linux/fs/xfs/xfs_dquot_item.c
Dave Chinner 5f9b4b0de8 xfs: xfs_log_force_lsn isn't passed a LSN
In doing an investigation into AIL push stalls, I was looking at the
log force code to see if an async CIL push could be done instead.
This lead me to xfs_log_force_lsn() and looking at how it works.

xfs_log_force_lsn() is only called from inode synchronisation
contexts such as fsync(), and it takes the ip->i_itemp->ili_last_lsn
value as the LSN to sync the log to. This gets passed to
xlog_cil_force_lsn() via xfs_log_force_lsn() to flush the CIL to the
journal, and then used by xfs_log_force_lsn() to flush the iclogs to
the journal.

The problem is that ip->i_itemp->ili_last_lsn does not store a
log sequence number. What it stores is passed to it from the
->iop_committing method, which is called by xfs_log_commit_cil().
The value this passes to the iop_committing method is the CIL
context sequence number that the item was committed to.

As it turns out, xlog_cil_force_lsn() converts the sequence to an
actual commit LSN for the related context and returns that to
xfs_log_force_lsn(). xfs_log_force_lsn() overwrites it's "lsn"
variable that contained a sequence with an actual LSN and then uses
that to sync the iclogs.

This caused me some confusion for a while, even though I originally
wrote all this code a decade ago. ->iop_committing is only used by
a couple of log item types, and only inode items use the sequence
number it is passed.

Let's clean up the API, CIL structures and inode log item to call it
a sequence number, and make it clear that the high level code is
using CIL sequence numbers and not on-disk LSNs for integrity
synchronisation purposes.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2021-06-21 10:12:33 -07:00

