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alistair23-linux/fs/lockd/svclock.c
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license 
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/lockd/svclock.c
*
* Handling of server-side locks, mostly of the blocked variety.
* This is the ugliest part of lockd because we tread on very thin ice.
* GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
* IMNSHO introducing the grant callback into the NLM protocol was one
* of the worst ideas Sun ever had. Except maybe for the idea of doing
* NFS file locking at all.
*
* I'm trying hard to avoid race conditions by protecting most accesses
* to a file's list of blocked locks through a semaphore. The global
* list of blocked locks is not protected in this fashion however.
* Therefore, some functions (such as the RPC callback for the async grant
* call) move blocked locks towards the head of the list *while some other
* process might be traversing it*. This should not be a problem in
* practice, because this will only cause functions traversing the list
* to visit some blocks twice.
*
* Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
*/
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc_xprt.h>
#include <linux/lockd/nlm.h>
#include <linux/lockd/lockd.h>
#include <linux/kthread.h>
#define NLMDBG_FACILITY NLMDBG_SVCLOCK
#ifdef CONFIG_LOCKD_V4
#define nlm_deadlock nlm4_deadlock
#else
#define nlm_deadlock nlm_lck_denied
#endif
static void nlmsvc_release_block(struct nlm_block *block);
static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
static void nlmsvc_remove_block(struct nlm_block *block);
static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
static void nlmsvc_freegrantargs(struct nlm_rqst *call);
static const struct rpc_call_ops nlmsvc_grant_ops;
/*
* The list of blocked locks to retry
*/
static LIST_HEAD(nlm_blocked);
static DEFINE_SPINLOCK(nlm_blocked_lock);
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
{
/*
* We can get away with a static buffer because this is only called
* from lockd, which is single-threaded.
*/
static char buf[2*NLM_MAXCOOKIELEN+1];
unsigned int i, len = sizeof(buf);
char *p = buf;
len--; /* allow for trailing \0 */
if (len < 3)
return "???";
for (i = 0 ; i < cookie->len ; i++) {
if (len < 2) {
strcpy(p-3, "...");
break;
}
sprintf(p, "%02x", cookie->data[i]);
p += 2;
len -= 2;
}
*p = '\0';
return buf;
}
#endif
/*
* Insert a blocked lock into the global list
*/
static void
nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
{
struct nlm_block *b;
struct list_head *pos;
dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
if (list_empty(&block->b_list)) {
kref_get(&block->b_count);
} else {
list_del_init(&block->b_list);
}
pos = &nlm_blocked;
if (when != NLM_NEVER) {
if ((when += jiffies) == NLM_NEVER)
when ++;
list_for_each(pos, &nlm_blocked) {
b = list_entry(pos, struct nlm_block, b_list);
if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
break;
}
/* On normal exit from the loop, pos == &nlm_blocked,
* so we will be adding to the end of the list - good
*/
}
list_add_tail(&block->b_list, pos);
block->b_when = when;
}
static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
{
spin_lock(&nlm_blocked_lock);
nlmsvc_insert_block_locked(block, when);
spin_unlock(&nlm_blocked_lock);
}
/*
* Remove a block from the global list
*/
static inline void
nlmsvc_remove_block(struct nlm_block *block)
{
if (!list_empty(&block->b_list)) {
spin_lock(&nlm_blocked_lock);
list_del_init(&block->b_list);
spin_unlock(&nlm_blocked_lock);
nlmsvc_release_block(block);
}
}
/*
* Find a block for a given lock
*/
static struct nlm_block *
nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
{
struct nlm_block *block;
struct file_lock *fl;
dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
file, lock->fl.fl_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end, lock->fl.fl_type);
list_for_each_entry(block, &nlm_blocked, b_list) {
fl = &block->b_call->a_args.lock.fl;
dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
block->b_file, fl->fl_pid,
(long long)fl->fl_start,
(long long)fl->fl_end, fl->fl_type,
nlmdbg_cookie2a(&block->b_call->a_args.cookie));
if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
kref_get(&block->b_count);
return block;
}
}
return NULL;
}
static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
{
if (a->len != b->len)
return 0;
if (memcmp(a->data, b->data, a->len))
return 0;
return 1;
}
/*
* Find a block with a given NLM cookie.
