linux/fs/xfs/xfs_log_cil.c
Dave Chinner d1583a3833 xfs: reduce the number of CIL lock round trips during commit
When commiting a transaction, we do a lock CIL state lock round trip
on every single log vector we insert into the CIL. This is resulting
in the lock being as hot as the inode and dcache locks on 8-way
create workloads. Rework the insertion loops to bring the number
of lock round trips to one per transaction for log vectors, and one
more do the busy extents.

Also change the allocation of the log vector buffer not to zero it
as we copy over the entire allocated buffer anyway.

This patch also includes a structural cleanup to the CIL item
insertion provided by Christoph Hellwig.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
2010-10-18 15:07:42 -05:00

803 lines
24 KiB
C

/*
* Copyright (c) 2010 Red Hat, Inc. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
#include "xfs_log_priv.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_error.h"
#include "xfs_alloc.h"
/*
* Perform initial CIL structure initialisation. If the CIL is not
* enabled in this filesystem, ensure the log->l_cilp is null so
* we can check this conditional to determine if we are doing delayed
* logging or not.
*/
int
xlog_cil_init(
struct log *log)
{
struct xfs_cil *cil;
struct xfs_cil_ctx *ctx;
log->l_cilp = NULL;
if (!(log->l_mp->m_flags & XFS_MOUNT_DELAYLOG))
return 0;
cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL);
if (!cil)
return ENOMEM;
ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL);
if (!ctx) {
kmem_free(cil);
return ENOMEM;
}
INIT_LIST_HEAD(&cil->xc_cil);
INIT_LIST_HEAD(&cil->xc_committing);
spin_lock_init(&cil->xc_cil_lock);
init_rwsem(&cil->xc_ctx_lock);
sv_init(&cil->xc_commit_wait, SV_DEFAULT, "cilwait");
INIT_LIST_HEAD(&ctx->committing);
INIT_LIST_HEAD(&ctx->busy_extents);
ctx->sequence = 1;
ctx->cil = cil;
cil->xc_ctx = ctx;
cil->xc_current_sequence = ctx->sequence;
cil->xc_log = log;
log->l_cilp = cil;
return 0;
}
void
xlog_cil_destroy(
struct log *log)
{
if (!log->l_cilp)
return;
if (log->l_cilp->xc_ctx) {
if (log->l_cilp->xc_ctx->ticket)
xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket);
kmem_free(log->l_cilp->xc_ctx);
}
ASSERT(list_empty(&log->l_cilp->xc_cil));
kmem_free(log->l_cilp);
}
/*
* Allocate a new ticket. Failing to get a new ticket makes it really hard to
* recover, so we don't allow failure here. Also, we allocate in a context that
* we don't want to be issuing transactions from, so we need to tell the
* allocation code this as well.
*
* We don't reserve any space for the ticket - we are going to steal whatever
* space we require from transactions as they commit. To ensure we reserve all
* the space required, we need to set the current reservation of the ticket to
* zero so that we know to steal the initial transaction overhead from the
* first transaction commit.
*/
static struct xlog_ticket *
xlog_cil_ticket_alloc(
struct log *log)
{
struct xlog_ticket *tic;
tic = xlog_ticket_alloc(log, 0, 1, XFS_TRANSACTION, 0,
KM_SLEEP|KM_NOFS);
tic->t_trans_type = XFS_TRANS_CHECKPOINT;
/*
* set the current reservation to zero so we know to steal the basic
* transaction overhead reservation from the first transaction commit.
*/
tic->t_curr_res = 0;
return tic;
}
/*
* After the first stage of log recovery is done, we know where the head and
* tail of the log are. We need this log initialisation done before we can
* initialise the first CIL checkpoint context.
*
* Here we allocate a log ticket to track space usage during a CIL push. This
* ticket is passed to xlog_write() directly so that we don't slowly leak log
* space by failing to account for space used by log headers and additional
* region headers for split regions.
*/
void
xlog_cil_init_post_recovery(
struct log *log)
{
if (!log->l_cilp)
return;
log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log);
log->l_cilp->xc_ctx->sequence = 1;
log->l_cilp->xc_ctx->commit_lsn = xlog_assign_lsn(log->l_curr_cycle,
log->l_curr_block);
}
/*
* Format log item into a flat buffers
*
* For delayed logging, we need to hold a formatted buffer containing all the
* changes on the log item. This enables us to relog the item in memory and
* write it out asynchronously without needing to relock the object that was
* modified at the time it gets written into the iclog.
