diff options
Diffstat (limited to 'ANDROID_3.4.5/fs/xfs/xfs_log_cil.c')
| -rw-r--r-- | ANDROID_3.4.5/fs/xfs/xfs_log_cil.c | 828 |
1 files changed, 828 insertions, 0 deletions
diff --git a/ANDROID_3.4.5/fs/xfs/xfs_log_cil.c b/ANDROID_3.4.5/fs/xfs/xfs_log_cil.c new file mode 100644 index 00000000..d4fadbe8 --- /dev/null +++ b/ANDROID_3.4.5/fs/xfs/xfs_log_cil.c @@ -0,0 +1,828 @@ +/* + * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it would be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include "xfs.h" +#include "xfs_fs.h" +#include "xfs_types.h" +#include "xfs_bit.h" +#include "xfs_log.h" +#include "xfs_inum.h" +#include "xfs_trans.h" +#include "xfs_trans_priv.h" +#include "xfs_log_priv.h" +#include "xfs_sb.h" +#include "xfs_ag.h" +#include "xfs_mount.h" +#include "xfs_error.h" +#include "xfs_alloc.h" +#include "xfs_discard.h" + +/* + * Perform initial CIL structure initialisation. + */ +int +xlog_cil_init( + struct log *log) +{ + struct xfs_cil *cil; + struct xfs_cil_ctx *ctx; + + cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL); + if (!cil) + return ENOMEM; + + ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL); + if (!ctx) { + kmem_free(cil); + return ENOMEM; + } + + INIT_LIST_HEAD(&cil->xc_cil); + INIT_LIST_HEAD(&cil->xc_committing); + spin_lock_init(&cil->xc_cil_lock); + init_rwsem(&cil->xc_ctx_lock); + init_waitqueue_head(&cil->xc_commit_wait); + + INIT_LIST_HEAD(&ctx->committing); + INIT_LIST_HEAD(&ctx->busy_extents); + ctx->sequence = 1; + ctx->cil = cil; + cil->xc_ctx = ctx; + cil->xc_current_sequence = ctx->sequence; + + cil->xc_log = log; + log->l_cilp = cil; + return 0; +} + +void +xlog_cil_destroy( + struct log *log) +{ + if (log->l_cilp->xc_ctx) { + if (log->l_cilp->xc_ctx->ticket) + xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket); + kmem_free(log->l_cilp->xc_ctx); + } + + ASSERT(list_empty(&log->l_cilp->xc_cil)); + kmem_free(log->l_cilp); +} + +/* + * Allocate a new ticket. Failing to get a new ticket makes it really hard to + * recover, so we don't allow failure here. Also, we allocate in a context that + * we don't want to be issuing transactions from, so we need to tell the + * allocation code this as well. + * + * We don't reserve any space for the ticket - we are going to steal whatever + * space we require from transactions as they commit. To ensure we reserve all + * the space required, we need to set the current reservation of the ticket to + * zero so that we know to steal the initial transaction overhead from the + * first transaction commit. + */ +static struct xlog_ticket * +xlog_cil_ticket_alloc( + struct log *log) +{ + struct xlog_ticket *tic; + + tic = xlog_ticket_alloc(log, 0, 1, XFS_TRANSACTION, 0, + KM_SLEEP|KM_NOFS); + tic->t_trans_type = XFS_TRANS_CHECKPOINT; + + /* + * set the current reservation to zero so we know to steal the basic + * transaction overhead reservation from the first transaction commit. + */ + tic->t_curr_res = 0; + return tic; +} + +/* + * After the first stage of log recovery is done, we know where the head and + * tail of the log are. We need this log initialisation done before we can + * initialise the first CIL checkpoint context. + * + * Here we allocate a log ticket to track space usage during a CIL push. This + * ticket is passed to xlog_write() directly so that we don't slowly leak log + * space by failing to account for space used by log headers and additional + * region headers for split regions. + */ +void +xlog_cil_init_post_recovery( + struct log *log) +{ + log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log); + log->l_cilp->xc_ctx->sequence = 1; + log->l_cilp->xc_ctx->commit_lsn = xlog_assign_lsn(log->l_curr_cycle, + log->l_curr_block); +} + +/* + * Format