- 根目录:
- fs
- xfs
- xfs_trans_ail.c
/*
* Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
* Copyright (c) 2008 Dave Chinner
* 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_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_trans_priv.h"
#include "xfs_error.h"
#ifdef DEBUG
/*
* Check that the list is sorted as it should be.
*/
STATIC void
xfs_ail_check(
struct xfs_ail *ailp,
xfs_log_item_t *lip)
{
xfs_log_item_t *prev_lip;
if (list_empty(&ailp->xa_ail))
return;
/*
* Check the next and previous entries are valid.
*/
ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
if (&prev_lip->li_ail != &ailp->xa_ail)
ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
prev_lip = list_entry(lip->li_ail.next, xfs_log_item_t, li_ail);
if (&prev_lip->li_ail != &ailp->xa_ail)
ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0);
#ifdef XFS_TRANS_DEBUG
/*
* Walk the list checking lsn ordering, and that every entry has the
* XFS_LI_IN_AIL flag set. This is really expensive, so only do it
* when specifically debugging the transaction subsystem.
*/
prev_lip = list_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
if (&prev_lip->li_ail != &ailp->xa_ail)
ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
prev_lip = lip;
}
#endif /* XFS_TRANS_DEBUG */
}
#else /* !DEBUG */
#define xfs_ail_check(a,l)
#endif /* DEBUG */
/*
* Return a pointer to the first item in the AIL. If the AIL is empty, then
* return NULL.
*/
static xfs_log_item_t *
xfs_ail_min(
struct xfs_ail *ailp)
{
if (list_empty(&ailp->xa_ail))
return NULL;
return list_first_entry(&ailp->xa_ail, xfs_log_item_t, li_ail);
}
/*
* Return a pointer to the last item in the AIL. If the AIL is empty, then
* return NULL.
*/
static xfs_log_item_t *
xfs_ail_max(
struct xfs_ail *ailp)
{
if (list_empty(&ailp->xa_ail))
return NULL;
return list_entry(ailp->xa_ail.prev, xfs_log_item_t, li_ail);
}
/*
* Return a pointer to the item which follows the given item in the AIL. If
* the given item is the last item in the list, then return NULL.
*/
static xfs_log_item_t *
xfs_ail_next(
struct xfs_ail *ailp,
xfs_log_item_t *lip)
{
if (lip->li_ail.next == &ailp->xa_ail)
return NULL;
return list_first_entry(&lip->li_ail, xfs_log_item_t, li_ail);
}
/*
* This is called by the log manager code to determine the LSN of the tail of
* the log. This is exactly the LSN of the first item in the AIL. If the AIL
* is empty, then this function returns 0.
*
* We need the AIL lock in order to get a coherent read of the lsn of the last
* item in the AIL.
*/
xfs_lsn_t
xfs_ail_min_lsn(
struct xfs_ail *ailp)
{
xfs_lsn_t lsn = 0;
xfs_log_item_t *lip;
spin_lock(&ailp->xa_lock);
lip = xfs_ail_min(ailp);
if (lip)
lsn = lip->li_lsn;
spin_unlock(&ailp->xa_lock);
return lsn;
}
/*
* Return the maximum lsn held in the AIL, or zero if the AIL is empty.
*/
static xfs_lsn_t
xfs_ail_max_lsn(
struct xfs_ail *ailp)
{
xfs_lsn_t lsn = 0;
xfs_log_item_t *lip;
spin_lock(&ailp->xa_lock);
lip = xfs_ail_max(ailp);
if (lip)
lsn = lip->li_lsn;
spin_unlock(&ailp->xa_lock);
return lsn;
}
/*
* AIL traversal cursor initialisation.
*
* The cursor keeps track of where our current traversal is up
* to by tracking the next ƣtem in the list for us. However, for
* this to be safe, removing an object from the AIL needs to invalidate
* any cursor that points to it. hence the traversal cursor needs to
* be linked to the struct xfs_ail so that deletion can search all the
* active cursors for invalidation.
*
* We don't link the push cursor because it is embedded in the struct
* xfs_ail and hence easily findable.
