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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: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Zhao Lei 2016-01-12 14:58:39 +08:00 коммит произвёл David Sterba
Родитель 8afd6841e1
Коммит 895a11b868
1 изменённых файлов: 10 добавлений и 18 удалений
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28
fs/btrfs/reada.c
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@ -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 @@ cleanup:
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,