linux-stable/fs/xfs/xfs_log_cil.c
Linus Torvalds babf0bb978 xfs: Changes for 5.19-rc1
This update includes:
 - support for printk message indexing.
 - large extent counts to provide support for up to 2^47 data extents and 2^32
   attribute extents, allowing us to scale beyond 4 billion data extents
   to billions of xattrs per inode.
 - conversion of various flags fields to be consistently declared as
   unsigned bit fields.
 - improvements to realtime extent accounting and converts them to per-cpu
   counters to match all the other block and inode accounting.
 - reworks core log formatting code to reduce iterations, have a shorter, cleaner
   fast path and generally be easier to understand and maintain.
 - improvements to rmap btree searches that reduce overhead by up
   to 30% resulting in xfs_scrub runtime reductions of 15%.
 - improvements to reflink that remove the size limitations in remapping operations
   and greatly reduce the size of transaction reservations.
 - reworks the minimum log size calculations to allow us to change transaction
   reservations without changing the minimum supported log size.
 - removal of quota warning support as it has never been used on Linux.
 - intent whiteouts to allow us to cancel intents that are completed entirely
   in memory rather than having use CPU and disk bandwidth formatting and writing
   them into the journal when it is not necessary. This makes rmap, reflink and
   extent freeing slightly more efficient, but provides massive improvements
   for....
 - Logged Attribute Replay feature support. This is a fundamental change to the
   way we modify attributes, laying the foundation for future integration of
   attribute modifications as part of other atomic transactional operations the
   filesystem performs.
 - Lots of cleanups and fixes for the logged attribute replay functionality.
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Merge tag 'xfs-5.19-for-linus' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs updates from Dave Chinner:
 "This is a big update with lots of new code. The summary below them
  all, so I'll just touch on teh higlights. The two main new features
  are Large Extent Counts and Logged Attribute Replay - these are two
  new foundational features that we are building more complex future
  features on top of.

  For upcoming functionality, we need to be able to store hundreds of
  millions of xattrs per inode. The Large Extent Count feature removes
  the limits that prevent this scale of xattr storage, and while we were
  modifying the on disk extent count format we also increased the number
  of data extents we support per inode from 2^32 to 2^47.

  We also need to be able to modify xattrs as part of larger atomic
  transactions rather than as standalone transactions. The Logged
  Attribute Replay feature introduces the infrastructure that allows us
  to use intents to record the attribute modifications in the journal
  before we start them, hence allowing other atomic transactions to log
  attribute modification intents and then defer the actual modification
  to later. If we then crash, log recovery then guarantees that the
  attribute is replayed in the context of the atomic transaction that
  logged the intent.

  A significant chunk of the commits in this merge are for the base
  attribute replay functionality along with fixes, improvements and
  cleanups related to this new functioanlity. Allison deserves a big
  round of thanks for her ongoing work to get this functionality into
  XFS.

  There are also many other smaller changes and improvements, so overall
  this is one of the bigger XFS merge requests in some time.

  I will be following up next week with another smaller pull request -
  we already have another round of fixes and improvements to the logged
  attribute replay functionality just about ready to go. They'll soak
  and test over the next week, and I'll send a pull request for them
  near the end of the merge window.

  Summary:

   - support for printk message indexing.

   - large extent counts to provide support for up to 2^47 data extents
     and 2^32 attribute extents, allowing us to scale beyond 4 billion
     data extents to billions of xattrs per inode.

   - conversion of various flags fields to be consistently declared as
     unsigned bit fields.

   - improvements to realtime extent accounting and converts them to
     per-cpu counters to match all the other block and inode accounting.

   - reworks core log formatting code to reduce iterations, have a
     shorter, cleaner fast path and generally be easier to understand
     and maintain.

   - improvements to rmap btree searches that reduce overhead by up to
     30% resulting in xfs_scrub runtime reductions of 15%.

   - improvements to reflink that remove the size limitations in
     remapping operations and greatly reduce the size of transaction
     reservations.

   - reworks the minimum log size calculations to allow us to change
     transaction reservations without changing the minimum supported log
     size.

   - removal of quota warning support as it has never been used on
     Linux.

   - intent whiteouts to allow us to cancel intents that are completed
     entirely in memory rather than having use CPU and disk bandwidth
     formatting and writing them into the journal when it is not
     necessary. This makes rmap, reflink and extent freeing slightly
     more efficient, but provides massive improvements for....

   - Logged Attribute Replay feature support. This is a fundamental
     change to the way we modify attributes, laying the foundation for
     future integration of attribute modifications as part of other
     atomic transactional operations the filesystem performs.

   - Lots of cleanups and fixes for the logged attribute replay
     functionality"

* tag 'xfs-5.19-for-linus' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (124 commits)
  xfs: can't use kmem_zalloc() for attribute buffers
  xfs: detect empty attr leaf blocks in xfs_attr3_leaf_verify
  xfs: ATTR_REPLACE algorithm with LARP enabled needs rework
  xfs: use XFS_DA_OP flags in deferred attr ops
  xfs: remove xfs_attri_remove_iter
  xfs: switch attr remove to xfs_attri_set_iter
  xfs: introduce attr remove initial states into xfs_attr_set_iter
  xfs: xfs_attr_set_iter() does not need to return EAGAIN
  xfs: clean up final attr removal in xfs_attr_set_iter
  xfs: remote xattr removal in xfs_attr_set_iter() is conditional
  xfs: XFS_DAS_LEAF_REPLACE state only needed if !LARP
  xfs: split remote attr setting out from replace path
  xfs: consolidate leaf/node states in xfs_attr_set_iter
  xfs: kill XFS_DAC_LEAF_ADDNAME_INIT
  xfs: separate out initial attr_set states
  xfs: don't set quota warning values
  xfs: remove warning counters from struct xfs_dquot_res
  xfs: remove quota warning limit from struct xfs_quota_limits
  xfs: rework deferred attribute operation setup
  xfs: make xattri_leaf_bp more useful
  ...
2022-05-25 19:34:40 -07:00