*/
STATIC void
xfs_trans_ail_cursor_init(
struct xfs_ail *ailp,
struct xfs_ail_cursor *cur)
{
cur->item = NULL;
if (cur == &ailp->xa_cursors)
return;
cur->next = ailp->xa_cursors.next;
ailp->xa_cursors.next = cur;
}
/*
* Set the cursor to the next item, because when we look
* up the cursor the current item may have been freed.
*/
STATIC void
xfs_trans_ail_cursor_set(
struct xfs_ail *ailp,
struct xfs_ail_cursor *cur,
struct xfs_log_item *lip)
{
if (lip)
cur->item = xfs_ail_next(ailp, lip);
}
/*
* Get the next item in the traversal and advance the cursor.
* If the cursor was invalidated (inidicated by a lip of 1),
* restart the traversal.
*/
struct xfs_log_item *
xfs_trans_ail_cursor_next(
struct xfs_ail *ailp,
struct xfs_ail_cursor *cur)
{
struct xfs_log_item *lip = cur->item;
if ((__psint_t)lip & 1)
lip = xfs_ail_min(ailp);
xfs_trans_ail_cursor_set(ailp, cur, lip);
return lip;
}
/*
* Now that the traversal is complete, we need to remove the cursor
* from the list of traversing cursors. Avoid removing the embedded
* push cursor, but use the fact it is always present to make the
* list deletion simple.
*/
void
xfs_trans_ail_cursor_done(
struct xfs_ail *ailp,
struct xfs_ail_cursor *done)
{
struct xfs_ail_cursor *prev = NULL;
struct xfs_ail_cursor *cur;
done->item = NULL;
if (done == &ailp->xa_cursors)
return;
prev = &ailp->xa_cursors;
for (cur = prev->next; cur; prev = cur, cur = prev->next) {
if (cur == done) {
prev->next = cur->next;
break;
}
}
ASSERT(cur);
}
/*
* Invalidate any cursor that is pointing to this item. This is
* called when an item is removed from the AIL. Any cursor pointing
* to this object is now invalid and the traversal needs to be
* terminated so it doesn't reference a freed object. We set the
* cursor item to a value of 1 so we can distinguish between an
* invalidation and the end of the list when getting the next item
* from the cursor.
*/
STATIC void
xfs_trans_ail_cursor_clear(
struct xfs_ail *ailp,
struct xfs_log_item *lip)
{
struct xfs_ail_cursor *cur;
/* need to search all cursors */
for (cur = &ailp->xa_cursors; cur; cur = cur->next) {
if (cur->item == lip)
cur->item = (struct xfs_log_item *)
((__psint_t)cur->item | 1);
}
}
/*
* Initialise the cursor to the first item in the AIL with the given @lsn.
* This searches the list from lowest LSN to highest. Pass a @lsn of zero
* to initialise the cursor to the first item in the AIL.
*/
xfs_log_item_t *
xfs_trans_ail_cursor_first(
struct xfs_ail *ailp,
struct xfs_ail_cursor *cur,
xfs_lsn_t lsn)
{
xfs_log_item_t *lip;
xfs_trans_ail_cursor_init(ailp, cur);
lip = xfs_ail_min(ailp);
if (lsn == 0)
goto out;
list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
goto out;
}
lip = NULL;
out:
xfs_trans_ail_cursor_set(ailp, cur, lip);
return lip;
}
/*
* Initialise the cursor to the last item in the AIL with the given @lsn.
* This searches the list from highest LSN to lowest. If there is no item with
* the value of @lsn, then it sets the cursor to the last item with an LSN lower
* than @lsn.
*/
static struct xfs_log_item *
__xfs_trans_ail_cursor_last(
struct xfs_ail *ailp,
xfs_lsn_t lsn)
{
xfs_log_item_t *lip;
list_for_each_entry_reverse(lip, &ailp->xa_ail, li_ail) {
if (XFS_LSN_CMP(lip->li_lsn, lsn) <= 0)
return lip;
}
return NULL;
}
/*
* Initialise the cursor to the last item in the AIL with the given @lsn.
* This searches the list from highest LSN to lowest.
*/
struct xfs_log_item *
xfs_trans_ail_cursor_last(
struct xfs_ail *ailp,
struct xfs_ail_cursor *cur,
xfs_lsn_t lsn)
{
xfs_trans_ail_cursor_init(ailp, cur);
cur->item = __xfs_trans_ail_cursor_last(ailp, lsn);
return cur->item;
}
/*
* splice the log item list into the AIL at the given LSN. We splice to the
* tail of the given LSN to maintain insert order for push traversals. The
* cursor is optional, allowing repeated updates to the same LSN to avoid
* repeated traversals.
