linux/fs/xfs/xfs_trans_item.c
Dave Chinner 71e330b593 xfs: Introduce delayed logging core code
The delayed logging code only changes in-memory structures and as
such can be enabled and disabled with a mount option. Add the mount
option and emit a warning that this is an experimental feature that
should not be used in production yet.

We also need infrastructure to track committed items that have not
yet been written to the log. This is what the Committed Item List
(CIL) is for.

The log item also needs to be extended to track the current log
vector, the associated memory buffer and it's location in the Commit
Item List. Extend the log item and log vector structures to enable
this tracking.

To maintain the current log format for transactions with delayed
logging, we need to introduce a checkpoint transaction and a context
for tracking each checkpoint from initiation to transaction
completion.  This includes adding a log ticket for tracking space
log required/used by the context checkpoint.

To track all the changes we need an io vector array per log item,
rather than a single array for the entire transaction. Using the new
log vector structure for this requires two passes - the first to
allocate the log vector structures and chain them together, and the
second to fill them out.  This log vector chain can then be passed
to the CIL for formatting, pinning and insertion into the CIL.

Formatting of the log vector chain is relatively simple - it's just
a loop over the iovecs on each log vector, but it is made slightly
more complex because we re-write the iovec after the copy to point
back at the memory buffer we just copied into.

This code also needs to pin log items. If the log item is not
already tracked in this checkpoint context, then it needs to be
pinned. Otherwise it is already pinned and we don't need to pin it
again.

The only other complexity is calculating the amount of new log space
the formatting has consumed. This needs to be accounted to the
transaction in progress, and the accounting is made more complex
becase we need also to steal space from it for log metadata in the
checkpoint transaction. Calculate all this at insert time and update
all the tickets, counters, etc correctly.

Once we've formatted all the log items in the transaction, attach
the busy extents to the checkpoint context so the busy extents live
until checkpoint completion and can be processed at that point in
time. Transactions can then be freed at this point in time.

Now we need to issue checkpoints - we are tracking the amount of log space
used by the items in the CIL, so we can trigger background checkpoints when the
space usage gets to a certain threshold. Otherwise, checkpoints need ot be
triggered when a log synchronisation point is reached - a log force event.

Because the log write code already handles chained log vectors, writing the
transaction is trivial, too. Construct a transaction header, add it
to the head of the chain and write it into the log, then issue a
commit record write. Then we can release the checkpoint log ticket
and attach the context to the log buffer so it can be called during
Io completion to complete the checkpoint.

We also need to allow for synchronising multiple in-flight
checkpoints. This is needed for two things - the first is to ensure
that checkpoint commit records appear in the log in the correct
sequence order (so they are replayed in the correct order). The
second is so that xfs_log_force_lsn() operates correctly and only
flushes and/or waits for the specific sequence it was provided with.

To do this we need a wait variable and a list tracking the
checkpoint commits in progress. We can walk this list and wait for
the checkpoints to change state or complete easily, an this provides
the necessary synchronisation for correct operation in both cases.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
2010-05-24 10:38:03 -05:00