1649 lines
50 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2010 Red Hat, Inc. All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_shared.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_extent_busy.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
#include "xfs_log.h"
#include "xfs_log_priv.h"
#include "xfs_trace.h"
struct workqueue_struct *xfs_discard_wq;
/*
* 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 xlog *log)
{
struct xlog_ticket *tic;
tic = xlog_ticket_alloc(log, 0, 1, 0);
/*
* 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;
}
/*
* 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.
*/
static bool
xlog_item_in_current_chkpt(
struct xfs_cil *cil,
struct xfs_log_item *lip)
{
if (list_empty(&lip->li_cil))
return false;
/*
* 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.
*/
return lip->li_seq == READ_ONCE(cil->xc_current_sequence);
}
bool
xfs_log_item_in_current_chkpt(
struct xfs_log_item *lip)
{
return xlog_item_in_current_chkpt(lip->li_log->l_cilp, lip);
}
/*
* Unavoidable forward declaration - xlog_cil_push_work() calls
* xlog_cil_ctx_alloc() itself.
*/
static void xlog_cil_push_work(struct work_struct *work);
static struct xfs_cil_ctx *
xlog_cil_ctx_alloc(void)
{
struct xfs_cil_ctx *ctx;
ctx = kmem_zalloc(sizeof(*ctx), KM_NOFS);
INIT_LIST_HEAD(&ctx->committing);
INIT_LIST_HEAD(&ctx->busy_extents);
INIT_WORK(&ctx->push_work, xlog_cil_push_work);
return ctx;
}
static void
xlog_cil_ctx_switch(
struct xfs_cil *cil,
struct xfs_cil_ctx *ctx)
{
ctx->sequence = ++cil->xc_current_sequence;
ctx->cil = cil;
cil->xc_ctx = ctx;
}
/*
* 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 xlog *log)
{
log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log);
log->l_cilp->xc_ctx->sequence = 1;
}
static inline int
xlog_cil_iovec_space(
uint niovecs)
{
return round_up((sizeof(struct xfs_log_vec) +
niovecs * sizeof(struct xfs_log_iovec)),
sizeof(uint64_t));
}
/*
* Allocate or pin log vector buffers for CIL insertion.
*
* The CIL currently uses disposable buffers for copying a snapshot of the
* modified items into the log during a push. The biggest problem with this is
* the requirement to allocate the disposable buffer during the commit if:
* a) does not exist; or
* b) it is too small
*
* If we do this allocation within xlog_cil_insert_format_items(), it is done
* under the xc_ctx_lock, which means that a CIL push cannot occur during
* the memory allocation. This means that we have a potential deadlock situation
* under low memory conditions when we have lots of dirty metadata pinned in
* the CIL and we need a CIL commit to occur to free memory.
*
* To avoid this, we need to move the memory allocation outside the
* xc_ctx_lock, but because the log vector buffers are disposable, that opens
* up a TOCTOU race condition w.r.t. the CIL committing and removing the log
* vector buffers between the check and the formatting of the item into the
* log vector buffer within the xc_ctx_lock.
*
* Because the log vector buffer needs to be unchanged during the CIL push
* process, we cannot share the buffer between the transaction commit (which
* modifies the buffer) and the CIL push context that is writing the changes
* into the log. This means skipping preallocation of buffer space is
* unreliable, but we most definitely do not want to be allocating and freeing
* buffers unnecessarily during commits when overwrites can be done safely.
*
* The simplest solution to this problem is to allocate a shadow buffer when a
* log item is committed for the second time, and then to only use this buffer
* if necessary. The buffer can remain attached to the log item until such time
* it is needed, and this is the buffer that is reallocated to match the size of
* the incoming modification. Then during the formatting of the item we can swap
* the active buffer with the new one if we can't reuse the existing buffer. We
* don't free the old buffer as it may be reused on the next modification if
* it's size is right, otherwise we'll free and reallocate it at that point.
*
* 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 attaches the vector to the log item in preparation
* for the formatting step which occurs under the xc_ctx_lock.
*
* While this means the memory footprint goes up, it avoids the repeated
* alloc/free pattern that repeated modifications of an item would otherwise
* cause, and hence minimises the CPU overhead of such behaviour.
*/
static void
xlog_cil_alloc_shadow_bufs(
struct xlog *log,
struct xfs_trans *tp)
{
struct xfs_log_item *lip;
list_for_each_entry(lip, &tp->t_items, li_trans) {
struct xfs_log_vec *lv;
int niovecs = 0;
int nbytes = 0;
int buf_size;
bool ordered = false;
/* Skip items which aren't dirty in this transaction. */
if (!test_bit(XFS_LI_DIRTY, &lip->li_flags))
continue;
/* get number of vecs and size of data to be stored */
lip->li_ops->iop_size(lip, &niovecs, &nbytes);
/*
* Ordered items need to be tracked but we do not wish to write
* them. We need a logvec to track the object, but we do not
* need an iovec or buffer to be allocated for copying data.
*/
if (niovecs == XFS_LOG_VEC_ORDERED) {
ordered = true;
niovecs = 0;
nbytes = 0;
}
/*
* We 64-bit align the length of each iovec so that the start of
* the next one is naturally aligned. We'll need to account for
* that slack space here.
*
* We also add the xlog_op_header to each region when
* formatting, but that's not accounted to the size of the item
* at this point. Hence we'll need an addition number of bytes
* for each vector to hold an opheader.
*
* Then round nbytes up to 64-bit alignment so that the initial
* buffer alignment is easy to calculate and verify.
*/
nbytes += niovecs *
(sizeof(uint64_t) + sizeof(struct xlog_op_header));
nbytes = round_up(nbytes, sizeof(uint64_t));
/*
* The data buffer needs to start 64-bit aligned, so round up
* that space to ensure we can align it appropriately and not
* overrun the buffer.
*/
