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r17314: Optimisation for POSIX locking. If we're downgrading

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a POSIX lock (applying a read-lock) and we overlap
pending read locks then send them an unlock message,
we may have allowed them to proceed.
Jeremy.
(This used to be commit a7a0b6ba50)
This commit is contained in:
Jeremy Allison 2006-07-29 19:14:24 +00:00 committed by Gerald (Jerry) Carter
parent 4e9df2fba3
commit 2c6030415e
4 changed files with 77 additions and 34 deletions
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8
source3/include/locking.h
View File

@ -23,11 +23,15 @@
#define _LOCKING_H
/* passed to br lock code - the UNLOCK_LOCK should never be stored into the tdb
and is used in calculating POSIX unlock ranges only. */
and is used in calculating POSIX unlock ranges only. We differentiate between
PENDING read and write locks to allow posix lock downgrades to trigger a lock
re-evaluation. */
enum brl_type {READ_LOCK, WRITE_LOCK, PENDING_LOCK, UNLOCK_LOCK};
enum brl_type {READ_LOCK, WRITE_LOCK, PENDING_READ_LOCK, PENDING_WRITE_LOCK, UNLOCK_LOCK};
enum brl_flavour {WINDOWS_LOCK = 0, POSIX_LOCK = 1};
#define IS_PENDING_LOCK(type) ((type) == PENDING_READ_LOCK || (type) == PENDING_WRITE_LOCK)
/* This contains elements that differentiate locks. The smbpid is a
client supplied pid, and is essentially the locking context for
this client */

