dm snapshot: avoid dropping lock in __find_pending_exception (c6621392) · Commits · 戴 / test

drivers/md/dm-snap.c

+24 −18

Original line number	Diff line number	Diff line
		@@ -992,23 +992,10 @@ __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk)
		* this.
		*/
		static struct dm_snap_pending_exception *
		__find_pending_exception(struct dm_snapshot s, struct bio bio)
		__find_pending_exception(struct dm_snapshot *s,
		struct dm_snap_pending_exception *pe, chunk_t chunk)
		{
		struct dm_snap_pending_exception pe, pe2;
		chunk_t chunk = sector_to_chunk(s, bio->bi_sector);

		/*
		* Create a new pending exception, we don't want
		* to hold the lock while we do this.
		*/
		up_write(&s->lock);
		pe = alloc_pending_exception(s);
		down_write(&s->lock);

		if (!s->valid) {
		free_pending_exception(pe);
		return NULL;
		}
		struct dm_snap_pending_exception *pe2;

		pe2 = __lookup_pending_exception(s, chunk);
		if (pe2) {
		@@ -1083,7 +1070,17 @@ static int snapshot_map(struct dm_target ti, struct bio bio,
		if (bio_rw(bio) == WRITE) {
		pe = __lookup_pending_exception(s, chunk);
		if (!pe) {
		pe = __find_pending_exception(s, bio);
		up_write(&s->lock);
		pe = alloc_pending_exception(s);
		down_write(&s->lock);

		if (!s->valid) {
		free_pending_exception(pe);
		r = -EIO;
		goto out_unlock;
		}

		pe = __find_pending_exception(s, pe, chunk);
		if (!pe) {
		__invalidate_snapshot(s, -ENOMEM);
		r = -EIO;
		@@ -1220,7 +1217,16 @@ static int __origin_write(struct list_head snapshots, struct bio bio)

		pe = __lookup_pending_exception(snap, chunk);
		if (!pe) {
		pe = __find_pending_exception(snap, bio);
		up_write(&snap->lock);
		pe = alloc_pending_exception(snap);
		down_write(&snap->lock);

		if (!snap->valid) {
		free_pending_exception(pe);
		goto next_snapshot;
		}

		pe = __find_pending_exception(snap, pe, chunk);
		if (!pe) {
		__invalidate_snapshot(snap, -ENOMEM);
		goto next_snapshot;

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