*/
static inline struct nlm_block *
nlmsvc_find_block(struct nlm_cookie *cookie)
{
struct nlm_block *block;
list_for_each_entry(block, &nlm_blocked, b_list) {
if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
goto found;
}
return NULL;
found:
dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
kref_get(&block->b_count);
return block;
}
/*
* Create a block and initialize it.
*
* Note: we explicitly set the cookie of the grant reply to that of
* the blocked lock request. The spec explicitly mentions that the client
* should _not_ rely on the callback containing the same cookie as the
* request, but (as I found out later) that's because some implementations
* do just this. Never mind the standards comittees, they support our
* logging industries.
*
* 10 years later: I hope we can safely ignore these old and broken
* clients by now. Let's fix this so we can uniquely identify an incoming
* GRANTED_RES message by cookie, without having to rely on the client's IP
* address. --okir
*/
static struct nlm_block *
nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
struct nlm_file *file, struct nlm_lock *lock,
struct nlm_cookie *cookie)
{
struct nlm_block *block;
struct nlm_rqst *call = NULL;
call = nlm_alloc_call(host);
if (call == NULL)
return NULL;
/* Allocate memory for block, and initialize arguments */
block = kzalloc(sizeof(*block), GFP_KERNEL);
if (block == NULL)
goto failed;
kref_init(&block->b_count);
INIT_LIST_HEAD(&block->b_list);
INIT_LIST_HEAD(&block->b_flist);
if (!nlmsvc_setgrantargs(call, lock))
goto failed_free;
/* Set notifier function for VFS, and init args */
call->a_args.lock.fl.fl_flags |= FL_SLEEP;
call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
nlmclnt_next_cookie(&call->a_args.cookie);
dprintk("lockd: created block %p...\n", block);
/* Create and initialize the block */
block->b_daemon = rqstp->rq_server;
block->b_host = host;
block->b_file = file;
file->f_count++;
/* Add to file's list of blocks */
list_add(&block->b_flist, &file->f_blocks);
/* Set up RPC arguments for callback */
block->b_call = call;
call->a_flags = RPC_TASK_ASYNC;
call->a_block = block;
return block;
failed_free:
kfree(block);
failed:
nlmsvc_release_call(call);
return NULL;
}
/*
* Delete a block.
* It is the caller's responsibility to check whether the file
* can be closed hereafter.
*/
static int nlmsvc_unlink_block(struct nlm_block *block)
{
int status;
dprintk("lockd: unlinking block %p...\n", block);
/* Remove block from list */
status = posix_unblock_lock(&block->b_call->a_args.lock.fl);
nlmsvc_remove_block(block);
return status;
}
static void nlmsvc_free_block(struct kref *kref)
{
struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
struct nlm_file *file = block->b_file;
dprintk("lockd: freeing block %p...\n", block);
/* Remove block from file's list of blocks */
list_del_init(&block->b_flist);
mutex_unlock(&file->f_mutex);
nlmsvc_freegrantargs(block->b_call);
nlmsvc_release_call(block->b_call);
nlm_release_file(block->b_file);
kfree(block);
}
static void nlmsvc_release_block(struct nlm_block *block)
{
if (block != NULL)
kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
}
/*
* Loop over all blocks and delete blocks held by
* a matching host.
*/
void nlmsvc_traverse_blocks(struct nlm_host *host,
struct nlm_file *file,
nlm_host_match_fn_t match)
{
struct nlm_block *block, *next;
restart:
mutex_lock(&file->f_mutex);
list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
if (!match(block->b_host, host))
continue;
/* Do not destroy blocks that are not on
* the global retry list - why? */
if (list_empty(&block->b_list))
continue;
kref_get(&block->b_count);
mutex_unlock(&file->f_mutex);
nlmsvc_unlink_block(block);
nlmsvc_release_block(block);
goto restart;
}
mutex_unlock(&file->f_mutex);
}
/*
* Initialize arguments for GRANTED call. The nlm_rqst structure
* has been cleared already.
