linux/fs/lockd/svclock.c

1068 lines
28 KiB
C
Raw Normal View History

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>
2017-11-01 14:07:57 +00:00
// 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 cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#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/exportfs.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)
{
spin_lock(&nlm_blocked_lock);
if (!list_empty(&block->b_list)) {
list_del_init(&block->b_list);
spin_unlock(&nlm_blocked_lock);
nlmsvc_release_block(block);
return;
}
spin_unlock(&nlm_blocked_lock);
}
/*
* 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.c.flc_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end,
lock->fl.c.flc_type);
spin_lock(&nlm_blocked_lock);
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->c.flc_pid,
(long long)fl->fl_start,
(long long)fl->fl_end, fl->c.flc_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);
spin_unlock(&nlm_blocked_lock);
return block;
}
}
spin_unlock(&nlm_blocked_lock);
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;
spin_lock(&nlm_blocked_lock);
list_for_each_entry(block, &nlm_blocked, b_list) {
if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
goto found;
}
spin_unlock(&nlm_blocked_lock);
return NULL;
found:
dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
kref_get(&block->b_count);
spin_unlock(&nlm_blocked_lock);
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.c.flc_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 = locks_delete_block(&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);
spin_lock(&nlm_blocked_lock);
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);
spin_unlock(&nlm_blocked_lock);
mutex_unlock(&file->f_mutex);
nlmsvc_unlink_block(block);
nlmsvc_release_block(block);
goto restart;
}
spin_unlock(&nlm_blocked_lock);
mutex_unlock(&file->f_mutex);
}
static struct nlm_lockowner *
nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
{
refcount_inc(&lockowner->count);
return lockowner;
}
void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
{
if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
return;
list_del(&lockowner->list);
spin_unlock(&lockowner->host->h_lock);
nlmsvc_release_host(lockowner->host);
kfree(lockowner);
}
static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
{
struct nlm_lockowner *lockowner;
list_for_each_entry(lockowner, &host->h_lockowners, list) {
if (lockowner->pid != pid)
continue;
return nlmsvc_get_lockowner(lockowner);
}
return NULL;
}
static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
{
struct nlm_lockowner *res, *new = NULL;
spin_lock(&host->h_lock);
res = __nlmsvc_find_lockowner(host, pid);
if (res == NULL) {
spin_unlock(&host->h_lock);
new = kmalloc(sizeof(*res), GFP_KERNEL);
spin_lock(&host->h_lock);
res = __nlmsvc_find_lockowner(host, pid);
if (res == NULL && new != NULL) {
res = new;
/* fs/locks.c will manage the refcount through lock_ops */
refcount_set(&new->count, 1);
new->pid = pid;
new->host = nlm_get_host(host);
list_add(&new->list, &host->h_lockowners);
new = NULL;
}
}
spin_unlock(&host->h_lock);
kfree(new);
return res;
}
void
nlmsvc_release_lockowner(struct nlm_lock *lock)
{
if (lock->fl.c.flc_owner)
nlmsvc_put_lockowner(lock->fl.c.flc_owner);
}
void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
pid_t pid)
{
fl->c.flc_owner = nlmsvc_find_lockowner(host, pid);
}
/*
* 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 = ((struct nlm_lockowner *) lock->fl.c.flc_owner)->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 inode *inode = nlmsvc_file_inode(file);
nfs: block notification on fs with its own ->lock NFSv4.1 supports an optional lock notification feature which notifies the client when a lock comes available. (Normally NFSv4 clients just poll for locks if necessary.) To make that work, we need to request a blocking lock from the filesystem. We turned that off for NFS in commit f657f8eef3ff ("nfs: don't atempt blocking locks on nfs reexports") [sic] because it actually blocks the nfsd thread while waiting for the lock. Thanks to Vasily Averin for pointing out that NFS isn't the only filesystem with that problem. Any filesystem that leaves ->lock NULL will use posix_lock_file(), which does the right thing. Simplest is just to assume that any filesystem that defines its own ->lock is not safe to request a blocking lock from. So, this patch mostly reverts commit f657f8eef3ff ("nfs: don't atempt blocking locks on nfs reexports") [sic] and commit b840be2f00c0 ("lockd: don't attempt blocking locks on nfs reexports"), and instead uses a check of ->lock (Vasily's suggestion) to decide whether to support blocking lock notifications on a given filesystem. Also add a little documentation. Perhaps someday we could add back an export flag later to allow filesystems with "good" ->lock methods to support blocking lock notifications. Reported-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> [ cel: Description rewritten to address checkpatch nits ] [ cel: Fixed warning when SUNRPC debugging is disabled ] [ cel: Fixed NULL check ] Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: Vasily Averin <vvs@virtuozzo.com>
2021-12-16 17:20:13 +00:00
struct nlm_block *block = NULL;
int error;
int mode;
int async_block = 0;
__be32 ret;
dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
inode->i_sb->s_id, inode->i_ino,
lock->fl.c.flc_type,
lock->fl.c.flc_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end,
wait);
if (!exportfs_lock_op_is_async(inode->i_sb->s_export_op)) {
async_block = wait;
wait = 0;
}
/* 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.c.flc_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;
}
spin_lock(&nlm_blocked_lock);
/*
* If this is a lock request for an already pending
* lock request we return nlm_lck_blocked without calling
* vfs_lock_file() again. Otherwise we have two pending
* requests on the underlaying ->lock() implementation but
* only one nlm_block to being granted by lm_grant().
