS);
}
spin_unlock(&cinode->writers_lock);
}
void cifs_done_oplock_break(struct cifsInodeInfo *cinode)
{
clear_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
wake_up_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK);
}
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);
}
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