95
source3/locking/brlock.c
View File

@ -98,7 +98,7 @@ static BOOL brl_conflict(const struct lock_struct *lck1,
const struct lock_struct *lck2)
{
/* Ignore PENDING locks. */
if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
if (IS_PENDING_LOCK(lck1->lock_type) || IS_PENDING_LOCK(lck2->lock_type))
return False;
/* Read locks never conflict. */
@ -129,7 +129,7 @@ static BOOL brl_conflict_posix(const struct lock_struct *lck1,
#endif
/* Ignore PENDING locks. */
if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
if (IS_PENDING_LOCK(lck1->lock_type) || IS_PENDING_LOCK(lck2->lock_type))
return False;
/* Read locks never conflict. */
@ -151,7 +151,7 @@ static BOOL brl_conflict_posix(const struct lock_struct *lck1,
static BOOL brl_conflict1(const struct lock_struct *lck1,
const struct lock_struct *lck2)
{
if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
if (IS_PENDING_LOCK(lck1->lock_type) || IS_PENDING_LOCK(lck2->lock_type))
return False;
if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
@ -184,7 +184,7 @@ static BOOL brl_conflict1(const struct lock_struct *lck1,
static BOOL brl_conflict_other(const struct lock_struct *lck1, const struct lock_struct *lck2)
{
if (lck1->lock_type == PENDING_LOCK || lck2->lock_type == PENDING_LOCK )
if (IS_PENDING_LOCK(lck1->lock_type) || IS_PENDING_LOCK(lck2->lock_type))
return False;
if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK)
@ -210,6 +210,19 @@ static BOOL brl_conflict_other(const struct lock_struct *lck1, const struct lock
return brl_overlap(lck1, lck2);
}
/****************************************************************************
Check if an unlock overlaps a pending lock.
****************************************************************************/
static BOOL brl_pending_overlap(const struct lock_struct *lock, const struct lock_struct *pend_lock)
{
if ((lock->start <= pend_lock->start) && (lock->start + lock->size > pend_lock->start))
return True;
if ((lock->start >= pend_lock->start) && (lock->start <= pend_lock->start + pend_lock->size))
return True;
return False;
}
/****************************************************************************
Amazingly enough, w2k3 "remembers" whether the last lock failure on a fnum
is the same as this one and changes its error code. I wonder if any
@ -320,7 +333,7 @@ static NTSTATUS brl_lock_windows(struct byte_range_lock *br_lck,
be mapped into a lower level POSIX one, and if so can
we get it ? */
if ((plock->lock_type != PENDING_LOCK) && lp_posix_locking(SNUM(fsp->conn))) {
if (!IS_PENDING_LOCK(plock->lock_type) && lp_posix_locking(SNUM(fsp->conn))) {
int errno_ret;
if (!set_posix_lock_windows_flavour(fsp,
plock->start,
@ -575,6 +588,7 @@ static NTSTATUS brl_lock_posix(struct byte_range_lock *br_lck,
struct lock_struct *locks = (struct lock_struct *)br_lck->lock_data;
struct lock_struct *tp;
BOOL lock_was_added = False;
BOOL signal_pending_read = False;
/* No zero-zero locks for POSIX. */
if (plock->start == 0 && plock->size == 0) {
@ -598,19 +612,28 @@ static NTSTATUS brl_lock_posix(struct byte_range_lock *br_lck,
count = 0;
for (i=0; i < br_lck->num_locks; i++) {
if (locks[i].lock_flav == WINDOWS_LOCK) {
struct lock_struct *curr_lock = &locks[i];
/* If we have a pending read lock, a lock downgrade should
trigger a lock re-evaluation. */
if (curr_lock->lock_type == PENDING_READ_LOCK &&
brl_pending_overlap(plock, curr_lock)) {
signal_pending_read = True;
}
if (curr_lock->lock_flav == WINDOWS_LOCK) {
/* Do any Windows flavour locks conflict ? */
if (brl_conflict(&locks[i], plock)) {
if (brl_conflict(curr_lock, plock)) {
/* No games with error messages. */
SAFE_FREE(tp);
return NT_STATUS_FILE_LOCK_CONFLICT;
}
/* Just copy the Windows lock into the new array. */
memcpy(&tp[count], &locks[i], sizeof(struct lock_struct));
memcpy(&tp[count], curr_lock, sizeof(struct lock_struct));
count++;
} else {
/* POSIX conflict semantics are different. */
if (brl_conflict_posix(&locks[i], plock)) {
if (brl_conflict_posix(curr_lock, plock)) {
/* Can't block ourselves with POSIX locks. */
/* No games with error messages. */
SAFE_FREE(tp);
@ -618,7 +641,7 @@ static NTSTATUS brl_lock_posix(struct byte_range_lock *br_lck,
}
/* Work out overlaps. */
count += brlock_posix_split_merge(&tp[count], &locks[i], plock, &lock_was_added);
