dm raid1: split touched state into two
Split the variable "touched" into two, "touched_dirtied" and "touched_cleaned", set when some region was dirtied or cleaned. This will be used to optimize flushes. After a transition from "dirty" to "clean" state we don't have flush hardware cache on the log device. After a transition from "clean" to "dirty" the cache must be flushed. Before a transition from "clean" to "dirty" state we don't have to flush all the raid legs. Before a transition from "dirty" to "clean" we must flush all the legs to make sure that they are really in sync. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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@ -208,7 +208,8 @@ struct log_header {
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struct log_c {
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struct dm_target *ti;
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int touched;
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int touched_dirtied;
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int touched_cleaned;
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uint32_t region_size;
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unsigned int region_count;
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region_t sync_count;
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@ -253,14 +254,14 @@ static inline void log_set_bit(struct log_c *l,
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uint32_t *bs, unsigned bit)
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{
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ext2_set_bit(bit, (unsigned long *) bs);
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l->touched = 1;
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l->touched_cleaned = 1;
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}
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static inline void log_clear_bit(struct log_c *l,
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uint32_t *bs, unsigned bit)
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{
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ext2_clear_bit(bit, (unsigned long *) bs);
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l->touched = 1;
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l->touched_dirtied = 1;
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}
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/*----------------------------------------------------------------
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@ -378,7 +379,8 @@ static int create_log_context(struct dm_dirty_log *log, struct dm_target *ti,
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}
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lc->ti = ti;
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lc->touched = 0;
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lc->touched_dirtied = 0;
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lc->touched_cleaned = 0;
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lc->region_size = region_size;
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lc->region_count = region_count;
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lc->sync = sync;
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@ -660,14 +662,16 @@ static int disk_flush(struct dm_dirty_log *log)
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struct log_c *lc = (struct log_c *) log->context;
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/* only write if the log has changed */
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if (!lc->touched)
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if (!lc->touched_cleaned && !lc->touched_dirtied)
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return 0;
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r = rw_header(lc, WRITE);
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if (r)
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fail_log_device(lc);
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else
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lc->touched = 0;
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else {
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lc->touched_dirtied = 0;
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lc->touched_cleaned = 0;
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}
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return r;
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}
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