[PATCH 2/2] btrfs: reada: simplify dev->reada_in_flight processing
From: Zhao Lei <hidden>
Date: 2016-01-12 07:48:44
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
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 <redacted> --- fs/btrfs/reada.c | 28 ++++++++++------------------ 1 file changed, 10 insertions(+), 18 deletions(-)
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 7b150b2..87c211a 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c@@ -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 {
@@ -118,7 +118,6 @@ 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);
@@ -129,8 +128,7 @@ 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); /*
@@ -215,9 +213,6 @@ cleanup: reada_extent_put(fs_info, re); /* one ref for each entry */ } - if (for_dev) - atomic_dec(&for_dev->reada_in_flight); - return; }
@@ -543,8 +538,6 @@ 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); }
@@ -710,12 +703,12 @@ 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); /*
@@ -740,6 +733,7 @@ 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;
@@ -864,10 +858,9 @@ 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",
@@ -894,15 +887,14 @@ 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,
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1.8.5.1