*
* This function builds a vector for the changes in each log item in the
* transaction. It then works out the length of the buffer needed for each log
* item, allocates them and formats the vector for the item into the buffer.
* The buffer is then attached to the log item are then inserted into the
* Committed Item List for tracking until the next checkpoint is written out.
*
* We don't set up region headers during this process; we simply copy the
* regions into the flat buffer. We can do this because we still have to do a
* formatting step to write the regions into the iclog buffer. Writing the
* ophdrs during the iclog write means that we can support splitting large
* regions across iclog boundares without needing a change in the format of the
* item/region encapsulation.
*
* Hence what we need to do now is change the rewrite the vector array to point
* to the copied region inside the buffer we just allocated. This allows us to
* format the regions into the iclog as though they are being formatted
* directly out of the objects themselves.
*/
static void
xlog_cil_format_items(
struct log *log,
struct xfs_log_vec *log_vector)
{
struct xfs_log_vec *lv;
ASSERT(log_vector);
for (lv = log_vector; lv; lv = lv->lv_next) {
void *ptr;
int index;
int len = 0;
/* build the vector array and calculate it's length */
IOP_FORMAT(lv->lv_item, lv->lv_iovecp);
for (index = 0; index < lv->lv_niovecs; index++)
len += lv->lv_iovecp[index].i_len;
lv->lv_buf_len = len;
lv->lv_buf = kmem_alloc(lv->lv_buf_len, KM_SLEEP|KM_NOFS);
ptr = lv->lv_buf;
for (index = 0; index < lv->lv_niovecs; index++) {
struct xfs_log_iovec *vec = &lv->lv_iovecp[index];
memcpy(ptr, vec->i_addr, vec->i_len);
vec->i_addr = ptr;
ptr += vec->i_len;
}
ASSERT(ptr == lv->lv_buf + lv->lv_buf_len);
}
}
/*
* Prepare the log item for insertion into the CIL. Calculate the difference in
* log space and vectors it will consume, and if it is a new item pin it as
* well.
*/
STATIC void
xfs_cil_prepare_item(
struct log *log,
struct xfs_log_vec *lv,
int *len,
int *diff_iovecs)
{
struct xfs_log_vec *old = lv->lv_item->li_lv;
if (old) {
/* existing lv on log item, space used is a delta */
ASSERT(!list_empty(&lv->lv_item->li_cil));
ASSERT(old->lv_buf && old->lv_buf_len && old->lv_niovecs);
*len += lv->lv_buf_len - old->lv_buf_len;
*diff_iovecs += lv->lv_niovecs - old->lv_niovecs;
kmem_free(old->lv_buf);
kmem_free(old);
} else {
/* new lv, must pin the log item */
ASSERT(!lv->lv_item->li_lv);
ASSERT(list_empty(&lv->lv_item->li_cil));
*len += lv->lv_buf_len;
*diff_iovecs += lv->lv_niovecs;
IOP_PIN(lv->lv_item);
}
/* attach new log vector to log item */
lv->lv_item->li_lv = lv;
/*
* If this is the first time the item is being committed to the
* CIL, store the sequence number on the log item so we can
* tell in future commits whether this is the first checkpoint
* the item is being committed into.
*/
if (!lv->lv_item->li_seq)
lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence;
}
/*
* Insert the log items into the CIL and calculate the difference in space
* consumed by the item. Add the space to the checkpoint ticket and calculate
* if the change requires additional log metadata. If it does, take that space
* as well. Remove the amount of space we addded to the checkpoint ticket from
* the current transaction ticket so that the accounting works out correctly.
*/
static void
xlog_cil_insert_items(
struct log *log,
struct xfs_log_vec *log_vector,
struct xlog_ticket *ticket)
{
struct xfs_cil *cil = log->l_cilp;
struct xfs_cil_ctx *ctx = cil->xc_ctx;
struct xfs_log_vec *lv;
int len = 0;
int diff_iovecs = 0;
int iclog_space;
ASSERT(log_vector);
/*
* Do all the accounting aggregation and switching of log vectors
* around in a separate loop to the insertion of items into the CIL.