355 lines
8.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2003 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_quota.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"
#include "xfs_trans_priv.h"
#include "xfs_qm.h"
#include "xfs_log.h"
static inline struct xfs_dq_logitem *DQUOT_ITEM(struct xfs_log_item *lip)
{
return container_of(lip, struct xfs_dq_logitem, qli_item);
}
/*
* returns the number of iovecs needed to log the given dquot item.
*/
STATIC void
xfs_qm_dquot_logitem_size(
struct xfs_log_item *lip,
int *nvecs,
int *nbytes)
{
*nvecs += 2;
*nbytes += sizeof(struct xfs_dq_logformat) +
sizeof(struct xfs_disk_dquot);
}
/*
* fills in the vector of log iovecs for the given dquot log item.
*/
STATIC void
xfs_qm_dquot_logitem_format(
struct xfs_log_item *lip,
struct xfs_log_vec *lv)
{
struct xfs_disk_dquot ddq;
struct xfs_dq_logitem *qlip = DQUOT_ITEM(lip);
struct xfs_log_iovec *vecp = NULL;
struct xfs_dq_logformat *qlf;
qlf = xlog_prepare_iovec(lv, &vecp, XLOG_REG_TYPE_QFORMAT);
qlf->qlf_type = XFS_LI_DQUOT;
qlf->qlf_size = 2;
qlf->qlf_id = qlip->qli_dquot->q_id;
qlf->qlf_blkno = qlip->qli_dquot->q_blkno;
qlf->qlf_len = 1;
qlf->qlf_boffset = qlip->qli_dquot->q_bufoffset;
xlog_finish_iovec(lv, vecp, sizeof(struct xfs_dq_logformat));
xfs_dquot_to_disk(&ddq, qlip->qli_dquot);
xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_DQUOT, &ddq,
sizeof(struct xfs_disk_dquot));
}
/*
* Increment the pin count of the given dquot.
*/
STATIC void
xfs_qm_dquot_logitem_pin(
struct xfs_log_item *lip)
{
struct xfs_dquot *dqp = DQUOT_ITEM(lip)->qli_dquot;
ASSERT(XFS_DQ_IS_LOCKED(dqp));
atomic_inc(&dqp->q_pincount);
}
/*
* Decrement the pin count of the given dquot, and wake up
* anyone in xfs_dqwait_unpin() if the count goes to 0. The
* dquot must have been previously pinned with a call to
* xfs_qm_dquot_logitem_pin().
*/
STATIC void
xfs_qm_dquot_logitem_unpin(
struct xfs_log_item *lip,
int remove)
{
struct xfs_dquot *dqp = DQUOT_ITEM(lip)->qli_dquot;
ASSERT(atomic_read(&dqp->q_pincount) > 0);
if (atomic_dec_and_test(&dqp->q_pincount))
wake_up(&dqp->q_pinwait);
}
/*
* This is called to wait for the given dquot to be unpinned.
* Most of these pin/unpin routines are plagiarized from inode code.
*/
void
xfs_qm_dqunpin_wait(
struct xfs_dquot *dqp)
{
ASSERT(XFS_DQ_IS_LOCKED(dqp));
if (atomic_read(&dqp->q_pincount) == 0)
return;
/*
* Give the log a push so we don't wait here too long.
*/
xfs_log_force(dqp->q_mount, 0);
wait_event(dqp->q_pinwait, (atomic_read(&dqp->q_pincount) == 0));
}
STATIC uint
xfs_qm_dquot_logitem_push(
struct xfs_log_item *lip,
struct list_head *buffer_list)
__releases(&lip->li_ailp->ail_lock)
__acquires(&lip->li_ailp->ail_lock)
{
struct xfs_dquot *dqp = DQUOT_ITEM(lip)->qli_dquot;
struct xfs_buf *bp = lip->li_buf;
uint rval = XFS_ITEM_SUCCESS;
int error;
if (atomic_read(&dqp->q_pincount) > 0)
return XFS_ITEM_PINNED;
if (!xfs_dqlock_nowait(dqp))
return XFS_ITEM_LOCKED;
/*
* Re-check the pincount now that we stabilized the value by
* taking the quota lock.
*/
if (atomic_read(&dqp->q_pincount) > 0) {
rval = XFS_ITEM_PINNED;
goto out_unlock;
}
/*
* Someone else is already flushing the dquot. Nothing we can do
* here but wait for the flush to finish and remove the item from
* the AIL.
*/
if (!xfs_dqflock_nowait(dqp)) {
rval = XFS_ITEM_FLUSHING;
goto out_unlock;
}
spin_unlock(&lip->li_ailp->ail_lock);
error = xfs_qm_dqflush(dqp, &bp);
if (!error) {
if (!xfs_buf_delwri_queue(bp, buffer_list))
rval = XFS_ITEM_FLUSHING;
xfs_buf_relse(bp);
} else if (error == -EAGAIN)
rval = XFS_ITEM_LOCKED;
spin_lock(&lip->li_ailp->ail_lock);
out_unlock:
xfs_dqunlock(dqp);
return rval;
}
STATIC void
xfs_qm_dquot_logitem_release(
struct xfs_log_item *lip)
{
struct xfs_dquot *dqp = DQUOT_ITEM(lip)->qli_dquot;
ASSERT(XFS_DQ_IS_LOCKED(dqp));
/*
* dquots are never 'held' from getting unlocked at the end of
* a transaction. Their locking and unlocking is hidden inside the
* transaction layer, within trans_commit. Hence, no LI_HOLD flag
* for the logitem.
*/
xfs_dqunlock(dqp);
}
STATIC void
xfs_qm_dquot_logitem_committing(