*/
static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
{
locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
call->a_args.lock.caller = utsname()->nodename;
call->a_args.lock.oh.len = lock->oh.len;
/* set default data area */
call->a_args.lock.oh.data = call->a_owner;
call->a_args.lock.svid = lock->fl.fl_pid;
if (lock->oh.len > NLMCLNT_OHSIZE) {
void *data = kmalloc(lock->oh.len, GFP_KERNEL);
if (!data)
return 0;
call->a_args.lock.oh.data = (u8 *) data;
}
memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
return 1;
}
static void nlmsvc_freegrantargs(struct nlm_rqst *call)
{
if (call->a_args.lock.oh.data != call->a_owner)
kfree(call->a_args.lock.oh.data);
locks_release_private(&call->a_args.lock.fl);
}
/*
* Deferred lock request handling for non-blocking lock
*/
static __be32
nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
{
__be32 status = nlm_lck_denied_nolocks;
block->b_flags |= B_QUEUED;
nlmsvc_insert_block(block, NLM_TIMEOUT);
block->b_cache_req = &rqstp->rq_chandle;
if (rqstp->rq_chandle.defer) {
block->b_deferred_req =
rqstp->rq_chandle.defer(block->b_cache_req);
if (block->b_deferred_req != NULL)
status = nlm_drop_reply;
}
dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
block, block->b_flags, ntohl(status));
return status;
}
/*
* Attempt to establish a lock, and if it can't be granted, block it
* if required.
*/
__be32
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
struct nlm_host *host, struct nlm_lock *lock, int wait,
struct nlm_cookie *cookie, int reclaim)
{
struct nlm_block *block = NULL;
int error;
__be32 ret;
dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
file_inode(file->f_file)->i_sb->s_id,
file_inode(file->f_file)->i_ino,
lock->fl.fl_type, lock->fl.fl_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end,
wait);
/* Lock file against concurrent access */
mutex_lock(&file->f_mutex);
/* Get existing block (in case client is busy-waiting)
* or create new block
*/
block = nlmsvc_lookup_block(file, lock);
if (block == NULL) {
block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
ret = nlm_lck_denied_nolocks;
if (block == NULL)
goto out;
lock = &block->b_call->a_args.lock;
} else
lock->fl.fl_flags &= ~FL_SLEEP;
if (block->b_flags & B_QUEUED) {
dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
block, block->b_flags);
if (block->b_granted) {
nlmsvc_unlink_block(block);
ret = nlm_granted;
goto out;
}
if (block->b_flags & B_TIMED_OUT) {
nlmsvc_unlink_block(block);
ret = nlm_lck_denied;
goto out;
}
ret = nlm_drop_reply;
goto out;
}
if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
ret = nlm_lck_denied_grace_period;
goto out;
}
if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
ret = nlm_lck_denied_grace_period;
goto out;
}
if (!wait)
lock->fl.fl_flags &= ~FL_SLEEP;
error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
lock->fl.fl_flags &= ~FL_SLEEP;
dprintk("lockd: vfs_lock_file returned %d\n", error);
switch (error) {
case 0:
ret = nlm_granted;
goto out;
case -EAGAIN:
/*
* If this is a blocking request for an
* already pending lock request then we need
* to put it back on lockd's block list
*/
if (wait)
break;
ret = nlm_lck_denied;
goto out;
case FILE_LOCK_DEFERRED:
if (wait)
break;
/* Filesystem lock operation is in progress
Add it to the queue waiting for callback */
ret = nlmsvc_defer_lock_rqst(rqstp, block);
goto out;
case -EDEADLK:
ret = nlm_deadlock;
goto out;
default: /* includes ENOLCK */
ret = nlm_lck_denied_nolocks;
goto out;
}
ret = nlm_lck_blocked;
/* Append to list of blocked */
nlmsvc_insert_block(block, NLM_NEVER);
out:
mutex_unlock(&file->f_mutex);
nlmsvc_release_block(block);
dprintk("lockd: nlmsvc_lock returned %u\n", ret);
return ret;
}
/*
* Test for presence of a conflicting lock.