* Then we can do a separate loop to update the CIL within a single
* lock/unlock pair. This reduces the number of round trips on the CIL
* lock from O(nr_logvectors) to O(1) and greatly reduces the overall
* hold time for the transaction commit.
*
* If this is the first time the item is being placed into the CIL in
* this context, pin it so it can't be written to disk until the CIL is
* flushed to the iclog and the iclog written to disk.
*
* We can do this safely because the context can't checkpoint until we
* are done so it doesn't matter exactly how we update the CIL.
*/
for (lv = log_vector; lv; lv = lv->lv_next)
xfs_cil_prepare_item(log, lv, &len, &diff_iovecs);
/* account for space used by new iovec headers */
len += diff_iovecs * sizeof(xlog_op_header_t);
spin_lock(&cil->xc_cil_lock);
/* move the items to the tail of the CIL */
for (lv = log_vector; lv; lv = lv->lv_next)
list_move_tail(&lv->lv_item->li_cil, &cil->xc_cil);
ctx->nvecs += diff_iovecs;
/*
* Now transfer enough transaction reservation to the context ticket
* for the checkpoint. The context ticket is special - the unit
* reservation has to grow as well as the current reservation as we
* steal from tickets so we can correctly determine the space used
* during the transaction commit.
*/
if (ctx->ticket->t_curr_res == 0) {
/* first commit in checkpoint, steal the header reservation */
ASSERT(ticket->t_curr_res >= ctx->ticket->t_unit_res + len);
ctx->ticket->t_curr_res = ctx->ticket->t_unit_res;
ticket->t_curr_res -= ctx->ticket->t_unit_res;
}
/* do we need space for more log record headers? */
iclog_space = log->l_iclog_size - log->l_iclog_hsize;
if (len > 0 && (ctx->space_used / iclog_space !=
(ctx->space_used + len) / iclog_space)) {
int hdrs;
hdrs = (len + iclog_space - 1) / iclog_space;
/* need to take into account split region headers, too */
hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
ctx->ticket->t_unit_res += hdrs;
ctx->ticket->t_curr_res += hdrs;
ticket->t_curr_res -= hdrs;
ASSERT(ticket->t_curr_res >= len);
}
ticket->t_curr_res -= len;
ctx->space_used += len;
spin_unlock(&cil->xc_cil_lock);
}
static void
xlog_cil_free_logvec(
struct xfs_log_vec *log_vector)
{
struct xfs_log_vec *lv;
for (lv = log_vector; lv; ) {
struct xfs_log_vec *next = lv->lv_next;
kmem_free(lv->lv_buf);
kmem_free(lv);
lv = next;
}
}
/*
* Mark all items committed and clear busy extents. We free the log vector
* chains in a separate pass so that we unpin the log items as quickly as
* possible.
*/
static void
xlog_cil_committed(
void *args,
int abort)
{
struct xfs_cil_ctx *ctx = args;
struct xfs_log_vec *lv;
int abortflag = abort ? XFS_LI_ABORTED : 0;
struct xfs_busy_extent *busyp, *n;
/* unpin all the log items */
for (lv = ctx->lv_chain; lv; lv = lv->lv_next ) {
xfs_trans_item_committed(lv->lv_item, ctx->start_lsn,
abortflag);
}
list_for_each_entry_safe(busyp, n, &ctx->busy_extents, list)
xfs_alloc_busy_clear(ctx->cil->xc_log->l_mp, busyp);
spin_lock(&ctx->cil->xc_cil_lock);
list_del(&ctx->committing);
spin_unlock(&ctx->cil->xc_cil_lock);
xlog_cil_free_logvec(ctx->lv_chain);
kmem_free(ctx);
}
/*
* Push the Committed Item List to the log. If @push_seq flag is zero, then it
* is a background flush and so we can chose to ignore it. Otherwise, if the
* current sequence is the same as @push_seq we need to do a flush. If
* @push_seq is less than the current sequence, then it has already been
* flushed and we don't need to do anything - the caller will wait for it to
* complete if necessary.
*
* @push_seq is a value rather than a flag because that allows us to do an
* unlocked check of the sequence number for a match. Hence we can allows log
* forces to run racily and not issue pushes for the same sequence twice. If we
* get a race between multiple pushes for the same sequence they will block on
* the first one and then abort, hence avoiding needless pushes.