struct xfs_log_item *lip,
xfs_csn_t seq)
{
return xfs_qm_dquot_logitem_release(lip);
}
static const struct xfs_item_ops xfs_dquot_item_ops = {
.iop_size = xfs_qm_dquot_logitem_size,
.iop_format = xfs_qm_dquot_logitem_format,
.iop_pin = xfs_qm_dquot_logitem_pin,
.iop_unpin = xfs_qm_dquot_logitem_unpin,
.iop_release = xfs_qm_dquot_logitem_release,
.iop_committing = xfs_qm_dquot_logitem_committing,
.iop_push = xfs_qm_dquot_logitem_push,
};
/*
* Initialize the dquot log item for a newly allocated dquot.
* The dquot isn't locked at this point, but it isn't on any of the lists
* either, so we don't care.
*/
void
xfs_qm_dquot_logitem_init(
struct xfs_dquot *dqp)
{
struct xfs_dq_logitem *lp = &dqp->q_logitem;
xfs_log_item_init(dqp->q_mount, &lp->qli_item, XFS_LI_DQUOT,
&xfs_dquot_item_ops);
lp->qli_dquot = dqp;
}
/*------------------ QUOTAOFF LOG ITEMS -------------------*/
static inline struct xfs_qoff_logitem *QOFF_ITEM(struct xfs_log_item *lip)
{
return container_of(lip, struct xfs_qoff_logitem, qql_item);
}
/*
* This returns the number of iovecs needed to log the given quotaoff item.
* We only need 1 iovec for an quotaoff item. It just logs the
* quotaoff_log_format structure.
*/
STATIC void
xfs_qm_qoff_logitem_size(
struct xfs_log_item *lip,
int *nvecs,
int *nbytes)
{
*nvecs += 1;
*nbytes += sizeof(struct xfs_qoff_logitem);
}
STATIC void
xfs_qm_qoff_logitem_format(
struct xfs_log_item *lip,
struct xfs_log_vec *lv)
{
struct xfs_qoff_logitem *qflip = QOFF_ITEM(lip);
struct xfs_log_iovec *vecp = NULL;
struct xfs_qoff_logformat *qlf;
qlf = xlog_prepare_iovec(lv, &vecp, XLOG_REG_TYPE_QUOTAOFF);
qlf->qf_type = XFS_LI_QUOTAOFF;
qlf->qf_size = 1;
qlf->qf_flags = qflip->qql_flags;
xlog_finish_iovec(lv, vecp, sizeof(struct xfs_qoff_logitem));
}
/*
* There isn't much you can do to push a quotaoff item. It is simply
* stuck waiting for the log to be flushed to disk.
*/
STATIC uint
xfs_qm_qoff_logitem_push(
struct xfs_log_item *lip,
struct list_head *buffer_list)
{
return XFS_ITEM_LOCKED;
}
STATIC xfs_lsn_t
xfs_qm_qoffend_logitem_committed(
struct xfs_log_item *lip,
xfs_lsn_t lsn)
{
struct xfs_qoff_logitem *qfe = QOFF_ITEM(lip);
struct xfs_qoff_logitem *qfs = qfe->qql_start_lip;
xfs_qm_qoff_logitem_relse(qfs);
kmem_free(lip->li_lv_shadow);
kmem_free(qfe);
return (xfs_lsn_t)-1;
}
STATIC void
xfs_qm_qoff_logitem_release(
struct xfs_log_item *lip)
{
struct xfs_qoff_logitem *qoff = QOFF_ITEM(lip);
if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
if (qoff->qql_start_lip)
xfs_qm_qoff_logitem_relse(qoff->qql_start_lip);
xfs_qm_qoff_logitem_relse(qoff);
}
}
static const struct xfs_item_ops xfs_qm_qoffend_logitem_ops = {
.iop_size = xfs_qm_qoff_logitem_size,
.iop_format = xfs_qm_qoff_logitem_format,
.iop_committed = xfs_qm_qoffend_logitem_committed,
.iop_push = xfs_qm_qoff_logitem_push,
.iop_release = xfs_qm_qoff_logitem_release,
};
static const struct xfs_item_ops xfs_qm_qoff_logitem_ops = {
.iop_size = xfs_qm_qoff_logitem_size,
.iop_format = xfs_qm_qoff_logitem_format,
.iop_push = xfs_qm_qoff_logitem_push,
.iop_release = xfs_qm_qoff_logitem_release,
};
/*
* Delete the quotaoff intent from the AIL and free it. On success,
* this should only be called for the start item. It can be used for
* either on shutdown or abort.
*/
void
xfs_qm_qoff_logitem_relse(
struct xfs_qoff_logitem *qoff)
{
struct xfs_log_item *lip = &qoff->qql_item;
ASSERT(test_bit(XFS_LI_IN_AIL, &lip->li_flags) ||
test_bit(XFS_LI_ABORTED, &lip->li_flags) ||
XFS_FORCED_SHUTDOWN(lip->li_mountp));
xfs_trans_ail_delete(lip, 0);
kmem_free(lip->li_lv_shadow);
kmem_free(qoff);
}
/*
* Allocate and initialize an quotaoff item of the correct quota type(s).
*/
struct xfs_qoff_logitem *
xfs_qm_qoff_logitem_init(
struct xfs_mount *mp,
struct xfs_qoff_logitem *start,
uint flags)
{
struct xfs_qoff_logitem *qf;
qf = kmem_zalloc(sizeof(struct xfs_qoff_logitem), 0);
xfs_log_item_init(mp, &qf->qql_item, XFS_LI_QUOTAOFF, start ?
&xfs_qm_qoffend_logitem_ops : &xfs_qm_qoff_logitem_ops);
qf->qql_item.li_mountp = mp;
qf->qql_start_lip = start;
qf->qql_flags = flags;
return qf;
}