442 lines
11 KiB
C

/*
* Copyright (c) 2000-2002,2005 Silicon Graphics, 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_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
/* XXX: from here down needed until struct xfs_trans has its own ailp */
#include "xfs_bit.h"
#include "xfs_buf_item.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
STATIC int xfs_trans_unlock_chunk(xfs_log_item_chunk_t *,
int, int, xfs_lsn_t);
/*
* This is called to add the given log item to the transaction's
* list of log items. It must find a free log item descriptor
* or allocate a new one and add the item to that descriptor.
* The function returns a pointer to item descriptor used to point
* to the new item. The log item will now point to its new descriptor
* with its li_desc field.
*/
xfs_log_item_desc_t *
xfs_trans_add_item(xfs_trans_t *tp, xfs_log_item_t *lip)
{
xfs_log_item_desc_t *lidp;
xfs_log_item_chunk_t *licp;
int i=0;
/*
* If there are no free descriptors, allocate a new chunk
* of them and put it at the front of the chunk list.
*/
if (tp->t_items_free == 0) {
licp = (xfs_log_item_chunk_t*)
kmem_alloc(sizeof(xfs_log_item_chunk_t), KM_SLEEP);
ASSERT(licp != NULL);
/*
* Initialize the chunk, and then
* claim the first slot in the newly allocated chunk.
*/
xfs_lic_init(licp);
xfs_lic_claim(licp, 0);
licp->lic_unused = 1;
xfs_lic_init_slot(licp, 0);
lidp = xfs_lic_slot(licp, 0);
/*
* Link in the new chunk and update the free count.
*/
licp->lic_next = tp->t_items.lic_next;
tp->t_items.lic_next = licp;
tp->t_items_free = XFS_LIC_NUM_SLOTS - 1;
/*
* Initialize the descriptor and the generic portion
* of the log item.
*
* Point the new slot at this item and return it.
* Also point the log item at its currently active
* descriptor and set the item's mount pointer.
*/
lidp->lid_item = lip;
lidp->lid_flags = 0;
lidp->lid_size = 0;
lip->li_desc = lidp;
lip->li_mountp = tp->t_mountp;
lip->li_ailp = tp->t_mountp->m_ail;
return lidp;
}
/*
* Find the free descriptor. It is somewhere in the chunklist
* of descriptors.
*/
licp = &tp->t_items;
while (licp != NULL) {
if (xfs_lic_vacancy(licp)) {
if (licp->lic_unused <= XFS_LIC_MAX_SLOT) {
i = licp->lic_unused;
ASSERT(xfs_lic_isfree(licp, i));
break;
}
for (i = 0; i <= XFS_LIC_MAX_SLOT; i++) {
if (xfs_lic_isfree(licp, i))
break;
}
ASSERT(i <= XFS_LIC_MAX_SLOT);
break;
}
licp = licp->lic_next;
}
ASSERT(licp != NULL);
/*
* If we find a free descriptor, claim it,
* initialize it, and return it.
*/
xfs_lic_claim(licp, i);
if (licp->lic_unused <= i) {
licp->lic_unused = i + 1;
xfs_lic_init_slot(licp, i);
}
lidp = xfs_lic_slot(licp, i);
tp->t_items_free--;
lidp->lid_item = lip;
lidp->lid_flags = 0;
lidp->lid_size = 0;
lip->li_desc = lidp;
lip->li_mountp = tp->t_mountp;
lip->li_ailp = tp->t_mountp->m_ail;
return lidp;
}
/*
* Free the given descriptor.
*
* This requires setting the bit in the chunk's free mask corresponding
* to the given slot.
*/
void
xfs_trans_free_item(xfs_trans_t *tp, xfs_log_item_desc_t *lidp)
{
uint slot;
xfs_log_item_chunk_t *licp;
xfs_log_item_chunk_t **licpp;
slot = xfs_lic_desc_to_slot(lidp);
licp = xfs_lic_desc_to_chunk(lidp);
xfs_lic_relse(licp, slot);
lidp->lid_item->li_desc = NULL;
tp->t_items_free++;
/*
* If there are no more used items in the chunk and this is not
* the chunk embedded in the transaction structure, then free
* the chunk. First pull it from the chunk list and then
* free it back to the heap. We didn't bother with a doubly
* linked list here because the lists should be very short
* and this is not a performance path. It's better to save
* the memory of the extra pointer.
*
* Also decrement the transaction structure's count of free items
* by the number in a chunk since we are freeing an empty chunk.
*/
if (xfs_lic_are_all_free(licp) && (licp != &(tp->t_items))) {
licpp = &(tp->t_items.lic_next);
while (*licpp != licp) {
ASSERT(*licpp != NULL);
licpp = &((*licpp)->lic_next);
}
*licpp = licp->lic_next;
kmem_free(licp);
tp->t_items_free -= XFS_LIC_NUM_SLOTS;
}
}
/*
* This is called to find the descriptor corresponding to the given
* log item. It returns a pointer to the descriptor.
* The log item MUST have a corresponding descriptor in the given
* transaction. This routine does not return NULL, it panics.
*
* The descriptor pointer is kept in the log item's li_desc field.
* Just return it.
*/
/*ARGSUSED*/
xfs_log_item_desc_t *
xfs_trans_find_item(xfs_trans_t *tp, xfs_log_item_t *lip)
{
ASSERT(lip->li_desc != NULL);
return lip->li_desc;
}
/*
* Return a pointer to the first descriptor in the chunk list.
* This does not return NULL if there are none, it panics.
*
* The first descriptor must be in either the first or second chunk.
* This is because the only chunk allowed to be empty is the first.
* All others are freed when they become empty.
*
* At some point this and xfs_trans_next_item() should be optimized
* to quickly look at the mask to determine if there is anything to
* look at.
*/
xfs_log_item_desc_t *
xfs_trans_first_item(xfs_trans_t *tp)