log item into a flat buffers + * + * For delayed logging, we need to hold a formatted buffer containing all the + * changes on the log item. This enables us to relog the item in memory and + * write it out asynchronously without needing to relock the object that was + * modified at the time it gets written into the iclog. + * + * This function builds a vector for the changes in each log item in the + * transaction. It then works out the length of the buffer needed for each log + * item, allocates them and formats the vector for the item into the buffer. + * The buffer is then attached to the log item are then inserted into the + * Committed Item List for tracking until the next checkpoint is written out. + * + * We don't set up region headers during this process; we simply copy the + * regions into the flat buffer. We can do this because we still have to do a + * formatting step to write the regions into the iclog buffer. Writing the + * ophdrs during the iclog write means that we can support splitting large + * regions across iclog boundares without needing a change in the format of the + * item/region encapsulation. + * + * Hence what we need to do now is change the rewrite the vector array to point + * to the copied region inside the buffer we just allocated. This allows us to + * format the regions into the iclog as though they are being formatted + * directly out of the objects themselves. + */ +static struct xfs_log_vec * +xlog_cil_prepare_log_vecs( + struct xfs_trans *tp) +{ + struct xfs_log_item_desc *lidp; + struct xfs_log_vec *lv = NULL; + struct xfs_log_vec *ret_lv = NULL; + + + /* Bail out if we didn't find a log item. */ + if (list_empty(&tp->t_items)) { + ASSERT(0); + return NULL; + } + + list_for_each_entry(lidp, &tp->t_items, lid_trans) { + struct xfs_log_vec *new_lv; + void *ptr; + int index; + int len = 0; + uint niovecs; + + /* Skip items which aren't dirty in this transaction. */ + if (!(lidp->lid_flags & XFS_LID_DIRTY)) + continue; + + /* Skip items that do not have any vectors for writing */ + niovecs = IOP_SIZE(lidp->lid_item); + if (!niovecs) + continue; + + new_lv = kmem_zalloc(sizeof(*new_lv) + + niovecs * sizeof(struct xfs_log_iovec), + KM_SLEEP); + + /* The allocated iovec region lies beyond the log vector. */ + new_lv->lv_iovecp = (struct xfs_log_iovec *)&new_lv[1]; + new_lv->lv_niovecs = niovecs; + new_lv->lv_item = lidp->lid_item; + + /* build the vector array and calculate it's length */ + IOP_FORMAT(new_lv->lv_item, new_lv->lv_iovecp); + for (index = 0; index < new_lv->lv_niovecs; index++) + len += new_lv->lv_iovecp[index].i_len; + + new_lv->lv_buf_len = len; + new_lv->lv_buf = kmem_alloc(new_lv->lv_buf_len, + KM_SLEEP|KM_NOFS); + ptr = new_lv->lv_buf; + + for (index = 0; index < new_lv->lv_niovecs; index++) { + struct xfs_log_iovec *vec = &new_lv->lv_iovecp[index]; + + memcpy(ptr, vec->i_addr, vec->i_len); + vec->i_addr = ptr; + ptr += vec->i_len; + } + ASSERT(ptr == new_lv->lv_buf + new_lv->lv_buf_len); + + if (!ret_lv) + ret_lv = new_lv; + else + lv->lv_next = new_lv; + lv = new_lv; + } + + return ret_lv; +} + +/* + * Prepare the log item for insertion into the CIL. Calculate the difference in + * log space and vectors it will consume, and if it is a new item pin it as + * well. + */ +STATIC void +xfs_cil_prepare_item( + struct log *log, + struct xfs_log_vec *lv, + int *len, + int *diff_iovecs) +{ + struct xfs_log_vec *old = lv->lv_item->li_lv; + + if (old) { + /* existing lv on log item, space used is a delta */ + ASSERT(!list_empty(&lv->lv_item->li_cil)); + ASSERT(old->lv_buf && old->lv_buf_len && old->lv_niovecs); + + *len += lv->lv_buf_len - old->lv_buf_len; + *diff_iovecs += lv->lv_niovecs - old->lv_niovecs; + kmem_free(old->lv_buf); + kmem_free(old); + } else { + /* new lv, must pin the log item */ + ASSERT(!lv->lv_item->li_lv); + ASSERT(list_empty(&lv->lv_item->li_cil)); + + *len += lv->lv_buf_len; + *diff_iovecs += lv->lv_niovecs; + IOP_PIN(lv->lv_item); + + } + + /* attach new log vector to log item */ + lv->lv_item->li_lv = lv; + + /* + * If this is the first time the item is being committed to the + * CIL, store the sequence number on the log item so we can + * tell in future commits whether this is the first checkpoint + * the item is being committed into. + */ + if (!lv->lv_item->li_seq) + lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence; +} + +/* + * Insert the log items into the CIL and calculate the difference in space + * consumed by the item. Add the space to the checkpoint ticket and calculate + * if the change requires additional log metadata. If it does, take that space + * as well. Remove the amount of space we added to the checkpoint ticket from + * the current transaction ticket so that the accounting works out correctly. + */ +static void +xlog_cil_insert_items( + struct log *log, + struct xfs_log_vec *log_vector, + struct xlog_ticket *ticket) +{ + struct xfs_cil *cil = log->l_cilp; + struct xfs_cil_ctx *ctx = cil->xc_ctx; + struct xfs_log_vec *lv; + int len = 0; + int diff_iovecs = 0; + int iclog_space; + + ASSERT(log_vector); + + /* + * Do all the accounting aggregation and switching of log vectors + * around in a separate loop to the insertion of items into the CIL. + * Then we can do a separate loop to update the CIL within a single + * lock/unlock pair. This reduces the number of round trips on the CIL + * lock from O(nr_logvectors) to O(1) and greatly reduces the overall + * hold time for the transaction commit. + * + * If this is the first time the item is being placed into the CIL in + * this context, pin it so it can't be written to disk until the CIL is + * flushed to the iclog and the iclog written to disk. + * + * We can do this safely because the context can't checkpoint until we + * are done so it doesn't matter exactly how we update the CIL. + */ + for (lv = log_vector; lv; lv = lv->lv_next) + xfs_cil_prepare_item(log, lv, &len, &diff_iovecs); + + /* account for space used by new iovec headers */ + len += diff_iovecs * sizeof(xlog_op_header_t); + + spin_lock(&cil->xc_cil_lock); + + /* move the items to the tail of the CIL */ + for (lv = log_vector; lv; lv = lv->lv_next) + list_move_tail(&lv->lv_item->li_cil, &cil->xc_cil); + + ctx->nvecs += diff_iovecs; + + /* + * Now transfer enough transaction reservation to the context ticket + * for the checkpoint. The context ticket is special - the unit + * reservation has to grow as well as the current reservation as we + * steal from tickets so we can correctly determine the space used + * during the transaction commit. + */ + if (ctx->ticket->t_curr_res == 0) { + /* first commit in checkpoint, steal the header reservation */ + ASSERT(ticket->t_curr_res >= ctx->ticket->t_unit_res + len); + ctx->ticket->t_curr_res = ctx->ticket->t_unit_res; + ticket->t_curr_res -= ctx->ticket->t_unit_res; + } + + /* do we need space for more log record headers? */ + iclog_space = log->l_iclog_size - log->l_iclog_hsize; + if (len > 0 && (ctx->space_used / iclog_space != + (ctx->space_used + len) / iclog_space)) { + int hdrs; + + hdrs = (len + iclog_space - 1) / iclog_space; + /* need to take into account split region headers, too */ + hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header); + ctx->ticket->t_unit_res += hdrs; + ctx->ticket->t_curr_res += hdrs; + ticket->t_curr_res -= hdrs; + ASSERT(ticket->t_curr_res >= len); + } + ticket->t_curr_res -= len; + ctx->space_used += len; + + spin_unlock(&cil->xc_cil_lock); +} + +static void +xlog_cil_free_logvec( + struct xfs_log_vec *log_vector) +{ + struct xfs_log_vec *lv; + + for (lv = log_vector; lv; ) { + struct xfs_log_vec *next = lv->lv_next; + kmem_free(lv->lv_buf); + kmem_free(lv); + lv = next; + } +} + +/* + * Mark all items committed and clear busy extents. We free the log vector + * chains in a separate pass so that we unpin the log items as quickly as + * possible. + */ +static void +xlog_cil_committed( + void *args, + int abort) +{ + struct xfs_cil_ctx *ctx = args; + struct xfs_mount *mp = ctx->cil->xc_log->l_mp; + + xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain, + ctx->start_lsn, abort); + + xfs_alloc_busy_sort(&ctx->busy_extents); + xfs_alloc_busy_clear(mp, &ctx->busy_extents, + (mp->m_flags & XFS_MOUNT_DISCARD) && !abort); + + spin_lock(&ctx->cil->xc_cil_lock); + list_del(&ctx->committing); + spin_unlock(&ctx->cil->xc_cil_lock); + + xlog_cil_free_logvec(ctx->lv_chain); + + if (!list_empty(&ctx->busy_extents)) { + ASSERT(mp->m_flags & XFS_MOUNT_DISCARD); + + xfs_discard_extents(mp, &ctx->busy_extents); + xfs_alloc_busy_clear(mp, &ctx->busy_extents, false); + } + + kmem_free(ctx); +} + +/* + * Push the Committed Item List to the log. If @push_seq flag is zero, then it + * is a background flush and so we can chose to ignore it. Otherwise, if the + * current sequence is the same as @push_seq we need to do a flush. If + * @push_seq is less than the current sequence, then it has already been + * flushed and we don't need to do anything - the caller will wait for it to + * complete if necessary. + * + * @push_seq is a value rather than a flag because that allows us to do an + * unlocked check of the sequence number for a match. Hence we can allows log + * forces to run racily and not issue pushes for the same sequence twice. If we + * get a race between multiple pushes for the same sequence they will block on + * the first one and then abort, hence avoiding needless pushes. + */ +STATIC int +xlog_cil_push( + struct log *log, + xfs_lsn_t push_seq) +{ + struct xfs_cil *cil = log->l_cilp; + struct xfs_log_vec *lv; + struct xfs_cil_ctx *ctx; + struct xfs_cil_ctx *new_ctx; + struct xlog_in_core *commit_iclog; + struct xlog_ticket *tic; + int num_lv; + int num_iovecs; + int len; + int error = 0; + struct xfs_trans_header thdr; + struct xfs_log_iovec lhdr; + struct xfs_log_vec lvhdr = { NULL }; + xfs_lsn_t commit_lsn; + + if (!cil) + return 0; + + ASSERT(!push_seq || push_seq <= cil->xc_ctx->sequence); + + new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS); + new_ctx->ticket = xlog_cil_ticket_alloc(log); + + /* + * Lock out transaction commit, but don't block for background pushes + * unless we are well over the CIL space limit. See the definition of + * XLOG_CIL_HARD_SPACE_LIMIT() for the full explanation of the logic + * used here. + */ + if (!down_write_trylock(&cil->xc_ctx_lock)) { + if (!push_seq && + cil->xc_ctx->space_used < XLOG_CIL_HARD_SPACE_LIMIT(log)) + goto out_free_ticket; + down_write(&cil->xc_ctx_lock); + } + ctx = cil->xc_ctx; + + /* check if we've anything to push */ + if (list_empty(&cil->xc_cil)) + goto out_skip; + + /* check for spurious background flush */ + if (!push_seq && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log)) + goto out_skip; + + /* check for a previously pushed seqeunce */ + if (push_seq && push_seq < cil->xc_ctx->sequence) + goto out_skip; + + /* + * pull all the log vectors off the items in the CIL, and + * remove the items from the CIL. We don't need the CIL lock + * here because it's only needed on the transaction