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Commit 895a11b8 authored by Zhao Lei's avatar Zhao Lei Committed by David Sterba
Browse files

btrfs: reada: simplify dev->reada_in_flight processing 



No need to decrease dev->reada_in_flight in __readahead_hook()'s
internal and reada_extent_put().
reada_extent_put() have no chance to decrease dev->reada_in_flight
in free operation, because reada_extent have additional refcnt when
scheduled to a dev.

We can put inc and dec operation for dev->reada_in_flight to one
place instead to make logic simple and safe, and move useless
reada_extent->scheduled_for to a bool flag instead.

Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 8afd6841

fs/btrfs/reada.c

+10 −18
Original line number Diff line number Diff line
@@ -72,7 +72,7 @@ struct reada_extent { 
	spinlock_t		lock;

	struct reada_zone	*zones[BTRFS_MAX_MIRRORS];

	int			nzones;

	struct btrfs_device	*scheduled_for;

	int			scheduled;

};



struct reada_zone {
@@ -115,7 +115,6 @@ static void __readahead_hook(struct btrfs_fs_info *fs_info, 
	u64 bytenr;

	u64 generation;

	struct list_head list;

	struct btrfs_device *for_dev;



	if (eb)

		level = btrfs_header_level(eb);
@@ -126,8 +125,7 @@ static void __readahead_hook(struct btrfs_fs_info *fs_info, 
	 * don't need the lock anymore

	 */

	list_replace_init(&re->extctl, &list);

	for_dev = re->scheduled_for;

	re->scheduled_for = NULL;

	re->scheduled = 0;

	spin_unlock(&re->lock);



	/*
@@ -212,9 +210,6 @@ static void __readahead_hook(struct btrfs_fs_info *fs_info, 
		reada_extent_put(fs_info, re);	/* one ref for each entry */

	}



	if (for_dev)

		atomic_dec(&for_dev->reada_in_flight);



	return;

}
@@ -535,8 +530,6 @@ static void reada_extent_put(struct btrfs_fs_info *fs_info, 
		kref_put(&zone->refcnt, reada_zone_release);

		spin_unlock(&fs_info->reada_lock);

	}

	if (re->scheduled_for)

		atomic_dec(&re->scheduled_for->reada_in_flight);



	kfree(re);

}
@@ -702,12 +695,12 @@ static int reada_start_machine_dev(struct btrfs_fs_info *fs_info, 
	spin_unlock(&fs_info->reada_lock);



	spin_lock(&re->lock);

	if (re->scheduled_for || list_empty(&re->extctl)) {

	if (re->scheduled || list_empty(&re->extctl)) {

		spin_unlock(&re->lock);

		reada_extent_put(fs_info, re);

		return 0;

	}

	re->scheduled_for = dev;

	re->scheduled = 1;

	spin_unlock(&re->lock);



	/*
@@ -732,6 +725,7 @@ static int reada_start_machine_dev(struct btrfs_fs_info *fs_info, 
	if (eb)

		free_extent_buffer(eb);



	atomic_dec(&dev->reada_in_flight);

	reada_extent_put(fs_info, re);



	return 1;
@@ -850,10 +844,9 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all) 
			if (ret == 0)

				break;

			printk(KERN_DEBUG

				"  re: logical %llu size %u empty %d for %lld",

				"  re: logical %llu size %u empty %d scheduled %d",

				re->logical, fs_info->tree_root->nodesize,

				list_empty(&re->extctl), re->scheduled_for ?

				re->scheduled_for->devid : -1);

				list_empty(&re->extctl), re->scheduled);



			for (i = 0; i < re->nzones; ++i) {

				printk(KERN_CONT " zone %llu-%llu devs",
@@ -880,15 +873,14 @@ static void dump_devs(struct btrfs_fs_info *fs_info, int all) 
					     index, 1);

		if (ret == 0)

			break;

		if (!re->scheduled_for) {

		if (!re->scheduled) {

			index = (re->logical >> PAGE_CACHE_SHIFT) + 1;

			continue;

		}

		printk(KERN_DEBUG

			"re: logical %llu size %u list empty %d for %lld",

			"re: logical %llu size %u list empty %d scheduled %d",

			re->logical, fs_info->tree_root->nodesize,

			list_empty(&re->extctl),

			re->scheduled_for ? re->scheduled_for->devid : -1);

			list_empty(&re->extctl), re->scheduled);

		for (i = 0; i < re->nzones; ++i) {

			printk(KERN_CONT " zone %llu-%llu devs",

				re->zones[i]->start,