*/
STATIC int
xlog_cil_push(
struct log *log,
xfs_lsn_t push_seq)
{
struct xfs_cil *cil = log->l_cilp;
struct xfs_log_vec *lv;
struct xfs_cil_ctx *ctx;
struct xfs_cil_ctx *new_ctx;
struct xlog_in_core *commit_iclog;
struct xlog_ticket *tic;
int num_lv;
int num_iovecs;
int len;
int error = 0;
struct xfs_trans_header thdr;
struct xfs_log_iovec lhdr;
struct xfs_log_vec lvhdr = { NULL };
xfs_lsn_t commit_lsn;
if (!cil)
return 0;
ASSERT(!push_seq || push_seq <= cil->xc_ctx->sequence);
new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
new_ctx->ticket = xlog_cil_ticket_alloc(log);
/*
* Lock out transaction commit, but don't block for background pushes
* unless we are well over the CIL space limit. See the definition of
* XLOG_CIL_HARD_SPACE_LIMIT() for the full explanation of the logic
* used here.
*/
if (!down_write_trylock(&cil->xc_ctx_lock)) {
if (!push_seq &&
cil->xc_ctx->space_used < XLOG_CIL_HARD_SPACE_LIMIT(log))
goto out_free_ticket;
down_write(&cil->xc_ctx_lock);
}
ctx = cil->xc_ctx;
/* check if we've anything to push */
if (list_empty(&cil->xc_cil))
goto out_skip;
/* check for spurious background flush */
if (!push_seq && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
goto out_skip;
/* check for a previously pushed seqeunce */
if (push_seq && push_seq < cil->xc_ctx->sequence)
goto out_skip;
/*
* pull all the log vectors off the items in the CIL, and
* remove the items from the CIL. We don't need the CIL lock
* here because it's only needed on the transaction commit
* side which is currently locked out by the flush lock.
*/
lv = NULL;
num_lv = 0;
num_iovecs = 0;
len = 0;
while (!list_empty(&cil->xc_cil)) {
struct xfs_log_item *item;
int i;
item = list_first_entry(&cil->xc_cil,
struct xfs_log_item, li_cil);
list_del_init(&item->li_cil);
if (!ctx->lv_chain)
ctx->lv_chain = item->li_lv;
else
lv->lv_next = item->li_lv;
lv = item->li_lv;
item->li_lv = NULL;
num_lv++;
num_iovecs += lv->lv_niovecs;
for (i = 0; i < lv->lv_niovecs; i++)
len += lv->lv_iovecp[i].i_len;
}
/*
* initialise the new context and attach it to the CIL. Then attach
* the current context to the CIL committing lsit so it can be found
* during log forces to extract the commit lsn of the sequence that
* needs to be forced.
*/
INIT_LIST_HEAD(&new_ctx->committing);
INIT_LIST_HEAD(&new_ctx->busy_extents);
new_ctx->sequence = ctx->sequence + 1;
new_ctx->cil = cil;
cil->xc_ctx = new_ctx;
/*
* mirror the new sequence into the cil structure so that we can do
* unlocked checks against the current sequence in log forces without
* risking deferencing a freed context pointer.
*/
cil->xc_current_sequence = new_ctx->sequence;
/*
* The switch is now done, so we can drop the context lock and move out
* of a shared context. We can't just go straight to the commit record,
* though - we need to synchronise with previous and future commits so
* that the commit records are correctly ordered in the log to ensure
* that we process items during log IO completion in the correct order.
*
* For example, if we get an EFI in one checkpoint and the EFD in the
* next (e.g. due to log forces), we do not want the checkpoint with
* the EFD to be committed before the checkpoint with the EFI. Hence
* we must strictly order the commit records of the checkpoints so
* that: a) the checkpoint callbacks are attached to the iclogs in the
* correct order; and b) the checkpoints are replayed in correct order
* in log recovery.
*
* Hence we need to add this context to the committing context list so
* that higher sequences will wait for us to write out a commit record
* before they do.
*/
spin_lock(&cil->xc_cil_lock);
list_add(&ctx->committing, &cil->xc_committing);
spin_unlock(&cil->xc_cil_lock);
up_write(&cil->xc_ctx_lock);
/*
* Build a checkpoint transaction header and write it to the log to
* begin the transaction. We need to account for the space used by the
* transaction header here as it is not accounted for in xlog_write().