commit + * side which is currently locked out by the flush lock. + */ + lv = NULL; + num_lv = 0; + num_iovecs = 0; + len = 0; + while (!list_empty(&cil->xc_cil)) { + struct xfs_log_item *item; + int i; + + item = list_first_entry(&cil->xc_cil, + struct xfs_log_item, li_cil); + list_del_init(&item->li_cil); + if (!ctx->lv_chain) + ctx->lv_chain = item->li_lv; + else + lv->lv_next = item->li_lv; + lv = item->li_lv; + item->li_lv = NULL; + + num_lv++; + num_iovecs += lv->lv_niovecs; + for (i = 0; i < lv->lv_niovecs; i++) + len += lv->lv_iovecp[i].i_len; + } + + /* + * initialise the new context and attach it to the CIL. Then attach + * the current context to the CIL committing lsit so it can be found + * during log forces to extract the commit lsn of the sequence that + * needs to be forced. + */ + INIT_LIST_HEAD(&new_ctx->committing); + INIT_LIST_HEAD(&new_ctx->busy_extents); + new_ctx->sequence = ctx->sequence + 1; + new_ctx->cil = cil; + cil->xc_ctx = new_ctx; + + /* + * mirror the new sequence into the cil structure so that we can do + * unlocked checks against the current sequence in log forces without + * risking deferencing a freed context pointer. + */ + cil->xc_current_sequence = new_ctx->sequence; + + /* + * The switch is now done, so we can drop the context lock and move out + * of a shared context. We can't just go straight to the commit record, + * though - we need to synchronise with previous and future commits so + * that the commit records are correctly ordered in the log to ensure + * that we process items during log IO completion in the correct order. + * + * For example, if we get an EFI in one checkpoint and the EFD in the + * next (e.g. due to log forces), we do not want the checkpoint with + * the EFD to be committed before the checkpoint with the EFI. Hence + * we must strictly order the commit records of the checkpoints so + * that: a) the checkpoint callbacks are attached to the iclogs in the + * correct order; and b) the checkpoints are replayed in correct order + * in log recovery. + * + * Hence we need to add this context to the committing context list so + * that higher sequences will wait for us to write out a commit record + * before they do. + */ + spin_lock(&cil->xc_cil_lock); + list_add(&ctx->committing, &cil->xc_committing); + spin_unlock(&cil->xc_cil_lock); + up_write(&cil->xc_ctx_lock); + + /* + * Build a checkpoint transaction header and write it to the log to + * begin the transaction. We need to account for the space used by the + * transaction header here as it is not accounted for in xlog_write(). + * + * The LSN we need to pass to the log items on transaction commit is + * the LSN reported by the first log vector write. If we use the commit + * record lsn then we can move the tail beyond the grant write head. + */ + tic = ctx->ticket; + thdr.th_magic = XFS_TRANS_HEADER_MAGIC; + thdr.th_type = XFS_TRANS_CHECKPOINT; + thdr.th_tid = tic->t_tid; + thdr.th_num_items = num_iovecs; + lhdr.i_addr = &thdr; + lhdr.i_len = sizeof(xfs_trans_header_t); + lhdr.i_type = XLOG_REG_TYPE_TRANSHDR; + tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t); + + lvhdr.lv_niovecs = 1; + lvhdr.lv_iovecp = &lhdr; + lvhdr.lv_next = ctx->lv_chain; + + error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0); + if (error) + goto out_abort_free_ticket; + + /* + * now that we've written the checkpoint into the log, strictly + * order the commit records so replay will get them in the right order. + */ +restart: + spin_lock(&cil->xc_cil_lock); + list_for_each_entry(new_ctx, &cil->xc_committing, committing) { + /* + * Higher sequences will wait for this one so skip them. + * Don't wait for own own sequence, either. + */ + if (new_ctx->sequence >= ctx->sequence) + continue; + if (!new_ctx->commit_lsn) { + /* + * It is still being pushed! Wait for the push to + * complete, then start again from the beginning. + */ + xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock); + goto restart; + } + } + spin_unlock(&cil->xc_cil_lock); + + /* xfs_log_done always frees the ticket on error. */ + commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0); + if (commit_lsn == -1) + goto out_abort; + + /* attach all the transactions w/ busy extents to iclog */ + ctx->log_cb.cb_func = xlog_cil_committed; + ctx->log_cb.cb_arg = ctx; + error = xfs_log_notify(log->l_mp, commit_iclog, &ctx->log_cb); + if (error) + goto out_abort; + + /* + * now the checkpoint commit is complete and we've attached the + * callbacks to the iclog we can assign the commit LSN to the context + * and wake up anyone who is waiting for the commit to complete. + */ + spin_lock(&cil->xc_cil_lock); + ctx->commit_lsn = commit_lsn; + wake_up_all(&cil->xc_commit_wait); + spin_unlock(&cil->xc_cil_lock); + + /* release the hounds! */ + return xfs_log_release_iclog(log->l_mp, commit_iclog); + +out_skip: + up_write(&cil->xc_ctx_lock); +out_free_ticket: + xfs_log_ticket_put(new_ctx->ticket); + kmem_free(new_ctx); + return 0; + +out_abort_free_ticket: + xfs_log_ticket_put(tic); +out_abort: + xlog_cil_committed(ctx, XFS_LI_ABORTED); + return XFS_ERROR(EIO); +} + +/* + * Commit a transaction with the given vector to the Committed Item List. + * + * To do this, we need to format the item, pin it in memory if required and + * account for the space used by the transaction. Once we have done that we + * need to release the unused reservation for the transaction, attach the + * transaction to the checkpoint context so we carry the busy extents through + * to checkpoint completion, and then unlock all the items in the transaction. + * + * For more specific information about the order of operations in + * xfs_log_commit_cil() please refer to the comments in + * xfs_trans_commit_iclog(). + * + * Called with the context lock already held in read mode to lock out + * background commit, returns without it held once background commits are + * allowed again. + */ +int +xfs_log_commit_cil( + struct xfs_mount *mp, + struct xfs_trans *tp, + xfs_lsn_t *commit_lsn, + int flags) +{ + struct log *log = mp->m_log; + int log_flags = 0; + int push = 0; + struct xfs_log_vec *log_vector; + + if (flags & XFS_TRANS_RELEASE_LOG_RES) + log_flags = XFS_LOG_REL_PERM_RESERV; + + /* + * Do all the hard work of formatting items (including memory + * allocation) outside the CIL context lock. This prevents stalling CIL + * pushes when we are low on memory and a transaction commit spends a + * lot of time in memory reclaim. + */ + log_vector = xlog_cil_prepare_log_vecs(tp); + if (!log_vector) + return ENOMEM; + + /* lock out background commit */ + down_read(&log->l_cilp->xc_ctx_lock); + if (commit_lsn) + *commit_lsn = log->l_cilp->xc_ctx->sequence; + + xlog_cil_insert_items(log, log_vector, tp->t_ticket); + + /* check we didn't blow the reservation */ + if (tp->t_ticket->t_curr_res < 0) + xlog_print_tic_res(log->l_mp, tp->t_ticket); + + /* attach the transaction to the CIL if it has any busy extents */ + if (!list_empty(&tp->t_busy)) { + spin_lock(&log->l_cilp->xc_cil_lock); + list_splice_init(&tp->t_busy, + &log->l_cilp->xc_ctx->busy_extents); + spin_unlock(&log->l_cilp->xc_cil_lock); + } + + tp->t_commit_lsn = *commit_lsn; + xfs_log_done(mp, tp->t_ticket, NULL, log_flags); + xfs_trans_unreserve_and_mod_sb(tp); + + /* + * Once all the items of the transaction have been copied to the CIL, + * the items can be unlocked and freed. + * + * This