*/
if (exportfs_lock_op_is_async(inode->i_sb->s_export_op) &&
!list_empty(&block->b_list)) {
spin_unlock(&nlm_blocked_lock);
ret = nlm_lck_blocked;
goto out;
}
/* Append to list of blocked */
nlmsvc_insert_block_locked(block, NLM_NEVER);
spin_unlock(&nlm_blocked_lock);
if (!wait)
lock->fl.c.flc_flags &= ~FL_SLEEP;
mode = lock_to_openmode(&lock->fl);
error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
lock->fl.c.flc_flags &= ~FL_SLEEP;
dprintk("lockd: vfs_lock_file returned %d\n", error);
switch (error) {
case 0:
nlmsvc_remove_block(block);
ret = nlm_granted;
goto out;
case -EAGAIN:
if (!wait)
nlmsvc_remove_block(block);
ret = async_block ? nlm_lck_blocked : 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:
nlmsvc_remove_block(block);
ret = nlm_deadlock;
goto out;
default: /* includes ENOLCK */
nlmsvc_remove_block(block);
ret = nlm_lck_denied_nolocks;
goto out;
}
ret = nlm_lck_blocked;
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;
int mode;
__be32 ret;
dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
nlmsvc_file_inode(file)->i_sb->s_id,
nlmsvc_file_inode(file)->i_ino,
lock->fl.c.flc_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;
}
mode = lock_to_openmode(&lock->fl);
error = vfs_test_lock(file->f_file[mode], &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.c.flc_type == F_UNLCK) {
ret = nlm_granted;
goto out;
}
dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
lock->fl.c.flc_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.c.flc_pid;
conflock->fl.c.flc_type = lock->fl.c.flc_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 = 0;
dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
nlmsvc_file_inode(file)->i_sb->s_id,
nlmsvc_file_inode(file)->i_ino,
lock->fl.c.flc_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.c.flc_type = F_UNLCK;
lock->fl.c.flc_file = file->f_file[O_RDONLY];
if (lock->fl.c.flc_file)
error = vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
&lock->fl, NULL);
lock->fl.c.flc_file = file->f_file[O_WRONLY];
if (lock->fl.c.flc_file)
error |= vfs_lock_file(lock->fl.c.flc_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;
int mode;
dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
nlmsvc_file_inode(file)->i_sb->s_id,
nlmsvc_file_inode(file)->i_ino,
lock->fl.c.flc_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) {
struct file_lock *fl = &block->b_call->a_args.lock.fl;
mode = lock_to_openmode(fl);
vfs_cancel_lock(block->b_file->f_file[mode], 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 fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
{
return nlmsvc_get_lockowner(owner);
}
static void nlmsvc_put_owner(fl_owner_t owner)
{
nlmsvc_put_lockowner(owner);
}
const struct lock_manager_operations nlmsvc_lock_operations = {
.lm_notify = nlmsvc_notify_blocked,
.lm_grant = nlmsvc_grant_deferred,
.lm_get_owner = nlmsvc_get_owner,
.lm_put_owner = nlmsvc_put_owner,
};
/*
* 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 mode;
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.c.flc_flags |= FL_SLEEP;
fl_start = lock->fl.fl_start;
fl_end = lock->fl.fl_end;
mode = lock_to_openmode(&lock->fl);
error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
lock->fl.c.flc_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;
struct file_lock *fl;
int error;
dprintk("grant_reply: looking for cookie %x, s=%d \n",
*(unsigned int *)(cookie->data), status);
if (!(block = nlmsvc_find_block(cookie)))
return;
switch (status) {
case nlm_lck_denied_grace_period:
/* Try again in a couple of seconds */
nlmsvc_insert_block(block, 10 * HZ);
break;
case nlm_lck_denied:
/* Client doesn't want it, just unlock it */
nlmsvc_unlink_block(block);
fl = &block->b_call->a_args.lock.fl;
fl->c.flc_type = F_UNLCK;
error = vfs_lock_file(fl->c.flc_file, F_SETLK, fl, NULL);
if (error)
pr_warn("lockd: unable to unlock lock rejected by client!\n");
break;
default:
/*
* Either it was accepted or the status makes no sense
* just unlink it either way.
*/
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.
*/
void
nlmsvc_retry_blocked(struct svc_rqst *rqstp)
{
unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
struct nlm_block *block;
spin_lock(&nlm_blocked_lock);
while (!list_empty(&nlm_blocked) && !svc_thread_should_stop(rqstp)) {
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);
if (timeout < MAX_SCHEDULE_TIMEOUT)
mod_timer(&nlmsvc_retry, jiffies + timeout);
}