*
* The LSN we need to pass to the log items on transaction commit is
* the LSN reported by the first log vector write. If we use the commit
* record lsn then we can move the tail beyond the grant write head.
*/
tic = ctx->ticket;
thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
thdr.th_type = XFS_TRANS_CHECKPOINT;
thdr.th_tid = tic->t_tid;
thdr.th_num_items = num_iovecs;
lhdr.i_addr = &thdr;
lhdr.i_len = sizeof(xfs_trans_header_t);
lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t);
lvhdr.lv_niovecs = 1;
lvhdr.lv_iovecp = &lhdr;
lvhdr.lv_next = ctx->lv_chain;
error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0);
if (error)
goto out_abort;
/*
* now that we've written the checkpoint into the log, strictly
* order the commit records so replay will get them in the right order.
*/
restart:
spin_lock(&cil->xc_cil_lock);
list_for_each_entry(new_ctx, &cil->xc_committing, committing) {
/*
* Higher sequences will wait for this one so skip them.
* Don't wait for own own sequence, either.
*/
if (new_ctx->sequence >= ctx->sequence)
continue;
if (!new_ctx->commit_lsn) {
/*
* It is still being pushed! Wait for the push to
* complete, then start again from the beginning.
*/
sv_wait(&cil->xc_commit_wait, 0, &cil->xc_cil_lock, 0);
goto restart;
}
}
spin_unlock(&cil->xc_cil_lock);
commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0);
if (error || commit_lsn == -1)
goto out_abort;
/* attach all the transactions w/ busy extents to iclog */
ctx->log_cb.cb_func = xlog_cil_committed;
ctx->log_cb.cb_arg = ctx;
error = xfs_log_notify(log->l_mp, commit_iclog, &ctx->log_cb);
if (error)
goto out_abort;
/*
* now the checkpoint commit is complete and we've attached the
* callbacks to the iclog we can assign the commit LSN to the context
* and wake up anyone who is waiting for the commit to complete.
*/
spin_lock(&cil->xc_cil_lock);
ctx->commit_lsn = commit_lsn;
sv_broadcast(&cil->xc_commit_wait);
spin_unlock(&cil->xc_cil_lock);
/* release the hounds! */
return xfs_log_release_iclog(log->l_mp, commit_iclog);
out_skip:
up_write(&cil->xc_ctx_lock);
out_free_ticket:
xfs_log_ticket_put(new_ctx->ticket);
kmem_free(new_ctx);
return 0;
out_abort:
xlog_cil_committed(ctx, XFS_LI_ABORTED);
return XFS_ERROR(EIO);
}
/*
* Commit a transaction with the given vector to the Committed Item List.
*
* To do this, we need to format the item, pin it in memory if required and
* account for the space used by the transaction. Once we have done that we
* need to release the unused reservation for the transaction, attach the
* transaction to the checkpoint context so we carry the busy extents through
* to checkpoint completion, and then unlock all the items in the transaction.
*
* For more specific information about the order of operations in
* xfs_log_commit_cil() please refer to the comments in
* xfs_trans_commit_iclog().
*
* Called with the context lock already held in read mode to lock out
* background commit, returns without it held once background commits are
* allowed again.
*/
int
xfs_log_commit_cil(
struct xfs_mount *mp,
struct xfs_trans *tp,
struct xfs_log_vec *log_vector,
xfs_lsn_t *commit_lsn,
int flags)
{
struct log *log = mp->m_log;
int log_flags = 0;
int push = 0;
if (flags & XFS_TRANS_RELEASE_LOG_RES)
log_flags = XFS_LOG_REL_PERM_RESERV;
if (XLOG_FORCED_SHUTDOWN(log)) {
xlog_cil_free_logvec(log_vector);
return XFS_ERROR(EIO);
}
/*
* do all the hard work of formatting items (including memory
* allocation) outside the CIL context lock. This prevents stalling CIL
* pushes when we are low on memory and a transaction commit spends a
* lot of time in memory reclaim.
