xfs: expose the log push threshold
commit ed1575daf71e4e21d8ae735b6e687c95454aaa17 upstream. Separate the computation of the log push threshold and the push logic in xlog_grant_push_ail. This enables higher level code to determine (for example) that it is holding on to a logged intent item and the log is so busy that it is more than 75% full. In that case, it would be desirable to move the log item towards the head to release the tail, which we will cover in the next patch. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Chandan Babu R <chandan.babu@oracle.com> Acked-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -10,6 +10,7 @@
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#include "xfs_trans.h"
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#include "xfs_trans_priv.h"
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#include "xfs_icreate_item.h"
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#include "xfs_log_priv.h"
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#include "xfs_log.h"
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kmem_zone_t *xfs_icreate_zone; /* inode create item zone */
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@ -1537,14 +1537,14 @@ xlog_commit_record(
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}
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/*
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* Push on the buffer cache code if we ever use more than 75% of the on-disk
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* log space. This code pushes on the lsn which would supposedly free up
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* the 25% which we want to leave free. We may need to adopt a policy which
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* pushes on an lsn which is further along in the log once we reach the high
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* water mark. In this manner, we would be creating a low water mark.
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* Compute the LSN that we'd need to push the log tail towards in order to have
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* (a) enough on-disk log space to log the number of bytes specified, (b) at
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* least 25% of the log space free, and (c) at least 256 blocks free. If the
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* log free space already meets all three thresholds, this function returns
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* NULLCOMMITLSN.
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*/
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STATIC void
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xlog_grant_push_ail(
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xfs_lsn_t
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xlog_grant_push_threshold(
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struct xlog *log,
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int need_bytes)
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{
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@ -1570,7 +1570,7 @@ xlog_grant_push_ail(
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free_threshold = max(free_threshold, (log->l_logBBsize >> 2));
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free_threshold = max(free_threshold, 256);
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if (free_blocks >= free_threshold)
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return;
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return NULLCOMMITLSN;
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xlog_crack_atomic_lsn(&log->l_tail_lsn, &threshold_cycle,
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&threshold_block);
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@ -1590,13 +1590,33 @@ xlog_grant_push_ail(
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if (XFS_LSN_CMP(threshold_lsn, last_sync_lsn) > 0)
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threshold_lsn = last_sync_lsn;
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return threshold_lsn;
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}
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/*
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* Push the tail of the log if we need to do so to maintain the free log space
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* thresholds set out by xlog_grant_push_threshold. We may need to adopt a
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* policy which pushes on an lsn which is further along in the log once we
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* reach the high water mark. In this manner, we would be creating a low water
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* mark.
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*/
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STATIC void
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xlog_grant_push_ail(
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struct xlog *log,
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int need_bytes)
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{
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xfs_lsn_t threshold_lsn;
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threshold_lsn = xlog_grant_push_threshold(log, need_bytes);
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if (threshold_lsn == NULLCOMMITLSN || XLOG_FORCED_SHUTDOWN(log))
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return;
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/*
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* Get the transaction layer to kick the dirty buffers out to
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* disk asynchronously. No point in trying to do this if
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* the filesystem is shutting down.
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*/
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if (!XLOG_FORCED_SHUTDOWN(log))
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xfs_ail_push(log->l_ailp, threshold_lsn);
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xfs_ail_push(log->l_ailp, threshold_lsn);
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}
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/*
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@ -146,4 +146,6 @@ void xfs_log_quiesce(struct xfs_mount *mp);
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bool xfs_log_check_lsn(struct xfs_mount *, xfs_lsn_t);
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bool xfs_log_in_recovery(struct xfs_mount *);
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xfs_lsn_t xlog_grant_push_threshold(struct xlog *log, int need_bytes);
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#endif /* __XFS_LOG_H__ */
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