buf_size = nbytes + xlog_cil_iovec_space(niovecs);
/*
* if we have no shadow buffer, or it is too small, we need to
* reallocate it.
*/
if (!lip->li_lv_shadow ||
buf_size > lip->li_lv_shadow->lv_size) {
/*
* We free and allocate here as a realloc would copy
* unnecessary data. We don't use kvzalloc() for the
* same reason - we don't need to zero the data area in
* the buffer, only the log vector header and the iovec
* storage.
*/
kmem_free(lip->li_lv_shadow);
lv = xlog_kvmalloc(buf_size);
memset(lv, 0, xlog_cil_iovec_space(niovecs));
lv->lv_item = lip;
lv->lv_size = buf_size;
if (ordered)
lv->lv_buf_len = XFS_LOG_VEC_ORDERED;
else
lv->lv_iovecp = (struct xfs_log_iovec *)&lv[1];
lip->li_lv_shadow = lv;
} else {
/* same or smaller, optimise common overwrite case */
lv = lip->li_lv_shadow;
if (ordered)
lv->lv_buf_len = XFS_LOG_VEC_ORDERED;
else
lv->lv_buf_len = 0;
lv->lv_bytes = 0;
lv->lv_next = NULL;
}
/* Ensure the lv is set up according to ->iop_size */
lv->lv_niovecs = niovecs;
/* The allocated data region lies beyond the iovec region */
lv->lv_buf = (char *)lv + xlog_cil_iovec_space(niovecs);
}
}
/*
* Prepare the log item for insertion into the CIL. Calculate the difference in
* log space it will consume, and if it is a new item pin it as well.
*/
STATIC void
xfs_cil_prepare_item(
struct xlog *log,
struct xfs_log_vec *lv,
struct xfs_log_vec *old_lv,
int *diff_len)
{
/* Account for the new LV being passed in */
if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED)
*diff_len += lv->lv_bytes;
/*
* If there is no old LV, this is the first time we've seen the item in
* this CIL context and so we need to pin it. If we are replacing the
* old_lv, then remove the space it accounts for and make it the shadow
* buffer for later freeing. In both cases we are now switching to the
* shadow buffer, so update the pointer to it appropriately.
*/
if (!old_lv) {
if (lv->lv_item->li_ops->iop_pin)
lv->lv_item->li_ops->iop_pin(lv->lv_item);
lv->lv_item->li_lv_shadow = NULL;
} else if (old_lv != lv) {
ASSERT(lv->lv_buf_len != XFS_LOG_VEC_ORDERED);
*diff_len -= old_lv->lv_bytes;
lv->lv_item->li_lv_shadow = old_lv;
}
/* 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;
}
/*
* 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 takes the prepared log vectors attached to each log item, and
* formats the changes into the log vector buffer. The buffer it uses is
* dependent on the current state of the vector in the CIL - the shadow lv is
* guaranteed to be large enough for the current modification, but we will only
* use that if we can't reuse the existing lv. If we can't reuse the existing
* lv, then simple swap it out for the shadow lv. We don't free it - that is
* done lazily either by th enext modification or the freeing of the log item.
*
* 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_insert_format_items(
struct xlog *log,
struct xfs_trans *tp,
int *diff_len)
{
struct xfs_log_item *lip;
/* Bail out if we didn't find a log item. */
if (list_empty(&tp->t_items)) {
ASSERT(0);
return;
}
list_for_each_entry(lip, &tp->t_items, li_trans) {
struct xfs_log_vec *lv;
struct xfs_log_vec *old_lv = NULL;
struct xfs_log_vec *shadow;
bool ordered = false;
/* Skip items which aren't dirty in this transaction. */
if (!test_bit(XFS_LI_DIRTY, &lip->li_flags))
continue;
/*
* The formatting size information is already attached to
* the shadow lv on the log item.
*/
shadow = lip->li_lv_shadow;
if (shadow->lv_buf_len == XFS_LOG_VEC_ORDERED)
ordered = true;
/* Skip items that do not have any vectors for writing */
if (!shadow->lv_niovecs && !ordered)
continue;
/* compare to existing item size */
old_lv = lip->li_lv;
if (lip->li_lv && shadow->lv_size <= lip->li_lv->lv_size) {
/* same or smaller, optimise common overwrite case */
lv = lip->li_lv;
lv->lv_next = NULL;
if (ordered)
goto insert;
/*
* set the item up as though it is a new insertion so
* that the space reservation accounting is correct.
*/
*diff_len -= lv->lv_bytes;
/* Ensure the lv is set up according to ->iop_size */
lv->lv_niovecs = shadow->lv_niovecs;
/* reset the lv buffer information for new formatting */
lv->lv_buf_len = 0;
lv->lv_bytes = 0;
lv->lv_buf = (char *)lv +
xlog_cil_iovec_space(lv->lv_niovecs);
} else {
/* switch to shadow buffer! */
lv = shadow;
lv->lv_item = lip;
if (ordered) {
/* track as an ordered logvec */
ASSERT(lip->li_lv == NULL);
goto insert;
}
}
ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t)));
lip->li_ops->iop_format(lip, lv);
insert:
xfs_cil_prepare_item(log, lv, old_lv, diff_len);
}
}
/*
* 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 added to the checkpoint ticket from
* the current transaction ticket so that the accounting works out correctly.
*/
static void
xlog_cil_insert_items(
struct xlog *log,
struct xfs_trans *tp,
uint32_t released_space)
{
struct xfs_cil *cil = log->l_cilp;
struct xfs_cil_ctx *ctx = cil->xc_ctx;
struct xfs_log_item *lip;
int len = 0;
int iclog_space;
int iovhdr_res = 0, split_res = 0, ctx_res = 0;
ASSERT(tp);
/*
* 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.
*/
xlog_cil_insert_format_items(log, tp, &len);
spin_lock(&cil->xc_cil_lock);
/* attach the transaction to the CIL if it has any busy extents */
if (!list_empty(&tp->t_busy))
list_splice_init(&tp->t_busy, &ctx->busy_extents);
/*
* 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) {
ctx_res = ctx->ticket->t_unit_res;
ctx->ticket->t_curr_res = ctx_res;
tp->t_ticket->t_curr_res -= ctx_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)) {
split_res = (len + iclog_space - 1) / iclog_space;
/* need to take into account split region headers, too */
split_res *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
ctx->ticket->t_unit_res += split_res;
ctx->ticket->t_curr_res += split_res;
tp->t_ticket->t_curr_res -= split_res;
ASSERT(tp->t_ticket->t_curr_res >= len);
}
tp->t_ticket->t_curr_res -= len;
tp->t_ticket->t_curr_res += released_space;
ctx->space_used += len;