*/
__be32
nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
struct nlm_host *host, struct nlm_lock *lock,
struct nlm_lock *conflock, struct nlm_cookie *cookie)
{
int error;
__be32 ret;
dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
file_inode(file->f_file)->i_sb->s_id,
file_inode(file->f_file)->i_ino,
lock->fl.fl_type,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end);
if (locks_in_grace(SVC_NET(rqstp))) {
ret = nlm_lck_denied_grace_period;
goto out;
}
error = vfs_test_lock(file->f_file, &lock->fl);
if (error) {
/* We can't currently deal with deferred test requests */
if (error == FILE_LOCK_DEFERRED)
WARN_ON_ONCE(1);
ret = nlm_lck_denied_nolocks;
goto out;
}
if (lock->fl.fl_type == F_UNLCK) {
ret = nlm_granted;
goto out;
}
dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
lock->fl.fl_type, (long long)lock->fl.fl_start,
(long long)lock->fl.fl_end);
conflock->caller = "somehost"; /* FIXME */
conflock->len = strlen(conflock->caller);
conflock->oh.len = 0; /* don't return OH info */
conflock->svid = lock->fl.fl_pid;
conflock->fl.fl_type = lock->fl.fl_type;
conflock->fl.fl_start = lock->fl.fl_start;
conflock->fl.fl_end = lock->fl.fl_end;
locks_release_private(&lock->fl);
ret = nlm_lck_denied;
out:
return ret;
}
/*
* Remove a lock.
* This implies a CANCEL call: We send a GRANT_MSG, the client replies
* with a GRANT_RES call which gets lost, and calls UNLOCK immediately
* afterwards. In this case the block will still be there, and hence
* must be removed.
*/
__be32
nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
{
int error;
dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
file_inode(file->f_file)->i_sb->s_id,
file_inode(file->f_file)->i_ino,
lock->fl.fl_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end);
/* First, cancel any lock that might be there */
nlmsvc_cancel_blocked(net, file, lock);
lock->fl.fl_type = F_UNLCK;
error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
}
/*
* Cancel a previously blocked request.
*
* A cancel request always overrides any grant that may currently
* be in progress.
* The calling procedure must check whether the file can be closed.
*/
__be32
nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
{
struct nlm_block *block;
int status = 0;
dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
file_inode(file->f_file)->i_sb->s_id,
file_inode(file->f_file)->i_ino,
lock->fl.fl_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end);
if (locks_in_grace(net))
return nlm_lck_denied_grace_period;
mutex_lock(&file->f_mutex);
block = nlmsvc_lookup_block(file, lock);
mutex_unlock(&file->f_mutex);
if (block != NULL) {
vfs_cancel_lock(block->b_file->f_file,
&block->b_call->a_args.lock.fl);
status = nlmsvc_unlink_block(block);
nlmsvc_release_block(block);
}
return status ? nlm_lck_denied : nlm_granted;
}
/*
* This is a callback from the filesystem for VFS file lock requests.
* It will be used if lm_grant is defined and the filesystem can not
* respond to the request immediately.
* For SETLK or SETLKW request it will get the local posix lock.
* In all cases it will move the block to the head of nlm_blocked q where
* nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
* deferred rpc for GETLK and SETLK.
*/
static void
nlmsvc_update_deferred_block(struct nlm_block *block, int result)
{
block->b_flags |= B_GOT_CALLBACK;
if (result == 0)
block->b_granted = 1;
else
block->b_flags |= B_TIMED_OUT;
}
static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
{
struct nlm_block *block;
int rc = -ENOENT;
spin_lock(&nlm_blocked_lock);
list_for_each_entry(block, &nlm_blocked, b_list) {
if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
block, block->b_flags);
if (block->b_flags & B_QUEUED) {
if (block->b_flags & B_TIMED_OUT) {
rc = -ENOLCK;
break;
}
nlmsvc_update_deferred_block(block, result);
} else if (result == 0)
block->b_granted = 1;
nlmsvc_insert_block_locked(block, 0);
svc_wake_up(block->b_daemon);
rc = 0;
break;
}
}
spin_unlock(&nlm_blocked_lock);
if (rc == -ENOENT)
printk(KERN_WARNING "lockd: grant for unknown block\n");
return rc;
}
/*
* Unblock a blocked lock request. This is a callback invoked from the
* VFS layer when a lock on which we blocked is removed.