*/
static void
xfs_ail_splice(
struct xfs_ail *ailp,
struct xfs_ail_cursor *cur,
struct list_head *list,
xfs_lsn_t lsn)
{
struct xfs_log_item *lip = cur ? cur->item : NULL;
struct xfs_log_item *next_lip;
/*
* Get a new cursor if we don't have a placeholder or the existing one
* has been invalidated.
*/
if (!lip || (__psint_t)lip & 1) {
lip = __xfs_trans_ail_cursor_last(ailp, lsn);
if (!lip) {
/* The list is empty, so just splice and return. */
if (cur)
cur->item = NULL;
list_splice(list, &ailp->xa_ail);
return;
}
}
/*
* Our cursor points to the item we want to insert _after_, so we have
* to update the cursor to point to the end of the list we are splicing
* in so that it points to the correct location for the next splice.
* i.e. before the splice
*
* lsn -> lsn -> lsn + x -> lsn + x ...
* ^
* | cursor points here
*
* After the splice we have:
*
* lsn -> lsn -> lsn -> lsn -> .... -> lsn -> lsn + x -> lsn + x ...
* ^ ^
* | cursor points here | needs to move here
*
* So we set the cursor to the last item in the list to be spliced
* before we execute the splice, resulting in the cursor pointing to
* the correct item after the splice occurs.
*/
if (cur) {
next_lip = list_entry(list->prev, struct xfs_log_item, li_ail);
cur->item = next_lip;
}
list_splice(list, &lip->li_ail);
}
/*
* Delete the given item from the AIL. Return a pointer to the item.
*/
static void
xfs_ail_delete(
struct xfs_ail *ailp,
xfs_log_item_t *lip)
{
xfs_ail_check(ailp, lip);
list_del(&lip->li_ail);
xfs_trans_ail_cursor_clear(ailp, lip);
}
static long
xfsaild_push(
struct xfs_ail *ailp)
{
xfs_mount_t *mp = ailp->xa_mount;
struct xfs_ail_cursor *cur = &ailp->xa_cursors;
xfs_log_item_t *lip;
xfs_lsn_t lsn;
xfs_lsn_t target;
long tout = 10;
int flush_log = 0;
int stuck = 0;
int count = 0;
int push_xfsbufd = 0;
spin_lock(&ailp->xa_lock);
target = ailp->xa_target;
xfs_trans_ail_cursor_init(ailp, cur);
lip = xfs_trans_ail_cursor_first(ailp, cur, ailp->xa_last_pushed_lsn);
if (!lip || XFS_FORCED_SHUTDOWN(mp)) {
/*
* AIL is empty or our push has reached the end.
*/
xfs_trans_ail_cursor_done(ailp, cur);
spin_unlock(&ailp->xa_lock);
goto out_done;
}
XFS_STATS_INC(xs_push_ail);
/*
* While the item we are looking at is below the given threshold
* try to flush it out. We'd like not to stop until we've at least
* tried to push on everything in the AIL with an LSN less than
* the given threshold.
*
* However, we will stop after a certain number of pushes and wait
* for a reduced timeout to fire before pushing further. This
* prevents use from spinning when we can't do anything or there is
* lots of contention on the AIL lists.
*/
lsn = lip->li_lsn;
while ((XFS_LSN_CMP(lip->li_lsn, target) <= 0)) {
int lock_result;
/*
* If we can lock the item without sleeping, unlock the AIL
* lock and flush the item. Then re-grab the AIL lock so we
* can look for the next item on the AIL. List changes are
* handled by the AIL lookup functions internally
*
* If we can't lock the item, either its holder will flush it
* or it is already being flushed or it is being relogged. In
* any of these case it is being taken care of and we can just
* skip to the next item in the list.