ctx->space_used -= released_space;
/*
* If we've overrun the reservation, dump the tx details before we move
* the log items. Shutdown is imminent...
*/
if (WARN_ON(tp->t_ticket->t_curr_res < 0)) {
xfs_warn(log->l_mp, "Transaction log reservation overrun:");
xfs_warn(log->l_mp,
" log items: %d bytes (iov hdrs: %d bytes)",
len, iovhdr_res);
xfs_warn(log->l_mp, " split region headers: %d bytes",
split_res);
xfs_warn(log->l_mp, " ctx ticket: %d bytes", ctx_res);
xlog_print_trans(tp);
}
/*
* Now (re-)position everything modified at the tail of the CIL.
* We do this here so we only need to take the CIL lock once during
* the transaction commit.
*/
list_for_each_entry(lip, &tp->t_items, li_trans) {
/* Skip items which aren't dirty in this transaction. */
if (!test_bit(XFS_LI_DIRTY, &lip->li_flags))
continue;
/*
* Only move the item if it isn't already at the tail. This is
* to prevent a transient list_empty() state when reinserting
* an item that is already the only item in the CIL.
*/
if (!list_is_last(&lip->li_cil, &cil->xc_cil))
list_move_tail(&lip->li_cil, &cil->xc_cil);
}
spin_unlock(&cil->xc_cil_lock);
if (tp->t_ticket->t_curr_res < 0)
xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
}
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 = next;
}
}
static void
xlog_discard_endio_work(
struct work_struct *work)
{
struct xfs_cil_ctx *ctx =
container_of(work, struct xfs_cil_ctx, discard_endio_work);
struct xfs_mount *mp = ctx->cil->xc_log->l_mp;
xfs_extent_busy_clear(mp, &ctx->busy_extents, false);
kmem_free(ctx);
}
/*
* Queue up the actual completion to a thread to avoid IRQ-safe locking for
* pagb_lock. Note that we need a unbounded workqueue, otherwise we might
* get the execution delayed up to 30 seconds for weird reasons.
*/
static void
xlog_discard_endio(
struct bio *bio)
{
struct xfs_cil_ctx *ctx = bio->bi_private;
INIT_WORK(&ctx->discard_endio_work, xlog_discard_endio_work);
queue_work(xfs_discard_wq, &ctx->discard_endio_work);
bio_put(bio);
}
static void
xlog_discard_busy_extents(
struct xfs_mount *mp,
struct xfs_cil_ctx *ctx)
{
struct list_head *list = &ctx->busy_extents;
struct xfs_extent_busy *busyp;
struct bio *bio = NULL;
struct blk_plug plug;
int error = 0;
ASSERT(xfs_has_discard(mp));
blk_start_plug(&plug);
list_for_each_entry(busyp, list, list) {
trace_xfs_discard_extent(mp, busyp->agno, busyp->bno,
busyp->length);
error = __blkdev_issue_discard(mp->m_ddev_targp->bt_bdev,
XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno),
XFS_FSB_TO_BB(mp, busyp->length),
GFP_NOFS, &bio);
if (error && error != -EOPNOTSUPP) {
xfs_info(mp,
"discard failed for extent [0x%llx,%u], error %d",
(unsigned long long)busyp->bno,
busyp->length,
error);
break;
}
}
if (bio) {
bio->bi_private = ctx;
bio->bi_end_io = xlog_discard_endio;
submit_bio(bio);
} else {
xlog_discard_endio_work(&ctx->discard_endio_work);
}
blk_finish_plug(&plug);
}
/*
* 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(
struct xfs_cil_ctx *ctx)
{
struct xfs_mount *mp = ctx->cil->xc_log->l_mp;
bool abort = xlog_is_shutdown(ctx->cil->xc_log);
/*
* If the I/O failed, we're aborting the commit and already shutdown.
* Wake any commit waiters before aborting the log items so we don't
* block async log pushers on callbacks. Async log pushers explicitly do
* not wait on log force completion because they may be holding locks
* required to unpin items.
*/
if (abort) {
spin_lock(&ctx->cil->xc_push_lock);
wake_up_all(&ctx->cil->xc_start_wait);
wake_up_all(&ctx->cil->xc_commit_wait);
spin_unlock(&ctx->cil->xc_push_lock);
}
xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain,
ctx->start_lsn, abort);
xfs_extent_busy_sort(&ctx->busy_extents);
xfs_extent_busy_clear(mp, &ctx->busy_extents,
xfs_has_discard(mp) && !abort);
spin_lock(&ctx->cil->xc_push_lock);
list_del(&ctx->committing);
spin_unlock(&ctx->cil->xc_push_lock);
xlog_cil_free_logvec(ctx->lv_chain);
if (!list_empty(&ctx->busy_extents))
xlog_discard_busy_extents(mp, ctx);
else
kmem_free(ctx);
}
void
xlog_cil_process_committed(
struct list_head *list)
{
struct xfs_cil_ctx *ctx;
while ((ctx = list_first_entry_or_null(list,
struct xfs_cil_ctx, iclog_entry))) {
list_del(&ctx->iclog_entry);
xlog_cil_committed(ctx);
}
}
/*
* Record the LSN of the iclog we were just granted space to start writing into.
* If the context doesn't have a start_lsn recorded, then this iclog will
* contain the start record for the checkpoint. Otherwise this write contains
* the commit record for the checkpoint.
*/
void
xlog_cil_set_ctx_write_state(
struct xfs_cil_ctx *ctx,
struct xlog_in_core *iclog)
{
struct xfs_cil *cil = ctx->cil;
xfs_lsn_t lsn = be64_to_cpu(iclog->ic_header.h_lsn);
ASSERT(!ctx->commit_lsn);
if (!ctx->start_lsn) {
spin_lock(&cil->xc_push_lock);
/*
* The LSN we need to pass to the log items on transaction
* commit is the LSN reported by the first log vector write, not
* the commit lsn. If we use the commit record lsn then we can
* move the grant write head beyond the tail LSN and overwrite
* it.
*/
ctx->start_lsn = lsn;
wake_up_all(&cil->xc_start_wait);
spin_unlock(&cil->xc_push_lock);
/*
* Make sure the metadata we are about to overwrite in the log
* has been flushed to stable storage before this iclog is
* issued.
*/
spin_lock(&cil->xc_log->l_icloglock);
iclog->ic_flags |= XLOG_ICL_NEED_FLUSH;
spin_unlock(&cil->xc_log->l_icloglock);
return;
}
/*
* Take a reference to the iclog for the context so that we still hold
* it when xlog_write is done and has released it. This means the
* context controls when the iclog is released for IO.
*/
atomic_inc(&iclog->ic_refcnt);
/*
* xlog_state_get_iclog_space() guarantees there is enough space in the
* iclog for an entire commit record, so we can attach the context
* callbacks now. This needs to be done before we make the commit_lsn
* visible to waiters so that checkpoints with commit records in the
* same iclog order their IO completion callbacks in the same order that