*
* This function doesn't grant the blocked lock instantly, but rather moves
* the block to the head of nlm_blocked where it can be picked up by lockd.
*/
static void
nlmsvc_notify_blocked(struct file_lock *fl)
{
struct nlm_block *block;
dprintk("lockd: VFS unblock notification for block %p\n", fl);
spin_lock(&nlm_blocked_lock);
list_for_each_entry(block, &nlm_blocked, b_list) {
if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
nlmsvc_insert_block_locked(block, 0);
spin_unlock(&nlm_blocked_lock);
svc_wake_up(block->b_daemon);
return;
}
}
spin_unlock(&nlm_blocked_lock);
printk(KERN_WARNING "lockd: notification for unknown block!\n");
}
static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
{
return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
}
/*
* Since NLM uses two "keys" for tracking locks, we need to hash them down
* to one for the blocked_hash. Here, we're just xor'ing the host address
* with the pid in order to create a key value for picking a hash bucket.
*/
static unsigned long
nlmsvc_owner_key(struct file_lock *fl)
{
return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
}
const struct lock_manager_operations nlmsvc_lock_operations = {
.lm_compare_owner = nlmsvc_same_owner,
.lm_owner_key = nlmsvc_owner_key,
.lm_notify = nlmsvc_notify_blocked,
.lm_grant = nlmsvc_grant_deferred,
};
/*
* Try to claim a lock that was previously blocked.
*
* Note that we use both the RPC_GRANTED_MSG call _and_ an async
* RPC thread when notifying the client. This seems like overkill...
* Here's why:
* - we don't want to use a synchronous RPC thread, otherwise
* we might find ourselves hanging on a dead portmapper.
* - Some lockd implementations (e.g. HP) don't react to
* RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
*/
static void
nlmsvc_grant_blocked(struct nlm_block *block)
{
struct nlm_file *file = block->b_file;
struct nlm_lock *lock = &block->b_call->a_args.lock;
int error;
loff_t fl_start, fl_end;
dprintk("lockd: grant blocked lock %p\n", block);
kref_get(&block->b_count);
/* Unlink block request from list */
nlmsvc_unlink_block(block);
/* If b_granted is true this means we've been here before.
* Just retry the grant callback, possibly refreshing the RPC
* binding */
if (block->b_granted) {
nlm_rebind_host(block->b_host);
goto callback;
}
/* Try the lock operation again */
/* vfs_lock_file() can mangle fl_start and fl_end, but we need
* them unchanged for the GRANT_MSG
*/
lock->fl.fl_flags |= FL_SLEEP;
fl_start = lock->fl.fl_start;
fl_end = lock->fl.fl_end;
error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
lock->fl.fl_flags &= ~FL_SLEEP;
lock->fl.fl_start = fl_start;
lock->fl.fl_end = fl_end;
switch (error) {
case 0:
break;
case FILE_LOCK_DEFERRED:
dprintk("lockd: lock still blocked error %d\n", error);
nlmsvc_insert_block(block, NLM_NEVER);
nlmsvc_release_block(block);
return;
default:
printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
-error, __func__);
nlmsvc_insert_block(block, 10 * HZ);
nlmsvc_release_block(block);
return;
}
callback:
/* Lock was granted by VFS. */
dprintk("lockd: GRANTing blocked lock.\n");
block->b_granted = 1;
/* keep block on the list, but don't reattempt until the RPC
* completes or the submission fails
*/
nlmsvc_insert_block(block, NLM_NEVER);
/* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
* will queue up a new one if this one times out
*/
error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
&nlmsvc_grant_ops);
/* RPC submission failed, wait a bit and retry */
if (error < 0)
nlmsvc_insert_block(block, 10 * HZ);
}
/*
* This is the callback from the RPC layer when the NLM_GRANTED_MSG
* RPC call has succeeded or timed out.