*/
lock_result = IOP_TRYLOCK(lip);
spin_unlock(&ailp->xa_lock);
switch (lock_result) {
case XFS_ITEM_SUCCESS:
XFS_STATS_INC(xs_push_ail_success);
IOP_PUSH(lip);
ailp->xa_last_pushed_lsn = lsn;
break;
case XFS_ITEM_PUSHBUF:
XFS_STATS_INC(xs_push_ail_pushbuf);
if (!IOP_PUSHBUF(lip)) {
stuck++;
flush_log = 1;
} else {
ailp->xa_last_pushed_lsn = lsn;
}
push_xfsbufd = 1;
break;
case XFS_ITEM_PINNED:
XFS_STATS_INC(xs_push_ail_pinned);
stuck++;
flush_log = 1;
break;
case XFS_ITEM_LOCKED:
XFS_STATS_INC(xs_push_ail_locked);
stuck++;
break;
default:
ASSERT(0);
break;
}
spin_lock(&ailp->xa_lock);
/* should we bother continuing? */
if (XFS_FORCED_SHUTDOWN(mp))
break;
ASSERT(mp->m_log);
count++;
/*
* Are there too many items we can't do anything with?
* If we we are skipping too many items because we can't flush
* them or they are already being flushed, we back off and
* given them time to complete whatever operation is being
* done. i.e. remove pressure from the AIL while we can't make
* progress so traversals don't slow down further inserts and
* removals to/from the AIL.
*
* The value of 100 is an arbitrary magic number based on
* observation.
*/
if (stuck > 100)
break;
lip = xfs_trans_ail_cursor_next(ailp, cur);
if (lip == NULL)
break;
lsn = lip->li_lsn;
}
xfs_trans_ail_cursor_done(ailp, cur);
spin_unlock(&ailp->xa_lock);
if (flush_log) {
/*
* If something we need to push out was pinned, then
* push out the log so it will become unpinned and
* move forward in the AIL.
*/
XFS_STATS_INC(xs_push_ail_flush);
xfs_log_force(mp, 0);
}
if (push_xfsbufd) {
/* we've got delayed write buffers to flush */
wake_up_process(mp->m_ddev_targp->bt_task);
}
/* assume we have more work to do in a short while */
out_done:
if (!count) {
/* We're past our target or empty, so idle */
ailp->xa_last_pushed_lsn = 0;
tout = 50;
} else if (XFS_LSN_CMP(lsn, target) >= 0) {
/*
* We reached the target so wait a bit longer for I/O to
* complete and remove pushed items from the AIL before we
* start the next scan from the start of the AIL.
*/
tout = 50;
ailp->xa_last_pushed_lsn = 0;
} else if ((stuck * 100) / count > 90) {
/*
* Either there is a lot of contention on the AIL or we
* are stuck due to operations in progress. "Stuck" in this
* case is defined as >90% of the items we tried to push
* were stuck.
*
* Backoff a bit more to allow some I/O to complete before
* continuing from where we were.
*/
tout = 20;
}
return tout;
}
static int
xfsaild(
void *data)
{
struct xfs_ail *ailp = data;
long tout = 0; /* milliseconds */
while (!kthread_should_stop()) {
if (tout && tout <= 20)
__set_current_state(TASK_KILLABLE);
else
__set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(tout ?
msecs_to_jiffies(tout) : MAX_SCHEDULE_TIMEOUT);
try_to_freeze();
tout = xfsaild_push(ailp);
}
return 0;
}
/*
* This routine is called to move the tail of the AIL forward. It does this by
* trying to flush items in the AIL whose lsns are below the given
* threshold_lsn.
*
* The push is run asynchronously in a workqueue, which means the caller needs
* to handle waiting on the async flush for space to become available.
* We don't want to interrupt any push that is in progress, hence we only queue
* work if we set the pushing bit approriately.
*
* We do this unlocked - we only need to know whether there is anything in the
* AIL at the time we are called. We don't need to access the contents of
* any of the objects, so the lock is not needed.
*/
void
xfs_ail_push(
struct xfs_ail *ailp,
xfs_lsn_t threshold_lsn)
{
xfs_log_item_t *lip;
lip = xfs_ail_min(ailp);
if (!lip || XFS_FORCED_SHUTDOWN(ailp->xa_mount) ||
XFS_LSN_CMP(threshold_lsn, ailp->xa_target) <= 0)
return;
/*
* Ensure that the new target is noticed in push code before it clears
* the XFS_AIL_PUSHING_BIT.