* the commit records appear in the iclog.
*/
spin_lock(&cil->xc_log->l_icloglock);
list_add_tail(&ctx->iclog_entry, &iclog->ic_callbacks);
spin_unlock(&cil->xc_log->l_icloglock);
/*
* Now we can record the commit LSN and wake anyone waiting for this
* sequence to have the ordered commit record assigned to a physical
* location in the log.
*/
spin_lock(&cil->xc_push_lock);
ctx->commit_iclog = iclog;
ctx->commit_lsn = lsn;
wake_up_all(&cil->xc_commit_wait);
spin_unlock(&cil->xc_push_lock);
}
/*
* Ensure that the order of log writes follows checkpoint sequence order. This
* relies on the context LSN being zero until the log write has guaranteed the
* LSN that the log write will start at via xlog_state_get_iclog_space().
*/
enum _record_type {
_START_RECORD,
_COMMIT_RECORD,
};
static int
xlog_cil_order_write(
struct xfs_cil *cil,
xfs_csn_t sequence,
enum _record_type record)
{
struct xfs_cil_ctx *ctx;
restart:
spin_lock(&cil->xc_push_lock);
list_for_each_entry(ctx, &cil->xc_committing, committing) {
/*
* Avoid getting stuck in this loop because we were woken by the
* shutdown, but then went back to sleep once already in the
* shutdown state.
*/
if (xlog_is_shutdown(cil->xc_log)) {
spin_unlock(&cil->xc_push_lock);
return -EIO;
}
/*
* Higher sequences will wait for this one so skip them.
* Don't wait for our own sequence, either.
*/
if (ctx->sequence >= sequence)
continue;
/* Wait until the LSN for the record has been recorded. */
switch (record) {
case _START_RECORD:
if (!ctx->start_lsn) {
xlog_wait(&cil->xc_start_wait, &cil->xc_push_lock);
goto restart;
}
break;
case _COMMIT_RECORD:
if (!ctx->commit_lsn) {
xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
goto restart;
}
break;
}
}
spin_unlock(&cil->xc_push_lock);
return 0;
}
/*
* Write out the log vector change now attached to the CIL context. This will
* write a start record that needs to be strictly ordered in ascending CIL
* sequence order so that log recovery will always use in-order start LSNs when
* replaying checkpoints.
*/
static int
xlog_cil_write_chain(
struct xfs_cil_ctx *ctx,
struct xfs_log_vec *chain,
uint32_t chain_len)
{
struct xlog *log = ctx->cil->xc_log;
int error;
error = xlog_cil_order_write(ctx->cil, ctx->sequence, _START_RECORD);
if (error)
return error;
return xlog_write(log, ctx, chain, ctx->ticket, chain_len);
}
/*
* Write out the commit record of a checkpoint transaction to close off a
* running log write. These commit records are strictly ordered in ascending CIL
* sequence order so that log recovery will always replay the checkpoints in the
* correct order.
*/
static int
xlog_cil_write_commit_record(
struct xfs_cil_ctx *ctx)
{
struct xlog *log = ctx->cil->xc_log;
struct xlog_op_header ophdr = {
.oh_clientid = XFS_TRANSACTION,
.oh_tid = cpu_to_be32(ctx->ticket->t_tid),
.oh_flags = XLOG_COMMIT_TRANS,
};
struct xfs_log_iovec reg = {
.i_addr = &ophdr,
.i_len = sizeof(struct xlog_op_header),
.i_type = XLOG_REG_TYPE_COMMIT,
};
struct xfs_log_vec vec = {
.lv_niovecs = 1,
.lv_iovecp = &reg,
};
int error;
if (xlog_is_shutdown(log))
return -EIO;
error = xlog_cil_order_write(ctx->cil, ctx->sequence, _COMMIT_RECORD);
if (error)
return error;
/* account for space used by record data */
ctx->ticket->t_curr_res -= reg.i_len;
error = xlog_write(log, ctx, &vec, ctx->ticket, reg.i_len);
if (error)
xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
return error;
}
struct xlog_cil_trans_hdr {
struct xlog_op_header oph[2];
struct xfs_trans_header thdr;
struct xfs_log_iovec lhdr[2];
};
/*
* Build a checkpoint transaction header to begin the journal transaction. We
* need to account for the space used by the transaction header here as it is
* not accounted for in xlog_write().
*
* This is the only place we write a transaction header, so we also build the
* log opheaders that indicate the start of a log transaction and wrap the
* transaction header. We keep the start record in it's own log vector rather
* than compacting them into a single region as this ends up making the logic
* in xlog_write() for handling empty opheaders for start, commit and unmount
* records much simpler.
*/
static void
xlog_cil_build_trans_hdr(
struct xfs_cil_ctx *ctx,
struct xlog_cil_trans_hdr *hdr,
struct xfs_log_vec *lvhdr,
int num_iovecs)
{
struct xlog_ticket *tic = ctx->ticket;
__be32 tid = cpu_to_be32(tic->t_tid);
memset(hdr, 0, sizeof(*hdr));
/* Log start record */
hdr->oph[0].oh_tid = tid;
hdr->oph[0].oh_clientid = XFS_TRANSACTION;
hdr->oph[0].oh_flags = XLOG_START_TRANS;
/* log iovec region pointer */
hdr->lhdr[0].i_addr = &hdr->oph[0];
hdr->lhdr[0].i_len = sizeof(struct xlog_op_header);
hdr->lhdr[0].i_type = XLOG_REG_TYPE_LRHEADER;
/* log opheader */
hdr->oph[1].oh_tid = tid;
hdr->oph[1].oh_clientid = XFS_TRANSACTION;
hdr->oph[1].oh_len = cpu_to_be32(sizeof(struct xfs_trans_header));
/* transaction header in host byte order format */
hdr->thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
hdr->thdr.th_type = XFS_TRANS_CHECKPOINT;
hdr->thdr.th_tid = tic->t_tid;
hdr->thdr.th_num_items = num_iovecs;
/* log iovec region pointer */
hdr->lhdr[1].i_addr = &hdr->oph[1];
hdr->lhdr[1].i_len = sizeof(struct xlog_op_header) +
sizeof(struct xfs_trans_header);
hdr->lhdr[1].i_type = XLOG_REG_TYPE_TRANSHDR;
lvhdr->lv_niovecs = 2;
lvhdr->lv_iovecp = &hdr->lhdr[0];
lvhdr->lv_bytes = hdr->lhdr[0].i_len + hdr->lhdr[1].i_len;
lvhdr->lv_next = ctx->lv_chain;
tic->t_curr_res -= lvhdr->lv_bytes;
}
/*
* 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.
*
* If a log item is marked with a whiteout, we do not need to write it to the
* journal and so we just move them to the whiteout list for the caller to
* dispose of appropriately.
*/
static void
xlog_cil_build_lv_chain(
struct xfs_cil *cil,
struct xfs_cil_ctx *ctx,
struct list_head *whiteouts,
uint32_t *num_iovecs,
uint32_t *num_bytes)
{
struct xfs_log_vec *lv = NULL;
while (!list_empty(&cil->xc_cil)) {
struct xfs_log_item *item;
item = list_first_entry(&cil->xc_cil,