needs to be done before we drop the CIL context lock because we + * have to update state in the log items and unlock them before they go + * to disk. If we don't, then the CIL checkpoint can race with us and + * we can run checkpoint completion before we've updated and unlocked + * the log items. This affects (at least) processing of stale buffers, + * inodes and EFIs. + */ + xfs_trans_free_items(tp, *commit_lsn, 0); + + /* check for background commit before unlock */ + if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log)) + push = 1; + + up_read(&log->l_cilp->xc_ctx_lock); + + /* + * We need to push CIL every so often so we don't cache more than we + * can fit in the log. The limit really is that a checkpoint can't be + * more than half the log (the current checkpoint is not allowed to + * overwrite the previous checkpoint), but commit latency and memory + * usage limit this to a smaller size in most cases. + */ + if (push) + xlog_cil_push(log, 0); + return 0; +} + +/* + * Conditionally push the CIL based on the sequence passed in. + * + * We only need to push if we haven't already pushed the sequence + * number given. Hence the only time we will trigger a push here is + * if the push sequence is the same as the current context. + * + * We return the current commit lsn to allow the callers to determine if a + * iclog flush is necessary following this call. + * + * XXX: Initially, just push the CIL unconditionally and return whatever + * commit lsn is there. It'll be empty, so this is broken for now. + */ +xfs_lsn_t +xlog_cil_force_lsn( + struct log *log, + xfs_lsn_t sequence) +{ + struct xfs_cil *cil = log->l_cilp; + struct xfs_cil_ctx *ctx; + xfs_lsn_t commit_lsn = NULLCOMMITLSN; + + ASSERT(sequence <= cil->xc_current_sequence); + + /* + * check to see if we need to force out the current context. + * xlog_cil_push() handles racing pushes for the same sequence, + * so no need to deal with it here. + */ + if (sequence == cil->xc_current_sequence) + xlog_cil_push(log, sequence); + + /* + * See if we can find a previous sequence still committing. + * We need to wait for all previous sequence commits to complete + * before allowing the force of push_seq to go ahead. Hence block + * on commits for those as well. + */ +restart: + spin_lock(&cil->xc_cil_lock); + list_for_each_entry(ctx, &cil->xc_committing, committing) { + if (ctx->sequence > sequence) + continue; + if (!ctx->commit_lsn) { + /* + * It is still being pushed! Wait for the push to + * complete, then start again from the beginning. + */ + xlog_wait(&cil->xc_commit_wait, &cil->xc_cil_lock); + goto restart; + } + if (ctx->sequence != sequence) + continue; + /* found it! */ + commit_lsn = ctx->commit_lsn; + } + spin_unlock(&cil->xc_cil_lock); + return commit_lsn; +} + +/* + * Check if the current log item was first committed in this sequence. + * We can't rely on just the log item being in the CIL, we have to check + * the recorded commit sequence number. + * + * Note: for this to be used in a non-racy manner, it has to be called with + * CIL flushing locked out. As a result, it should only be used during the + * transaction commit process when deciding what to format into the item. + */ +bool +xfs_log_item_in_current_chkpt( + struct xfs_log_item *lip) +{ + struct xfs_cil_ctx *ctx; + + if (list_empty(&lip->li_cil)) + return false; + + ctx = lip->li_mountp->m_log->l_cilp->xc_ctx; + + /* + * li_seq is written on the first commit of a log item to record the + * first checkpoint it is written to. Hence if it is different to the + * current sequence, we're in a new checkpoint. + */ + if (XFS_LSN_CMP(lip->li_seq, ctx->sequence) != 0) + return false; + return true; +} |