*/
smp_wmb();
xfs_trans_ail_copy_lsn(ailp, &ailp->xa_target, &threshold_lsn);
smp_wmb();
wake_up_process(ailp->xa_task);
}
/*
* Push out all items in the AIL immediately
*/
void
xfs_ail_push_all(
struct xfs_ail *ailp)
{
xfs_lsn_t threshold_lsn = xfs_ail_max_lsn(ailp);
if (threshold_lsn)
xfs_ail_push(ailp, threshold_lsn);
}
/*
* This is to be called when an item is unlocked that may have
* been in the AIL. It will wake up the first member of the AIL
* wait list if this item's unlocking might allow it to progress.
* If the item is in the AIL, then we need to get the AIL lock
* while doing our checking so we don't race with someone going
* to sleep waiting for this event in xfs_trans_push_ail().
*/
void
xfs_trans_unlocked_item(
struct xfs_ail *ailp,
xfs_log_item_t *lip)
{
xfs_log_item_t *min_lip;
/*
* If we're forcibly shutting down, we may have
* unlocked log items arbitrarily. The last thing
* we want to do is to move the tail of the log
* over some potentially valid data.
*/
if (!(lip->li_flags & XFS_LI_IN_AIL) ||
XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
return;
}
/*
* This is the one case where we can call into xfs_ail_min()
* without holding the AIL lock because we only care about the
* case where we are at the tail of the AIL. If the object isn't
* at the tail, it doesn't matter what result we get back. This
* is slightly racy because since we were just unlocked, we could
* go to sleep between the call to xfs_ail_min and the call to
* xfs_log_move_tail, have someone else lock us, commit to us disk,
* move us out of the tail of the AIL, and then we wake up. However,
* the call to xfs_log_move_tail() doesn't do anything if there's
* not enough free space to wake people up so we're safe calling it.
*/
min_lip = xfs_ail_min(ailp);
if (min_lip == lip)
xfs_log_move_tail(ailp->xa_mount, 1);
} /* xfs_trans_unlocked_item */
/*
* xfs_trans_ail_update - bulk AIL insertion operation.
*
* @xfs_trans_ail_update takes an array of log items that all need to be
* positioned at the same LSN in the AIL. If an item is not in the AIL, it will
* be added. Otherwise, it will be repositioned by removing it and re-adding
* it to the AIL. If we move the first item in the AIL, update the log tail to
* match the new minimum LSN in the AIL.
*
* This function takes the AIL lock once to execute the update operations on
* all the items in the array, and as such should not be called with the AIL
* lock held. As a result, once we have the AIL lock, we need to check each log
* item LSN to confirm it needs to be moved forward in the AIL.
*
* To optimise the insert operation, we delete all the items from the AIL in
* the first pass, moving them into a temporary list, then splice the temporary
* list into the correct position in the AIL. This avoids needing to do an
* insert operation on every item.
*
* This function must be called with the AIL lock held. The lock is dropped
* before returning.
*/
void
xfs_trans_ail_update_bulk(
struct xfs_ail *ailp,
struct xfs_ail_cursor *cur,
struct xfs_log_item **log_items,
int nr_items,
xfs_lsn_t lsn) __releases(ailp->xa_lock)
{
xfs_log_item_t *mlip;
xfs_lsn_t tail_lsn;
int mlip_changed = 0;
int i;
LIST_HEAD(tmp);
mlip = xfs_ail_min(ailp);
for (i = 0; i < nr_items; i++) {
struct xfs_log_item *lip = log_items[i];
if (lip->li_flags & XFS_LI_IN_AIL) {
/* check if we really need to move the item */
if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)
continue;
xfs_ail_delete(ailp, lip);
if (mlip == lip)
mlip_changed = 1;
} else {
lip->li_flags |= XFS_LI_IN_AIL;
}
lip->li_lsn = lsn;
list_add(&lip->li_ail, &tmp);
}
xfs_ail_splice(ailp, cur, &tmp, lsn);
if (!mlip_changed) {
spin_unlock(&ailp->xa_lock);
return;
}
/*
* It is not safe to access mlip after the AIL lock is dropped, so we
* must get a copy of li_lsn before we do so. This is especially
* important on 32-bit platforms where accessing and updating 64-bit
* values like li_lsn is not atomic.