struct xfs_log_item, li_cil);
if (test_bit(XFS_LI_WHITEOUT, &item->li_flags)) {
list_move(&item->li_cil, whiteouts);
trace_xfs_cil_whiteout_skip(item);
continue;
}
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_iovecs += lv->lv_niovecs;
/* we don't write ordered log vectors */
if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED)
*num_bytes += lv->lv_bytes;
}
}
static void
xlog_cil_cleanup_whiteouts(
struct list_head *whiteouts)
{
while (!list_empty(whiteouts)) {
struct xfs_log_item *item = list_first_entry(whiteouts,
struct xfs_log_item, li_cil);
list_del_init(&item->li_cil);
trace_xfs_cil_whiteout_unpin(item);
item->li_ops->iop_unpin(item, 1);
}
}
/*
* Push the Committed Item List to the log.
*
* If the current sequence is the same as xc_push_seq we need to do a flush. If
* xc_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.
*
* xc_push_seq is checked unlocked against the sequence number for a match.
* Hence we can allow 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 void
xlog_cil_push_work(
struct work_struct *work)
{
struct xfs_cil_ctx *ctx =
container_of(work, struct xfs_cil_ctx, push_work);
struct xfs_cil *cil = ctx->cil;
struct xlog *log = cil->xc_log;
struct xfs_cil_ctx *new_ctx;
int num_iovecs = 0;
int num_bytes = 0;
int error = 0;
struct xlog_cil_trans_hdr thdr;
struct xfs_log_vec lvhdr = { NULL };
xfs_csn_t push_seq;
bool push_commit_stable;
LIST_HEAD (whiteouts);
new_ctx = xlog_cil_ctx_alloc();
new_ctx->ticket = xlog_cil_ticket_alloc(log);
down_write(&cil->xc_ctx_lock);
spin_lock(&cil->xc_push_lock);
push_seq = cil->xc_push_seq;
ASSERT(push_seq <= ctx->sequence);
push_commit_stable = cil->xc_push_commit_stable;
cil->xc_push_commit_stable = false;
/*
* As we are about to switch to a new, empty CIL context, we no longer
* need to throttle tasks on CIL space overruns. Wake any waiters that
* the hard push throttle may have caught so they can start committing
* to the new context. The ctx->xc_push_lock provides the serialisation
* necessary for safely using the lockless waitqueue_active() check in
* this context.
*/
if (waitqueue_active(&cil->xc_push_wait))
wake_up_all(&cil->xc_push_wait);
/*
* Check if we've anything to push. If there is nothing, then we don't
* move on to a new sequence number and so we have to be able to push
* this sequence again later.
*/
if (list_empty(&cil->xc_cil)) {
cil->xc_push_seq = 0;
spin_unlock(&cil->xc_push_lock);
goto out_skip;
}
/* check for a previously pushed sequence */
if (push_seq < ctx->sequence) {
spin_unlock(&cil->xc_push_lock);
goto out_skip;
}
/*
* We are now going to push this context, so add it to the committing
* list before we do anything else. This ensures that anyone waiting on
* this push can easily detect the difference between a "push in
* progress" and "CIL is empty, nothing to do".
*
* IOWs, a wait loop can now check for:
* the current sequence not being found on the committing list;
* an empty CIL; and
* an unchanged sequence number
* to detect a push that had nothing to do and therefore does not need
* waiting on. If the CIL is not empty, we get put on the committing
* list before emptying the CIL and bumping the sequence number. Hence
* an empty CIL and an unchanged sequence number means we jumped out
* above after doing nothing.
*
* Hence the waiter will either find the commit sequence on the
* committing list or the sequence number will be unchanged and the CIL
* still dirty. In that latter case, the push has not yet started, and
* so the waiter will have to continue trying to check the CIL
* committing list until it is found. In extreme cases of delay, the
* sequence may fully commit between the attempts the wait makes to wait
* on the commit sequence.
*/
list_add(&ctx->committing, &cil->xc_committing);
spin_unlock(&cil->xc_push_lock);
xlog_cil_build_lv_chain(cil, ctx, &whiteouts, &num_iovecs, &num_bytes);
/*
* Switch the contexts 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.
*
* xfs_log_force_seq requires us to mirror the new sequence into the cil
* structure atomically with the addition of this sequence to the
* committing list. This also ensures that we can do unlocked checks
* against the current sequence in log forces without risking
* deferencing a freed context pointer.
*/
spin_lock(&cil->xc_push_lock);
xlog_cil_ctx_switch(cil, new_ctx);
spin_unlock(&cil->xc_push_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().
*/
xlog_cil_build_trans_hdr(ctx, &thdr, &lvhdr, num_iovecs);
num_bytes += lvhdr.lv_bytes;
error = xlog_cil_write_chain(ctx, &lvhdr, num_bytes);
if (error)
goto out_abort_free_ticket;
error = xlog_cil_write_commit_record(ctx);
if (error)
goto out_abort_free_ticket;
xfs_log_ticket_ungrant(log, ctx->ticket);
/*
* If the checkpoint spans multiple iclogs, wait for all previous iclogs
* to complete before we submit the commit_iclog. We can't use state
* checks for this - ACTIVE can be either a past completed iclog or a
* future iclog being filled, while WANT_SYNC through SYNC_DONE can be a
* past or future iclog awaiting IO or ordered IO completion to be run.
* In the latter case, if it's a future iclog and we wait on it, the we
* will hang because it won't get processed through to ic_force_wait
* wakeup until this commit_iclog is written to disk. Hence we use the
* iclog header lsn and compare it to the commit lsn to determine if we
* need to wait on iclogs or not.
*/
spin_lock(&log->l_icloglock);
if (ctx->start_lsn != ctx->commit_lsn) {
xfs_lsn_t plsn;
plsn = be64_to_cpu(ctx->commit_iclog->ic_prev->ic_header.h_lsn);
if (plsn && XFS_LSN_CMP(plsn, ctx->commit_lsn) < 0) {
/*
* Waiting on ic_force_wait orders the completion of
* iclogs older than ic_prev. Hence we only need to wait
* on the most recent older iclog here.
*/
xlog_wait_on_iclog(ctx->commit_iclog->ic_prev);
spin_lock(&log->l_icloglock);
}
/*
* We need to issue a pre-flush so that the ordering for this
* checkpoint is correctly preserved down to stable storage.
*/
