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xfs: share code for grant head availability checks 

Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
This commit is contained in:
Christoph Hellwig 2012-02-20 02:31:30 +00:00 committed by Ben Myers
parent e179840d74
commit 42ceedb3ca
1 changed files with 60 additions and 73 deletions
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133
fs/xfs/xfs_log.c
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@ -245,6 +245,60 @@ shutdown:
return XFS_ERROR(EIO);
}
/*
* Atomically get the log space required for a log ticket.
*
* Once a ticket gets put onto head->waiters, it will only return after the
* needed reservation is satisfied.
*
* This function is structured so that it has a lock free fast path. This is
* necessary because every new transaction reservation will come through this
* path. Hence any lock will be globally hot if we take it unconditionally on
* every pass.
*
* As tickets are only ever moved on and off head->waiters under head->lock, we
* only need to take that lock if we are going to add the ticket to the queue
* and sleep. We can avoid taking the lock if the ticket was never added to
* head->waiters because the t_queue list head will be empty and we hold the
* only reference to it so it can safely be checked unlocked.
*/
STATIC int
xlog_grant_head_check(
struct log *log,
struct xlog_grant_head *head,
struct xlog_ticket *tic,
int *need_bytes)
{
int free_bytes;
int error = 0;
ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
/*
* If there are other waiters on the queue then give them a chance at
* logspace before us. Wake up the first waiters, if we do not wake
* up all the waiters then go to sleep waiting for more free space,
* otherwise try to get some space for this transaction.
*/
*need_bytes = xlog_ticket_reservation(log, head, tic);
free_bytes = xlog_space_left(log, &head->grant);
if (!list_empty_careful(&head->waiters)) {
spin_lock(&head->lock);
if (!xlog_grant_head_wake(log, head, &free_bytes) ||
free_bytes < *need_bytes) {
error = xlog_grant_head_wait(log, head, tic,
*need_bytes);
}
spin_unlock(&head->lock);
} else if (free_bytes < *need_bytes) {
spin_lock(&head->lock);
error = xlog_grant_head_wait(log, head, tic, *need_bytes);
spin_unlock(&head->lock);
}
return error;
}
static void
xlog_tic_reset_res(xlog_ticket_t *tic)
{
@ -2511,59 +2565,18 @@ restart:
return 0;
} /* xlog_state_get_iclog_space */
/*
* Atomically get the log space required for a log ticket.
*
* Once a ticket gets put onto the reserveq, it will only return after the
* needed reservation is satisfied.
*
* This function is structured so that it has a lock free fast path. This is
* necessary because every new transaction reservation will come through this
* path. Hence any lock will be globally hot if we take it unconditionally on
* every pass.
*
* As tickets are only ever moved on and off the l_reserve.waiters under the
* l_reserve.lock, we only need to take that lock if we are going to add
* the ticket to the queue and sleep. We can avoid taking the lock if the ticket
* was never added to the reserveq because the t_queue list head will be empty
* and we hold the only reference to it so it can safely be checked unlocked.
*/
STATIC int
xlog_grant_log_space(
struct log *log,
struct xlog_ticket *tic)
{
int free_bytes, need_bytes;
int need_bytes;
int error = 0;
ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
trace_xfs_log_grant_enter(log, tic);
/*
* If there are other waiters on the queue then give them a chance at
* logspace before us. Wake up the first waiters, if we do not wake
* up all the waiters then go to sleep waiting for more free space,
* otherwise try to get some space for this transaction.
*/
need_bytes = tic->t_unit_res;
if (tic->t_flags & XFS_LOG_PERM_RESERV)
need_bytes *= tic->t_ocnt;
free_bytes = xlog_space_left(log, &log->l_reserve_head.grant);
if (!list_empty_careful(&log->l_reserve_head.waiters)) {
spin_lock(&log->l_reserve_head.lock);
if (!xlog_grant_head_wake(log, &log->l_reserve_head, &free_bytes) ||
free_bytes < need_bytes) {
error = xlog_grant_head_wait(log, &log->l_reserve_head,
tic, need_bytes);
}
spin_unlock(&log->l_reserve_head.lock);
} else if (free_bytes < need_bytes) {
spin_lock(&log->l_reserve_head.lock);
error = xlog_grant_head_wait(log, &log->l_reserve_head, tic,
need_bytes);
spin_unlock(&log->l_reserve_head.lock);
}
error = xlog_grant_head_check(log, &log->l_reserve_head, tic,
&need_bytes);
if (error)
return error;
@ -2576,16 +2589,13 @@ xlog_grant_log_space(
/*
* Replenish the byte reservation required by moving the grant write head.
*
* Similar to xlog_grant_log_space, the function is structured to have a lock
* free fast path.
*/
STATIC int
xlog_regrant_write_log_space(
struct log *log,
struct xlog_ticket *tic)
{
int free_bytes, need_bytes;
int need_bytes;
int error = 0;
tic->t_curr_res = tic->t_unit_res;
@ -2594,33 +2604,10 @@ xlog_regrant_write_log_space(
if (tic->t_cnt > 0)
return 0;
ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
trace_xfs_log_regrant_write_enter(log, tic);
/*
* If there are other waiters on the queue then give them a chance at
* logspace before us. Wake up the first waiters, if we do not wake
* up all the waiters then go to sleep waiting for more free space,
* otherwise try to get some space for this transaction.
*/
need_bytes = tic->t_unit_res;
free_bytes = xlog_space_left(log, &log->l_write_head.grant);
if (!list_empty_careful(&log->l_write_head.waiters)) {
spin_lock(&log->l_write_head.lock);
if (!xlog_grant_head_wake(log, &log->l_write_head, &free_bytes) ||
free_bytes < need_bytes) {
error = xlog_grant_head_wait(log, &log->l_write_head,
tic, need_bytes);
}
spin_unlock(&log->l_write_head.lock);
} else if (free_bytes < need_bytes) {
spin_lock(&log->l_write_head.lock);
error = xlog_grant_head_wait(log, &log->l_write_head, tic,
need_bytes);
spin_unlock(&log->l_write_head.lock);
}
error = xlog_grant_head_check(log, &log->l_write_head, tic,
&need_bytes);
if (error)
return error;