* Like all RPC callbacks, it is invoked by the rpciod process, so it
* better not sleep. Therefore, we put the blocked lock on the nlm_blocked
* chain once more in order to have it removed by lockd itself (which can
* then sleep on the file semaphore without disrupting e.g. the nfs client).
*/
static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
{
struct nlm_rqst *call = data;
struct nlm_block *block = call->a_block;
unsigned long timeout;
dprintk("lockd: GRANT_MSG RPC callback\n");
spin_lock(&nlm_blocked_lock);
/* if the block is not on a list at this point then it has
* been invalidated. Don't try to requeue it.
*
* FIXME: it's possible that the block is removed from the list
* after this check but before the nlmsvc_insert_block. In that
* case it will be added back. Perhaps we need better locking
* for nlm_blocked?
*/
if (list_empty(&block->b_list))
goto out;
/* Technically, we should down the file semaphore here. Since we
* move the block towards the head of the queue only, no harm
* can be done, though. */
if (task->tk_status < 0) {
/* RPC error: Re-insert for retransmission */
timeout = 10 * HZ;
} else {
/* Call was successful, now wait for client callback */
timeout = 60 * HZ;
}
nlmsvc_insert_block_locked(block, timeout);
svc_wake_up(block->b_daemon);
out:
spin_unlock(&nlm_blocked_lock);
}
/*
* FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
* .rpc_release rpc_call_op
*/
static void nlmsvc_grant_release(void *data)
{
struct nlm_rqst *call = data;
nlmsvc_release_block(call->a_block);
}
static const struct rpc_call_ops nlmsvc_grant_ops = {
.rpc_call_done = nlmsvc_grant_callback,
.rpc_release = nlmsvc_grant_release,
};
/*
* We received a GRANT_RES callback. Try to find the corresponding
* block.
*/
void
nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
{
struct nlm_block *block;
dprintk("grant_reply: looking for cookie %x, s=%d \n",
*(unsigned int *)(cookie->data), status);
if (!(block = nlmsvc_find_block(cookie)))
return;
if (status == nlm_lck_denied_grace_period) {
/* Try again in a couple of seconds */
nlmsvc_insert_block(block, 10 * HZ);
} else {
/*
* Lock is now held by client, or has been rejected.
* In both cases, the block should be removed.
*/
nlmsvc_unlink_block(block);
}
nlmsvc_release_block(block);
}
/* Helper function to handle retry of a deferred block.
* If it is a blocking lock, call grant_blocked.
* For a non-blocking lock or test lock, revisit the request.
*/
static void
retry_deferred_block(struct nlm_block *block)
{
if (!(block->b_flags & B_GOT_CALLBACK))
block->b_flags |= B_TIMED_OUT;
nlmsvc_insert_block(block, NLM_TIMEOUT);
dprintk("revisit block %p flags %d\n", block, block->b_flags);
if (block->b_deferred_req) {
block->b_deferred_req->revisit(block->b_deferred_req, 0);
block->b_deferred_req = NULL;
}
}
/*
* Retry all blocked locks that have been notified. This is where lockd
* picks up locks that can be granted, or grant notifications that must
* be retransmitted.
*/
unsigned long
nlmsvc_retry_blocked(void)
{
unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
struct nlm_block *block;
spin_lock(&nlm_blocked_lock);
while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
if (block->b_when == NLM_NEVER)
break;
if (time_after(block->b_when, jiffies)) {
timeout = block->b_when - jiffies;
break;
}
spin_unlock(&nlm_blocked_lock);
dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
block, block->b_when);
if (block->b_flags & B_QUEUED) {
dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
block, block->b_granted, block->b_flags);
retry_deferred_block(block);
} else
nlmsvc_grant_blocked(block);
spin_lock(&nlm_blocked_lock);
}
spin_unlock(&nlm_blocked_lock);
return timeout;
}
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