ctx->commit_iclog->ic_flags |= XLOG_ICL_NEED_FLUSH;
}
/*
* The commit iclog must be written to stable storage to guarantee
* journal IO vs metadata writeback IO is correctly ordered on stable
* storage.
*
* If the push caller needs the commit to be immediately stable and the
* commit_iclog is not yet marked as XLOG_STATE_WANT_SYNC to indicate it
* will be written when released, switch it's state to WANT_SYNC right
* now.
*/
ctx->commit_iclog->ic_flags |= XLOG_ICL_NEED_FUA;
if (push_commit_stable &&
ctx->commit_iclog->ic_state == XLOG_STATE_ACTIVE)
xlog_state_switch_iclogs(log, ctx->commit_iclog, 0);
xlog_state_release_iclog(log, ctx->commit_iclog);
/* Not safe to reference ctx now! */
spin_unlock(&log->l_icloglock);
xlog_cil_cleanup_whiteouts(&whiteouts);
return;
out_skip:
up_write(&cil->xc_ctx_lock);
xfs_log_ticket_put(new_ctx->ticket);
kmem_free(new_ctx);
return;
out_abort_free_ticket:
xfs_log_ticket_ungrant(log, ctx->ticket);
ASSERT(xlog_is_shutdown(log));
xlog_cil_cleanup_whiteouts(&whiteouts);
if (!ctx->commit_iclog) {
xlog_cil_committed(ctx);
return;
}
spin_lock(&log->l_icloglock);
xlog_state_release_iclog(log, ctx->commit_iclog);
/* Not safe to reference ctx now! */
spin_unlock(&log->l_icloglock);
}
/*
* 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.
*/
static void
xlog_cil_push_background(
struct xlog *log) __releases(cil->xc_ctx_lock)
{
struct xfs_cil *cil = log->l_cilp;
/*
* The cil won't be empty because we are called while holding the
* context lock so whatever we added to the CIL will still be there
*/
ASSERT(!list_empty(&cil->xc_cil));
/*
* Don't do a background push if we haven't used up all the
* space available yet.
*/
if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log)) {
up_read(&cil->xc_ctx_lock);
return;
}
spin_lock(&cil->xc_push_lock);
if (cil->xc_push_seq < cil->xc_current_sequence) {
cil->xc_push_seq = cil->xc_current_sequence;
queue_work(cil->xc_push_wq, &cil->xc_ctx->push_work);
}
/*
* Drop the context lock now, we can't hold that if we need to sleep
* because we are over the blocking threshold. The push_lock is still
* held, so blocking threshold sleep/wakeup is still correctly
* serialised here.
*/
up_read(&cil->xc_ctx_lock);
/*
* If we are well over the space limit, throttle the work that is being
* done until the push work on this context has begun. Enforce the hard
* throttle on all transaction commits once it has been activated, even
* if the committing transactions have resulted in the space usage
* dipping back down under the hard limit.
*
* The ctx->xc_push_lock provides the serialisation necessary for safely
* using the lockless waitqueue_active() check in this context.
*/
if (cil->xc_ctx->space_used >= XLOG_CIL_BLOCKING_SPACE_LIMIT(log) ||
waitqueue_active(&cil->xc_push_wait)) {
trace_xfs_log_cil_wait(log, cil->xc_ctx->ticket);
ASSERT(cil->xc_ctx->space_used < log->l_logsize);
xlog_wait(&cil->xc_push_wait, &cil->xc_push_lock);
return;
}
spin_unlock(&cil->xc_push_lock);
}
/*
* xlog_cil_push_now() is used to trigger an immediate CIL push to the sequence
* number that is passed. When it returns, the work will be queued for
* @push_seq, but it won't be completed.
*
* If the caller is performing a synchronous force, we will flush the workqueue
* to get previously queued work moving to minimise the wait time they will
* undergo waiting for all outstanding pushes to complete. The caller is
* expected to do the required waiting for push_seq to complete.
*
* If the caller is performing an async push, we need to ensure that the
* checkpoint is fully flushed out of the iclogs when we finish the push. If we
* don't do this, then the commit record may remain sitting in memory in an
* ACTIVE iclog. This then requires another full log force to push to disk,
* which defeats the purpose of having an async, non-blocking CIL force
* mechanism. Hence in this case we need to pass a flag to the push work to
* indicate it needs to flush the commit record itself.
*/
static void
xlog_cil_push_now(
struct xlog *log,
xfs_lsn_t push_seq,
bool async)
{
struct xfs_cil *cil = log->l_cilp;
if (!cil)
return;
ASSERT(push_seq && push_seq <= cil->xc_current_sequence);
/* start on any pending background push to minimise wait time on it */
if (!async)
flush_workqueue(cil->xc_push_wq);
spin_lock(&cil->xc_push_lock);
/*
* If this is an async flush request, we always need to set the
* xc_push_commit_stable flag even if something else has already queued
* a push. The flush caller is asking for the CIL to be on stable
* storage when the next push completes, so regardless of who has queued
* the push, the flush requires stable semantics from it.
*/
cil->xc_push_commit_stable = async;
/*
* If the CIL is empty or we've already pushed the sequence then
* there's no more work that we need to do.
*/
if (list_empty(&cil->xc_cil) || push_seq <= cil->xc_push_seq) {
spin_unlock(&cil->xc_push_lock);
return;
}
cil->xc_push_seq = push_seq;
queue_work(cil->xc_push_wq, &cil->xc_ctx->push_work);
spin_unlock(&cil->xc_push_lock);
}
bool
xlog_cil_empty(
struct xlog *log)
{
struct xfs_cil *cil = log->l_cilp;
bool empty = false;
spin_lock(&cil->xc_push_lock);
if (list_empty(&cil->xc_cil))
empty = true;
spin_unlock(&cil->xc_push_lock);
return empty;
}
/*
* If there are intent done items in this transaction and the related intent was
* committed in the current (same) CIL checkpoint, we don't need to write either
* the intent or intent done item to the journal as the change will be
* journalled atomically within this checkpoint. As we cannot remove items from
* the CIL here, mark the related intent with a whiteout so that the CIL push
* can remove it rather than writing it to the journal. Then remove the intent
* done item from the current transaction and release it so it doesn't get put
* into the CIL at all.
*/
static uint32_t
xlog_cil_process_intents(
struct xfs_cil *cil,
struct xfs_trans *tp)
{
struct xfs_log_item *lip, *ilip, *next;
uint32_t len = 0;