*/
mlip = xfs_ail_min(ailp);
tail_lsn = mlip->li_lsn;
spin_unlock(&ailp->xa_lock);
xfs_log_move_tail(ailp->xa_mount, tail_lsn);
}
/*
* xfs_trans_ail_delete_bulk - remove multiple log items from the AIL
*
* @xfs_trans_ail_delete_bulk takes an array of log items that all need to
* removed from the AIL. The caller is already holding the AIL lock, and done
* all the checks necessary to ensure the items passed in via @log_items are
* ready for deletion. This includes checking that the items are in the AIL.
*
* For each log item to be removed, unlink it from the AIL, clear the IN_AIL
* flag from the item and reset the item's lsn to 0. If we remove the first
* item in the AIL, update the log tail to match the new minimum LSN in the
* AIL.
*
* This function will not drop the AIL lock until all items are removed from
* the AIL to minimise the amount of lock traffic on the AIL. This does not
* greatly increase the AIL hold time, but does significantly reduce the amount
* of traffic on the lock, especially during IO completion.
*
* This function must be called with the AIL lock held. The lock is dropped
* before returning.
*/
void
xfs_trans_ail_delete_bulk(
struct xfs_ail *ailp,
struct xfs_log_item **log_items,
int nr_items) __releases(ailp->xa_lock)
{
xfs_log_item_t *mlip;
xfs_lsn_t tail_lsn;
int mlip_changed = 0;
int i;
mlip = xfs_ail_min(ailp);
for (i = 0; i < nr_items; i++) {
struct xfs_log_item *lip = log_items[i];
if (!(lip->li_flags & XFS_LI_IN_AIL)) {
struct xfs_mount *mp = ailp->xa_mount;
spin_unlock(&ailp->xa_lock);
if (!XFS_FORCED_SHUTDOWN(mp)) {
xfs_alert_tag(mp, XFS_PTAG_AILDELETE,
"%s: attempting to delete a log item that is not in the AIL",
__func__);
xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
}
return;
}
xfs_ail_delete(ailp, lip);
lip->li_flags &= ~XFS_LI_IN_AIL;
lip->li_lsn = 0;
if (mlip == lip)
mlip_changed = 1;
}
if (!mlip_changed) {
spin_unlock(&ailp->xa_lock);
return;
}
/*
* It is not safe to access mlip after the AIL lock is dropped, so we
* must get a copy of li_lsn before we do so. This is especially
* important on 32-bit platforms where accessing and updating 64-bit
* values like li_lsn is not atomic. It is possible we've emptied the
* AIL here, so if that is the case, pass an LSN of 0 to the tail move.
*/
mlip = xfs_ail_min(ailp);
tail_lsn = mlip ? mlip->li_lsn : 0;
spin_unlock(&ailp->xa_lock);
xfs_log_move_tail(ailp->xa_mount, tail_lsn);
}
/*
* The active item list (AIL) is a doubly linked list of log
* items sorted by ascending lsn. The base of the list is
* a forw/back pointer pair embedded in the xfs mount structure.
* The base is initialized with both pointers pointing to the
* base. This case always needs to be distinguished, because
* the base has no lsn to look at. We almost always insert
* at the end of the list, so on inserts we search from the
* end of the list to find where the new item belongs.
*/
/*
* Initialize the doubly linked list to point only to itself.
*/
int
xfs_trans_ail_init(
xfs_mount_t *mp)
{
struct xfs_ail *ailp;
ailp = kmem_zalloc(sizeof(struct xfs_ail), KM_MAYFAIL);
if (!ailp)
return ENOMEM;
ailp->xa_mount = mp;
INIT_LIST_HEAD(&ailp->xa_ail);
spin_lock_init(&ailp->xa_lock);
ailp->xa_task = kthread_run(xfsaild, ailp, "xfsaild/%s",
ailp->xa_mount->m_fsname);
if (IS_ERR(ailp->xa_task))
goto out_free_ailp;
mp->m_ail = ailp;
return 0;
out_free_ailp:
kmem_free(ailp);
return ENOMEM;
}
void
xfs_trans_ail_destroy(
xfs_mount_t *mp)
{
struct xfs_ail *ailp = mp->m_ail;
kthread_stop(ailp->xa_task);
kmem_free(ailp);
}