count += brlock_posix_split_merge(&tp[count], curr_lock, plock, &lock_was_added);
}
}
@ -631,7 +654,7 @@ static NTSTATUS brl_lock_posix(struct byte_range_lock *br_lck,
be mapped into a lower level POSIX one, and if so can
we get it ? */
if ((plock->lock_type != PENDING_LOCK) && lp_posix_locking(SNUM(br_lck->fsp->conn))) {
if (!IS_PENDING_LOCK(plock->lock_type) && lp_posix_locking(SNUM(br_lck->fsp->conn))) {
int errno_ret;
/* The lower layer just needs to attempt to
@ -661,7 +684,34 @@ static NTSTATUS brl_lock_posix(struct byte_range_lock *br_lck,
br_lck->num_locks = count;
SAFE_FREE(br_lck->lock_data);
br_lck->lock_data = (void *)tp;
locks = tp;
br_lck->modified = True;
/* A successful downgrade from write to read lock can trigger a lock
re-evalutation where waiting readers can now proceed. */
if (signal_pending_read) {
/* Send unlock messages to any pending read waiters that overlap. */
for (i=0; i < br_lck->num_locks; i++) {
struct lock_struct *pend_lock = &locks[i];
/* Ignore non-pending locks. */
if (!IS_PENDING_LOCK(pend_lock->lock_type)) {
continue;
}
if (pend_lock->lock_type == PENDING_READ_LOCK &&
brl_pending_overlap(plock, pend_lock)) {
DEBUG(10,("brl_lock_posix: sending unlock message to pid %s\n",
procid_str_static(&pend_lock->context.pid )));
message_send_pid(pend_lock->context.pid,
MSG_SMB_UNLOCK,
NULL, 0, True);
}
}
}
return NT_STATUS_OK;
}
@ -710,19 +760,6 @@ NTSTATUS brl_lock(struct byte_range_lock *br_lck,
return ret;
}
/****************************************************************************
Check if an unlock overlaps a pending lock.
****************************************************************************/
static BOOL brl_pending_overlap(const struct lock_struct *lock, const struct lock_struct *pend_lock)
{
if ((lock->start <= pend_lock->start) && (lock->start + lock->size > pend_lock->start))
return True;
if ((lock->start >= pend_lock->start) && (lock->start <= pend_lock->start + pend_lock->size))
return True;
return False;
}
/****************************************************************************
Unlock a range of bytes - Windows semantics.
****************************************************************************/
@ -807,7 +844,7 @@ static BOOL brl_unlock_windows(struct byte_range_lock *br_lck, const struct lock
struct lock_struct *pend_lock = &locks[j];
/* Ignore non-pending locks. */
if (pend_lock->lock_type != PENDING_LOCK) {
if (!IS_PENDING_LOCK(pend_lock->lock_type)) {
continue;
}
@ -866,7 +903,7 @@ static BOOL brl_unlock_posix(struct byte_range_lock *br_lck, const struct lock_s
unsigned int tmp_count;
/* Only remove our own locks - ignore fnum. */
if (lock->lock_type == PENDING_LOCK ||
if (IS_PENDING_LOCK(lock->lock_type) ||
!brl_same_context(&lock->context, &plock->context)) {
memcpy(&tp[count], lock, sizeof(struct lock_struct));
count++;
@ -974,7 +1011,7 @@ static BOOL brl_unlock_posix(struct byte_range_lock *br_lck, const struct lock_s
struct lock_struct *pend_lock = &locks[j];
/* Ignore non-pending locks. */
if (pend_lock->lock_type != PENDING_LOCK) {
if (!IS_PENDING_LOCK(pend_lock->lock_type)) {
continue;
}
@ -1173,7 +1210,7 @@ BOOL brl_lock_cancel(struct byte_range_lock *br_lck,
/* For pending locks we *always* care about the fnum. */
if (brl_same_context(&lock->context, &context) &&
lock->fnum == br_lck->fsp->fnum &&
lock->lock_type == PENDING_LOCK &&
IS_PENDING_LOCK(lock->lock_type) &&
lock->lock_flav == lock_flav &&
lock->start == start &&
lock->size == size) {
@ -1288,7 +1325,7 @@ void brl_close_fnum(struct byte_range_lock *br_lck)
struct lock_struct *pend_lock = &locks[j];
/* Ignore our own or non-pending locks. */
if (pend_lock->lock_type != PENDING_LOCK) {
if (!IS_PENDING_LOCK(pend_lock->lock_type)) {
continue;
}

6
source3/locking/locking.c
View File

@ -55,8 +55,10 @@ const char *lock_type_name(enum brl_type lock_type)
return "READ";
case WRITE_LOCK:
return "WRITE";
case PENDING_LOCK:
return "PENDING";
case PENDING_READ_LOCK:
return "PENDING_READ";
case PENDING_WRITE_LOCK:
return "PENDING_WRITE";
default:
return "other";
}

2
source3/smbd/blocking.c
View File

@ -137,7 +137,7 @@ BOOL push_blocking_lock_request( struct byte_range_lock *br_lck,
procid_self(),
offset,
count,
PENDING_LOCK,
lock_type == READ_LOCK ? PENDING_READ_LOCK : PENDING_WRITE_LOCK,
blr->lock_flav,
lock_timeout ? True : False); /* blocking_lock. */