list_for_each_entry_safe(lip, next, &tp->t_items, li_trans) {
if (!(lip->li_ops->flags & XFS_ITEM_INTENT_DONE))
continue;
ilip = lip->li_ops->iop_intent(lip);
if (!ilip || !xlog_item_in_current_chkpt(cil, ilip))
continue;
set_bit(XFS_LI_WHITEOUT, &ilip->li_flags);
trace_xfs_cil_whiteout_mark(ilip);
len += ilip->li_lv->lv_bytes;
kmem_free(ilip->li_lv);
ilip->li_lv = NULL;
xfs_trans_del_item(lip);
lip->li_ops->iop_release(lip);
}
return len;
}
/*
* 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.
*
* 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.
*/
void
xlog_cil_commit(
struct xlog *log,
struct xfs_trans *tp,
xfs_csn_t *commit_seq,
bool regrant)
{
struct xfs_cil *cil = log->l_cilp;
struct xfs_log_item *lip, *next;
uint32_t released_space = 0;
/*
* Do all necessary memory allocation before we lock the CIL.
* This ensures the allocation does not deadlock with a CIL
* push in memory reclaim (e.g. from kswapd).
*/
xlog_cil_alloc_shadow_bufs(log, tp);
/* lock out background commit */
down_read(&cil->xc_ctx_lock);
if (tp->t_flags & XFS_TRANS_HAS_INTENT_DONE)
released_space = xlog_cil_process_intents(cil, tp);
xlog_cil_insert_items(log, tp, released_space);
if (regrant && !xlog_is_shutdown(log))
xfs_log_ticket_regrant(log, tp->t_ticket);
else
xfs_log_ticket_ungrant(log, tp->t_ticket);
tp->t_ticket = NULL;
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 possibly 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.
*/
trace_xfs_trans_commit_items(tp, _RET_IP_);
list_for_each_entry_safe(lip, next, &tp->t_items, li_trans) {
xfs_trans_del_item(lip);
if (lip->li_ops->iop_committing)
lip->li_ops->iop_committing(lip, cil->xc_ctx->sequence);
}
if (commit_seq)
*commit_seq = cil->xc_ctx->sequence;
/* xlog_cil_push_background() releases cil->xc_ctx_lock */
xlog_cil_push_background(log);
}
/*
* Flush the CIL to stable storage but don't wait for it to complete. This
* requires the CIL push to ensure the commit record for the push hits the disk,
* but otherwise is no different to a push done from a log force.
*/
void
xlog_cil_flush(
struct xlog *log)
{
xfs_csn_t seq = log->l_cilp->xc_current_sequence;
trace_xfs_log_force(log->l_mp, seq, _RET_IP_);
xlog_cil_push_now(log, seq, true);
/*
* If the CIL is empty, make sure that any previous checkpoint that may
* still be in an active iclog is pushed to stable storage.
*/
if (list_empty(&log->l_cilp->xc_cil))
xfs_log_force(log->l_mp, 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.
*/
xfs_lsn_t
xlog_cil_force_seq(
struct xlog *log,
xfs_csn_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);
if (!sequence)
sequence = cil->xc_current_sequence;
trace_xfs_log_force(log->l_mp, sequence, _RET_IP_);
/*
* 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.
*/
restart:
xlog_cil_push_now(log, sequence, false);
/*
* 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.
*/
spin_lock(&cil->xc_push_lock);
list_for_each_entry(ctx, &cil->xc_committing, committing) {
/*
* Avoid getting stuck in this loop because we were woken by the
* shutdown, but then went back to sleep once already in the
* shutdown state.
*/
if (xlog_is_shutdown(log))
goto out_shutdown;
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.
*/
XFS_STATS_INC(log->l_mp, xs_log_force_sleep);
xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
goto restart;
}
if (ctx->sequence != sequence)
continue;
/* found it! */
commit_lsn = ctx->commit_lsn;
}
/*
* The call to xlog_cil_push_now() executes the push in the background.
* Hence by the time we have got here it our sequence may not have been
* pushed yet. This is true if the current sequence still matches the
* push sequence after the above wait loop and the CIL still contains
* dirty objects. This is guaranteed by the push code first adding the
* context to the committing list before emptying the CIL.
*
* Hence if we don't find the context in the committing list and the
* current sequence number is unchanged then the CIL contents are
* significant. If the CIL is empty, if means there was nothing to push
* and that means there is nothing to wait for. If the CIL is not empty,
* it means we haven't yet started the push, because if it had started
* we would have found the context on the committing list.
*/
if (sequence == cil->xc_current_sequence &&
!list_empty(&cil->xc_cil)) {
spin_unlock(&cil->xc_push_lock);
goto restart;
}
spin_unlock(&cil->xc_push_lock);
return commit_lsn;
/*
* We detected a shutdown in progress. We need to trigger the log force
* to pass through it's iclog state machine error handling, even though
* we are already in a shutdown state. Hence we can't return
* NULLCOMMITLSN here as that has special meaning to log forces (i.e.
* LSN is already stable), so we return a zero LSN instead.
*/
out_shutdown:
spin_unlock(&cil->xc_push_lock);
return 0;
}
/*
* Perform initial CIL structure initialisation.
*/
int
xlog_cil_init(
struct xlog *log)
{
struct xfs_cil *cil;
struct xfs_cil_ctx *ctx;
cil = kmem_zalloc(sizeof(*cil), KM_MAYFAIL);
if (!cil)
return -ENOMEM;
/*
* Limit the CIL pipeline depth to 4 concurrent works to bound the
* concurrency the log spinlocks will be exposed to.
*/
cil->xc_push_wq = alloc_workqueue("xfs-cil/%s",
XFS_WQFLAGS(WQ_FREEZABLE | WQ_MEM_RECLAIM | WQ_UNBOUND),
4, log->l_mp->m_super->s_id);
if (!cil->xc_push_wq)
goto out_destroy_cil;
INIT_LIST_HEAD(&cil->xc_cil);
INIT_LIST_HEAD(&cil->xc_committing);
spin_lock_init(&cil->xc_cil_lock);
spin_lock_init(&cil->xc_push_lock);
init_waitqueue_head(&cil->xc_push_wait);
init_rwsem(&cil->xc_ctx_lock);
init_waitqueue_head(&cil->xc_start_wait);
init_waitqueue_head(&cil->xc_commit_wait);
cil->xc_log = log;
log->l_cilp = cil;
ctx = xlog_cil_ctx_alloc();
xlog_cil_ctx_switch(cil, ctx);
return 0;
out_destroy_cil:
kmem_free(cil);
return -ENOMEM;
}
void
xlog_cil_destroy(
struct xlog *log)
{
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));
destroy_workqueue(log->l_cilp->xc_push_wq);
kmem_free(log->l_cilp);
}