*/
xlog_cil_format_items(log, log_vector);
/* lock out background commit */
down_read(&log->l_cilp->xc_ctx_lock);
if (commit_lsn)
*commit_lsn = log->l_cilp->xc_ctx->sequence;
xlog_cil_insert_items(log, log_vector, tp->t_ticket);
/* check we didn't blow the reservation */
if (tp->t_ticket->t_curr_res < 0)
xlog_print_tic_res(log->l_mp, tp->t_ticket);
/* attach the transaction to the CIL if it has any busy extents */
if (!list_empty(&tp->t_busy)) {
spin_lock(&log->l_cilp->xc_cil_lock);
list_splice_init(&tp->t_busy,
&log->l_cilp->xc_ctx->busy_extents);
spin_unlock(&log->l_cilp->xc_cil_lock);
}
tp->t_commit_lsn = *commit_lsn;
xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
xfs_trans_unreserve_and_mod_sb(tp);
/*
* Once all the items of the transaction have been copied to the CIL,
* the items can be unlocked and freed.
*
* This needs to be done before we drop the CIL context lock because we
* have to update state in the log items and unlock them before they go
* to disk. If we don't, then the CIL checkpoint can race with us and
* we can run checkpoint completion before we've updated and unlocked
* the log items. This affects (at least) processing of stale buffers,
* inodes and EFIs.
*/
xfs_trans_free_items(tp, *commit_lsn, 0);
/* check for background commit before unlock */
if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log))
push = 1;
up_read(&log->l_cilp->xc_ctx_lock);
/*
* We need to push CIL every so often so we don't cache more than we
* can fit in the log. The limit really is that a checkpoint can't be
* more than half the log (the current checkpoint is not allowed to
* overwrite the previous checkpoint), but commit latency and memory
* usage limit this to a smaller size in most cases.
*/
if (push)
xlog_cil_push(log, 0);
return 0;
}
/*
* Conditionally push the CIL based on the sequence passed in.
*
* We only need to push if we haven't already pushed the sequence
* number given. Hence the only time we will trigger a push here is
* if the push sequence is the same as the current context.
*
* We return the current commit lsn to allow the callers to determine if a
* iclog flush is necessary following this call.
*
* XXX: Initially, just push the CIL unconditionally and return whatever
* commit lsn is there. It'll be empty, so this is broken for now.
*/
xfs_lsn_t
xlog_cil_force_lsn(
struct log *log,
xfs_lsn_t sequence)
{
struct xfs_cil *cil = log->l_cilp;
struct xfs_cil_ctx *ctx;
xfs_lsn_t commit_lsn = NULLCOMMITLSN;
ASSERT(sequence <= cil->xc_current_sequence);
/*
* check to see if we need to force out the current context.
* xlog_cil_push() handles racing pushes for the same sequence,
* so no need to deal with it here.
*/
if (sequence == cil->xc_current_sequence)
xlog_cil_push(log, sequence);
/*
* See if we can find a previous sequence still committing.
* We need to wait for all previous sequence commits to complete
* before allowing the force of push_seq to go ahead. Hence block
* on commits for those as well.
*/
restart:
spin_lock(&cil->xc_cil_lock);
list_for_each_entry(ctx, &cil->xc_committing, committing) {
if (ctx->sequence > sequence)
continue;
if (!ctx->commit_lsn) {
/*
* It is still being pushed! Wait for the push to
* complete, then start again from the beginning.
*/
sv_wait(&cil->xc_commit_wait, 0, &cil->xc_cil_lock, 0);
goto restart;
}
if (ctx->sequence != sequence)
continue;
/* found it! */
commit_lsn = ctx->commit_lsn;
}
spin_unlock(&cil->xc_cil_lock);
return commit_lsn;
}
/*
* Check if the current log item was first committed in this sequence.
* We can't rely on just the log item being in the CIL, we have to check
* the recorded commit sequence number.
*
* Note: for this to be used in a non-racy manner, it has to be called with
* CIL flushing locked out. As a result, it should only be used during the
* transaction commit process when deciding what to format into the item.
*/
bool
xfs_log_item_in_current_chkpt(
struct xfs_log_item *lip)
{
struct xfs_cil_ctx *ctx;
if (!(lip->li_mountp->m_flags & XFS_MOUNT_DELAYLOG))
return false;
if (list_empty(&lip->li_cil))
return false;
ctx = lip->li_mountp->m_log->l_cilp->xc_ctx;
/*
* li_seq is written on the first commit of a log item to record the
* first checkpoint it is written to. Hence if it is different to the
* current sequence, we're in a new checkpoint.
*/
if (XFS_LSN_CMP(lip->li_seq, ctx->sequence) != 0)
return false;
return true;
}