shmem_file_write is redundant

[wrt350n-kernel.git] / fs / xfs / xfs_trans_item.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"

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;
                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;
        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, sizeof(xfs_log_item_chunk_t));
                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,
        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, NULLCOMMITLSN);
                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, NULLCOMMITLSN);
                next_licp = licp->lic_next;
                kmem_free(licp, sizeof(xfs_log_item_chunk_t));
                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, sizeof(xfs_log_item_chunk_t));
                        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;
}


/*
 * This is called to add the given busy item to the transaction's
 * list of busy items.  It must find a free busy item descriptor
 * or allocate a new one and add the item to that descriptor.
 * The function returns a pointer to busy descriptor used to point
 * to the new busy entry.  The log busy entry will now point to its new
 * descriptor with its ???? field.
 */
xfs_log_busy_slot_t *
xfs_trans_add_busy(xfs_trans_t *tp, xfs_agnumber_t ag, xfs_extlen_t idx)
{
        xfs_log_busy_chunk_t    *lbcp;
        xfs_log_busy_slot_t     *lbsp;
        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_busy_free == 0) {
                lbcp = (xfs_log_busy_chunk_t*)
                       kmem_alloc(sizeof(xfs_log_busy_chunk_t), KM_SLEEP);
                ASSERT(lbcp != NULL);
                /*
                 * Initialize the chunk, and then
                 * claim the first slot in the newly allocated chunk.
                 */
                XFS_LBC_INIT(lbcp);
                XFS_LBC_CLAIM(lbcp, 0);
                lbcp->lbc_unused = 1;
                lbsp = XFS_LBC_SLOT(lbcp, 0);

                /*
                 * Link in the new chunk and update the free count.
                 */
                lbcp->lbc_next = tp->t_busy.lbc_next;
                tp->t_busy.lbc_next = lbcp;
                tp->t_busy_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.
                 */
                lbsp->lbc_ag = ag;
                lbsp->lbc_idx = idx;
                return lbsp;
        }

        /*
         * Find the free descriptor. It is somewhere in the chunklist
         * of descriptors.
         */
        lbcp = &tp->t_busy;
        while (lbcp != NULL) {
                if (XFS_LBC_VACANCY(lbcp)) {
                        if (lbcp->lbc_unused <= XFS_LBC_MAX_SLOT) {
                                i = lbcp->lbc_unused;
                                break;
                        } else {
                                /* out-of-order vacancy */
                                cmn_err(CE_DEBUG, "OOO vacancy lbcp 0x%p\n", lbcp);
                                ASSERT(0);
                        }
                }
                lbcp = lbcp->lbc_next;
        }
        ASSERT(lbcp != NULL);
        /*
         * If we find a free descriptor, claim it,
         * initialize it, and return it.
         */
        XFS_LBC_CLAIM(lbcp, i);
        if (lbcp->lbc_unused <= i) {
                lbcp->lbc_unused = i + 1;
        }
        lbsp = XFS_LBC_SLOT(lbcp, i);
        tp->t_busy_free--;
        lbsp->lbc_ag = ag;
        lbsp->lbc_idx = idx;
        return lbsp;
}


/*
 * xfs_trans_free_busy
 * Free all of the busy lists from a transaction
 */
void
xfs_trans_free_busy(xfs_trans_t *tp)
{
        xfs_log_busy_chunk_t    *lbcp;
        xfs_log_busy_chunk_t    *lbcq;

        lbcp = tp->t_busy.lbc_next;
        while (lbcp != NULL) {
                lbcq = lbcp->lbc_next;
                kmem_free(lbcp, sizeof(xfs_log_busy_chunk_t));
                lbcp = lbcq;
        }

        XFS_LBC_INIT(&tp->t_busy);
        tp->t_busy.lbc_unused = 0;
}