{
xfs_log_item_chunk_t *licp;
int i;
licp = &tp->t_items;
/*
* If it's not in the first chunk, skip to the second.
*/
if (xfs_lic_are_all_free(licp)) {
licp = licp->lic_next;
}
/*
* Return the first non-free descriptor in the chunk.
*/
ASSERT(!xfs_lic_are_all_free(licp));
for (i = 0; i < licp->lic_unused; i++) {
if (xfs_lic_isfree(licp, i)) {
continue;
}
return xfs_lic_slot(licp, i);
}
cmn_err(CE_WARN, "xfs_trans_first_item() -- no first item");
return NULL;
}
/*
* Given a descriptor, return the next descriptor in the chunk list.
* This returns NULL if there are no more used descriptors in the list.
*
* We do this by first locating the chunk in which the descriptor resides,
* and then scanning forward in the chunk and the list for the next
* used descriptor.
*/
/*ARGSUSED*/
xfs_log_item_desc_t *
xfs_trans_next_item(xfs_trans_t *tp, xfs_log_item_desc_t *lidp)
{
xfs_log_item_chunk_t *licp;
int i;
licp = xfs_lic_desc_to_chunk(lidp);
/*
* First search the rest of the chunk. The for loop keeps us
* from referencing things beyond the end of the chunk.
*/
for (i = (int)xfs_lic_desc_to_slot(lidp) + 1; i < licp->lic_unused; i++) {
if (xfs_lic_isfree(licp, i)) {
continue;
}
return xfs_lic_slot(licp, i);
}
/*
* Now search the next chunk. It must be there, because the
* next chunk would have been freed if it were empty.
* If there is no next chunk, return NULL.
*/
if (licp->lic_next == NULL) {
return NULL;
}
licp = licp->lic_next;
ASSERT(!xfs_lic_are_all_free(licp));
for (i = 0; i < licp->lic_unused; i++) {
if (xfs_lic_isfree(licp, i)) {
continue;
}
return xfs_lic_slot(licp, i);
}
ASSERT(0);
/* NOTREACHED */
return NULL; /* keep gcc quite */
}
/*
* This is called to unlock all of the items of a transaction and to free
* all the descriptors of that transaction.
*
* It walks the list of descriptors and unlocks each item. It frees
* each chunk except that embedded in the transaction as it goes along.
*/
void
xfs_trans_free_items(
xfs_trans_t *tp,
xfs_lsn_t commit_lsn,
int flags)
{
xfs_log_item_chunk_t *licp;
xfs_log_item_chunk_t *next_licp;
int abort;
abort = flags & XFS_TRANS_ABORT;
licp = &tp->t_items;
/*
* Special case the embedded chunk so we don't free it below.
*/
if (!xfs_lic_are_all_free(licp)) {
(void) xfs_trans_unlock_chunk(licp, 1, abort, commit_lsn);
xfs_lic_all_free(licp);
licp->lic_unused = 0;
}
licp = licp->lic_next;
/*
* Unlock each item in each chunk and free the chunks.
*/
while (licp != NULL) {
ASSERT(!xfs_lic_are_all_free(licp));
(void) xfs_trans_unlock_chunk(licp, 1, abort, commit_lsn);
next_licp = licp->lic_next;
kmem_free(licp);
licp = next_licp;
}
/*
* Reset the transaction structure's free item count.
*/
tp->t_items_free = XFS_LIC_NUM_SLOTS;
tp->t_items.lic_next = NULL;
}
/*
* This is called to unlock the items associated with a transaction.
* Items which were not logged should be freed.
* Those which were logged must still be tracked so they can be unpinned
* when the transaction commits.
*/
void
xfs_trans_unlock_items(xfs_trans_t *tp, xfs_lsn_t commit_lsn)
{
xfs_log_item_chunk_t *licp;
xfs_log_item_chunk_t *next_licp;
xfs_log_item_chunk_t **licpp;
int freed;
freed = 0;
licp = &tp->t_items;
/*
* Special case the embedded chunk so we don't free.
*/
if (!xfs_lic_are_all_free(licp)) {
freed = xfs_trans_unlock_chunk(licp, 0, 0, commit_lsn);
}
licpp = &(tp->t_items.lic_next);
licp = licp->lic_next;
/*
* Unlock each item in each chunk, free non-dirty descriptors,
* and free empty chunks.
*/
while (licp != NULL) {
ASSERT(!xfs_lic_are_all_free(licp));
freed += xfs_trans_unlock_chunk(licp, 0, 0, commit_lsn);
next_licp = licp->lic_next;
if (xfs_lic_are_all_free(licp)) {
*licpp = next_licp;
kmem_free(licp);
freed -= XFS_LIC_NUM_SLOTS;
} else {
licpp = &(licp->lic_next);
}
ASSERT(*licpp == next_licp);
licp = next_licp;
}
/*
* Fix the free descriptor count in the transaction.
*/
tp->t_items_free += freed;
}
/*
* Unlock each item pointed to by a descriptor in the given chunk.
* Stamp the commit lsn into each item if necessary.
* Free descriptors pointing to items which are not dirty if freeing_chunk
* is zero. If freeing_chunk is non-zero, then we need to unlock all
* items in the chunk.
*
* Return the number of descriptors freed.
*/
STATIC int
xfs_trans_unlock_chunk(
xfs_log_item_chunk_t *licp,
int freeing_chunk,
int abort,
xfs_lsn_t commit_lsn)
{
xfs_log_item_desc_t *lidp;
xfs_log_item_t *lip;
int i;
int freed;
freed = 0;
lidp = licp->lic_descs;
for (i = 0; i < licp->lic_unused; i++, lidp++) {
if (xfs_lic_isfree(licp, i)) {
continue;
}
lip = lidp->lid_item;
lip->li_desc = NULL;
if (commit_lsn != NULLCOMMITLSN)
IOP_COMMITTING(lip, commit_lsn);
if (abort)
lip->li_flags |= XFS_LI_ABORTED;
IOP_UNLOCK(lip);
/*
* Free the descriptor if the item is not dirty
* within this transaction and the caller is not
* going to just free the entire thing regardless.
*/
if (!(freeing_chunk) &&
(!(lidp->lid_flags & XFS_LID_DIRTY) || abort)) {
xfs_lic_relse(licp, i);
freed++;
}
}
return freed;
}